ARITOMO Yoshihiro

Researcher Information

Degree

• Ph. D（1998/03 Konan University）

J-Global ID

• 201501016723175576

Research Areas

• Natural sciences / Theoretical studies related to particle-, nuclear-, cosmic ray and astro-physics / Reaction Theory

Association Memberships

• ATOMIC ENERGY SOCIETY OF JAPAN   THE PHYSICAL SOCIETY OF JAPAN   

Published Papers

• Postfission properties of uranium isotopes: A hybrid method with Langevin dynamics and the Hauser-Feshbach statistical model

  S. Tanaka; N. Nishimura; F. Minato; Y. Aritomo

  Physical Review C American Physical Society (APS) 108 (5) 2469-9985 2023/11
• The evaluation of the fission mode and fragment yields of neutron-rich nuclei by the dynamical model

  Shoya Tanaka; Nobuya Nishimura; Itoshi Nishimura; Yoshihiro Aritomo

  EPJ Web of Conferences EDP Sciences 279 11021 - 11021 2023/03 

  Nucleosynthesis by the rapid neutron-capture process (r-process) produces elements heavier than iron via neutron-rich nuclides, observed in the solar system and stars with various metallicities. In the r-process, fission plays a fundamental role by recycling the matter during neutron irradiation and by shaping the final r-abundance distribution. Nevertheless, due to the difficulty of experimental approaches, most of the fission data available for r-process calculations are based on theoretical predictions with phenomenological models. In this study, we focused on the transition of fission mode from asymmetric to symmetric in neutron-rich isotopes, which has been suggested in recent experiments for fermium isotopes. We investigated the fission of neutron-rich nuclei by a theoretical calculation based on the dynamical model and employed Langevin equations.
• Modes of massive nucleon transfer appearing in quasifission processes for collisions of superheavy nuclei

  Shota Amano; Yoshihiro Aritomo; Masahisa Ohta

  Physical Review C American Physical Society (APS) 106 (2) 024610  2469-9985 2022/08 [Refereed]
   

  Background: It is challenging to distinguish between fusion-fission and quasifission experimentally. To deter-mine the characteristics of quasifission processes associated with dominant phenomena in heavy-ion collisions is important for estimating precisely the fusion cross section, which is relevant to the synthesis of new elements. We classified fusion-fission and quasifission processes theoretically in the past for an accurate assessment of the fusion cross section [Y. Aritomo and M. Ohta, Nucl. Phys. A 744, 3 (2004)]. However, no detailed analysis focused on each process was performed.Purpose: In this work, we aimed to analyze the dynamical characteristics of quasifission processes in terms of the Langevin equation model. We specify the quasifission processes, and analyze the scission configuration. Finally, we clarify the origin of several modes included in quasifission.Method: The calculation framework is the multidimensional dynamical model of nucleus-nucleus collisions based on the Langevin equations.Results: It is shown that several quasifission modes exist leading to different fragment deformations. The timescale of the quasifission process differs for several different modes. Each scission configuration and total kinetic energy also differ.Conclusions: The different quasifission modes are caused by the neck relaxation controlling the mass drift toward symmetry. This means that it is possible to discuss the time-dependent functional form of the neck parameter e for the quasifission process in the framework of the dynamical model based on Langevin equations.
• Fusion cross section and total kinetic energy of fission fragments by the dynamical dissipative surface-friction model

  S. Amano; Y. Aritomo; M. Ohta

  Eurasian Journal of Physics and Functional Materials L. N. Gumilyov Eurasian National University 6 (1) 6 - 17 2522-9869 2022/03 [Refereed]
  
• Fission mechanism inferred from nuclear shape fluctuation by the Langevin equation

  Y. Aritomo; A. Iwamoto; K. Nishio; M. Ohta

  Physical Review C American Physical Society ({APS}) 105 (3) 2022/03 [Refereed]
  
• Angular momentum transfer in multinucleon transfer channels of O18+Np237

  S. Tanaka; K. Hirose; K. Nishio; K. R. Kean; H. Makii; R. Orlandi; K. Tsukada; Y. Aritomo

  Physical Review C American Physical Society (APS) 105 (2) 2469-9985 2022/02 [Refereed]
  
• Measurement of fission-fragment mass distributions in the multinucleon transfer channels of the O18+Np237 reaction

  M. J. Vermeulen; K. Nishio; K. Hirose; K. R. Kean; H. Makii; R. Orlandi; K. Tsukada; I. Tsekhanovich; A. N. Andreyev; S. Ishizaki; M. Okubayashi; S. Tanaka; Y. Aritomo

  Physical Review C American Physical Society (APS) 102 (5) 2469-9985 2020/11 [Refereed]
  
• Modeling of Nuclear Reactions with Langevin Calculations

  S. Amano; Y. Aritomo; Y. Miyamoto; S. Ishizaki; M. Okubayashi

  Bulletin of the Russian Academy of Sciences: Physics 84 (8) 1034 - 1048 2020/09 [Refereed]
  
• Origin of dramatic change of fission mode in fermium

  Yuuya MIYAMOTO; Yoshihiro ARITOMO; Shoya TANAKA; Kentaro HIROSE; Katsuhisa NISHIO

  JPS Conf. Proc. 32 010003  2020/07 [Refereed]
  
• Role of multichance fission in highly excited heavy nuclei

  Shoya TANAKA; Kentaro HIROSE; Katsuhisa NISHIO; Yoshihiro ARITOMO

  JPS Conf. Proc. , 32 010004  2020/07 [Refereed]
  
• Dynamical Approach for Synthesis of Superheavy Elements

  Yoshihiro ARITOMO

  JPS Conf. Proc. 32 010017  2020/07 [Refereed]
  
• Estimation of Synthesizing New Superheavy Elements

  Y. Aritomo; S.Amano; M. Okubayashi; B. Yanagi; K.Nishio; M.Ohta

  Physics of Atomic Nuclei 83 (4) 545 - 549 2020/04 [Refereed]
  
• Effects of multichance fission on isotope dependence of fission fragment mass distributions at high energies

  S. Tanaka; Y. Aritomo; Y. Miyamoto; K. Hirose; K. Nishio

  Physical Review C American Physical Society ({APS}) 100 (6) 064605  2469-9985 2019/12 [Refereed]
  
• Origin of the dramatic change of fission mode in fermium isotopes investigated using Langevin equations

  Y. Miyamoto; Y. Aritomo; S. Tanaka; K. Hirose; K. Nishio

  Physical Review C American Physical Society (APS) 99 (5) 051601(R)  2469-9985 2019/05 [Refereed]
  
• Dynamical Approach for Synthesis of Superheavy Elements: Fusion Mechanism and Nuclear Structure

  Y. Aritomo; N. Liyana; B. Yanagi; H. Hachikubo

  Eurasian Journal of Physics and Functional Materials 3 (3) 197 - 203 2019 [Refereed]
  
• Dynamical Study on the Synthesis of Superheavy Elements

  Yoshihiro Aritomo

  Frontiers in Nuclear and Particle Physics 2 255 - 282 2019 [Refereed]
  
• Estimation for Synthesis of Superheavy Elements

  Yoshihiro Aritomo; Nur Liyana; Shoya Tanaka; Yuuya Miyamoto; Baku Yanagi; Kouichi Hagino; Taiki Tanaka; Katsuhisa Nishio; Masahisa Ohta

  Proceedings of the Ito International Research Center Symposium "Perspectives of the Physics of Nuclear Structure" Journal of the Physical Society of Japan 2018/12 [Refereed]
  
• Study of fission using multi-nucleon transfer reactions

  Katsuhisa Nishio; Kentaro Hirose; Mark Vermeulen; Hiroyuki Makii; Riccardo Orlandi; Kazuaki Tsukada; Masato Asai; Atsushi Toyoshima; Tetsuya K. Sato; Yuichiro Nagame; Satoshi Chiba; Yoshihiro Aritomo; Shouya Tanaka; Tsutomu Ohtsuki; Igor Tsekhanovich; Costel M. Petrache; Andrei Andreyev; Andrei Andreyev

  EPJ Web of Conferences EDP Sciences 169 00013  2101-6275 2018/03 [Refereed]
   

  © The Authors, published by EDP Sciences, 2018. Multi-nucleon transfer channels of the reactions of18O+232Th,18O+238U,18O+248Cm were used to measure fission-fragment mass distribution for various nuclides and their excitation energy dependence. Predominantly asymmetric fission is observed at low excitation energies for all the studied cases, with an increase of the symmetric fission towards high excitation energies. Experimental data are compared with predictions of the fluctuation-dissipation model, where effects of multi-chance fission (neutron evaporation prior to fission) was introduced. It was shown that a reliable understanding of the observed fission fragment mass distributions can be obtained only invoking multi-chance fissions.
• Study of fission using multi-nucleon transfer reactions

  Katsuhisa Nishio; Kentaro Hirose; Mark Vermeulen; Hiroyuki Makii; Riccardo Orlandi; Kazuaki Tsukada; Masato Asai; Atsushi Toyoshima; Tetsuya K. Sato; Yuichiro Nagame; Satoshi Chiba; Yoshihiro Aritomo; Shouya Tanaka; Tsutomu Ohtsuki; Igor Tsekhanovich; Costel M. Petrache; Andrei Andreyev

  SCIENTIFIC WORKSHOP ON NUCLEAR FISSION DYNAMICS AND THE EMISSION OF PROMPT NEUTRONS AND GAMMA RAYS (THEORY-4) E D P SCIENCES 169 2100-014X 2018 

  Multi-nucleon transfer channels of the reactions of O-18+Th-232, O-18+U-238, O-18+Cm-248 were used to measure fission-fragment mass distribution for various nuclides and their excitation energy dependence. Predominantly asymmetric fission is observed at low excitation energies for all the studied cases, with an increase of the symmetric fission towards high excitation energies. Experimental data are compared with predictions of the fluctuation-dissipation model, where effects of multi-chance fission (neutron evaporation prior to fission) was introduced. It was shown that a reliable understanding of the observed fission fragment mass distributions can be obtained only invoking multi-chance fissions.
• Study of fission using multi-nucleon transfer reactions

  Katsuhisa Nishio; Kentaro Hirose; Mark Vermeulen; Hiroyuki Makii; Riccardo Orlandi; Kazuaki Tsukada; Masato Asai; Atsushi Toyoshima; Tetsuya K. Sato; Yuichiro Nagame; Satoshi Chiba; Yoshihiro Aritomo; Shouya Tanaka; Tsutomu Ohtsuki; Igor Tsekhanovich; Costel M. Petrache; Andrei Andreyev

  SCIENTIFIC WORKSHOP ON NUCLEAR FISSION DYNAMICS AND THE EMISSION OF PROMPT NEUTRONS AND GAMMA RAYS (THEORY-4) E D P SCIENCES 169 2100-014X 2018 [Refereed]
   

  Multi-nucleon transfer channels of the reactions of O-18+Th-232, O-18+U-238, O-18+Cm-248 were used to measure fission-fragment mass distribution for various nuclides and their excitation energy dependence. Predominantly asymmetric fission is observed at low excitation energies for all the studied cases, with an increase of the symmetric fission towards high excitation energies. Experimental data are compared with predictions of the fluctuation-dissipation model, where effects of multi-chance fission (neutron evaporation prior to fission) was introduced. It was shown that a reliable understanding of the observed fission fragment mass distributions can be obtained only invoking multi-chance fissions.
• Study of fission using multi-nucleon transfer reactions

  Katsuhisa Nishio; Kentaro Hirose; Vermeulen Mark; Hiroyuki Makii; Riccardo Orlandi; Kazuaki Tsukada; Masato Asai; Atsushi Toyoshima; Tetsuya K. Sato; Yuichiro Nagame; Satoshi Chiba; Yoshihiro Aritomo; Shouya Tanaka; Tsutomu Ohtsuki; Igor Tsekhanovich; Costel M. Petrache; Andrei Andreyev; Andrei Andreyev

  EPJ Web of Conferences EDP Sciences 163 00041  2101-6275 2017/11 [Refereed]
   

  © The Authors, published by EDP Sciences, 2017. It is shown that multi-nucleon transfer reaction is a powerful tool to study fission of exotic neutronrich actinide nuclei, which cannot be accessed by particle-capture or heavy-ion fusion reactions. In this work, multi-nucleon transfer channels of the reactions of18O+232Th,18O+238U,18O+248Cm, and18O+237Np were used to measure fission-fragment mass distribution for each transfer channel. Predominantly asymmetric fission is observed at low excitation energies for all the studied cases, with an increase of the symmetric fission towards high excitation energies. Experimental data are compared with predictions of the fluctuation-dissipation model, where effects of multi-chance fission (neutron evaporation prior to fission) was introduced. It is shown that mass-asymmetric structure remaining at high excitation energies originates from low-excited and less neutronrich excited nuclei due to higher-order chance fissions.
• Estimation of evaporation residue cross section for the synthesis of superheavy nuclei

  Yoshihiro Aritomo; Shyou Sawada; Nur Liyana; Jin Nakagawa; Shoya Tanaka; Ken'Etsu Hanabusa

  EPJ Web of Conferences 163 2101-6275 2017/11 [Refereed]
   

  © The Authors, published by EDP Sciences, 2017. To estimate the evaporation residue cross section of superheavy nuclei, we clarify the parameter dependence of the models. At the first attempt, we focus our attention on the parameters of the statistical model, and investigate the parameter dependence of the survival probability. Then we discuss the the evaporation residue cross section for each parameter.
• Role of Multichance Fission in the Description of Fission-Fragment Mass Distributions at High Energies

  K. Hirose; K. Nishio; S. Tanaka; R. Leguillon; H. Makii; I. Nishinaka; R. Orlandi; K. Tsukada; J. Smallcombe; M. J. Vermeulen; S. Chiba; Y. Aritomo; T. Ohtsuki; K. Nakano; S. Araki; Y. Watanabe; R. Tatsuzawa; N. Takaki; N. Tamura; S. Goto; I. Tsekhanovich; A. N. Andreyev

  PHYSICAL REVIEW LETTERS AMER PHYSICAL SOC 119 (22) 0031-9007 2017/11 [Refereed]
   

  Fission-fragment mass distributions were measured for U237-240, Np239-242, and Pu241-244 populated in the excitation-energy range from 10 to 60 MeV by multinucleon transfer channels in the reaction O-18 + U-238 at the Japan Atomic Energy Agency tandem facility. Among them, the data for U-240 and Np-240,Np- 241,Np- 242 were observed for the first time. It was found that the mass distributions for all the studied nuclides maintain a double-humped shape up to the highest measured energy in contrast to expectations of predominantly symmetric fission due to the washing out of nuclear shell effects. From a comparison with the dynamical calculation based on the fluctuation-dissipation model, this behavior of the mass distributions was unambiguously attributed to the effect of multichance fission.
• STUDY OF FISSION USING MULTI-NUCLEON TRANSFER REACTIONS

  Katsuhisa Nishio; Kentaro Hirose; Vermeulen Mark; Hiroyuki Makii; Riccardo Orlandi; Kazuaki Tsukada; Masato Asai; Atsushi Toyoshima; Tetsuya K. Sato; Yuichiro Nagame; Satoshi Chiba; Yoshihiro Aritomo; Shouya Tanaka; Tsutomu Ohtsuki; Igor Tsekhanovich; Costel M. Petrache; Andrei Andreyev

  FUSION17 E D P SCIENCES 163 2100-014X 2017 

  It is shown that multi-nucleon transfer reaction is a powerful tool to study fission of exotic neutron rich actinide nuclei, which cannot be accessed by particle-capture or heavy-ion fusion reactions. In this work, multi-nucleon transfer channels of the reactions of 180+232Th, 180+238u, 180+248<^>m, u and 180+237Np were used to measure fission-fragment mass distribution for each transfer channel. Predominantly asymmetric fission is observed at low excitation energies for all the studied cases, with an increase of the symmetric fission towards high excitation energies. Experimental data are compared with predictions of the fluctuation-dissipation model, where effects of multi-chance fission (neutron evaporation prior to fission) was introduced. It is shown that mass-asymmetric structure remaining at high excitation energies originates from low-excited and less neutron rich excited nuclei due to higher-order chance fissions.
• Estimation of evaporation residue cross section for the synthesis of super heavy nuclei.

  Yoshihiro Aritomo; Shyou Sawada; Nur Liyana; Jin Nakagawa; Shoya Tanaka; Ken'etsu Hanabusa

  FUSION17 E D P SCIENCES 163 2100-014X 2017 [Refereed]
   

  To estimate the evaporation residue cross section of superheavy nuclei, we clarify the parameter dependence of the models. At the first attempt, we focus our attention on the parameters of the statistical model, and investigate the parameter dependence of the survival probability. Then we discuss the the evaporation residue cross section for each parameter.
• STUDY OF FISSION USING MULTI-NUCLEON TRANSFER REACTIONS

  Katsuhisa Nishio; Kentaro Hirose; Vermeulen Mark; Hiroyuki Makii; Riccardo Orlandi; Kazuaki Tsukada; Masato Asai; Atsushi Toyoshima; Tetsuya K. Sato; Yuichiro Nagame; Satoshi Chiba; Yoshihiro Aritomo; Shouya Tanaka; Tsutomu Ohtsuki; Igor Tsekhanovich; Costel M. Petrache; Andrei Andreyev

  FUSION17 E D P SCIENCES 163 2100-014X 2017 [Refereed]
   

  It is shown that multi-nucleon transfer reaction is a powerful tool to study fission of exotic neutron rich actinide nuclei, which cannot be accessed by particle-capture or heavy-ion fusion reactions. In this work, multi-nucleon transfer channels of the reactions of 180+232Th, 180+238u, 180+248<^>m, u and 180+237Np were used to measure fission-fragment mass distribution for each transfer channel. Predominantly asymmetric fission is observed at low excitation energies for all the studied cases, with an increase of the symmetric fission towards high excitation energies. Experimental data are compared with predictions of the fluctuation-dissipation model, where effects of multi-chance fission (neutron evaporation prior to fission) was introduced. It is shown that mass-asymmetric structure remaining at high excitation energies originates from low-excited and less neutron rich excited nuclei due to higher-order chance fissions.
• Experimental fission study using multi-nucleon transfer reactions

  Katsuhisa Nishio; Kentaro Hirose; Romain Leguillon; Hiroyuki Makii; Riccardo Orlandi; Kazuaki Tsukada; James Smallcombe; Satoshi Chiba; Yoshihiro Aritomo; Shouya Tanaka; Tsutomu Ohtsuki; Igor Tsekhanovich; Costel M. Petrache; Andrei Andreyev

  ND 2016: INTERNATIONAL CONFERENCE ON NUCLEAR DATA FOR SCIENCE AND TECHNOLOGY E D P SCIENCES 146 (146) 2100-014X 2017 [Refereed]
   

  It is shown that the multi-nucleon transfer reactions is a powerful tool to study fission of exotic neutron-rich actinide nuclei, which cannot be accessed by particle-capture or heavy-ion fusion reactions. In this work, multi-nucleon transfer channels of the reactions of O-18+Th-232, O-18+U-238 and O-18+Cm-248 are used to study fission for various nuclei from many excited states. Identification of fissioning nuclei and of their excitation energy is performed on an event-by-event basis, through the measurement of outgoing ejectile particle in coincidence with fission fragments. Fission fragment mass distributions are measured for each transfer channel. Predominantly asymmetric fission is observed at low excitation energies for all studied cases, with a gradual increase of the symmetric mode towards higher excitation energy. The experimental distributions are found to be in general agreement with predictions of the fluctuation-dissipation model. Role of multi-chance fission in fission fragment mass distributions is discussed, where it is shown that mass-asymmetric structure remaining at high excitation energies originates from low-excited nuclei by evaporation of neutrons.
• Fission fragments mass distributions of nuclei populated bythemultinucleon transfer channels of the O-18+Th-232 reaction

  R. Leguillon; K. Nishio; K. Hirose; H. Makii; I. Nishinaka; R. Orlandi; K. Tsukada; J. Smallcombe; S. Chiba; Y. Aritomo; T. Ohtsuki; R. Tatsuzawa; N. Takaki; N. Tamura; S. Goto; I. Tsekhanovich; C. M. Petrache; A. N. Andreyev

  PHYSICS LETTERS B ELSEVIER SCIENCE BV 761 125 - 130 0370-2693 2016/10 [Refereed]
   

  It is shown that the multinucleon transfer reactions is a powerful tool to study fission of exotic neutron-rich actinide nuclei, which cannot be accessed by particle-capture or heavy-ion fusion reactions. In this work, multinucleon transfer channels of the O-18 + Th-232 reaction are used to study fission of fourteen nuclei Th-231,Th-232,Th-233,Th-234, Pa-232,Pa-233,Pa-234,Pa-235,Pa-236, and U-234,U-235,U-236,U-237,U-238. Identification of fissioning nuclei and of their excitation energy is performed on an event-by-event basis, through the measurement of outgoing ejectile particle in coincidence with fission fragments. Fission fragment mass distributions are measured for each transfer channel, in selected bins of excitation energy. In particular, the mass distributions of Th-231,Th-234 and Pa-234,Pa-235,Pa-236 are measured for the first time. Predominantly asymmetric fission is observed at low excitation energies for all studied cases, with a gradual increase of the symmetric mode towards higher excitation energy. The experimental distributions are found to be in general agreement with predictions of the fluctuation-dissipation model. (C) 2016 The Author(s). Published by Elsevier B.V.
• A Comprehensive Approach to Determination of Nuclear Data of Unstable Nuclei

  Satoshi Chiba; Katsuhisa Nishio; Yohihiro Aritomo; Hiroyuki Koura; Osamu Iwamoto; Hiroyuki Makii; Ichiro Nishinaka; Kentaro Hirose

  EPJ Web of Conferences EDP Sciences 106 2100-014X 2016/02 [Refereed]
   

  A comprehensive approach to determine nuclear data of unstable nuclei will be described. It consists of a measurement of fission and capture cross sections, mass distribution of fission fragments (independent fission yields) and number of prompt fission neutrons by the method of surrogate reactions. A multi-dimensional Langevin model is being developed to estimate the independent fission yields theoretically. Furthermore, the β decay properties of the fission fragments, almost all are neutron-rich unstable nuclei, are investigated systematically by improving the gross theory of β decay, which will yield information on the decay heat and delayed-neutron data.
• A Comprehensive Approach to Determination of Nuclear Data of Unstable Nuclei

  Satoshi Chiba; Katsuhisa Nishio; Yohihiro Aritomo; Hiroyuki Koura; Osamu Iwamoto; Hiroyuki Makii; Ichiro Nishinaka; Kentaro Hirose

  ISRD 15 - INTERNATIONAL SYMPOSIUM ON REACTOR DOSIMETRY E D P SCIENCES 106 2100-014X 2016 [Refereed]
   

  A comprehensive approach to determine nuclear data of unstable nuclei will be described. It consists of a measurement of fission and capture cross sections, mass distribution of fission fragments (independent fission yields) and number of prompt fission neutrons by the method of surrogate reactions. A multi-dimensional Langevin model is being developed to estimate the independent fission yields theoretically. Furthermore, the beta decay properties of the fission fragments, almost all are neutron-rich unstable nuclei, are investigated systematically by improving the gross theory of beta decay, which will yield information on the decay heat and delayed-neutron data
• The transport coefficient of collective motion within the two-center shell model shape parameterization

  Fedir Ivanyuk; Satoshi Chiba; Yoshihiro Aritomo

  JOURNAL OF NUCLEAR SCIENCE AND TECHNOLOGY TAYLOR & FRANCIS LTD 53 (6) 737 - 748 0022-3131 2016 [Refereed]
   

  The transport coefficients of large-scale nuclear collective motion (potential energy, tensors of friction and mass) used in the description of fission process or fusion-fission reactions with the help of Langevin equations are calculated within the two-center shell-model shape parameterization. The transport coefficients are defined both in the macroscopic (wall formula for friction and Werner-Wheeler approximation for the mass tensor) and microscopic (linear response theory and local harmonic approximation) approaches. It is shown that at low excitation energy, the macroscopic and microscopic quantities differ substantially in dependence both on deformation and temperature. Thus, the microscopic effect in transport coefficients should be taken in account by the description of low-energy nuclear collisions and fission process.
• Dynamical approach to isotopic-distribution of fission fragments from actinide nuclei

  Chikako Ishizuka; Satoshi Chiba; Alexander V. Karpov; Yoshihiro Aritomo

  CNR*15 - 5TH INTERNATIONAL WORKSHOP ON COMPOUND-NUCLEAR REACTIONS AND RELATED TOPICS E D P SCIENCES 122 2100-014X 2016 [Refereed]
   

  Measurements of the isotope distribution of fission fragments, often denoted as the primary fission yield (pre-neutron yield) or independent fission yield (post-neutron yield) are still challenging at low excitation energies, so that it is important to investigate it within a theory. Such quantities are vital for applications as well. In this study, fragment distributions from the fission of U isotopes at low excitation energies are studied using a dynamical model. The potential energy surface is derived from the two center shell model including the shell and pairing corrections. In order to calculate the charge distribution of fission fragments, we introduce a new parameter eta(Z) as the charge asymmetry, in addition to three parameters describing a nuclear shape, z as the distance between two centers of mass, delta as fragment deformation, and eta(A) as the mass asymmetry. Using this model, we calculated the isotopic distribution of U-236 for the n-induced process U-235 + n -> U-236 at low excitation energies. As a result, we found that the current model can well reproduce isotopic fission-fragment distribution which can be compared favorably with major libraries.
• Independent fission yields studied based on Langevin equation

  Yoshihiro Aritomo; Satoshi Chiba; Katsuhisa Nishio

  Progress in Nuclear Energy Elsevier {BV} 85 568 - 572 2015/11
• Independent fission yields studied based on Langevin equation

  Yoshihiro Aritomo; Satoshi Chiba; Katsuhisa Nishio

  PROGRESS IN NUCLEAR ENERGY PERGAMON-ELSEVIER SCIENCE LTD 85 568 - 572 0149-1970 2015/11 [Refereed]
   

  Mass distributions of fission fragments of U and Pu isotopes at low excitation energies are studied using a dynamical model based on the fluctuation-dissipation theorem formulated as Langevin equations. Though the Langevin approaches have been applied successfully to the fission process at high excitation energy, it is the first time to obtain the mass distribution of fission fragments for the neutron-induced fission of U-233'235 and Pu-239. It was found that the shell effect of the potential energy landscape has the dominant role in determining the mass distribution. The calculation results show the asymmetric fission and the good agreement with the experimental data without any parameter adjustments. Using this approach, we obtain the independent protons and neutrons fission yields of n + U-233. The present approach can serve as a basis for more refined analysis being planned in the future aiming at a realistic description of the whole process of fission, starting from the compound nuclei at various excitation energies reaching to the fission products populated after g-decay. (C) 2015 Elsevier Ltd. All rights reserved.
• 27pSH-9 Systematic behavior of fission fragment mass distribution for nuclei populated by multi-nucleon transfer reactions

  Leguillon R.; Nishio K.; Hirose K.; Makii H.; Nishinaka I.; Orlandi R.; Ishii T.; Tsukada K.; Aritomo Y.; Chiba S.; Ohtsuki T.

  Meeting Abstracts of the Physical Society of Japan The Physical Society of Japan (JPS) 70 319 - 319 2189-079X 2015
• The Scission Point Configuration and the Multiplicity of Prompt Neutrons

  F. A. Ivanyuk; S. Chiba; Y. Aritomo

  SCIENTIFIC WORKSHOP ON NUCLEAR FISSION DYNAMICS AND THE EMISSION OF PROMPT NEUTRONS AND GAMMA RAYS, THEORY-3 ELSEVIER SCIENCE BV 64 28 - 33 1875-3892 2015 [Refereed]
   

  We defined the optimal shape which fissioning nuclei attain just before the scission and calculated the deformation energy as function of the mass asymmetry and elongation at the scission point. The calculated deformation energy is used in quasi-static approximation for estimation of the mass distribution of fission fragments, total kinetic and excitation energy of fission fragments, and the total number of prompt neutrons. The calculated results reproduce rather well the experimental data on the position of the peaks in the mass distribution of fission fragments, the total kinetic and excitation energy of fission fragments. The calculated value of neutron multiplicitiy is somewhat larger than experimental results. (C) 2015 The Authors. Published by Elsevier B.V.
• The Scission Point Configuration and the Multiplicity of Prompt Neutrons

  F. A. Ivanyuk; S. Chiba; Y. Aritomo

  Physics Procedia Elsevier B.V. 64 28 - 33 1875-3892 2015 [Refereed]
   

  We defined the optimal shape which fissioning nuclei attain just before the scission and calculated the deformation energy as function of the mass asymmetry and elongation at the scission point. The calculated deformation energy is used in quasi-static approximation for estimation of the mass distribution of fission fragments, total kinetic and excitation energy of fission fragments, and the total number of prompt neutrons. The calculated results reproduce rather well the experimental data on the position of the peaks in the mass distribution of fission fragments, the total kinetic and excitation energy of fission fragments. The calculated value of neutron multiplicitiy is somewhat larger than experimental results.
• A comprehensive approach to estimate delayed-neutron data of actinides and minor-actinides

  Satoshi Chiba; Katsuhisa Nishio; Yoshihiro Aritomo; Hiroyuki Koura; Osamu Iwamoto; Teruhiko Kugo

  FOURTH INTERNATIONAL SYMPOSIUM ON INNOVATIVE NUCLEAR ENERGY SYSTEMS (INES-4) ELSEVIER SCIENCE BV 71 205 - 212 1876-6102 2015 [Refereed]
   

  A project is described on a comprehensive approach to improve accuracy of delayed-neutron data of actinides and minor actinides by the summation calculations. This project consists of 1) measurement of fission fragment mass distribution (FFMD) of nuclei for which direct measurements using neutrons are not practical, 2) estimation of independent fission yields by developing a dynamical model of fission, 3) improvement of a beta-decay theory for better reproductions of decay characteristics of fission fragments, 4) nuclear data evaluation based on the above activities and summation calculations of decay-heat and delayed neutron data and 5) benchmark by using reactor data. Through these activities, understanding of the basic fission process will be advanced as well. (C) 2015 The Authors. Published by Elsevier Ltd.
• Fission dynamics at low excitation energy

  Y. Aritomo; S. Chiba; F. Ivanyuk

  Physical Review C - Nuclear Physics American Physical Society 90 (5) 1089-490X 2014/11 

  The mass asymmetry in the fission of U236 at low excitation energy is clarified by the analysis of the trajectories obtained by solving the Langevin equations for the shape degrees of freedom. It is demonstrated that the position of the peaks in the mass distribution of fission fragments is determined mainly by the saddle point configuration originating from the shell correction energy. The width of the peaks, on the other hand, results from the shape fluctuations close to the scission point caused by the random force in the Langevin equation. We have found out that the fluctuations between elongated and compact shapes are essential for the fission process. According to our results the fission does not occur with continuous stretching in the prolate direction, similarly to that observed in starch syrup, but is accompanied by the fluctuations between elongated and compact shapes. This picture presents a new viewpoint of fission dynamics and the splitting mechanism.
• Scission-point configuration within the two-center shell model shape parameterization

  F. A. Ivanyuk; S. Chiba; Y. Aritomo

  Physical Review C - Nuclear Physics American Physical Society 90 (5) 1089-490X 2014/11 [Refereed]
   

  Within the two-center shell model parameterization we defined the optimal shape that fissioning nuclei attain just before the scission and calculated the total deformation energy (liquid-drop part plus the shell correction) as a function of the mass asymmetry and elongation at the scission point. The three minima corresponding to one mass-symmetric and two mass-asymmetric peaks in the mass distribution of fission fragments are found in the deformation energy at the scission point. The calculated deformation energy is used in a quasistatic approximation for the estimation of the total kinetic and excitation energies of fission fragments and the total number of emitted prompt neutrons. The calculated results reproduce rather well the experimental data on the position of the peaks in the mass distribution of fission fragments, and the total kinetic and excitation energies of fission fragments. The calculated value of neutron multiplicity is somewhat larger than experimental results.
• Scission-point configuration within the two-center shell model shape parameterization

  F. A. Ivanyuk; S. Chiba; Y. Aritomo

  PHYSICAL REVIEW C AMER PHYSICAL SOC 90 (5) 2469-9985 2014/11 [Refereed]
   

  Within the two-center shell model parameterization we defined the optimal shape that fissioning nuclei attain just before the scission and calculated the total deformation energy (liquid-drop part plus the shell correction) as a function of the mass asymmetry and elongation at the scission point. The three minima corresponding to one mass-symmetric and two mass-asymmetric peaks in the mass distribution of fission fragments are found in the deformation energy at the scission point. The calculated deformation energy is used in a quasistatic approximation for the estimation of the total kinetic and excitation energies of fission fragments and the total number of emitted prompt neutrons. The calculated results reproduce rather well the experimental data on the position of the peaks in the mass distribution of fission fragments, and the total kinetic and excitation energies of fission fragments. The calculated value of neutron multiplicity is somewhat larger than experimental results.
• Fission dynamics at low excitation energy

  Y. Aritomo; S. Chiba; F. Ivanyuk

  PHYSICAL REVIEW C AMER PHYSICAL SOC 90 (5) 2469-9985 2014/11 [Refereed]
   

  The mass asymmetry in the fission of U-236 at low excitation energy is clarified by the analysis of the trajectories obtained by solving the Langevin equations for the shape degrees of freedom. It is demonstrated that the position of the peaks in the mass distribution of fission fragments is determined mainly by the saddle point configuration originating from the shell correction energy. The width of the peaks, on the other hand, results from the shape fluctuations close to the scission point caused by the random force in the Langevin equation. We have found out that the fluctuations between elongated and compact shapes are essential for the fission process. According to our results the fission does not occur with continuous stretching in the prolate direction, similarly to that observed in starch syrup, but is accompanied by the fluctuations between elongated and compact shapes. This picture presents a new viewpoint of fission dynamics and the splitting mechanism.
• Study of Heavy-ion Induced Fission for Heavy Element Synthesis

  K. Nishio; H. Ikezoe; S. Hofmann; D. Ackermann; Y. Aritomo; V. F. Comas; Ch. E. Duellmann; S. Heinz; A. Heredia; F. P. Hessberger; K. Hirose; J. Khuyagbaatar; B. Kindler; I. Kojouharov; B. Lommel; M. Makii; R. Mann; S. Mitsuoka; I. Nishinaka; T. Ohtsuki; S. Saro; M. Schaedel; A. G. Popeko; A. Tuerler; Y. Wakabayashi; Y. Watanabe; A. Yakushev; A. Yeremin

  NUCLEAR DATA SHEETS ACADEMIC PRESS INC ELSEVIER SCIENCE 119 299 - 302 0090-3752 2014/05 [Refereed]
   

  Fission fragment mass distributions were measured in heavy-ion induced fission of U-238. The mass distributions changed drastically with incident energy. The results are explained by a change of the ratio between fusion and quasifission with nuclear orientation. A calculation based on a fluctuation dissipation model reproduced the mass distributions and their incident energy dependence. Fusion probability was determined in the analysis. Evaporation residue cross sections were calculated with a statistical model for the reactions of Si-30+U-238 and S-34+U-238 using the obtained fusion probability in the entrance channel. The results agree with the measured cross sections of (263,264)Sg and (267,268)Hs, produced by Si-30+U-238 and S-34+U-238, respectively. It is also suggested that sub-barrier energies can be used for heavy element synthesis.
• Surrogate Reactions Research at JAEA/Tokyo Tech

  S. Chiba; K. Nishio; H. Makii; Y. Aritomo; I. Nishinaka; T. Ishii; K. Tsukada; M. Asai; K. Furutaka; S. Hashimoto; H. Koura; K. Ogata; T. Ohtsuki; T. Nagayama

  NUCLEAR DATA SHEETS ACADEMIC PRESS INC ELSEVIER SCIENCE 119 229 - 232 0090-3752 2014/05 [Refereed]
   

  The research activities at JAEA and Tokyo Tech. in the development of a surrogate method based on multi-nucleon transfer reactions induced by (mainly) heavy-ion projectiles are presented. This project consists of 3 parts: the development of an apparatus to measure (1) fission cross sections and (2) neutron capture cross sections, and (3) the development of the underlying theoretical framework. Equipment has already been developed and preliminary experiments carried out to validate the methods and to provide new data. At the same time, theories to describe the surrogate reaction processes were constructed and conditions for the surrogate ratio method to derive the correct neutron-induced cross sections were investigated.
• Study of heavy-ion induced fission for heavy-element synthesis

  K. Nishio; H. Ikezoe; S. Hofmann; F. P. Hessberger; D. Ackermann; S. Antalic; Y. Aritomo; V. F. Comas; Ch. E. Duellman; A. Gorshkov; R. Graeger; S. Heinz; J. A. Heredia; K. Hirose; J. Khuyagbaatar; B. Kindler; I. Kojouharov; B. Lommel; H. Makii; R. Mann; S. Mitsuoka; Y. Nagame; I. Nishinaka; T. Ohtsuki; A. G. Popeko; S. Saro; M. Schaedel; A. Tuerler; Y. Wakabayashi; Y. Watanabe; A. Yakushev; A. V. Yeremin

  INPC 2013 - INTERNATIONAL NUCLEAR PHYSICS CONFERENCE, VOL. 1 E D P SCIENCES 66 03065-1 - 4 2100-014X 2014 [Refereed]
   

  Fission fragment mass distributions were measured in heavy-ion induced fissions using U-238 target nucleus. The measured mass distributions changed drastically with incident energy. The results are explained by a change of the ratio between fusion and qasifission with nuclear orientation. A calculation based on a fluctuation dissipation model reproduced the mass distributions and their incident energy dependence. Fusion probability was determined in the analysis, and the values were consistent with those determined from the evaporation residue cross sections.
• Study of heavy-ion induced fission for heavy-element synthesis

  K. Nishio; H. Ikezoe; S. Hofmann; F. P. Heßberger; D. Ackermann; S. Antalic; Y. Aritomo; V. F. Comas; Ch E. Düllman; A. Gorshkov; R. Graeger; S. Heinz; J. A. Heredia; K. Hirose; J. Khuyagbaatar; B. Kindler; I. Kojouharov; B. Lommel; H. Makii; R. Mann; S. Mitsuoka; Y. Nagame; I. Nishinaka; T. Ohtsuki; A. G. Popeko; S. Saro; M. Schädel; A. Türler; Y. Wakabayashi; Y. Watanabe; A. Yakushev; A. V. Yeremin

  EPJ Web of Conferences 66 2101-6275 2014 

  Fission fragment mass distributions were measured in heavy-ion induced fissions using 238U target nucleus. The measured mass distributions changed drastically with incident energy. The results are explained by a change of the ratio between fusion and qasifission with nuclear orientation. A calculation based on a fluctuation dissipation model reproduced the mass distributions and their incident energy dependence. Fusion probability was determined in the analysis, and the values were consistent with those determined from the evaporation residue cross sections. © Owned by the authors, published by EDP Sciences, 2014.
• Fission process of nuclei at low excitation energies with a Langevin approach

  Y. Aritomo; S. Chiba

  Physical Review C - Nuclear Physics American Physical Society 88 (4) 1089-490X 2013/10 

  Fragment mass distributions from the fission of U and Pu isotopes at low excitation energies are studied using a dynamical model based on the fluctuation-dissipation theorem formulated as Langevin equations. The present calculations reproduced the overall trend of the asymmetric mass distribution without parameter adjustment for the first time using the Langevin approach. The Langevin trajectories show a complicated time evolution on the potential surface, which causes the time delay of fission, showing that dynamical treatment is vital. It was found that the shell effect of the potential energy landscape has a dominant role in determining the mass distribution, although it is rather insensitive to the strength of dissipation. Nevertheless, it is essential to include the effect of dissipation, because it has a crucial role in giving "fluctuation" to Langevin trajectories as well as for explaining the multiplicities of pre-scission neutrons as the excitation energy increases. Therefore, the present approach can serve as a basis for more refined analysis. © 2013 American Physical Society.
• In-beam Fissio Study at JAEA for Heavy Element Synthesis

  K. Nishio; H. Ikezoe; S. Hofmann; D. Ackermann; Y. Aritomo; V. F. Comas; Ch. E. Duellmann; S. Heinz; J. A. Heredia; F. P. Hessberger; K. Hirose; J. Khuyagbaatar; B. Kindler; I. Kojouharov; B. Lommel; M. Makii; R. Mann; S. Mitsuoka; I. Nishinaka; T. Ohtsuki; S. Saro; M. Schaedel; A. G. Popeko; A. Tuerler; Y. Wakabayashi; Y. Watanabe; A. Yakushev; A. Yeremin

  INTERNATIONAL CONFERENCE ON RECENT TRENDS IN NUCLEAR PHYSICS-2012 (ICRTNP-2012) AMER INST PHYSICS 1524 68 - 72 0094-243X 2013 

  Fission fragment mass distributions were measured in the heavy-ion induced fission using U-238 target nucleus. The mass distributions changed drastically with incident energy. The results are explained by a change of the ratio between fusion and qasifission with nuclear orientation. A calculation based on a fluctuation dissipation model reproduced the mass distributions and their incident energy dependence. Fusion probability was determined in the analysis. Evaporation residue cross sections were calculated with a statistical model in the reactions of Si-30+U-238 and S-34+U-238 using the obtained fusion probability in the entrance channel. The results agree with the measured cross sections of (263,264)Sg and (267,268)Hs, produced by Si-30+U-238 and S-34+U-238, respectively. It is also suggested that the sub-barrier energies can be used for heavy element synthesis.
• Fusion probabilities in the reactions Ca-40,Ca-48+U-238 at energies around the Coulomb barrier

  K. Nishio; S. Mitsuoka; I. Nishinaka; H. Makii; Y. Wakabayashi; H. Ikezoe; K. Hirose; T. Ohtsuki; Y. Aritomo; S. Hofmann

  PHYSICAL REVIEW C AMER PHYSICAL SOC 86 (3) 0556-2813 2012/09 

  Fission cross sections and fission fragment mass distributions were measured in the reactions of Ca-40+U-238 and Ca-48+U-238 at energies around the Coulomb barrier. Fusion probabilities were calculated based on the fluctuation dissipation model. The measured mass distributions for both reactions showed an asymmetric shape at low incident energies, whereas the distribution changed to a flat shape at higher energies. The variation of the mass distribution is explained by a change of the ratio between fusion and quasifission with nuclear orientation. The calculation reproduced the mass distributions and their energy dependence. The trajectories for fusion-fission were used to determine the fusion probability. Fusion probabilities for both reactions are identical as function of the center-of-mass energy (E-c.m.), but they differ when plotted as function of the excitation energy (E*). Evaporation residue cross sections were calculated for the reaction Ca-48+U-238 using a statistical model and the obtained fusion cross sections as input values. The results are compared to experimental data.
• Dynamical approach to heavy-ion induced fission using actinide target nuclei at energies around the Coulomb barrier

  Y. Aritomo; K. Hagino; K. Nishio; S. Chiba

  PHYSICAL REVIEW C AMER PHYSICAL SOC 85 (4) 0556-2813 2012/04 

  In order to describe heavy-ion fusion reactions around the Coulomb barrier with an actinide target nucleus, we propose a model which combines the coupled-channels approach and a fluctuation-dissipation model for dynamical calculations. This model takes into account couplings to the collective states of the interacting nuclei in the penetration of the Coulomb barrier and the subsequent dynamical evolution of a nuclear shape from the contact configuration. In the fluctuation-dissipation model with a Langevin equation, the effect of nuclear orientation at the initial impact on the prolately deformed target nucleus is considered. Fusion-fission, quasifission, and deep quasifission are separated as different Langevin trajectories on the potential energy surface. Using this model, we analyze the experimental data for the mass distribution of fission fragments (MDFF) in the reactions of S-34,S-36 + U-238 and Si-30 + U-238 at several incident energies around the Coulomb barrier. We find that the time scale in the quasifission as well as the deformation of fission fragments at the scission point are different between the Si-30 + U-238 and S-36 + U-238 systems, causing different mass asymmetries of the quasifission.
• Dynamical approach to fusion-fission process in superheavy mass region

  Y. Aritomo; D. J. Hinde; A. Wakhle; R. du Rietz; M. Dasgupta; K. Hagino; S. Chiba; K. Nishio

  HEAVY ION ACCELERATOR SYMPOSIUM ON FUNDAMENTAL AND APPLIED SCIENCE 2012 E D P SCIENCES 35 2100-014X 2012 [Refereed]
   

  In order to describe heavy-ion fusion reactions around the Coulomb barrier with an actinide target nucleus, we propose a model which combines the coupled-channels approach and a fluctuation-dissipation model for dynamical calculations. This model takes into account couplings to the collective states of the interacting nuclei in the penetration of the Coulomb barrier and the subsequent dynamical evolution of a nuclear shape from the contact configuration. In the fluctuation-dissipation model with a Langevin equation, the effect of nuclear orientation at the initial impact on the prolately deformed target nucleus is considered. Fusion-fission, quasi-fission and deep quasi-fission are separated as different Langevin trajectories on the potential energy surface. Using this model, we analyze the experimental data for the mass distribution of fission fragments (MDFF) in the reaction of S-36 + U-238 at several incident energies around the Coulomb barrier.
• Dynamical Approach to Heavy-ion Induced Fusion Using Actinide Target

  Y. Aritomo; K. Hagino; S. Chiba; K. Nishio

  NUCLEAR STRUCTURE AND DYNAMICS '12 AMER INST PHYSICS 1491 303 - 306 0094-243X 2012 

  To treat heavy-ion reactions using actinide target nucleus, we propose a model which takes into account the coupling to the collective states of interacting nuclei in the penetration of the Coulomb barrier and the dynamical evolution of nuclear shape from the contact configuration. A fluctuation-dissipation model (Langevin equation) was applied in the dynamical calculation, where effect of nuclear orientation at the initial impact on the prolately deformed target nucleus was considered. Using this model, we analyzed the experimental data for the mass distribution of fission fragments (MDFF) in the reaction of S-36+U-238 at several incident energies. Fusion-fission, quasifission and deep-quasi-fission are separated as different trajectories on the potential energy surface. We estimated the fusion cross section of the reaction.
• Dynamical approach to fusion-fission process in superheavy mass region

  Y. Aritomo; D. J. Hinde; A. Wakhle; R. Du Rietz; M. Dasgupta; K. Hagino; S. Chiba; K. Nishio

  EPJ Web of Conferences 35 2101-6275 2012 

  In order to describe heavy-ion fusion reactions around the Coulomb barrier with an actinide target nucleus, we propose a model which combines the coupled-channels approach and a fluctuation-dissipation model for dynamical calculations. This model takes into account couplings to the collective states of the interacting nuclei in the penetration of the Coulomb barrier and the subsequent dynamical evolution of a nuclear shape from the contact configuration. In the fluctuation-dissipation model with a Langevin equation, the effect of nuclear orientation at the initial impact on the prolately deformed target nucleus is considered. Fusion-fission, quasi-fission and deep quasi-fission are separated as different Langevin trajectories on the potential energy surface. Using this model, we analyze the experimental data for the mass distribution of fission fragments (MDFF) in the reaction of 36S+ 238U at several incident energies around the Coulomb barrier. © Owned by the authors 2012.
• Spin-dependent observables in surrogate reactions

  Satoshi Chiba; Osamu Iwamoto; Yoshihiro Aritomo

  PHYSICAL REVIEW C AMER PHYSICAL SOC 84 (5) 054602.1-054602.5  0556-2813 2011/11 [Refereed]
   

  Several quantities that can be observed in surrogate ratio methods (SRM) are investigated for nuclei of uranium region to see if they can be used to infer the spin-and-parity distributions that are crucially important to the validity of SRM. The evaporation neutron spectra and cascading gamma-ray spectra are calculated by the Hauser-Feshbach theory, while fission fragment mass distributions are calculated by the fluctuation-dissipation theorem. It was found that the energy spectrum of cascading. rays and those of evaporated neutrons become softer as the spin of the decaying nuclei increases. The multiplicity of emitted. rays increases drastically as the spin increases. Both these effects are brought about by the fact that transition from high-spin states to low-lying levels are hindered. The mass distribution of fission fragments also shows a clear spin dependence, namely, the mass-symmetric fission is enhanced when the spin of the decaying system is large. This can be interpreted as an enhancement of mass division controlled by the liquid-drop energy relative to the shell correction part. The present results indicate that there are possibilities to use these observables to infer populated spin distributions in the surrogate reactions.
• Investigation of fission properties and evaporation residue measurement in the reactions using 238U target nucleus

  K. Nishio; H. Ikezoe; S. Hofmann; D. Ackermann; S. Antalic; Y. Aritomo; V. F. Comas; Ch E. Düllmann; A. Gorshkov; R. Graeger; K. Hagino; S. Heinz; J. A. Heredia; K. Hirose; J. Khuyagbaatar; B. Kindler; I. Kojouharov; B. Lommel; H. Makii; R. Mann; S. Mitsuoka; Y. Nagame; I. Nishinaka; T. Ohtsuki; A. G. Popeko; S. Saro; M. Schädel; A. Türler; Y. Wakabayashi; Y. Watanabe; A. Yakushev; A. V. Yeremin

  EPJ Web of Conferences EDP Sciences 17 2100-014X 2011/10 

  Fragment mass distributions for fission after full momentum transfer were measured in the reactions of 30Si,34,36 S,31P,40Ar + 238U at bombarding energies around the Coulomb barrier. Mass distributions change significantly as a function of incident beam energy. The asymmetric fission probability increases at sub-barrier energy. The phenomenon is interpreted as an enhanced quasifission probability owing to orientation effects on fusion and/or quasifission. The evaporation residue (ER) cross sections were measured in the reactions of 30Si + 238U and 34S + 238U to obtain information on fusion. In the latter reaction, significant suppression of fusion was implied. This suggests that fission events different from compound nucleus are included in the masssymmetric fragments. The results are supported by a model calculation based on a dynamical calculation using Langevin equation, in which the mass distribution for fusion-fission and quasifission fragments are separately determined.
• Dynamical model of surrogate reactions

  Y. Aritomo; S. Chiba; K. Nishio

  PHYSICAL REVIEW C AMER PHYSICAL SOC 84 (2) 0556-2813 2011/08 

  A new dynamical model is developed to describe the whole process of surrogate reactions: Transfer of several nucleons at an initial stage, thermal equilibration of residues leading to washing out of shell effects, and decay of populated compound nuclei are treated in a unified framework. Multidimensional Langevin equations are employed to describe time evolution of collective coordinates with a time-dependent potential energy surface corresponding to different stages of surrogate reactions. The new model is capable of calculating spin distributions of the compound nuclei, one of the most important quantities in the surrogate technique. Furthermore, various observables of surrogate reactions can be calculated, for example, energy and angular distribution of ejectile and mass distributions of fission fragments. These features are important to assess validity of the proposed model itself, to understand mechanisms of the surrogate reactions, and to determine unknown parameters of the model. It is found that spin distributions of compound nuclei produced in (18)O + (238)U -> (16)O + (240)*U and (18)O + (236)U -> (16)O + (238)*U reactions are equivalent and much less than 10 (h) over bar and therefore satisfy conditions proposed by Chiba and Iwamoto [ Phys. Rev. C 81, 044604 (2010)] if they are used as a pair in the surrogate ratio method.
• Spin-dependent observables in surrogate reactions

  Satoshi Chiba; Osamu Iwamoto; Yoshihiro Aritomo

  PHYSICAL REVIEW C AMER PHYSICAL SOC 84 (5) 0556-2813 2011/05 [Refereed]
   

  Observables emitted from various spin states in compound U nuclei are investigated to validate usefulness of the surrogate reaction method. It was found that energy spectrum of cascading $\gamma$-rays and their multiplicities, spectrum of evaporated neutrons, and mass-distribution of fission fragments show clear dependence on the spin of decaying nuclei. The present results indicate that they can be used to infer populated spin distributions which significantly affect the decay branching ratio of the compound system produced by the surrogate reactions.
• Investigation of fission properties and evaporation residue measurement in the reactions using U-238 target nucleus

  K. Nishio; H. Ikezoe; S. Hofmann; D. Ackermann; S. Antalic; Y. Aritomo; V. F. Comas; Ch E. Duellmann; A. Gorshkov; R. Graeger; K. Hagino; S. Heinz; J. A. Heredia; K. Hirose; J. Khuyagbaatar; B. Kindler; I. Kojouharov; B. Lommel; H. Makii; R. Mann; S. Mitsuoka; Y. Nagame; I. Nishinaka; T. Ohtsuki; A. G. Popeko; S. Saro; M. Schaedel; A. Tuerler; Y. Wakabayashi; Y. Watanabe; A. Yakushev; A. V. Yeremin

  5TH INTERNATIONAL CONFERENCE FUSION11 E D P SCIENCES 17 2100-014X 2011 [Refereed]
   

  Fragment mass distributions for fission after full momentum transfer were measured in the reactions of Si-30,S-34,S-36,P-31,Ar-40 + U-238 at bombarding energies around the Coulomb barrier. Mass distributions change significantly as a function of incident beam energy. The asymmetric fission probability increases at sub-barrier energy. The phenomenon is interpreted as an enhanced quasifission probability owing to orientation effects on fusion and/or quasifission. The evaporation residue (ER) cross sections were measured in the reactions of Si-30 + U-238 and S-34 + U-238 to obtain information on fusion. In the latter reaction, significant suppression of fusion was implied. This suggests that fission events different from compound nucleus are included in the mass-symmetric fragments. The results are supported by a model calculation based on a dynamical calculation using Langevin equation, in which the mass distribution for fusion-fission and quasifission fragments are separately determined.
• Research Group for Reactions Involving Heavy Nuclei

  CHIBA Satoshi; NISHIO Katsuhisa; MITSUOKA Shinichi; KOURA Hroyuki; NISHINAKA Ichiro; UTSUNO Yutaka; MAKII Hiroyuki; WAKABAYASHI Yasuo; ARITOMO Yoshihiro; OTA Shuya; NAGAYAMA Tatsuro

  Ann Rep ASRC 2011 12  2011
• Evidence for quasifission in the sub-barrier reaction of Si-30+U-238

  K. Nishio; H. Ikezoe; I. Nishinaka; S. Mitsuoka; K. Hirose; T. Ohtsuki; Y. Watanabe; Y. Aritomo; S. Hofmann

  PHYSICAL REVIEW C AMER PHYSICAL SOC 82 (4) 0556-2813 2010/10 

  Fragment mass distributions for fission after full momentum transfer were measured for the Si-30 + U-238 reaction at bombarding energies around the Coulomb barrier. At energies above the Bass barrier, the mass distributions were Gaussian with mass symmetry. An asymmetric fission channel with mass A(L)/A(H) approximate to 90/178 emerged at the sub-barrier energies, where competition between fusion and quasifission was suggested from the evaporation residue (ER) cross section produced in the fusion Si-30 + U-238. We thus conclude the asymmetric channel is attributed to quasifission. It was supported by a model calculation using the Langevin equation to give the fragment mass distribution, where fusion-fission and quasifission were separated. The observed mass asymmetry for quasifission as well as the calculation is significantly smaller than those observed in actinide targets bombarded with heavier projectiles, which suggests that the system Si-30 + U-238 approaches the shape of the compound nucleus before disintegrating as quasifission.
• Nuclear orientation in the reaction S-34+U-238 and synthesis of the new isotope (268)Hs

  K. Nishio; S. Hofmann; F. P. Hessberger; D. Ackermann; S. Antalic; Y. Aritomo; V. F. Comas; Ch. E. Duellmann; A. Gorshkov; R. Graeger; K. Hagino; S. Heinz; J. A. Heredia; K. Hirose; H. Ikezoe; J. Khuyagbaatar; B. Kindler; I. Kojouharov; B. Lommel; R. Mann; S. Mitsuoka; Y. Nagame; I. Nishinaka; T. Ohtsuki; A. G. Popeko; S. Saro; M. Schaedel; A. Tuerler; Y. Watanabe; A. Yakushev; A. V. Yeremin

  PHYSICAL REVIEW C AMER PHYSICAL SOC 82 (2) 0556-2813 2010/08 

  The synthesis of isotopes of the element hassium was studied using the reaction S-34 + U-238 -> (272)Hs*. At a kinetic energy of 163.0 MeV in the center-of-mass system we observed one alpha-decay chain starting at the isotope (267)Hs. The cross section was 1.8(-1.5)(+4.2) pb. At 152.0 MeV one decay of the new isotope (268)Hs was observed. It decays with a half-life of 0.38(-0.17)(+1.8) s by 9479 +/- 16 keV alpha-particle emission. Spontaneous fission of the daughter nucleus (264)Sg was confirmed. The measured cross section was 0.54(-0.45)(+1.3) pb. In-beam measurements of fission-fragment mass distributions were performed to obtain information on the fusion probability at various orientations of the deformed target nucleus. The distributions changed from symmetry to asymmetry when the beam energy was changed from above-barrier to sub-barrier values, indicating orientation effects on fusion and/ or quasifission. It was found that the distribution of symmetric mass fragments originates not only from fusion-fission, but has a strong component from quasifission. The result was supported by a calculation based on a dynamical description using the Langevin equation, in which the mass distributions for fusion-fission and quasifission fragments were separately determined.
• FUSION-FISSION AND QUASI-FISSION PROCESSES IN REACTIONS USING ACTINIDE TARGET NUCLEI

  Yoshihiro Aritomo

  INTERNATIONAL JOURNAL OF MODERN PHYSICS E-NUCLEAR PHYSICS WORLD SCIENTIFIC PUBL CO PTE LTD 19 (5-6) 813 - 824 0218-3013 2010/06 [Refereed]
   

  We analyzed experimental data obtained for the mass distribution of fission fragments in the reactions (36)S+(238)U and (30)Si+(238)U at several incident energies, which were performed by the JAEA group. Using the dynamical model with the Langevin equation, we precisely investigate the incident energy dependence of the mass distribution of fission fragments. We also consider the fine structures in the mass distribution of fission fragments caused by the nuclear structure at a low incident energy. It is explained why the mass distribution of fission fragments has different features in the two reactions. The fusion cross sections are also estimated.
• Analysis of dynamical process with mass distribution of fission fragmentin heavy ion reactions

  Y. Aritomo

  EPJ Web of Conferences EDP Sciences 2 2100-014X 2010/03 

  We analyzed experimental data obtained for the mass distribution of fission fragments in the reactions 36S+238U and 30Si+238U at several incident energies, which were performed by the JAEA group. Using the dynamical model with the Langevin equation, we precisely investigate the incident energy dependence of the mass distribution of fission fragments. We also consider the fine structures in the mass distribution of fission fragments caused by the nuclear structure at a low incident energy. It is explained why the mass distribution of fission fragments has different features in the two reactions. The fusion cross sections are also estimated.
• Analysis of dynamical process with mass distribution of fission fragment in heavy ion reactions

  Y. Aritomo

  CNR '09: SECOND INTERNATIONAL WORKSHOP ON COMPOUND NUCLEAR REACTIONS AND RELATED TOPICS E D P SCIENCES 2 2100-014X 2010 [Refereed]
   

  We analyzed experimental data obtained for the mass distribution of fission fragments in the reactions S-36+U-238 and Si-30+U-235 at several incident energies, which were performed by the JAEA group. Using the dynamical model with the Langevin equation, we precisely investigate the incident energy dependence of the mass distribution of fission fragments. We also consider the fine structures in the mass distribution of fission fragments caused by the nuclear structure at a low incident energy. It is explained why the mass distribution of fission fragments has different features in the two reactions. The fusion cross sections are also estimated.
• Analysis of Dynamical Process with Mass Distribution of Fission Fragments Using Actinide Target Nuclei

  Y. Aritomo

  INTERNATIONAL SYMPOSIUM ON EXOTIC NUCLEI 2009 AMER INST PHYSICS 1224 356 - 365 0094-243X 2010 

  We analyzed experimental data obtained for the mass distribution of fission fragments in the reactions (36)S+(238)U and (30)Si+(238)U at several incident energies, which were performed by the JAEA group. Using the dynamical model with the Langevin equation, we precisely investigate the incident energy dependence of the mass distribution of fission fragments. We also consider the fine structures in the mass distribution of fission fragments caused by the nuclear structure at a low incident energy. It is explained why the mass distribution of fission fragments has different features in the two reactions. The fusion cross sections are also estimated.
• Analysis of dynamical processes using the mass distribution of fission fragments in heavy-ion reactions

  Y. Aritomo

  PHYSICAL REVIEW C AMER PHYSICAL SOC 80 (6) 0556-2813 2009/12 

  We analyze experimental data obtained for the mass distribution of fission fragments in the reactions S-36+U-238 and Si-30+U-238 at several incident energies, which were performed by the Japan Atomic Energy Agency (JAEA) group. The analysis of the mass distribution of fission fragments is a powerful tool for understanding the mechanism of the reaction in the heavy and superheavy-mass regions. Using the dynamical model with the Langevin equation, we precisely investigate the incident energy dependence of the mass distribution of fission fragments. This study is the first attempt to treat such experimental data systematically. We also consider the fine structures in the mass distribution of fission fragments caused by the nuclear structure at a low incident energy. It is explained why the mass distribution of fission fragments has different features in the two reactions. The fusion cross sections are also estimated.
• FUSION-FISSION DYNAMICS IN SUPERHEAVY MASS REGION

  Yoshihiro Aritomo

  INTERNATIONAL JOURNAL OF MODERN PHYSICS E-NUCLEAR PHYSICS WORLD SCIENTIFIC PUBL CO PTE LTD 18 (10) 2145 - 2149 0218-3013 2009/11 [Refereed]
   

  In heavy nucleus collision experiments, the fusion-fission cross section is derived from counting mass-symmetric fission events. However, a discrepancy exists between the experimental and theoretical estimations of the fusion cross section. We attempt to clarify the origin of the discrepancy and remove it by performing a dynamical calculation. The trajectory calculation has been performed in three-dimensional coordinate space with the Langevin equation.
• Analysis of Mass Distribution of Fission Fragment in Superheavy Mass Region

  Y. Aritomo

  PERSPECTIVES IN NUCLEAR PHYSICS AMER INST PHYSICS 1120 27 - 31 0094-243X 2009 

  Recently our FLNR theoretical group completes a calculation model to treat all reaction processes in heavy and superheavy mass region, which is so called "Unified model". Using a lot of available experimental data, we verify the validity of our model and establish a reliable model to describe the whole reaction process. As examples of the application of our model, we discuss two cases that are quasi-fission process and deep inelastic collision. We show the calculation results of the mass distribution of fission fragments in the reaction (36)S + (236)U. Also, we discuss the possibility for the production of new heavy neutron-rich nuclei in the low-energy multi-neutron transfer process.
• TIME-DEPENDENT POTENTIAL ENERGY FOR FUSION AND FISSION PROCESSES

  A. V. Karpov; V. I. Zagrebaev; Y. Aritomo; M. A. Naumenko; W. Greiner

  DYNAMICAL ASPECTS OF NUCLEAR FISSION WORLD SCIENTIFIC PUBL CO PTE LTD 112 - + 2008 

  The problem of description of low-energy nuclear dynamics and derivation of multi-dimensional potential energy surface depending on several collective degrees of freedom is discussed. Multi-dimensional adiabatic potential is constructed basing on extended version of the two-center shell model. It has correct asymptotic value and height of the Coulomb barrier in the entrance channel (fusion) and appropriate behavior in the exit one, giving required mass and energy distributions of reaction products and fission fragments. Explicit time-dependence of the driving potential was introduced in order to take into account difference of diabatic and adiabatic regimes of motion of nuclear system at above-barrier energies and also difference of nuclear shapes in fusion and fission channels (neck formation). Derived driving potential is proposed to be used for unified analysis of the processes of deep-inelastic scattering, fusion and fission at low-energy collisions of heavy ions.
• DYNAMICS OF CAPTURE QUASIFISSION AND FUSION-FISSION COMPETITION

  L. Stuttge; C. Schmitt; O. Dorvaux; N. Rowley; T. Materna; F. Hanappe; V. Bouchat; Y. Aritomo; A. Bogatchev; I. Itkis; M. Itkis; M. Jandel; G. Knyajeva; J. Kliman; E. Kozulin; N. Kondratiev; L. Krupa; Y. Oganessian; I. Pokrovski; E. Prokhorova; V. Voskresenski; N. Amar; S. Grevy; J. Peter; G. Giardina

  DYNAMICAL ASPECTS OF NUCLEAR FISSION WORLD SCIENTIFIC PUBL CO PTE LTD 22 - + 2008 

  An overview of the different experimental approaches to disentangle the quasi-fission and the fusion-fission processes in the heavy and superheavy mass region is presented. Indeed the separation of these two processes is essential in order to get a correct and complete insight of the mechanisms leading to the synthesis of superheavy elements. The importance of the neutron information through a new analysis protocol is detailed. Future perspectives are presented.
• POSSIBILITY OF SYNTHESIZING DOUBLY MAGIC SUPERHEAVY NUCLEI

  Y. Aritomo; M. Ohta; F. Hanappe; T. Materna; L. Stuttge; O. Dorvaux

  DYNAMICAL ASPECTS OF NUCLEAR FISSION WORLD SCIENTIFIC PUBL CO PTE LTD 155 - + 2008 

  Fusion-fission process in superheavy mass region is investigated on the basis of the fluctuation-dissipation dynamics. We analyze the trajectory in three-dimensional coordinate space with the Langevin equation. To investigate the fusion-fission process more precisely, we propose to take into account the prescission neutron multiplicity in connection with fission fragments. For the survival process, we apply the dynamical model instead of the statistical model. The possibility of synthesizing a doubly magic superheavy nucleus, (291)114(184), is investigated taking into account the temperature dependence of the potential energy owing to neutron emission.
• Potential energy of a heavy nuclear system in fusion-fission processes

  V. Zagrebaev; A. Karpov; Y. Aritomo; M. Naumenko; W. Greiner

  PHYSICS OF PARTICLES AND NUCLEI MAIK NAUKA/INTERPERIODICA/SPRINGER 38 (4) 469 - 491 1063-7796 2007/07 

  We discuss the problem of description of low-energy nuclear dynamics and the derivation of a multi-dimensional potential energy surface that depends on several collective degrees of freedom and allows a unified analysis of deep inelastic scattering, fusion, and fission processes. A unified description is required due to the strong coupling and significant overlapping of these reaction channels in heavy nuclear systems, which are used, in particular, for synthesis of superheavy elements. The multidimensional adiabatic potential is derived based on an extended version of the two-center shell model. This model leads to a correct asymptotic value and height of the Coulomb barrier in the entrance channel (fusion), and appropriate behavior in the exit channel, giving the required mass and energy distributions of reaction products and fission fragments. The derived driving potential is proposed to be applied in a consistent dynamic analysis of low-energy interactions of heavy nuclei.
• Possibility of synthesizing a doubly magic superheavy nucleus

  Y. Aritomo

  PHYSICAL REVIEW C AMERICAN PHYSICAL SOC 75 (2) 0556-2813 2007/02 

  The possibility of synthesizing a doubly magic superheavy nucleus, (298)114(184), is investigated on the basis of fluctuation-dissipation dynamics. In order to synthesize this nucleus, we must generate more neutron-rich compound nuclei because of the neutron emissions from excited compound nuclei. The compound nucleus (304)114 has two advantages to achieving a high survival probability. First, because of low neutron separation energy and rapid cooling, the shell correction energy recovers quickly. Secondly, owing to neutron emissions, the neutron number in the nucleus approaches that of the double closed shell and the nucleus attains a large fission barrier. Because of these two effects, the survival probability of (304)114 does not decrease until the excitation energy E-*=50 MeV. These properties lead to a rather high evaporation residue cross section.
• Fission fragment mass distribution for nuclei in the r-process region

  S. Tatsuda; K. Hashizume; T. Wada; M. Ohta; K. Sumiyoshi; K. Otsuki; T. Kajino; H. Koura; S. Chiba; Y. Aritomo

  TOURS SYMPOSIUM ON NUCLEAR PHYSICS VI AMER INST PHYSICS 891 423 - + 0094-243X 2007 

  The fission fragment mass distribution is estimated theoretically on about 2000 nuclides which might have a critical role on the r-process nucleosynthesis through fission (Z > 85). The mass distribution of fission fragment is derived by considering the location and the depth of valleys of potential energy surface near scission point of nuclei calculated by means of the liquid drop model with the shell energy correction by the Two-Center shell model. The guiding principle of determining the fission mass asymmetry is the behavior of the fission paths from the saddle to the scission point given by the Langevin calculation.
• A reassessment of surface friction model for maximum cold fusion reactions in superheavy mass region

  A. Fukushima; A. Nasirov; Y. Aritomo; T. Wada; M. Ohta

  TOURS SYMPOSIUM ON NUCLEAR PHYSICS VI AMER INST PHYSICS 891 443 - + 0094-243X 2007 

  We have made a study on the capture process of Ca-40,48(+) Pb-208 systems with a dynamical approach based on the surface friction model. The deformation of the nuclei due to the mutual excitation is taken into account. We have calculated the capture cross sections for several values of the friction coefficients. It was shown that, in the cold fusion reactions, the friction parameters of the surface friction model needs to be reexamined.
• Potential energy of heavy nuclear system in low-energy fusion-fission processes

  A. V. Karpov; V. I. Zagrebaev; Y. Aritomo; M. A. Naumenko; W. Greiner

  International Symposium on Exotic Nuclei AMER INST PHYSICS 912 286 - 298 0094-243X 2007 

  The problem of description of low-energy nuclear dynamics and derivation of multidimensional potential energy surface depending on several collective degrees of freedom is discussed. Multi-dimensional adiabatic potential is constructed basing on extended version of the two-center shell model. It has correct asymptotic value and height of the Coulomb barrier in the entrance channel (fusion) and appropriate behavior in the exit one, giving required mass and energy distributions of reaction products and fission fragments. Explicit time-dependence of the driving potential was introduced in order to take into account difference of diabatic and adiabatic regimes of motion of nuclear system at above-barrier energies and also difference of nuclear shapes in fusion and fission channels (neck formation). Derived driving potential is proposed to be used for unified analysis of the processes of deep-inelastic scattering, fusion and fission at low-energy collisions of heavy ions.
• Roles of shell effects in fusion process for synthesis of superheavy elements

  Y. Aritomo

  International Symposium on Exotic Nuclei AMER INST PHYSICS 912 266 - 275 0094-243X 2007 

  The effects of shell correction energy for fusion process are investigated on the basis of the fluctuation-dissipation dynamics. In the superheavy mass region, shell correction energy plays a very important role and enhances the fusion probability when the colliding partner has a strong shell structure. By analyzing the trajectory in three-dimensional coordinate space with the Langevin equation, we reveal the mechanism of the enhancement of the fusion probability caused by 'cold fusion valleys' and the temporary pocket which appears in fusion process.
• Fusion hindrance and roles of shell effects in superheavy mass region

  Y. Aritomo

  NUCLEAR PHYSICS A ELSEVIER SCIENCE BV 780 (3-4) 222 - 246 0375-9474 2006/12 

  We present the first attempt of systematically investigating the effects of shell correction energy for a dynamical process, which includes fusion, fusion-fission and quasi-fission processes. In the superheavy mass region, for the fusion process, shell correction energy plays a very important role and enhances the fusion probability when the colliding partner has a strong shell structure. By analyzing the trajectory in three-dimensional coordinate space with the Langevin equation, we reveal the mechanism of the enhancement of the fusion probability caused by 'cold fusion valleys'. The temperature dependence of shell correction energy is considered. (c) 2006 Elsevier B.V. All rights reserved.
• Pre-scission neutron multiplicity associated with the dynamical process in the superheavy-mass region

  Yoshihiro Aritomo; Masahisa Ohta; Francis Hanappe

  JOURNAL OF PHYSICS G-NUCLEAR AND PARTICLE PHYSICS IOP PUBLISHING LTD 32 (11) 2245 - 2259 0954-3899 2006/11 [Refereed]
   

  The fusion-fission process accompanied by neutron emission is studied in the superheavy-mass region on the basis of the fluctuation-dissipation model combined with a statistical model. The calculation of the trajectory or the shape evolution in the deformation space of the nucleus with neutron emission is performed. Each process ( quasi-fission, fusion-fission and deep quasi-fission processes) has a characteristic travelling time from the point of contact of colliding nuclei to the scission point. These dynamical aspects of the whole process are discussed in terms of the pre-scission neutron multiplicity, which depends on the time spent on each process. We have presented the details of the characteristics of our model calculation in the reactions Ca-48 + Pb-208 and Ca-48 + Pu-244, and shown how the structure of the distribution of the pre-scission neutron multiplicity depends on the incident energy.
• Role of the nuclear shell structure and orientation angles of deformed reactants in complete fusion

  AK Nasirov; Y Aritomo; A Fukushima; M Ohta; T Wada; G Giardina; G Mandaglio; A Muminov; RK Utamuratov

  INTERNATIONAL JOURNAL OF MODERN PHYSICS E-NUCLEAR PHYSICS WORLD SCIENTIFIC PUBL CO PTE LTD 15 (2) 311 - 317 0218-3013 2006/03 

  The dependence of the capture and fusion excitation functions on the nuclear shell structure and initial orientation angles of the symmetry axis of the deformed projectile- and target-nucleus are explored by the dynamical model based on the dinuclear system concept and Langevin calculations. The fusion cross sections for O-16+U-238 and Ni-60+Sm-154 reactions obtained by averaging of the results for the all orientation angles are in good agreement with the experimental data. The capture and fusion cross sections for the O-16+U-238 reaction are nearly the same while those are different for the 60Ni+154Sm reaction due to presence of the hindrance to fusion as quasifission. The largest of the fusion cross section for the orientation angles of the reactants in the range 60 degrees < alpha(i) < 90 degrees (A) in comparison with that for angles 0 degrees < alpha(i) < 30 degrees (B) was explained by the increase of the quasifission contribution in the last case (B). The physical reason of this phenomenon is connected by the largest of the intrinsic fusion barrier B*(fus) in case (B) than that for the case (A). The observed difference between the excitation functions of evaporation residues for the Kr-86 + Xe-130 and Sn-124 + Zr-92 reactions is explained by the difference between the B*(fus) values which depend on the nuclear shell corrections.
• Origin of the drastic decrease of fusion probability in superheavy mass region

  Yoshihiro Aritomo; Masahisa Ohta

  Nuclear Physics A 764 (1-4) 149 - 159 0375-9474 2006/01 

  The fusion-fission process in the superheavy mass region is studied systematically by solving the time evolution of nuclear shape in three-dimensional deformation space using the Langevin equation. By analyzing the trajectory in the deformation space, we identify the critical area when the trajectory's destination is determined to be the fusion or the quasi-fission process. It is also clarified that the potential landscape around the critical area is crucial for estimating the fusion probability, and its dependence on the atomic number is presented. © 2005 Elsevier B.V. All rights reserved.
• Fusion hindrance and the role of shell effects in the superheavy mass region

  Y. Aritomo

  FUSION06: Reaction Mechanisms and Nuclear Structure at the Coulomb Barrier AMER INST PHYSICS 853 259 - 264 0094-243X 2006 

  We present the first attempt of the systematical investigation about the effects of shell correction energy for dynamical processes, which include fusion, fusion-fission and quasi-fission processes. In the superheavy mass region, for the fusion process, the shell correction energy plays a very important role and enhances the fusion probability, when the colliding partner has strong shell structure. By analyzing the trajectory in the three-dimensional coordinate space with a Langevin equation, we reveal the mechanism of the enhancement of the fusion probability caused by shell effects.
• The role of orientation of nucleus symmetry axis in fusion dynamics

  A Nasirov; A Fukushima; Y Toyoshima; Y Aritomo; A Muminov; S Kalandarov; R Utamuratov

  NUCLEAR PHYSICS A ELSEVIER SCIENCE BV 759 (3-4) 342 - 369 0375-9474 2005/09 

  The dependence of the fusion excitation function on the orientation angles of the symmetry axis of deformed projectile- and target-nucleus relative to the beam direction is studied. The averaged over all orientations values of the fusion-fission cross sections obtained for O-16+U-238 and Ni-60+ Sm-154 reactions are compared with the experimental data. The capture and fusion cross sections for the O-16 + U-238 reaction are nearly the same while those are different for the Ni-60 + 154Sm reaction due to sufficient contribution of the quasifission events. The large values of the fusion cross section are obtained in the range 60 degrees < alpha(i) < 90 degrees of the orientation angles of the projectile- and target-nucleus. This phenomenon is explained by the dependence of the intrinsic fusion and quasifission barriers on the orientation angles of reactants. (c) 2005 Elsevier B.V. All rights reserved.
• Analysis of fusion-fission dynamics by pre-scission neutron emission in Ni-58+Pb-208 system

  Y Aritomo; M Ohta; T Materna; F Hanappe; O Dorvaux; L Stuttge

  NUCLEAR PHYSICS A ELSEVIER SCIENCE BV 759 (3-4) 309 - 326 0375-9474 2005/09 

  We analyzed the experimental data of the pre-scission neutron multiplicity in connection with fission fragments in the reaction Ni-58 + Pb-208 at the incident energy corresponding to the excitation energy of the compound nucleus E* = 185.9 MeV, which was performed by DeMoN group. The relation between the pre-scission neutron multiplicity and each reaction process having different reaction time is investigated. In order to study the fusion-fission process accompanied by neutron emission, the fluctuation-dissipation model combined with a statistical model is employed. It is found that the fusion-fission process and the quasi-fission process are clearly distinguished in correlation with the pre-scission neutron multiplicity. (c) 2005 Elsevier B.V. All rights reserved.
• Trajectory analysis for fusion path in superheavy-mass region

  Y Aritomo; M Ohta

  NUCLEAR PHYSICS A ELSEVIER SCIENCE BV 753 (1-2) 152 - 173 0375-9474 2005/05 

  We propose an effective method for the precise investigation of the fusion-fission mechanism in the superheavy-mass region, using the fluctuation-dissipation model. The trajectory calculation with friction is performed in the nuclear deformation space using the Langevin equation. In the reaction Ca-41 + (244)pu, the trajectories are classified into the fusion-fission process, the quasi-fission process and the deep quasi-fission process. By analyzing the time evolution of each trajectory, the mechanism of each process is clearly revealed, i.e., it is explained why a trajectory takes a characteristic path in this model. We discuss, in particular, the condition under which the fusion path is followed, which is crucial in the discussion of the possibility of synthesizing superheavy elements. (c) 2005 Elsevier B.V. All rights reserved.
• Dynamical calculation for fusion-fission probability in superheavy mass region, where mass symmetric fission events originate

  Y Aritomo; M Ohta

  NUCLEAR PHYSICS A ELSEVIER SCIENCE BV 744 3 - 14 0375-9474 2004/11 

  We discuss dynamically the fusion-fission mechanism in the superheavy mass region. By analyzing the mass distribution of fission fragments, we distinguish between the fusion-fission process and the quasi-fission process. We investigate these two processes using the fluctuation-dissipation model. The three-dimensional Langevin equation is employed. We classify the dynamical process by analyzing the trajectory in the nuclear deformation space. In the superheavy mass region, we found that 90-99% of mass symmetric fission events come from the quasi-fission process, in which the system hardly reaches the spherical region. The fusion cross section is also estimated precisely. (C) 2004 Elsevier B.V. All rights reserved.
• Tracking Dissipation in Capture Reactions

  MATERNA T.; HANAPPE F.; ARITOMO Y.; STUTTGE L.; DORVAUX O.; SCHMITT C.; OHTA M.

  Progress of Theoretical Physics Progress of Theoretical Physics 154 (154) 442 - 448 0375-9687 2004/07 [Refereed]
   

  Nuclear dissipation in capture reactions is investigated using backtracing. Combining the analysis procedure with dynamical models, the difficult and long-standing problem of competition and mixing of quasi-fission and fusion-fission is solved for the first time. At low excitation energy a new protocol able to handle low statistics data gives access to the prescission neutron multiplicity in two different systems ^<48>Ca + ^<208>Pb, Pu. The results are in agreement with a domination of fusion-fission in the case of ^<256>No and an equal mixing of quasi-fission and fusion-fission in the case of Z = 114. The nature of the relevant dissipation is determined as one-body dissipation.
• Problems of Dynamical Calculation for Synthesis of Superheavy Elements

  ARITOMO Yoshihiro; OHTA Masahisa; MATERNA Thomas; HANAPPE Francis; STUTTGE Louise

  Progress of Theoretical Physics Progress of Theoretical Physics 154 (154) 449 - 456 0375-9687 2004/07 [Refereed]
   

  We discuss the fusion-fission process in super heavy mass region. In dynamical calculation, we list up the problems and discuss the sensitivity of the parameters. Using the fluctuation-dissipation model we investigate the fusion-fission process and estimate the fusion cross section precisely.
• Analysis of fusion-fission dynamics in superheavy mass region by pre-scission neutron multiplicities

  Y Aritomo; M Ohta; T Materna; F Hanappe; L Stuttge

  NUCLEAR PHYSICS A ELSEVIER SCIENCE BV 738 221 - 225 0375-9474 2004/06 

  We discuss the fusion-fission process in superheavy mass region. By analyzing the mass distribution of fission fragments, we can distinguish between fusion-fission process and quasi-fission process. We investigate these two processes using the fluctuation-dissipation model. In the dynamical calculation, we employ the three-dimensional Langevin equation. We find 90 similar to 99% of mass symmetric fission events come from the quasi-fission process in the superheavy mass region. In order to classify the fusion-fission process more precisely, we analyze the pre-scission neutron multiplicity.
• Capture and dissipation in the superheavy region

  T Materna; Y Aritomo; N Amar; A Bogatchev; Bouchat, V; O Dorvaux; G Giardina; S Grevy; F Hanappe; Itkis, I; M Itkis; M Jandel; G Knyajeva; J Kliman; E Kozulin; N Kondratiev; L Krupa; J Peter; E Prokhorova; Pokrovsky, I; C Schmitt; L Stuttge; Voskresensky, V

  NUCLEAR PHYSICS A ELSEVIER SCIENCE BV 734 184 - 187 0375-9474 2004/04 [Refereed]
   

  The competition between fusion-fission and quasi-fission in the reactions Ca-48 + Pb-208 and Ca-48 + Pu-244 (E* = 40MeV) is investigated using the pre-scission neutron multiplicity distributions (PSNMD)obtained with a new analysis protocol.
• Dynamics of fusion-fission process with neutron evaporation in superheavy mass region

  Y Aritomo; M Ohta; T Materna; F Hanappe; L Stuttge

  NUCLEAR PHYSICS A ELSEVIER SCIENCE BV 734 180 - 183 0375-9474 2004/04 [Refereed]
   

  The fusion-fission process for the synthesis of superheavy elements is discussed on the basis of the fluctuation-dissipation model. We employ three-dimensional Langevin equation. We investigate the fusion-fission process by analyzing not only the mass distribution of fission fragments but also the neutron multiplicity in fusion-fission process.
• Tracking dissipation in capture reactions

  T Materna; Bouchat, V; Kinnard, V; F Hanappe; O Dorvaux; C Schmitt; L Stuttge; K Siwek-Wilczynska; Y Aritomo; A Bogatchev; E Prokhorova; M Ohta

  INTERNATIONAL JOURNAL OF MODERN PHYSICS E-NUCLEAR PHYSICS WORLD SCIENTIFIC PUBL CO PTE LTD 13 (1) 285 - 292 0218-3013 2004/02 

  Nuclear dissipation in capture reactions is investigated using backtracing. Combining the analysis procedure with dynamical models, the difficult and long-standing problem of competition and mixing of quasi-fission and fusion-fission is solved for the first time. At low excitation energy a new protocol able to handle low statistics data gives access to the prescission neutron multiplicity in two different systems Ca-48 + Pb-208, Pu. The results are in agreement with a domination of fusion-fission in the case of No-256 and an equal mixing of quasi-fission and fusion-fission in the case of Z = 114. The nature of the relevant dissipation is determined as one-body dissipation.
• Dynamical calculation for fusion-fission process in superheavy mass region

  Y Aritomo; M Ohta; T Materna; F Hanappe; L Stuttge

  INTERNATIONAL JOURNAL OF MODERN PHYSICS E-NUCLEAR PHYSICS WORLD SCIENTIFIC PUBL CO PTE LTD 13 (1) 301 - 304 0218-3013 2004/02 

  The fusion-fission process for the synthesis of superheavy elements is discussed on the basis of fluctuation-dissipation model. We employ three-dimensional Langevin equation. We investigate the fusion-fission process by analyzing not only the mass distribution of fission fragments but also neutron multiplicity on fusion-fission process.
• Fusion-fission dynamics of superheavy nuclei by the fluctuation-dissipation model

  Y Aritomo; M Ohta; T Matema; F Hanappe; L Stuttge

  STRUCTURE AND DYNAMICS OF ELEMENTARY MATTER SPRINGER 166 395 - 405 2004 [Refereed]
   

  We discuss the fusion-fission process in superheavy mass region. By analyzing the mass distribution of fission fragments, we can distinguish between fusion-fission process and quasi-fission process. We investigate the process using the fluctuation-dissipation model and employ the three-dimensional Langevin equation. We find a lot of mass symmetric fission events come from the quasi-fission process in the superheavy mass region. In order to classify the fusion-fission paths and compare with the experimental data directly, we analyze the pre-scission neutron emission in the correlation with the fission fragments. The neutron multiplicity depends on the travelling time of the trajectory. It is useful to investigate the fusion-fission process.
• Tracking dissipation in capture reactions

  T Materna; Bouchat, V; Kinnard, V; F Hanappe; O Dorvaux; C Schmitt; L Stuttge; K Siwek-Wilczynska; Y Aritomo; A Bogatchev; E Prokhorova; M Ohta

  LABYRINTH IN NUCLEAR STRUCTURE AMER INST PHYSICS 701 200 - 207 0094-243X 2004 [Refereed]
   

  Nuclear dissipation in capture reactions is investigated using backtracing. Combining the analysis procedure with dynamical models, the difficult and long-standing problem of competition and mixing of quasi-fission and fusion-fission is solved for the first time. At low excitation energy a new protocol able to handle low statistics data gives access to the prescission neutron multiplicity in two different systems Ca-48 + Pb-208, Pu. The results are in agreement with a domination of fusion-fission in the case of No-256 and an equal mixing of quasi-fission and fusion-fission in the case of Z = 114. The nature of the relevant dissipation is determined as one-body dissipation.
• Tracking dissipation in capture reactions in the superheavy region

  T Materna; Bouchat, V; F Hanappe; O Dorvaux; C Schmitt; L Stuttge; Y Aritomo; A Bogatchev; Itkis, I; M Itkis; M Jandel; G Knyajeva; J Kliman; E Kozulin; N Kondratiev; L Krupa; E Prokhorova; Pokrovski, I; Voskresenski, V; N Amar; S Grevy; J Peter; G Giardina

  SEMINAR ON FISSION: PONT D'OYE V WORLD SCIENTIFIC PUBL CO PTE LTD 191 - 198 2004 [Refereed]
   

  The competition between fusion-fission and quasi-fission in the reactions Ca-48+Pb-208 and Ca-48+Pu-244 (E* = 40 MeV) is investigated with the CORSET and DEMON detectors. The development of a new analysis method, T(H)OMATE, enables us to obtain the pre-scission neutron multiplicity distributions (PSNMD) that allows to disentangle the contributions of fusion-fission and quasi-fission for the first time for a superheavy system at such a low excitation energy. The ratio of the fusion cross-section over the capture cross-section is found to be of the order of 10%.
• Tracking dissipation in capture reactions

  T Materna; Bouchat, V; Kinnard, V; F Hanappe; O Dorvaux; C Schmitt; L Stuttge; K Siwek-Wilczynska; Y Aritomo; A Bogatchev; E Prokhorova; M Ohta

  TOURS SYMPOSIUM ON NUCLEAR PHYSICS V AMER INST PHYSICS 704 139 - 146 0094-243X 2004 

  Nuclear dissipation in capture reactions is investigated using backtracing. Combining the analysis procedure with dynamical models, the difficult and long-standing problem of competition and mixing of quasi-fission and fusion-fission is solved for the first time. At low excitation energy a new protocol able to handle low statistics data gives access to the prescission neutron multiplicity in two different systems Ca-48 + Pb-208, Pu. The results are in agreement with a domination of fusion-fission in the case of 256 No and an equal mixing of quasi-fission and fusion-fission in the case of Z = 114. The nature of the relevant dissipation is determined as one-body dissipation.
• On the excitation energy for maximum cold fusion reactions in superheavy mass region

  A Fukushima; T Wada; M Ohta; Y Aritomo

  TOURS SYMPOSIUM ON NUCLEAR PHYSICS V AMER INST PHYSICS 704 557 - 562 0094-243X 2004 

  We have analyzed cold fusion reactions, especially, (HI(Heavy-Ion), xn) reactions with Pb-208 target series. The ratio a(f)/a(n) used in the statistical model is determined by fitting experimental data Gamma(n)/Gamma(total) for Z=102 and the extrapolative use is made for Z>103. Theoretical predictions for excitation functions in Pb-208(Ti-50, V-51, Cr-54, Mn-55, Fe-58, Co-59, Cu-65, Zn-70, xn) reactions are compared with experiments. We found that peak positions of (HI, xn) reactions except for the sub-barrier fusion enhancement effect stay almost constant when we increase the Z-number of compound nucleus from Z=104 to Z=110.
• Dynamics of fusion-fission process in superheavy mass region

  Y Aritomo; M Ohta; T Materna; F Hanappe; L Stuttge

  TOURS SYMPOSIUM ON NUCLEAR PHYSICS V AMER INST PHYSICS 704 147 - 156 0094-243X 2004 

  The fusion-fission process for the synthesis of superheavy elements is discussed on the basis of the fluctuation-dissipation model. Recently the experiments at Dubna on fission of superheavy nuclei were carried out, and the mass and total kinetic energy distributions of fission fragments were measured. By analyzing the mass distribution of fission fragments, we can distinguish between fusion-fission process and quasi-fission process. We employ three-dimensional Langevin equation. We find almost all of the mass symmetric fission events come from the quasi-fission process in the superheavy mass region. In order to classify the fusion-fission paths and compare with the experimental data directly, we analyze the pre-scission neutron emission in the correlation with fission fragments. The neutron multiplicity depends on the travelling time of the trajectory. It is useful to investigate the fusion-fission process.
• On evaporation residue cross sections producing nuclei with Z=104-120

  M Ohta; Y Aritomo; K Hashizume

  ACTA PHYSICA HUNGARICA NEW SERIES-HEAVY ION PHYSICS AKADEMIAI KIADO RT 19 (1-2) 61 - 66 1219-7580 2004 

  A phenomenological method to predict the evaporation residue cross section in the superheavy mass region is presented. It makes us possible to understand what are the main contributors to the cross section and to perform a systematic analysis for understanding the fusion-fission mechanism by finding a deviation from the average property by means of this method.
• Analysis of fusion-fission process with neutron evaporation in superheavy mass region

  Y Aritomo; M Ohta

  ACTA PHYSICA HUNGARICA NEW SERIES-HEAVY ION PHYSICS AKADEMIAI KIADO 19 (1-2) 85 - 86 1219-7580 2004 

  The fusion-fission process for the synthesis of superheavy elements is discussed on the basis of the fluctuation-dissipation dynamics. We analyze the experimental data using a three-dimensional Langevin calculation. We take the neutron emission into account in the Langevin calculation and compare the results with experimental data. Also we discuss the evaporation residue cross section for superheavy elements.
• Tracking dissipation in capture reactions

  T Materna; C Schmitt; Y Aritomo; J Bartel; B Benoit; AA Bogatchev; ED Breddand; O Dorvaux; G Giardina; F Hanappe; MG Itkis; IM Itkis; J Kliman; GN Kniajeva; NA Kondratiev; EM Kozulin; L Krupa; YT Oganessian; Pokrovsky, IV; EV Prokhorova; N Rowley; K Siwek-Wilczynska; L Stuttge

  PHYSICS OF ATOMIC NUCLEI MAIK NAUKA/INTERPERIODICA PUBL 66 (6) 1168 - 1172 1063-7788 2003/06 

  Nuclear dissipation in capture reactions is investigated using backtracing, a new analysis protocol. Combining analysis procedure with dynamical models, the difficult and long-standing problem of competition and mixing between quasifission and fusion-fission is solved for the first time. The nature of the relevant dissipation is determined as one-body dissipation. At low excitation energy where shell effects are strongly effective, the shape of the mass distribution could be a powerful check of the nature and the magnitude of the dissipation. (C) 2003 MAIK "Nauka/Interperiodica".
• Analysis of fusion-fission process with neutron evaporation in superheavy mass region

  Y Aritomo; M Ohta

  PHYSICS OF ATOMIC NUCLEI MAIK NAUKA/INTERPERIODICA PUBL 66 (6) 1105 - 1113 1063-7788 2003/06 

  The fusion-fission process for the synthesis of superheavy elements is discussed on the basis of fluctuation-dissipation dynamics. Recently, experiments at Dubna on fission of superheavy nuclei were carried out, and the mass and total kinetic energy distributions of fission fragments were measured. The fusion-fission cross section was derived from the experiments. We analyze the data using a three-dimensional Langevin calculation. We present a clear understanding of the competition between the fusion and the quasifission. We emphasize that a one- or two-dimensional model of Langevin calculation is not sufficient to estimate the fusion cross section in the superheavy mass region. Also, experiments on the emission of neutrons in correlation with fission fragments were conducted. It is useful to investigate the fusion-fission dynamics. We take into account the neutron emission with a Langevin calculation and compare it with experimental data. Finally, we discuss the evaporation residue cross section for superheavy elements. (C) 2003 MAIK "Nauka/Interperiodica".
• An idea for predicting the evaporation residue cross section in superheavy mass region

  M Ohta; Y Aritomo

  PHYSICS OF ATOMIC NUCLEI MAIK NAUKA/INTERPERIODICA PUBL 66 (6) 1026 - 1032 1063-7788 2003/06 

  A trial to clarify the main contributors to the evaporation residue cross section in the superheavy mass region is presented. The precise analysis of these factors enables us to understand more clearly the trend of experimental data decreasing exponentially when the atomic number of the residue nucleus increases. It is found that almost all of the experimental data producing nuclei with Z = 104 to 114 are fitted with a common parameter set within a reasonable allowance, i.e., +/-0.7 order. In this sense, this model has a reliable predictability for the synthesis of new elements. (C) 2003 MAIK "Nauka/Interperiodica".
• Fusion-Fission Process of Superheavy Elements with Fluctuation-Dissipation Model

  ARITOMO Yoshihiro

  Progress of Theoretical Physics Progress of Theoretical Physics 146 (146) 503 - 507 0375-9687 2002/12 [Refereed]
   

  The fusion-fission process for the synthesis of superheavy elements is discussed based on fluctuation-dissipation dynamics. Recent data from Dubna on a fusion-fission cross section derived from fission experiments in the reactions ^48Ca+^208Pb, ^48Ca+^238U, ^48Ca+^244Pu and ^48Ca+^248Cm are analyzed using a three-dimensional Langevin calculation. We found that the quasi-fission process contributes to the yield of mass symmetric fission fragments. In superheavy mass region, the dynamical deformation of fragments is very important. The one- or two-dimensional calculation is not enough to describe the dynamics of fusion-fission process.
• Fusion-fission process of superheavy elements with fluctuation-dissipation model

  Yoshihiro Aritomo; Yoshihiro Aritomo

  Progress of Theoretical Physics 503 - 507 0033-068X 2002/12 

  The fusion-fission process for the synthesis of superheavy elements is discussed based on fluctuation-dissipation dynamics. Recent data from Dubna on a fusion-fission cross section derived from fission experiments in the reactions 48Ca+208Pb, 48Ca+238U, 48Ca+244Pu and 48Ca+248Cm are analyzed using a three-dimensional Langevin calculation. We found that the quasi-fission process contributes to the yield of mass symmetric fission fragments. In superheavy mass region, the dynamical deformation of fragments is very important. The one- or two-dimensional calculation is not enough to describe the dynamics of fusion-fission process.
• Synthesis of superheavy nuclei: How accurately can we describe it and calculate the cross sections?

  Zagrebaev, VI; Y Aritomo; MG Itkis; YT Oganessian; M Ohta

  PHYSICAL REVIEW C AMERICAN PHYSICAL SOC 65 (1) 146071 - 1460714 0556-2813 2002/01 

  A thorough analysis of all stages of heavy ion fusion reaction leading to the formation of a heavy evaporation residue has been performed. The main goal of the analysis was to gain better understanding of the whole process and to find out what factors and quantities, in particular, bring major uncertainty into the calculated cross sections, how reliable the calculation of the cross sections of superheavy element formation may be and what additional theoretical and experimental studies should be made in this field.
• Systematics on superheavy elements formation

  Masahisa Ohta; Yoshihiro Aritomo

  Journal of Nuclear Science and Technology 39 586 - 591 0022-3131 2002 

  Based on numerical results by three dimensional Langevin calculation, a functional form of formation probability is derived. Combining with survival probability estimated by the statistical model, we reproduced a general trend of experimental data and understandings. Through our systematic analysis, we propose the Synthesis Index (SI) which is useful for searching which entrance channel is preferable to produce new elements. © 2014 Atomic Energy Society of Japan.
• Reaction theory for the synthesis of superheavy elements

  T Wada; Y Aritomo; T Ichikawa; M Ohta; Y Abe

  4TH SYMPOSIUM ON NUCLEAR PHYSICS AMER INST PHYSICS 561 411 - 420 0094-243X 2001 [Refereed]
   

  The dynamical process of synthesizing superheavy elements is studied on the basis of the fluctuation-dissipative dynamics. The whole process is divided into three stages, i.e., the approaching stage, the formation stage, and the surviving stage. For the study of the formation stage, a three-dimensional Langevin equation is used from the contact of two nuclei to calculate the competition between the complete fusion and the quasi-fission. We estimate the effects of the nuclear deformation on the fusion probability. The results are consistent with the experimental results. For the description of the surviving stage, a statistical model is used to estimate the competition between the fission and the evaporation process. In this stage, it is very important to include the temperature-dependent shell correction to the fission barrier and the collective enhancement of the level density. From the study of the isotope dependence of the production cross section, the survival probability is found to be very sensitive to the separation energy of neutron. The results show the importance of the use of neutron-rich beams and targets.
• Theoretical predictions of residues cross sections of superheavy elements

  Y Abe; K Okazaki; Y Aritomo; T Tokuda; T Wada; M Ohta

  NUCLEAR SHELLS - 50 YEARS WORLD SCIENTIFIC PUBL CO PTE LTD 240 - 243 2000 [Refereed]
   

  Dynamical reaction theories are reviewed for synthesis of superheavy elements. Characteristic features of formation and surviving are discussed with reference to possible incident channels. Theoretical predictions are presented on favorable incident channels and on optimum: energies for synthesis of Z = 114.
• Fusion-fission dynamics for synthesis of superheavy elements

  Y Aritomo; K Okazaki; T Wada; M Ohta; Y Abe

  NUCLEAR SHELLS - 50 YEARS WORLD SCIENTIFIC PUBL CO PTE LTD 276 - 285 2000 [Refereed]
   

  The fusion-fission process for synthesizing superheavy elements is studied on the basis of the dissipative dynamics. We use a multi-dimensional Langevin equation for the first stage where the reaction system evolves from the contact configuration of two incident nuclei to the later time when the complete dissipation of the initial relative kinetic energy is accomplished, and a two-dimensional Smoluchowski equation for the following stage. The evaporation residue cross sections for superheavy elements have been shown to have an optimum value at a certain initial energy, due to the balance between the diffusibility for fusion at high temperature and the restoration of the shell correction energy against fission at low temperature. The isotope dependence is also discussed. The results show the impotence of the use of the neutron-rich beams and targets.
• Theory of nuclear reactions leading to superheavy elements

  Y Abe; K Okazaki; Y Aritomo; T Wada; M Ohta

  PROCEEDINGS OF THE 7TH INTERNATIONAL CONFERENCE ON CLUSTERING ASPECTS OF NUCLEAR STRUCTURE AND DYNAMICS WORLD SCIENTIFIC PUBL CO PTE LTD 394 - 401 2000 [Refereed]
   

  Dynamical reaction theory is presented for synthesis of superheavy elements. Characteristic features of formation and surviving are discussed, which combinedly determine final residue cross sections of superheavy elements. Preliminary results on Z=114 are also given.
• Recent status of reaction theories for synthesis of superheavy elements

  Y Abe; K Okazaki; T Wada; M Ohta; Y Aritomo

  INTERNATIONAL SYMPOSIUM ON QUASIPARTICLE AND PHONON EXCITATIONS IN NUCLEI (SOLOVIEV 99) WORLD SCIENTIFIC PUBL CO PTE LTD 1 - 9 2000 [Refereed]
   

  An overview of the present status of our knowledges is given on heavy-ion reaction mechanisms crucial for synthesis of the superheavy elements. Examples of the preliminary results are also given for Z=114.
• Multi-dimensional fluctuation-dissipation dynamics of the synthesis of superheavy elements

  T. Wada; Y. Aritomo; T. Tokuda; K. Okazaki; M. Ohta; Y. Abe

  NUCLEAR PHYSICS A ELSEVIER SCIENCE BV 654 (1) 888C - 891C 0375-9474 1999/07 

  We study the dynamical process of synthesizing superheavy elements on the basis of the fluctuation-dissipative dynamics with a multi-dimensional diffusion model. A multidimensional Langevin equation is used from the contact of two nuclei. After the dissipation of relative kinetic energy, a two-dimensional Smoluchowski equation is adopted taking into account the temperature dependent shell correction energy. The fusion probability is large for high incident energies. For low incident energies, owing to the restoration of the shell correction energy, the survival provability against fission is large. The competition between the two factors results in the optimum energy at 20-30 MeV. A three-dimensional model is used for the treatment of mass-asymmetric incident channels.
• Fluctuation-dissipation model for synthesis of superheavy elements

  Y Aritomo; T Wada; M Ohta; Y Abe

  PHYSICAL REVIEW C AMERICAN PHYSICAL SOC 59 (2) 796 - 809 0556-2813 1999/02 

  Fusion-fission dynamics in superheavy elements is investigated by an approximate fluctuation-dissipation model, i.e., a diffusion model in the deformation space, assuming that the kinetic energy of the incident ion dissipates immediately after the contact. The probability accumulated inside the fission barrier is calculated by the one-dimensional Smoluchowski equation taking account of the temperature dependence of the shell correction energy. A new mechanism for an optimum condition is found as a compromise of two conflicting requirements: higher incident energy for larger fusion probability and lower excitation energy of compound nuclei for larger survival probability. Enhancements of the residue cross sections at the optimum condition are obtained for the cases in which the cooling is quick to restore the shell correction energy, combined with slow fissioning motion due to the strong friction. With symmetric combinations of incident ions, the (HI, 3-4n) channels show the enhancement. [S0556-2813(99)01501-0].
• Favorable combination for the synthesis of superheavy elements

  M Ohta; K Okazaki; T Wada; Y Aritomo; Y Abe

  ACTA PHYSICA HUNGARICA NEW SERIES-HEAVY ION PHYSICS AKADEMIAI KIADO 10 (2-3) 253 - 264 1219-7580 1999 

  Suitable target-projectile combinations for synthesis of the superheavy element Z = 114 are discussed for the case of the two isotopes A = 298 and A = 290, which are the neutron-rich isotope and the normal one, respectively. In our framework of estimating the evaporation residue cross section by using the Langevin or the diffusion equation, it is shown that the fusion reaction leading to a neutron-rich nucleus has an advantage around the entrance channel mass asymmetry parameter alpha = 0.65. On the contrary, lower mass asymmetry is favorable in the case of the normal nucleus, although the absolute value of the cross section is depressed drastically. We also present quantitatively the importance of neutron richness in the synthesis of superheavy elements.
• Diffusion model for the synthesis of superheavy elements

  Y Aritomo; K Okazaki; T Wada; M Ohta; Y Abe

  TOURS SYMPOSIUM ON NUCLEAR PHYSICS III AMER INST PHYSICS (425) 61 - 71 0094-243X 1998 [Refereed]
   

  The fusion-fission process for synthesizing superheavy elements is studied on the basis of the dissipative dynamics. The nse a multi-dimensional Langevin equation for the first stage where the reaction system evolves from the contact configuration of two incident nuclei to the later time when the complete dissipation of the initial relative kinetic energy is accomplished, and a two-dimensional Smoluchowski equation for the following stage. The evaporation residue cross sections for superheavy elements have been shown to have an optimum value at a certain initial energy, due to the balance between the diffusibility for fusion at high temperature and the restoration of the shell correction energy against fission at low temperature. The isotope dependence is also discussed.
• Simulation for fusion and fusion-fission dynamics in heavy nuclei

  K Okazaki; K Hatogai; Y Aritomo; T Tokuda; T Wada; M Ohta; Y Abe

  TOURS SYMPOSIUM ON NUCLEAR PHYSICS III AMER INST PHYSICS (425) 107 - 110 0094-243X 1998 [Refereed]
   

  Starting from the contact configuration of colliding nuclei: the evolution of the nuclear shape is simulated in two-dimensional deformation space fixing the asymmetry by means of the Langevin equation under the influence of the one body dissipation. It is quantitatively shown that, in heavy mass region, the asymmetry of the entrance channel plays an important role to get an optimum fusion probability in connection with the extra barrier to be overcome. It is necessary to take into account this effect together with the excitation energy at Bass barrier to consider the optimum target-projectile combination for the synthesis of super heavy elements.
• Multi-dimensional diffusion model for the synthesis of superheavy elements

  T Wada; Y Aritomo; T Tokuda; K Okazaki; M Ohta; Y Abe

  PROCEEDINGS OF THE XVII RCNP INTERNATIONAL SYMPOSIUM ON INNOVATIVE COMPUTATIONAL METHODS IN NUCLEAR MANY-BODY PROBLEMS WORLD SCIENTIFIC PUBL CO PTE LTD 461 - 469 1998 [Refereed]
   

  We study the dynamical process of synthesizing superheavy elements on the basis of the fluctuation-dissipative dynamics with a multi-dimensional diffusion model. To treat the effect of the initial kinetic energy properly, a multi-dimensional Langevin equation is used for the first stage of the process, from the contact of two nuclei to the time when the relative kinetic energy dissipates completely For the description of the second stage, a two-dimensional Smoluchowski equation is adopted taking into account the temperature dependent shell correction energy and the cooling due to the neutron evaporations is treated with the statistical model. The fusion probability is large for high incident energies due to the strong diffusion. For low incident energies, owing to the restoration of the shell correction energy, fission is suppressed and the survival provability is large. The competition between these two factors results in the optimum energy around 20-30 MeV. From the study of the isotope dependence of the production cross section, the importance of the use of neutron-rich nuclei is remarked.
• A new mechanism for synthesis of superheavy elements

  Y Abe; Y Aritomo; T Wada; M Ohta

  JOURNAL OF PHYSICS G-NUCLEAR AND PARTICLE PHYSICS IOP PUBLISHING LTD 23 (10) 1275 - 1284 0954-3899 1997/10 

  A dynamical theory is proposed for nuclear reactions leading to residues of superheavy elements. Fusion and fission processes are treated consistently by a diffusion equation which describes a time-dependent probability distribution in the collective coordinate or deformation space. The potential energy in the equation is time-dependent, because cooling due to particle evaporation gradually restores the shell correction energy which gives rise to a potential pocket essential for the stabilization of the superheavy elements around Z = 114 and N = 184. It is shown that there is an optimum initial excitation energy or incident energy of reactions as the result of a compromise between two conflicting requirements; higher energies which favour larger fusion probabilities and lower energies which favour larger residue probabilities or a quicker restoration of the shell-correction energy. A promising experimental direction is suggested.
• Dynamics of the superheavy element synthesis with a diffusion model

  T Wada; Y Aritomo; T Tokuda; M Ohta; Y Abe

  NUCLEAR PHYSICS A ELSEVIER SCIENCE BV 616 (1-2) C446 - C453 0375-9474 1997/04 

  A diffusion model is proposed for the dynamical treatment of the synthesis of superheavy elements. Fusion-fission process is analyzed by one-dimensional Smoluchowski equation with liquid drop model potential of no pocket and the temperature dependent shell correction energy which generates the pocket around the spherical shape. Competition between fission and neutron evaporation is taken into account in terms of the continuous cooling by neutron evaporation. The evaporation residue cross sections of superheavy elements have been shown to have an optimum value at a certain temperature, due to the balance between the diffusibility for fusion at high temperature and the restoration of the shell correction energy against fission at low temperature. The isotope dependence of the evaporation residue cross section is found to be very strong. Neutron rich compound system with small neutron separation energy is favorable for larger cross section because of the quick restoration of the shell correction energy.
• Diffusion mechanism for synthesis of superheavy elements

  Y Aritomo; T Wada; M Ohta; Y Abe

  PHYSICAL REVIEW C AMER PHYSICAL SOC 55 (3) R1011 - R1014 2469-9985 1997/03 [Refereed]
   

  The fusion-fission process in heavy systems is analyzed by the Smoluchowski equation with the finite-range droplet model potential of no pocket and the temperature-dependent shell correction energy which generates the pocket around the spherical shape. The evaporation residue cross sections of superheavy elements have been shown to have an optimum value at a certain initial temperature, due to the balance between the diffusibility for fusion at high temperature and the restoration of the shell correction energy against fission at low temperature.
• Diffusion mechanism for synthesis of superheavy elements

  Y. Aritomo; T. Wada; M. Ohta; Y. Abe

  Physical Review C - Nuclear Physics 55 (3) R1011 - R1014 1089-490X 1997 

  The fusion-fission process in heavy systems is analyzed by the Smoluchowski equation with the finite-range droplet model potential of no pocket and the temperature-dependent shell correction energy which generates the pocket around the spherical shape. The evaporation residue cross sections of superheavy elements have been shown to have an optimum value at a certain initial temperature, due to the balance between the diffusibility for fusion at high temperature and the restoration of the shell correction energy against fission at low temperature. © 1997 The American Physical Society.

Books etc

• 元素周期表

  有友嘉浩 (Joint editor超重元素領域)製作・著作：文部科学省、企画・製作 株式会社化学同人 2017/02
• The Papanicolaou Society of Cytopathology System for Reporting Pancreaticobiliary Cytology: Definitions, Criteria and Explanatory Notes

  Martha Bishop Pitman; Lester Layfield Springer 2015/05 3319165887 96
• Autophagy and Cancer (Current Cancer Research)

  Hong-Gang Wang Springer 2015/02 1489991778 261
• 原子力・量子・核融合事典

  有友嘉浩 (Contributor核分裂の理論的説明)丸善出版 2014/12
• Exotic Nuclei: EXON-2012

  Yu E Penionzhkevich; Yu G Sobolev; Yu E Penionzhkevich; Yu G Sobole World Scientific Publishing Company 2013/06 9814508853 580
• Nuclear Structure in China 2012: Proceedings of the 14th National Conference on Nuclear Structure in China

  Jie Meng; Jie Meng; Cai-Wan Shen; En-Guang Zhao; Shan-Gui Zhou World Scientific Publishing Company 2012/11 9814447471 388
• Theory of Nuclear Fission: A Textbook (Lecture Notes in Physics)

  Hans J. Krappe; Krzysztof Pomorski Springer 2012/02 364223514X 330
• Clusters in Nuclei: Volume 1 (Lecture Notes in Physics)

  Christian Beck Springer 2010/09 9783642138980 316
• Dynamical Aspects of Nuclear Fission: Proceedings of the 6th International Conference, Smolenice Castle, Slovak Republic, 2-6 Ocotber 2006

  J. Kliman; M. G. Itkis; S. Gmuca World Scientific Pub Co Inc 2009/11 9812837523 362
• The Euroschool Lectures on Physics with Exotic Beams, Vol. III (Lecture Notes in Physics)

  J.S. Al-Khalili; Ernst Roeckl Springer 2008/12 3540858385 311
• International Symposium On Exotic Nuclei: Peterhof, Russia, July 5-12, 2004

  International; Symposium on; Exotic Nuclei; Yu E. Penionzhkevich; E. A. Cherepanov World Scientific Pub Co Inc 2005/12 981256392X 737
• Structure and Dynamics of Elementary Matter (Nato Science Series II:)

  Walter Greiner; Mikhail G. Itkis; Joachim Reinhardt; Mehmet Cem Güçlü Springer 2004/11 1402024460 676

Conference Activities & Talks

• Analysis of Evaporation Residue Cross Section in Synthesizing Superheavy Element Region  [Not invited]

  ANUAR Nur Liyana Mohd; ARITOMO Yoshihiro; TANAKA Shoya; YANAGI Baku

  日本物理学会講演概要集(CD-ROM)  2018/03
• Estimation for possibility of synthesizing superheavy element using Dynamical model  [Not invited]

  ANUAR Nur Liyana Mohd; TANAKA Shoya; YANAGI Baku; MIYAMOTO Yuuya; SHALADDIN Ahma; Kushairi Mohd; ARITOMO Yoshihiro

  日本物理学会講演概要集(CD-ROM)  2017/09
• 21aAC-8 Effect on particle evaporation during fusion-fission process for synthesis of superheavy elements  [Not invited]

  Aritomo Y; Hagino K; Nishio K; Ohta M

  Meeting Abstracts of the Physical Society of Japan  2016
• 低エネルギー核分裂過程の動的機構の解明  [Not invited]

  ARITOMO YOSHIHIRO; HOSODA DAISUKE; CHIBA SATOSHI

  日本原子力学会春の年会予稿集(CD-ROM)  2015/03
• 27aSP-7 Effect on particle evaporation during fusion-fission process for synthesis of superheavy elements  [Not invited]

  Aritomo Y; Hagino K; Nishio K; Ohta M

  Meeting Abstracts of the Physical Society of Japan  2015
• 21pCB-7 Fission properties of trans-Bk nuclei with Langevin approach  [Not invited]

  Aritomo Y; Hosoda D; Chiba S; Nishio K

  Meeting Abstracts of the Physical Society of Japan  2015
• 25pSF-4 Experimental research on fusion-fission and multi-nucleon transfer reactions at JAEA  [Not invited]

  Hirose K; Nishio K; Nishinaka I; Mitsuoka S; Makii H; Ikezoe H; Orlandi R; Leguillon R; Smallcombe J; Tsukada K; Asai M; Nagame Y; Andreyev A; Hofmann S; Ackermann D; Hessberger F. P; Heinz S; Khuyagbaatar J; Kindler B; Comas V. F; Heredia J. A; Kojouharov I; Lommel B; Mann R; Dullmann Ch. E; Yakushev A; Popeko A. G; Yeremin A; Kuusiniemi P; Antalic S; Saro S; Chiba S; Ohtsuki; Aritomo Y; Hagino, Yan S; Tatsuzawa R; Takaki N; Tamura N; Goto S; Watanabe Y

  Meeting Abstracts of the Physical Society of Japan  2015
• 25pSF-5 Shell effect in fission process with Langevin approach  [Not invited]

  Aritomo Y

  Meeting Abstracts of the Physical Society of Japan  2015
• 4次元ランジュバン方程式を用いた核分裂モードの研究  [Not invited]

  ARITOMO YOSHIHIRO; HOSODA DAISUKE; CHIBA SATOSHI

  日本原子力学会秋の大会予稿集(CD-ROM)  2014/08
• 動的模型による核分裂機構の系統的研究  [Not invited]

  HOSODA DAISUKE; ARITOMO YOSHIHIRO; CHIBA SATOSHI

  日本原子力学会秋の大会予稿集(CD-ROM)  2014/08
• 核分裂片質量数及びTKE分布に対する対相関及びネック半径の影響  [Not invited]

  HOSODA DAISUKE; ARITOMO YOSHIHIRO; CHIBA SATOSHI

  日本原子力学会春の年会予稿集(CD-ROM)  2014/03
• 核分裂における断裂点付近の形状と分裂モードの解析  [Not invited]

  ARITOMO YOSHIHIRO; HOSODA DAISUKE; CHIBA SATOSHI; HANABUSA KEN'ETSU

  日本原子力学会春の年会予稿集(CD-ROM)  2014/03
• 30aTB-12 Dynamics of fission process with dynamical approach  [Not invited]

  Aritomo Yoshihiro; Hosoda Daisuke; Chiba Satoshi; Iwamoto Akira

  Meeting abstracts of the Physical Society of Japan  2014/03
• 動力学模型を用いた核分裂過程のダイナミクス  [Not invited]

  ARITOMO YOSHIHIRO; HOSODA DAISUKE; CHIBA SATOSHI; IWAMOTO AKIRA

  日本物理学会講演概要集  2014/03
• Fission process of low excited nuclei with dynamical approach  [Not invited]

  Aritomo Yoshihiro; Chiba Satoshi

  Meeting abstracts of the Physical Society of Japan  2013/08
• 動力学模型による低励起核分裂の計算  [Not invited]

  ARITOMO YOSHIHIRO; CHIBA SATOSHI

  日本物理学会講演概要集  2013/08
• 高燃焼度原子炉動特性評価のための遅発中性子収率高精度化に関する研究開発(3)ランジュバン方程式による核分裂片独立収率の計算手法の開発  [Not invited]

  ARITOMO YOSHIHIRO; CHIBA SATOSHI; NISHIO KATSUHISA; HANABUSA KEN'ETSU

  日本原子力学会秋の大会予稿集(CD-ROM)  2013/08
• JAEAにおける代理反応研究の成果(1)全体計画と理論研究  [Not invited]

  CHIBA SATOSHI; ARITOMO YOSHIHIRO; KOURA HIROYUKI; IWAMOTO OSAMU; UTSUNO YUTAKA; HASHIMOTO SHINTARO

  日本原子力学会秋の大会予稿集(CD-ROM)  2012/09
• 20aBH-8 Analysis of surrogate reaction using unified model  [Not invited]

  Aritomo Y; Chiba S; Hashimoto S

  Meeting abstracts of the Physical Society of Japan  2010/03
• 23aSC-10 Initial conditions for the analysis of heavy-ion fusion reactions with the multi-dimensional Langevin equations  [Not invited]

  Fukushima A; Wada T; Ohta M; Nasirov A; Aritomo Y

  Meeting abstracts of the Physical Society of Japan  2006/08
• 23aSC-8 Fission fragment mass distributions in the r-process region II  [Not invited]

  Samyn M; Goriely S

  Meeting abstracts of the Physical Society of Japan  2006/08
• 23aSC-9 Fission fragment mass distributions in the r-process region  [Not invited]

  Tatsuta S; Yamamoto K; Wada T; Ohta M; Sumiyoshi K; Otsuki K; Kajino T; Koura H; Chiba S

  Meeting abstracts of the Physical Society of Japan  2006/08
• 29pWF-2 An improved dynamical approach to fusion processes with the multi-dimensional Langevin equations  [Not invited]

  Fukushima A; Wada T; Ohta M; Nasirov A; Aritomo Y

  Meeting abstracts of the Physical Society of Japan  2006/03
• Prediction for the maximum cross section of superheavy nuclei II  [Not invited]

  OHTA M; ARITOMO Y

  Meeting abstracts of the Physical Society of Japan  2003/03
• Systematics of cross sections for synthesizing superheavy nudei and the status of preparation for synthesizing an unknown 113th element at RIKEN  [Not invited]

  Morita K; Ohta M; Aritomo Y

  Meeting abstracts of the Physical Society of Japan  2002/08
• Prediction for the maximum cross section of superheavy nuclei II  [Not invited]

  OHTA M; ARITOMO Y

  Meeting abstracts of the Physical Society of Japan  2002/08
• Analysis of fusion-fission process with neutron evaporation in superheavy mass region  [Not invited]

  ARITOMO Y; OHTA M

  Meeting abstracts of the Physical Society of Japan  2002/08
• 24aXC-10 超重元素領域における融合分裂経路の動的解析  [Not invited]

  有友 嘉浩; 太田 雅久

  日本物理学会講演概要集  2002/03
• 24aXC-9 超重元素合成断面積の解析と予測  [Not invited]

  太田 雅久; 有友 嘉浩; 福島 賛; 橋詰 和明; 和田 隆宏

  日本物理学会講演概要集  2002/03
• Systematic trend on the synthesis of superheavy elements(I)  [Not invited]

  Ohta M; Aritomo Y; Wada T; Ichikawa T

  Meeting abstracts of the Physical Society of Japan  2001/03
• 質量非対称融合反応による超重核合成(原子核動力学における散逸と減衰,研究会報告)  [Not invited]

  岡崎 謙一郎; 徳田 卓也; 有友 嘉浩; 和田 隆宏; 太田 雅久; 阿部 恭久

  素粒子論研究  1999/06 

  超重核を合成する融合・分裂反応の動的な過程は、揺動散逸動力学で記述される。異なる入射チャネルからの融合反応を調べるために変形自由度に質量非対称度を加えた多次元ランジュバン方程式を数値的に解く。入射時での質量非対称度が大きくなると、fusion hindranceが緩和され融合しやすくなるが、同時に合成系の励起エネルギーが高くなるため、分裂もしやすくなる。いくつかの異なる入射チャネルからの質量非対称融合・分裂反応について蒸発残留核断面積の計算を行い、超重核合成のための入射核、標的核の最適化について述べる。
• 29p-YF-12 The Estimation for the Evaporation Residue Cross Section of Fusion Reactions <48>^Ca^+<238>^U etc.with Dissipation-Fluctuation Dynamics  [Not invited]

  Okazaki K; Tokuda T; Aritomo Y; Wada T; Ohta M; Abe Y

  Meeting abstracts of the Physical Society of Japan  1999/03
• The Evaporation Residue Cross Section in Super Heavy Mass Region with Mass Asymmetry  [Not invited]

  OKAZAKI K; TOKUDA T; ARITOMO Y; WADA T; OHTA M; ABE Y

  Meeting abstracts of the Physical Society of Japan  1998/09
• On the Synthesis of Super Heavy Element by Asymmetry Fusion Reaction  [Not invited]

  OKAZAKI K; TOKUDA T; ARITOMO Y; WADA T; OHTA M; ABE Y

  Meeting abstracts of the Physical Society of Japan  1998/03
• 23p-A-3 Estimation of Evaporation Residue Cross Section of Superheavy Elements by multi-dimensional Diffusion Model  [Not invited]

  Aritomo Y; Okazaki K; Wada T; Ohta M; Abe Y

  Meeting abstracts of the Physical Society of Japan  1997/09
• 23p-A-1 Relaxation of Collective Degrees of Freedom in Heavy Nuclear Fusion Reaction  [Not invited]

  Okazaki K; Tokuda T; Aritomo Y; Wada T; Ohta M; Abe Y

  Meeting abstracts of the Physical Society of Japan  1997/09
• 28p-YM-4 Estimation of Evaporation Residue Cross Section of Superheavy Elements by 2-dimensional Diffusion Model  [Not invited]

  Aritomo Y; Wada T; Ohta M; Abe Y

  Meeting abstracts of the Physical Society of Japan  1997/03
• 6a-F-4 Systematics of Evaporation Residue Cross Section of Superheavy Elements by Diffusion Model  [Not invited]

  Aritomo Y; Wada T; Ohta M; Abe Y

  Abstracts of the meeting of the Physical Society of Japan. Sectional meeting  1996/09
• 6a-F-3 Cooling Property of Excited Nuclei in Superheavy Mass Region  [Not invited]

  Tokuda T; Aritomo Y; Wada T; Ohta M

  Abstracts of the meeting of the Physical Society of Japan. Sectional meeting  1996/09
• 30p-SB-10 Estimation of Evaporation Residue Cross Section of Superheavy Elements by Diffusion Model  [Not invited]

  Aritomo Y; Wada T; Ohta M; Abe Y

  Abstracts of the meeting of the Physical Society of Japan. Sectional meeting  1995/09

MISC

• Angular momentum transfer in multi-nucleon transfer reactions by the measurement of fission fragment angular distributions

  田中翔也; 有友嘉浩; 廣瀬健太郎; 西尾勝久  日本物理学会講演概要集(CD-ROM)  77-  (1)  2022
• Calculation of low excitation fission of 226Th in dynamical model

  宮堺渉; 有友嘉浩; 高木慎弥  日本物理学会講演概要集(CD-ROM)  77-  (1)  2022
• Evaluation of the possibility of new element synthesis using changes in shell structure during the fusion process.

  高木慎弥; 天野翔太; 宮堺渉; 山本匠真; 有友嘉浩  日本物理学会講演概要集(CD-ROM)  77-  (1)  2022
• Development and calculation of dynamical model considering neutron emission during fission process

  山崎僚太; 田中翔也; 高木慎弥; 有友嘉浩; 西尾勝久  日本物理学会講演概要集(CD-ROM)  77-  (1)  2022
• A systematic measurement of mass-centroids for light/heavy fragments in actinide fission

  廣瀬健太郎; 西尾勝久; LEGUILLON Romain; VERMEULEN Mark; RATHA Kean Kun; RATHA Kean Kun; 牧井宏之; ORLANDI Riccardo; 塚田和明; 浅井雅人; 佐藤哲也; 伊藤由太; 洲嵜ふみ; 有友嘉浩; 田中翔也; 田中翔也; 前川北斗; 千葉敏; ANDREYEV Andrei; ANDREYEV Andrei  日本原子力学会春の年会予稿集(CD-ROM)  2022-  2022
• 動力学模型を用いた融合反応における接線方向の摩擦と入射エネルギーの依存性

  天野翔太; 有友嘉浩  原子核研究  66-  (Supplement 3)  2022
• Fission fragment distributions of neutron-rich nuclei based on Langevin calculations: toward r-process simulations

  Mizuki Okubayashi; Shoya Tanaka; Yoshihiro Aritomo; Shoma Ishizaki; Shota Amano; Nobuya Nishimura  2021/05
• 近畿大学 理工学部 電気電子工学科 核反応エネルギー研究室

  有友 嘉浩  原子核研究 / 原子核研究編集委員会 編  65-  (2)  6  -18  2021/03
• 中性子過剰ウラン同位体の核分裂がrプロセス元素合成に与える影響

  西村信哉; 奥村瑞貴; 田中翔也; 田中翔也; 有友嘉浩  日本天文学会年会講演予稿集  2021-  2021
• Measurement of fission-fragment mass distributions in the multinucleon transfer channels of the ¹⁸O+²³⁷Np reaction

  西尾勝久; VERMEULEN Mark J.; 廣瀬健太郎; KEAN Kun Ratha; KEAN Kun Ratha; 牧井宏之; ORLANDI R.; 塚田和明; TSEKHANOVICH Igor; ANDREYEV Andrei N.; ANDREYEV Andrei N.; 石崎翔馬; 奥林瑞貴; 田中翔也; 有友嘉浩  日本原子力学会春の年会予稿集(CD-ROM)  2021-  2021
• Evaporated residual nuclei in Super-heavy nucleus region

  奥川誠也; 有友嘉浩; 天野翔太; 太田雅久  日本物理学会講演概要集(CD-ROM)  76-  (1)  2021
• The analysis for dynamics of superheavy element formation process in nucleon transfer reaction

  天野翔太; 有友嘉浩; 石崎翔馬; 奥林瑞貴  日本物理学会講演概要集(CD-ROM)  76-  (1)  2021
• Fission properties of neutron-rich nuclei using the Langevin approach toward application to r-process calculations

  奥林瑞貴; 有友嘉浩; 田中翔也; 田中翔也; 石崎翔馬; 天野翔太; 西村信哉  日本物理学会講演概要集(CD-ROM)  76-  (1)  2021
• Development of dynamical model considering neutron emission during fission process

  山崎僚太; 田中翔也; 有友嘉浩; 西尾勝久  日本物理学会講演概要集(CD-ROM)  76-  (1)  2021
• Development of Systematic Theoretical Evaluation Method for Superheavy Element Synthesis

  有友嘉浩; 高木慎弥; 泉拓実; 天野翔太; 太田雅久; 西尾勝久  日本物理学会講演概要集(CD-ROM)  76-  (1)  2021
• Analysis of the fission process of ²⁵⁸Md by dynamical model

  石崎翔馬; 奥林瑞貴; 有友嘉浩; 西尾勝久; 廣瀬健太郎  日本物理学会講演概要集(CD-ROM)  76-  (1)  2021
• Fission experiment using Es-254 at JAEA Tokai tandem accelerator facility

  廣瀬健太郎; 西尾勝久; 牧井宏之; ORLANDI R.; 塚田和明; 浅井雅人; 佐藤哲也; 伊藤由太; 洲嵜ふみ; 永目諭一郎; VERMEULEN M.J.; CHIERA N. M.; ANDREYEV A.N.; YAN S.; LIN C.J.; 有友嘉浩; 田中翔也; 宮本裕也; 奥林瑞貴; 石崎翔馬; RATHA K.; 千葉敏; TSEKHANOVICH I.; 大槻勤; 久保野茂; 田中泰貴; 森本幸司; RYKACZEWSKI K.; BOLL R.A.; 豊嶋厚史; 鈴木颯人; 床井健運  日本物理学会講演概要集(CD-ROM)  76-  (1)  2021
• Measurement of fission-fragment mass distributions of nuclei populated in multinucleon transfer channels of the ¹⁸O+²³⁷Np reaction

  西尾勝久; VERMEULEN M.J.; 廣瀬健太郎; KEAN K.R.; KEAN K.R.; 牧井宏之; ORLANDI R.; 塚田和明; TSEKHANOVICH I.; ANDREYEV A.N.; 石崎翔馬; 奥林瑞貴; 田中翔也; 田中翔也; 有友嘉浩  日本物理学会講演概要集(CD-ROM)  76-  (1)  2021
• Nuclear fission of ²⁵⁸Md produced in the ⁴He+²⁵⁴Es reaction

  西尾勝久; 廣瀬健太郎; 牧井宏之; ORLANDI R.; KEAN K.R.; KEAN K.R.; 塚田和明; 豊嶋厚史; 浅井雅人; 佐藤哲也; CHIELA N.M.; 富塚知博; 富塚知博; 床井健運; 床井健運; 柳原陸斗; 柳原陸斗; 鈴木颯人; 鈴木颯人; 永目諭一郎; ANDREYEV A.N.; ANDREYEV A.N.; 田中泰貴; 田中泰貴; 森本幸司; 石崎翔馬; 奥林瑞貴; 宮本裕也; 田中翔也; 有友嘉浩; 久保野茂; RYKACZEWSKI K.P.; BOLL R.A.  日本原子力学会秋の大会予稿集(CD-ROM)  2021-  2021
• ⁴He+²⁵⁴Esで生成される²⁵⁸Md原子核の核分裂

  西尾勝久; 廣瀬健太郎; 牧井宏之; ORLANDI R.; KEAN K.R.; KEAN K.R.; 塚田和明; 豊島厚史; 浅井雅人; 佐藤哲也; CHIELA N.M.; 富塚知博; 富塚知博; 床井健運; 床井健運; 柳原陸斗; 柳原陸斗; 鈴木颯人; 鈴木颯人; 永目諭一郎; ANDREYEV A.N.; ANDREYEV A.N.; 田中泰貴; 田中泰貴; 森本幸司; 石崎翔馬; 奥林瑞貴; 宮本裕也; 田中翔也; 有友嘉浩; 久保野茂; RYKACZEWSKI K.P.; BOLL R.A.  日本物理学会講演概要集(CD-ROM)  76-  (2)  2021
• Study of Fission Fragment Kinetic Energy using Dynamical Model

  宮本裕也; 有友嘉浩; 西尾勝久  日本原子力学会春の年会予稿集(CD-ROM)  2020-  2020
• Survival probability of superheavy compound nuclei with angular momentum

  有友嘉浩; 重清直也; 太田雅久  日本物理学会講演概要集(CD-ROM)  75-  (1)  2020
• Origin of the Dramatic Change of Fission Mode in Fermium Isotope Investigated Using Langevin Equations

  有友嘉浩; 宮本裕也; 西尾勝久  日本物理学会誌  75-  (10)  631  -636  2020
• 高励起複合核における核分裂および中性子放出の競合過程

  田中翔也; 田中翔也; 廣瀬健太郎; 西尾勝久; 有友嘉浩; 太田雅久  日本原子力学会春の年会予稿集(CD-ROM)  2019-  2019
• 動力学模型による融合分裂過程の軌道解析

  有友嘉浩; 田中翔也; ANUAR Liyana; 宮本裕也; 柳漠; 西尾勝久  日本物理学会講演概要集(CD-ROM)  74-  (1)  2019
• 揺動散逸模型における軌道の振る舞いの特殊性

  小川晃史; 有友嘉浩; 田中翔也; 宮本裕也; 石崎翔馬; 太田雅久  日本物理学会講演概要集(CD-ROM)  74-  (1)  2019
• 動力学模型を用いた核子移行反応による中性子過剰核の生成

  天野翔太; 有友嘉浩; 宮本裕也; 小西柾輝  日本物理学会講演概要集(CD-ROM)  74-  (1)  2019
• マイナーアクチノイドの核変換シミュレーション

  小西柾輝; 天野翔太; 宮本裕也; 有友嘉浩  日本物理学会講演概要集(CD-ROM)  74-  (1)  2019
• 動力学模型を用いた重イオン原子核衝突反応における多核子移行反応の理論解析

  宮本裕也; 天野翔太; 下川真門; 有友嘉浩  日本物理学会講演概要集(CD-ROM)  74-  (2)  2019
• 重イオン・多核子移行反応を用いた核分裂の理論評価

  田中翔也; 西尾勝久; 廣瀬健太郎; 有友嘉浩  日本物理学会講演概要集(CD-ROM)  74-  (2)  2019
• 高エネルギー領域における複合核の中性子数および角運動量の変化が核分裂片質量分布へ与える影響

  田中翔也; 田中翔也; 廣瀬健太郎; 西尾勝久; 有友嘉浩  日本原子力学会秋の大会予稿集(CD-ROM)  2019-  2019
• ⁴He+²⁵⁴Es反応で生成される²⁵⁸Mdの核分裂特性の測定

  西尾勝久; 廣瀬健太郎; 牧井宏之; ORLANDI Riccardo; KEAN Kun Ratha; KEAN Kun Ratha; 塚田和明; 浅井雅人; 豊島厚史; 佐藤哲也; 伊藤由太; CHIERA Nadine M.; 松田誠; 永目諭一郎; 田中泰貴; 田中泰貴; 森本幸司; 奥林瑞貴; 石崎翔馬; 田中翔也; 冨塚知博; 冨塚知博; 床井健運; 床井健運; 鈴木颯人; 鈴木颯人; 千葉敏; 有友嘉浩; TSEKHANOVICH Igor; ANDREYEV Andrei N.; ANDREYEV Andrei N.; 久保野茂; BOLL Rose A.; RYKACZEWSKI Krzysztof P.  日本原子力学会秋の大会予稿集(CD-ROM)  2019-  2019
• 動力学模型によるマルチチャンス核分裂の評価

  田中翔也; 廣瀬健太郎; 西尾勝久; 有友嘉浩; 太田雅久  日本原子力学会春の年会予稿集(CD-ROM)  2018-  2018
• Nuclear fission properties of Fermium isotopes calculated by dynamical model

  Miyamoto Y.; Nishio K.; Hirose K.; Tanaka S.; Aritomo Y.  Meeting Abstracts of the Physical Society of Japan  73-  (1)  195  -195  2018
• Systematic estimation of evaporation residue cross sections for superheavy elements using the dynamical model

  Yanagi Baku; Anuar Nur Liyana Mohd; Hagino Kouichi; Aritomo Yoshihiro; Ohta M.  Meeting Abstracts of the Physical Society of Japan  73-  (1)  181  -181  2018
• Estimation of Surrogate reaction process using Dynamical model and Statistical model

  Tanaka Shoya; Nishio Katsuhisa; Hirose Kentaro; Ohta Masahisa; Miyamoto Yuya; Aritomo Yoshihiro  Meeting Abstracts of the Physical Society of Japan  73-  (1)  179  -179  2018
• Mechanism of fusion-fission process in superheavy mass region by dynamical model

  Hachikubo Hiroki; Liyana Nur; Tanaka Shoya; Yanagi Baku; Miyamoto Yuya; Aritomo Yoshihiro  Meeting Abstracts of the Physical Society of Japan  73-  (1)  180  -180  2018
• Effect of nuclear structure on fusion process in super heavy mass region.

  Aritomo Yoshihiro; Hachikubo Hiroki; Tanaka Syouya; Anuar Liyana; Miyamoto Yuya; Yanagi Baku  Meeting Abstracts of the Physical Society of Japan  73-  (1)  178  -178  2018
• Analysis of evaporation residue cross section in synthesizing superheavy element region

  Anuar Nur Liyana Mohd; Aritomo Yoshihiro; Tanaka Shoya; Yanagi Baku  Meeting Abstracts of the Physical Society of Japan  73-  (0)  171  -171  2018
• ランジュバン計算によるmulti-chance fissionの研究

  田中翔也; 廣瀬健太郎; 西尾勝久; 有友嘉浩  日本物理学会講演概要集(CD-ROM)  72-  (1)  2017
• Estimation for possibility of synthesizing superheavy element using Dynamical model.

  Anuar Nur Liyana Mohd; Aritomo Yoshihiro; Tanaka Shoya; Yanagi Baku; Miyamoto Yuuya; Shaladdin Ahmad Kushairi Mohd  Meeting Abstracts of the Physical Society of Japan  72-  (0)  131  -131  2017
• Estimation of fission fragment mass distributions by dynamical model including multi-chance fission

  Tanaka Shoya; Hirose Kentaro; Nishio Katsuhisa; Ohta Masahisa; Aritomo Yoshihiro; Liyana Nur; Miyamoto Yuya; Yanagi Baku; Kushairi Ahmad  Meeting Abstracts of the Physical Society of Japan  72-  (2)  130  -130  2017
• Analysis of fusion-fission process in super-heavy and heavy mass region using dynamical model

  Aritomo Yoshihiro; Tanaka Shouya; Tanaka Taiki; Hayashi Yoshiki; Kobayashi Shouta; Nakagawa Jin; Sawada Shou; Anuar Nur Liyana Binti Mohd  Meeting Abstracts of the Physical Society of Japan  72-  (1)  205  -205  2017
• Isotopic distribution of 235U + n .RAR. 236U at low E* using 4D-Langevin calculation

  ISHIZUKA Chikako; CHIBA Satoshi; KARPOV Alexander V; ARITOMO Yoshihiro  日本原子力研究開発機構JAEA-Conf(Web)  (2016-004)  99‐103 (WEB ONLY)  2016/09
• 重イオン反応による新たな核分裂核データ取得方法を確立

  西尾勝久; 廣瀬健太郎; 千葉敏; 有友嘉浩  プレス発表  2016/08
• 核分裂研究のためのランジュバン計算の4次元化(2)4次元ランジュバン核分裂計算のための微視的ポテンシャル

  浅野大雅; 和田隆宏; 有友嘉浩; 太田雅久  日本原子力学会春の年会予稿集(CD-ROM)  2016-  2016
• 核分裂研究のためのランジュバン計算の4次元化(3)液滴ポテンシャルを用いた4次元ランジュバン核分裂計算

  有友嘉浩; 浅野大雅; 和田隆宏; 太田雅久  日本原子力学会春の年会予稿集(CD-ROM)  2016-  2016
• 核分裂研究のためのランジュバン計算の4次元化(1)ランジュバン方程式を用いた核分裂計算

  和田隆宏; 浅野大雅; 有友嘉浩; 太田雅久  日本原子力学会春の年会予稿集(CD-ROM)  2016-  2016
• Possibility of synthesizing a doubly magic superheavy nucleus using dynamical model.

  Aritomo Yoshihiro  Meeting Abstracts of the Physical Society of Japan  71-  (0)  116  -116  2016
• 21aAC-8 Effect on particle evaporation during fusion-fission process for synthesis of superheavy elements

  Aritomo Y.; Hagino K.; Nishio K.; Ohta M.  Meeting Abstracts of the Physical Society of Japan  71-  (0)  230  -230  2016
• 低エネルギー核分裂過程の動的機構の解明

  有友嘉浩; 細田大輔; 千葉敏  日本原子力学会春の年会予稿集(CD-ROM)  2015-  2015
• ランジュバン模型による荷電分布の改良

  石塚知香子; 千葉敏; 有友嘉浩; KARPOV A. V.  日本原子力学会秋の大会予稿集(CD-ROM)  2015-  2015
• 27aSP-8 Improvement of charge distribution with the Langevin model

  Ishizuka C.; Satoshi C.; Aritomo Y.; Karpov A. V.  Meeting Abstracts of the Physical Society of Japan  70-  (0)  164  -164  2015
• 25pSF-4 Experimental research on fusion-fission and multi-nucleon transfer reactions at JAEA

  Hirose K.; Tsukada K.; Asai M.; Nagame Y.; Andreyev A.; Hofmann S.; Ackermann D.; Hessberger F. P.; Heinz S.; Khuyagbaatar J.; Kindler B.; Nishio K.; Comas V. F.; Heredia J. A.; Kojouharov I.; Lommel B.; Mann R.; Dullmann Ch. E.; Yakushev A.; Popeko A. G.; Yeremin A.; Kuusiniemi P.; Nishinaka I.; Antalic S.; Saro S.; Chiba S.; Ohtsuki; Aritomo Y.; Hagino; Yan S.; Tatsuzawa R.; Takaki N.; Tamura N.; Mitsuoka S.; Goto S.; Watanabe Y.; Makii H.; Ikezoe H.; Orlandi R.; Leguillon R.; Smallcombe J.  Meeting Abstracts of the Physical Society of Japan  70-  (0)  240  -241  2015
• 21pCB-7 Fission properties of trans-Bk nuclei with Langevin approach

  Aritomo Y.; Hosoda D.; Chiba S.; Nishio K.  Meeting Abstracts of the Physical Society of Japan  70-  (0)  137  -137  2015
• 25pSF-5 Shell effect in fission process with Langevin approach

  Aritomo Y.  Meeting Abstracts of the Physical Society of Japan  70-  (0)  242  -242  2015
• 27aSP-7 Effect on particle evaporation during fusion-fission process for synthesis of superheavy elements

  Aritomo Y.; Hagino K.; Nishio K.; Ohta M.  Meeting Abstracts of the Physical Society of Japan  70-  (0)  163  -163  2015
• 核分裂における断裂点付近の形状と分裂モードの解析

  有友嘉浩; 細田大輔; 千葉敏; 英憲悦  日本原子力学会春の年会予稿集(CD-ROM)  2014-  2014
• 4次元ランジュバン方程式を用いた核分裂モードの研究

  有友嘉浩; 細田大輔; 千葉敏  日本原子力学会秋の大会予稿集(CD-ROM)  2014-  2014
• 核分裂片質量数及びTKE分布に対する対相関及びネック半径の影響

  細田大輔; 有友嘉浩; 千葉敏  日本原子力学会春の年会予稿集(CD-ROM)  2014-  2014
• 動的模型による核分裂機構の系統的研究

  細田大輔; 有友嘉浩; 千葉敏  日本原子力学会秋の大会予稿集(CD-ROM)  2014-  2014
• 30aTB-12 Dynamics of fission process with dynamical approach

  Aritomo Yoshihiro; Hosoda Daisuke; Chiba Satoshi; Iwamoto Akira  Meeting Abstracts of the Physical Society of Japan  69-  (0)  65  -65  2014
• 高燃焼度原子炉動特性評価のための遅発中性子収率高精度化に関する研究開発(3)ランジュバン方程式による核分裂片独立収率の計算手法の開発

  有友嘉浩; 千葉敏; 西尾勝久; 英憲悦  日本原子力学会秋の大会予稿集(CD-ROM)  2013-  2013
• Fission process of low excited nuclei with dynamical approach

  Aritomo Yoshihiro; Chiba Satoshi  Meeting Abstracts of the Physical Society of Japan  68-  (0)  51  -51  2013
• Fusion of Massive Systems and Superheavy Elements

  Hagino Kouichi; Aritomo Yoshihiro  Butsuri  68-  (10)  654  -661  2013
• New fission mechanism peculiar to proton-rich nuclei

  ANDREYEV Andrei; NISHIO Katsuhisa; DERKX Xavier; LANE Joseph; LIBERATI Valentina; SANDHU Kalvinder; CHIBA Satoshi; MITSUOKA Shin‐ichi; NISHINAKA Ichiro; MAKII Hiroyuki; WAKABAYASHI Yasuo; ARITOMO Yoshihiro; OTA Shuya; NAGAYAMA Tatsuro; GHYS Lars; OHTSUKI Tsutomu  日本原子力研究開発機構JAEA-Review(Web)  (2012-036)  9-13 (WEB ONLY)  2012/10
• Research in Surrogate Reactions at JAEA:(1)Overview and Theoretical Research

  Chiba Satoshi; Aritomo Yoshihiro; Koura Hiroyuki; Iwamoto Osamu; Utsuno Yutaka; Hashimoto Shintaro  Proceedings of Annual / Fall Meetings of Atomic Energy Society of Japan  2012-  (0)  50  -50  2012
• Fission neutrons in surrogate reactions

  ARITOMO YOSHIHIRO; CHIBA SATOSHI; NISHIO KASTUHISA  Proceedings of Annual / Fall Meetings of Atomic Energy Society of Japan  2011-  (0)  68  -68  2011
• Status of Theoretical Investigation of Surrogate Reactions

  Chiba Satoshi; Ogata Kazuyuki; Hashimoto Shintaro; Aritomo Yoshihiro  Proceedings of Annual / Fall Meetings of Atomic Energy Society of Japan  2011-  (0)  45  -45  2011
• Theoretical Research on Surrogate Reaction:(2) Application of the unified model to surrogate reaction

  ARITOMO YOSHIHIRO; CHIBA SATOSHI; HASHIMOTO SHINTARO; UTSUNO YUTAKA; KOURA HIROYUKI  Proceedings of Annual / Fall Meetings of Atomic Energy Society of Japan  2010-  (0)  42  -42  2010
• Theoretical Research on Surrogate Reaction:- 3. Study of excited states produced by direct reaction process -

  HASHIMOTO SHINTARO; CHIBA SATOSHI; ARITOMO YOSHIHIRO; UTSUNO YUTAKA  Proceedings of Annual / Fall Meetings of Atomic Energy Society of Japan  2010-  (0)  43  -43  2010
• Analysis of fission-process of compound nucleus produced by surrogate reaction

  ARITOMO YOSHIHIRO; CHIBA SATOSHI; NISHIO KASTUHISA  Proceedings of Annual / Fall Meetings of Atomic Energy Society of Japan  2010-  (0)  87  -87  2010
• 20aBH-8 Analysis of surrogate reaction using unified model

  Aritomo Y.; Chiba S.; Hashimoto S.  Meeting Abstracts of the Physical Society of Japan  65-  (0)  36  -36  2010
• Possibility of synthesizing doubly closed superheavy nucleus(International Workshop on Nuclear Structure-New Pictures in the Extended Isospin Space(NS07)-)

  ARITOMO YOSHIHIRO  Soryushiron Kenkyu Electronics  115-  (3)  C50  2007  [Refereed]
  
• 29pWF-2 An improved dynamical approach to fusion processes with the multi-dimensional Langevin equations

  Fukushima A.; Wada T.; Ohta M.; Nasirov A.; Aritomo Y.  Meeting Abstracts of the Physical Society of Japan  61-  (0)  41  -41  2006
• 23aSC-10 Initial conditions for the analysis of heavy-ion fusion reactions with the multi-dimensional Langevin equations

  Fukushima A.; Wada T.; Ohta M.; Nasirov A.; Aritomo Y.  Meeting Abstracts of the Physical Society of Japan  61-  (0)  24  -24  2006
• Prediction for the maximum cross section of superheavy nuclei II

  OHTA M.; ARITOMO Y.  Meeting Abstracts of the Physical Society of Japan  58-  (0)  38  -38  2003
• 24aXC-9 超重元素合成断面積の解析と予測

  太田 雅久; 有友 嘉浩; 福島 賛; 橋詰 和明; 和田 隆宏  日本物理学会講演概要集  57-  (0)  22  -22  2002
• 24aXC-10 超重元素領域における融合分裂経路の動的解析

  有友 嘉浩; 太田 雅久  日本物理学会講演概要集  57-  (0)  22  -22  2002
• Analysis of fusion-fission process with neutron evaporation in superheavy mass region

  ARITOMO Y.; OHTA M.  Meeting Abstracts of the Physical Society of Japan  57-  (0)  23  -23  2002
• Prediction for the maximum cross section of superheavy nuclei II

  OHTA M.; ARITOMO Y.  Meeting Abstracts of the Physical Society of Japan  57-  (0)  24  -24  2002
• Systematics of cross sections for synthesizing superheavy nudei and the status of preparation for synthesizing an unknown 113th element at RIKEN

  Morita K.; Ohta M.; Aritomo Y.  Meeting Abstracts of the Physical Society of Japan  57-  (0)  24  -24  2002
• Systematic trend on the synthesis of superheavy elements(I)

  Ohta M.; Aritomo Y.; Wada T.; Ichikawa T.  Meeting Abstracts of the Physical Society of Japan  56-  (0)  22  -22  2001
• Dubna, The Center of Investigation for Superheavy Elements(La Toccata)

  Aritomo Yoshihiro  Butsuri  56-  (9)  695  -697  2001
• DIFFUSION MODEL FOR SYNTHESIS OF SUPERHEAVY ELEMENTS

  Aritomo Y.; Kosenko G.I.; Oganessian Yu.Ts.; Okazaki K.; Wada T.; Ohta M.; Abe Y.  Soryushiron Kenkyu  99-  (3)  C68  1999/06
• 揺動散逸動力学による⁴⁸Ca+²³⁸U融合反応等の蒸発残留核断面積の評価

  岡崎謙一郎; 徳田卓也; 和田隆宏; 有友嘉浩; 太田雅久; 阿部恭久  日本物理学会講演概要集  54-  (1)  1999
• 29p-YF-12 The Estimation for the Evaporation Residue Cross Section of Fusion Reactions <48>^Ca^+<238>^U etc.with Dissipation-Fluctuation Dynamics

  Okazaki K.; Tokuda T.; Aritomo Y.; Wada T.; Ohta M.; Abe Y.  Meeting Abstracts of the Physical Society of Japan  54-  (0)  32  -32  1999
• 質量非対称融合反応による超重核合成(原子核動力学における散逸と減衰,研究会報告)

  岡崎 謙一郎; 徳田 卓也; 有友 嘉浩; 和田 隆宏; 太田 雅久; 阿部 恭久  素粒子論研究  99-  (3)  C60  -C65  1999
• The Evaporation Residue Cross Section in Super Heavy Mass Region with Mass Asymmetry

  OKAZAKI K.; TOKUDA T.; ARITOMO Y.; WADA T.; OHTA M.; ABE Y.  Meeting Abstracts of the Physical Society of Japan  53-  (0)  32  -32  1998
• On the Synthesis of Super Heavy Element by Asymmetry Fusion Reaction

  OKAZAKI K.; TOKUDA T.; ARITOMO Y.; WADA T.; OHTA M.; ABE Y.  Meeting Abstracts of the Physical Society of Japan  53-  (0)  40  -40  1998
• 23p-A-1 Relaxation of Collective Degrees of Freedom in Heavy Nuclear Fusion Reaction

  Okazaki K.; Tokuda T.; Aritomo Y.; Wada T.; Ohta M.; Abe Y.  Meeting Abstracts of the Physical Society of Japan  52-  (0)  49  -49  1997
• 23p-A-3 Estimation of Evaporation Residue Cross Section of Superheavy Elements by multi-dimensional Diffusion Model

  Aritomo Y.; Okazaki K.; Wada T.; Ohta M.; Abe Y.  Meeting Abstracts of the Physical Society of Japan  52-  (0)  50  -50  1997
• 28p-YM-4 Estimation of Evaporation Residue Cross Section of Superheavy Elements by 2-dimensional Diffusion Model

  Aritomo Y.; Wada T.; Ohta M.; Abe Y.  Meeting Abstracts of the Physical Society of Japan  52-  (0)  40  -40  1997
• 6a-F-3 Cooling Property of Excited Nuclei in Superheavy Mass Region

  Tokuda T.; Aritomo Y.; Wada T.; Ohta M.  Meeting Abstracts of the Physical Society of Japan  1996-  (0)  56  -56  1996
• 6a-F-4 Systematics of Evaporation Residue Cross Section of Superheavy Elements by Diffusion Model

  Aritomo Y.; Wada T.; Ohta M.; Abe Y.  Meeting Abstracts of the Physical Society of Japan  1996-  (0)  57  -57  1996
• 30p-SB-10 Estimation of Evaporation Residue Cross Section of Superheavy Elements by Diffusion Model

  Aritomo Y.; Wada T.; Ohta M.; Abe Y.  Meeting Abstracts of the Physical Society of Japan  1995-  (0)  88  -88  1995

Awards & Honors

• 2020/12 EPJ Steering Committee EPJ Distinguished Referee in 2020
   

  受賞者: Yoshihiro Aritomo
• 2012/09 日本原子力学会 核データ部会 学術賞
   代理反応の理論的研究 

  受賞者: 千葉敏;岩本修;西尾勝久;橋本慎太郎;有友嘉浩;緒方一介
• 2003/01 The Scientific Council of the Joint Institute for Nuclear Research Awarded. The second prize of the Joint Institute for Nuclear Research.
   

  受賞者: Yoshihiro Aritomo

Research Grants & Projects

• A unified understanding of r-process nucleosynthesis from gravitational wave and kilonova observations

  Japan Society for the Promotion of Science：Grants-in-Aid for Scientific Research

  Date (from‐to) : 2021/04 -2024/03 

  Author : 西村 信哉; 湊 太志; LIANG HAOZHAO; 今井 伸明; 西村 俊二; 有友 嘉浩

   

  本研究計画では、宇宙における重元素生成のうち、金やプラチナ、ウラン等のアクチノイドの起源であるrプロセスを対象とする。rプロセスは、連星中性子星の合体や超新星などの爆発的な天体環境で起こると考えられる。rプロセス元素合成の起こる環境では、高い中性子数密度により中性子捕獲が爆発的に進み、大量の中性子過剰核が形成される。それらの中性子過剰核の多くは実験で確認されておらず、現在行われているrプロセスの計算では不定性の大きい理論予測値に基づいている。本研究計画では、中性子過剰核の反応・崩壊率の理論計算をアップデートし、rプロセス計算に適用し影響を調べる。さらに、原子核の不定性を考慮したモンテカルロ元素合成計算を用いて、不定性の定量的な評価とともに重要な反応率を同定する。 本年度は、主として中性子過剰核に関する崩壊の分岐比の計算と核分裂の動力学計算において進展があった。中性子過剰核がベータ崩壊することで、新たな核種の励起状態が得られるが、その後、ガンマ線を放出し脱励起するか中性子を出す、あるいは、重い核では核分裂する。これらの違いは原子核の構造によるが、この分岐比はrプロセス元素合成への影響が大きい。我々は、最新の理論計算により核図表の広い範囲にわたって、この値を計算した。ウランやより重い超重元素などは核分裂を引き起こす。分裂は確率過程であり、実際にどのような分布になるかは動力学計算を用いて評価する必要がある。我々は中性子過剰核でも未到の領域を対象に核分裂計算を行い、核分裂分布を計算した。 また、我々は、以上の反応・崩壊率のアップデートに基づいて、モンテカルロ元素合成計算により諸量の影響を調べた。同じ計算の枠組みで陽子過剰核での元素合成についても着目し、中性子過剰核で今のところ達成できない核反応の実験について最新の反応率を評価し、元素合成への影響を調べた。
• 融合ダイナミクスに起因する殻構造の変化を利用した未知超重元素生成の理論研究

  日本学術振興会：科学研究費助成事業 基盤研究(C)

  Date (from‐to) : 2020/04 -2023/03 

  Author : 有友 嘉浩

   

  研究実施計画に基づき本年度は、昨年度に整備したプログラムコードを用いて、新元素合成に関する様々な計算を行った。特に未知原子核である120番元素の合成を中心に、融合確率、融合過程の軌道解析とその反応メカニズムの解析、および残留核断面積の計算を行い、その妥当性を評価した。 変形空間でのポテンシャルの状況を詳細に解析し、殻補正エネルギーによる準安定な形状を見つけ出し、動力学模型における融合軌道が、準安定な状態、すなわちポテンシャル上のポケットにトラップされるかどうかについて、入射条件を様々に変化しながら解析を行った。融合過程における準安定な状態は、原子核の比較的大きく変形した地点に存在する。超重元素領域における融合反応過程では、標的核と入射核の同士の大きなクーロン反発により、大きく変形すると考えられ、軌道も同様に変形領域に向かう。この時、変形領域に存在するポテンシャルのポケットにトラップされる現象が見られた。このような軌道の存在確率や、どのような条件（入射核と標的核の組み合わせ、入射エネルギーなどの初期条件）の場合、より多くこの領域に到達できるのか、またトラップされるのかを試行錯誤で調べた。 原子番号120番元素を生成する場合、標的核による中性子過剰な核を使用するほうが、変形領域のポケットの地点と軌道の到達点が一致することを見出した。融合確率を算出し、スタンダードな統計模型コードを利用して蒸発残留核断面積を算出したが、まだ試算の段階であり、今後はこの手法で精度を上げていき、より現実的な実験の提案を行うことを目的とする。このような成果は、2022年3月の物理学会等で口頭発表を行った。
• New approach for synthesis of superheavy elements using dynamical model

  Japan Society for the Promotion of Science：Grants-in-Aid for Scientific Research

  Date (from‐to) : 2017/04 -2020/03 

  Author : Aritomo Yoshihiro

   

  To synthesis of superheavy elements, the shell structure is very important not only in the stability of nuclei, but also the fusion process, especially the cold fusion reaction. We employ the Langevin equation with the microscopic transport coefficients and calculate the fusion cross section for the reaction 70Zn+ 208 Pb as a test. We found the enhancement of the fusion probability due to the small friction. In the dynamical process, the effect of nuclear structure is investigated precisely. We suggest new approach for synthesis of superheavy elements.
• 動力学模型による未知超重元素の新しい生成手法の研究

  独立行政法人 日本学術振興会：2017年度 基盤研究(C)

  Date (from‐to) : 2017/04 -2020/03 

  Author : 有友嘉浩
• No. 03-01-6417

  INTAS：INTAS projects

  Date (from‐to) : 2003/09 -2007/08 

  Author : Francis Hanappe
• No. 04-02-04008

  Russia and Germany：the Russian Foundation for Basic Research project and Deutsche Forschungsgemeinschaft

  Date (from‐to) : 2004/09 -2005/09 

  Author : V. Zagrebaev
• 超重元素合成における理論的研究

  日本学術振興会：科学研究費助成事業 特別研究員奨励費

  Date (from‐to) : 2001 -2003 

  Author : 有友 嘉浩

   

  超重元素合成の実験的研究は活発さを増し、今年度はロシアのドウブナーで115番元素および113番元素の2つの新元素合成に成功した。同じ時期、理化学研究所でも113番元素の合成に取り組んでおり、現在国際間でこのような競争が激化してきている。本研究ではこの領域での反応理論を構築し、実験計画に有用な情報を与えることである。 最終的な目標は超重核の蒸発残留核断面積を求めることであるが、絶対値が数ピコバーンという微小な現象を精度良く扱うには今の理論の枠組みでは不十分であり、モデルの改良や不定なパラメーターの決定が不可欠である。したがって、蒸発残留格段面積を求める際に不可欠な融合断面積を精度良く求めるために融合分裂反応機構の解明に焦点を当て研究を行った。微小な現象も記述できる散逸揺動模型を導入し、原子核の変形空間における形状の時間発展(軌道)を解析をすることで融合分裂過程の解明を試みた。実験では分裂片の質量分布が測定されており、このデータと計算による軌道を比較することで、分裂片が複合核から来ているか否かを判定することが可能である。この手法を用いて融合断面積を詳細に決定した。計算結果から、超重核領域では質量対称分裂のイベントの90パーセント以上は複合核を経由しないでquasi-fission過程から来ていることが分かった。 さらに詳細に解析するには、分裂片の質量分布だけでなく、中性子放出多重度を用いることが有効である。計算における軌道の行程の長さは実験では中性子放出多重度と相関関係がある。すなわち軌道の時間尺度と中性子放出の時間尺度は対応し、このことを使って融合分裂過程の詳細な解析を試みた。 58Ni+208Pbにおいて入射エネルギーが励起エネルギーに換算して180MeVの場合、実験で測定された中性子多重度は4個と8個の周りにそれぞれピークをもつ。計算でもこの二山は再現され、前者はquasi-fission過程から放出された中性子であり、後者は融合分裂過程からのものであることを示すことが出来た。超重核領域の実験でも中性子放出多重度は2山を持つことが測定されており、このような実験データを詳細に再現することが今後の課題である。
• 拡散模型による超重元素の生成断面積の研究

  財団法人 日本科学協会：笹川科学研究助成

  Date (from‐to) : 1996/04 -1998/03 

  Author : 有友嘉浩

Other link

researchmap

https://researchmap.jp/aritomo