KINDAI UNIVERSITY


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ARITOMO Yoshihiro

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FacultyDepartment of Electric and Electronic Engineering / Graduate School of Science and Engineering Research / Atomic Energy Research Institute
PositionAssociate Professor
Degree
Commentator Guidehttps://www.kindai.ac.jp/meikan/1376-aritomo-yoshihiro.html
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Last Updated :2020/09/30

Research Activities

Research Areas

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

Published Papers

  • Modeling of Nuclear Reactions with Langevin Calculations, 84(8), 1034 - 1048, Sep. 2020 , Refereed
  • Estimation of Synthesizing New Superheavy Elements, Y. Aritomo, S.Amano, M. Okubayashi, B. Yanagi, K.Nishio, M.Ohta, Physics of Atomic Nuclei, Physics of Atomic Nuclei, 83(4), 545 - 549, Apr. 2020 , 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, 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, Frontiers in Nuclear and Particle Physics, 2, 255 - 282, 2019 , 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, EPJ Web of Conferences, 169, Mar. 2018 , Refereed
    Summary:© 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, 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, EPJ Web of Conferences, 163, Nov. 2017 , Refereed
    Summary:© 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, EPJ Web of Conferences, 163, Nov. 2017 , Refereed
    Summary:© 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.
  • 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, PHYSICS LETTERS B, 761, 125 - 130, Oct. 2016 , Refereed
    Summary: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.
  • 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, Ann Rep ASRC, 2011, 12, 2011
  • 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, Jul. 30 2004 , Refereed
    Summary: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, Jul. 30 2004 , Refereed
    Summary: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.
  • Fusion-Fission Process of Superheavy Elements with Fluctuation-Dissipation Model, ARITOMO Yoshihiro, Progress of Theoretical Physics, Progress of Theoretical Physics, 146(146), 503 - 507, Dec. 26 2002 , Refereed
    Summary: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, Progress of Theoretical Physics, 503 - 507, Dec. 01 2002
    Summary: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.
  • 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, Physical Review C, 100(6), 064605, Dec. 13 2019 , 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, Physical Review C, 99(5), 051601(R), May 14 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", Proceedings of the Ito International Research Center Symposium "Perspectives of the Physics of Nuclear Structure", Dec. 27 2018 , 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, SCIENTIFIC WORKSHOP ON NUCLEAR FISSION DYNAMICS AND THE EMISSION OF PROMPT NEUTRONS AND GAMMA RAYS (THEORY-4), SCIENTIFIC WORKSHOP ON NUCLEAR FISSION DYNAMICS AND THE EMISSION OF PROMPT NEUTRONS AND GAMMA RAYS (THEORY-4), 169, 2018 , Refereed
    Summary: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.
  • 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, PHYSICAL REVIEW LETTERS, 119(22), Nov. 2017 , Refereed
    Summary: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.
  • 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, FUSION17, 163, 2017 , Refereed
    Summary: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, FUSION17, 163, 2017 , Refereed
    Summary: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, ND 2016: INTERNATIONAL CONFERENCE ON NUCLEAR DATA FOR SCIENCE AND TECHNOLOGY, 146(146), 2017 , Refereed
    Summary: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.
  • 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, EPJ Web of Conferences, 106, Feb. 03 2016 , Refereed
    Summary: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, ISRD 15 - INTERNATIONAL SYMPOSIUM ON REACTOR DOSIMETRY, 106, 2016 , Refereed
    Summary: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, JOURNAL OF NUCLEAR SCIENCE AND TECHNOLOGY, 53(6), 737 - 748, 2016 , Refereed
    Summary: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, CNR*15 - 5TH INTERNATIONAL WORKSHOP ON COMPOUND-NUCLEAR REACTIONS AND RELATED TOPICS, 122, 2016 , Refereed
    Summary: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, PROGRESS IN NUCLEAR ENERGY, 85, 568 - 572, Nov. 2015 , Refereed
    Summary: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.
  • 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, SCIENTIFIC WORKSHOP ON NUCLEAR FISSION DYNAMICS AND THE EMISSION OF PROMPT NEUTRONS AND GAMMA RAYS, THEORY-3, 64, 28 - 33, 2015 , Refereed
    Summary: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, Physics Procedia, 64, 28 - 33, 2015 , Refereed
    Summary: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), FOURTH INTERNATIONAL SYMPOSIUM ON INNOVATIVE NUCLEAR ENERGY SYSTEMS (INES-4), 71, 205 - 212, 2015 , Refereed
    Summary: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, Physical Review C - Nuclear Physics, 90(5), Nov. 18 2014
    Summary: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, Physical Review C - Nuclear Physics, 90(5), Nov. 14 2014 , Refereed
    Summary: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, PHYSICAL REVIEW C, 90(5), Nov. 2014 , Refereed
    Summary: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, PHYSICAL REVIEW C, 90(5), Nov. 2014 , Refereed
    Summary: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, NUCLEAR DATA SHEETS, 119, 299 - 302, May 2014 , Refereed
    Summary: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, NUCLEAR DATA SHEETS, 119, 229 - 232, May 2014 , Refereed
    Summary: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, INPC 2013 - INTERNATIONAL NUCLEAR PHYSICS CONFERENCE, VOL. 1, 66, 03065-1 - 4, 2014 , Refereed
    Summary: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, EPJ Web of Conferences, 66, 2014
    Summary: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, Physical Review C - Nuclear Physics, 88(4), Oct. 23 2013
    Summary: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), INTERNATIONAL CONFERENCE ON RECENT TRENDS IN NUCLEAR PHYSICS-2012 (ICRTNP-2012), 1524, 68 - 72, 2013
    Summary: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, PHYSICAL REVIEW C, 86(3), Sep. 2012
    Summary: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, PHYSICAL REVIEW C, 85(4), Apr. 2012
    Summary: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, HEAVY ION ACCELERATOR SYMPOSIUM ON FUNDAMENTAL AND APPLIED SCIENCE 2012, 35, 2012 , Refereed
    Summary: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, NUCLEAR STRUCTURE AND DYNAMICS '12, 1491, 303 - 306, 2012
    Summary: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, EPJ Web of Conferences, 35, 2012
    Summary: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, PHYSICAL REVIEW C, 84(5), 054602.1-054602.5, Nov. 2011 , Refereed
    Summary: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.
  • Spin-dependent observables in surrogate reactions, Satoshi Chiba, Osamu Iwamoto, Yoshihiro Aritomo, PHYSICAL REVIEW C, PHYSICAL REVIEW C, 84(5), Nov. 2011 , Refereed
    Summary: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, EPJ Web of Conferences, 17, Oct. 19 2011
    Summary: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, PHYSICAL REVIEW C, 84(2), Aug. 2011
    Summary: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.
  • 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, 5TH INTERNATIONAL CONFERENCE FUSION11, 17, 2011 , Refereed
    Summary: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.
  • 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, PHYSICAL REVIEW C, 82(4), Oct. 2010
    Summary: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, PHYSICAL REVIEW C, 82(2), Aug. 2010
    Summary: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, INTERNATIONAL JOURNAL OF MODERN PHYSICS E-NUCLEAR PHYSICS, 19(5-6), 813 - 824, Jun. 2010 , Refereed
    Summary: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, EPJ Web of Conferences, 2, Mar. 09 2010
    Summary: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, CNR '09: SECOND INTERNATIONAL WORKSHOP ON COMPOUND NUCLEAR REACTIONS AND RELATED TOPICS, 2, 2010 , Refereed
    Summary: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, INTERNATIONAL SYMPOSIUM ON EXOTIC NUCLEI 2009, 1224, 356 - 365, 2010
    Summary: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, PHYSICAL REVIEW C, 80(6), Dec. 2009
    Summary: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, INTERNATIONAL JOURNAL OF MODERN PHYSICS E-NUCLEAR PHYSICS, 18(10), 2145 - 2149, Nov. 2009 , Refereed
    Summary: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, PERSPECTIVES IN NUCLEAR PHYSICS, 1120, 27 - 31, 2009
    Summary: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, DYNAMICAL ASPECTS OF NUCLEAR FISSION, 112 - +, 2008
    Summary: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, DYNAMICAL ASPECTS OF NUCLEAR FISSION, 22 - +, 2008
    Summary: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, DYNAMICAL ASPECTS OF NUCLEAR FISSION, 155 - +, 2008
    Summary: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, PHYSICS OF PARTICLES AND NUCLEI, 38(4), 469 - 491, Jul. 2007
    Summary: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, PHYSICAL REVIEW C, 75(2), Feb. 2007
    Summary: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, TOURS SYMPOSIUM ON NUCLEAR PHYSICS VI, 891, 423 - +, 2007
    Summary: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, TOURS SYMPOSIUM ON NUCLEAR PHYSICS VI, 891, 443 - +, 2007
    Summary: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, International Symposium on Exotic Nuclei, 912, 286 - 298, 2007
    Summary: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, International Symposium on Exotic Nuclei, 912, 266 - 275, 2007
    Summary: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, NUCLEAR PHYSICS A, 780(3-4), 222 - 246, Dec. 2006
    Summary: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, JOURNAL OF PHYSICS G-NUCLEAR AND PARTICLE PHYSICS, 32(11), 2245 - 2259, Nov. 2006 , Refereed
    Summary: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, INTERNATIONAL JOURNAL OF MODERN PHYSICS E-NUCLEAR PHYSICS, 15(2), 311 - 317, Mar. 2006
    Summary: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, Nuclear Physics A, 764(1-4), 149 - 159, Jan. 09 2006
    Summary: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, FUSION06: Reaction Mechanisms and Nuclear Structure at the Coulomb Barrier, 853, 259 - 264, 2006
    Summary: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, NUCLEAR PHYSICS A, 759(3-4), 342 - 369, Sep. 2005
    Summary: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, NUCLEAR PHYSICS A, 759(3-4), 309 - 326, Sep. 2005
    Summary: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, NUCLEAR PHYSICS A, 753(1-2), 152 - 173, May 2005
    Summary: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, NUCLEAR PHYSICS A, 744, 3 - 14, Nov. 2004
    Summary: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.
  • 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, NUCLEAR PHYSICS A, 738, 221 - 225, Jun. 2004
    Summary: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, NUCLEAR PHYSICS A, 734, 184 - 187, Apr. 2004 , Refereed
    Summary: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, NUCLEAR PHYSICS A, 734, 180 - 183, Apr. 2004 , Refereed
    Summary: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, INTERNATIONAL JOURNAL OF MODERN PHYSICS E-NUCLEAR PHYSICS, 13(1), 285 - 292, Feb. 2004
    Summary: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, INTERNATIONAL JOURNAL OF MODERN PHYSICS E-NUCLEAR PHYSICS, 13(1), 301 - 304, Feb. 2004
    Summary: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, STRUCTURE AND DYNAMICS OF ELEMENTARY MATTER, 166, 395 - 405, 2004 , Refereed
    Summary: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, LABYRINTH IN NUCLEAR STRUCTURE, 701, 200 - 207, 2004 , Refereed
    Summary: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, SEMINAR ON FISSION: PONT D'OYE V, 191 - 198, 2004 , Refereed
    Summary: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, TOURS SYMPOSIUM ON NUCLEAR PHYSICS V, 704, 139 - 146, 2004
    Summary: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, TOURS SYMPOSIUM ON NUCLEAR PHYSICS V, 704, 557 - 562, 2004
    Summary: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, TOURS SYMPOSIUM ON NUCLEAR PHYSICS V, 704, 147 - 156, 2004
    Summary: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, ACTA PHYSICA HUNGARICA NEW SERIES-HEAVY ION PHYSICS, 19(1-2), 61 - 66, 2004
    Summary: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, ACTA PHYSICA HUNGARICA NEW SERIES-HEAVY ION PHYSICS, 19(1-2), 85 - 86, 2004
    Summary: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, PHYSICS OF ATOMIC NUCLEI, 66(6), 1168 - 1172, Jun. 2003
    Summary: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, PHYSICS OF ATOMIC NUCLEI, 66(6), 1105 - 1113, Jun. 2003
    Summary: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, PHYSICS OF ATOMIC NUCLEI, 66(6), 1026 - 1032, Jun. 2003
    Summary: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".
  • 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, PHYSICAL REVIEW C, 65(1), 146071 - 1460714, Jan. 2002
    Summary: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, Journal of Nuclear Science and Technology, 39, 586 - 591, 2002
    Summary: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, 4TH SYMPOSIUM ON NUCLEAR PHYSICS, 561, 411 - 420, 2001 , Refereed
    Summary: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, NUCLEAR SHELLS - 50 YEARS, 240 - 243, 2000 , Refereed
    Summary: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, NUCLEAR SHELLS - 50 YEARS, 276 - 285, 2000 , Refereed
    Summary: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, PROCEEDINGS OF THE 7TH INTERNATIONAL CONFERENCE ON CLUSTERING ASPECTS OF NUCLEAR STRUCTURE AND DYNAMICS, 394 - 401, 2000 , Refereed
    Summary: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), INTERNATIONAL SYMPOSIUM ON QUASIPARTICLE AND PHONON EXCITATIONS IN NUCLEI (SOLOVIEV 99), 1 - 9, 2000 , Refereed
    Summary: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, NUCLEAR PHYSICS A, 654(1), 888C - 891C, Jul. 1999
    Summary: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, PHYSICAL REVIEW C, 59(2), 796 - 809, Feb. 1999
    Summary: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, ACTA PHYSICA HUNGARICA NEW SERIES-HEAVY ION PHYSICS, 10(2-3), 253 - 264, 1999
    Summary: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, TOURS SYMPOSIUM ON NUCLEAR PHYSICS III, (425), 61 - 71, 1998 , Refereed
    Summary: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, TOURS SYMPOSIUM ON NUCLEAR PHYSICS III, (425), 107 - 110, 1998 , Refereed
    Summary: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, PROCEEDINGS OF THE XVII RCNP INTERNATIONAL SYMPOSIUM ON INNOVATIVE COMPUTATIONAL METHODS IN NUCLEAR MANY-BODY PROBLEMS, 461 - 469, 1998 , Refereed
    Summary: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, JOURNAL OF PHYSICS G-NUCLEAR AND PARTICLE PHYSICS, 23(10), 1275 - 1284, Oct. 1997
    Summary: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, NUCLEAR PHYSICS A, 616(1-2), C446 - C453, Apr. 1997
    Summary: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, PHYSICAL REVIEW C, 55(3), R1011 - R1014, Mar. 1997 , Refereed
    Summary: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, Physical Review C - Nuclear Physics, 55(3), R1011 - R1014, 1997
    Summary: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

  • The Papanicolaou Society of Cytopathology System for Reporting Pancreaticobiliary Cytology: Definitions, Criteria and Explanatory Notes, Martha Bishop Pitman, Lester Layfield, Springer,   2015 05 31 , 3319165887
  • Autophagy and Cancer (Current Cancer Research), Hong-Gang Wang, Springer,   2015 02 08 , 1489991778
  • Exotic Nuclei: EXON-2012, Yu E Penionzhkevich, Yu G Sobolev, Yu E Penionzhkevich, Yu G Sobole, World Scientific Publishing Company,   2013 06 25 , 9814508853
  • 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 27 , 9814447471
  • Theory of Nuclear Fission: A Textbook (Lecture Notes in Physics), Hans J. Krappe, Krzysztof Pomorski, Springer,   2012 02 06 , 364223514X
  • Clusters in Nuclei: Volume 1 (Lecture Notes in Physics), Christian Beck, Springer,   2010 09 18 , 9783642138980
  • 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 13 , 9812837523
  • The Euroschool Lectures on Physics with Exotic Beams, Vol. III (Lecture Notes in Physics), J.S. Al-Khalili, Ernst Roeckl, Springer,   2008 12 16 , 3540858385
  • 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 30 , 981256392X
  • Structure and Dynamics of Elementary Matter (Nato Science Series II:), Walter Greiner, Mikhail G. Itkis, Joachim Reinhardt, Mehmet Cem Güçlü, Springer,   2004 11 03 , 1402024460

Conference Activities & Talks

  • Analysis of Evaporation Residue Cross Section in Synthesizing Superheavy Element Region, 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 23
  • Estimation for possibility of synthesizing superheavy element using Dynamical model, 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 25
  • 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,   2016
  • 低エネルギー核分裂過程の動的機構の解明, ARITOMO YOSHIHIRO, HOSODA DAISUKE, CHIBA SATOSHI, 日本原子力学会春の年会予稿集(CD-ROM),   2015 03 05
  • 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,   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,   2015
  • 25pSF-4 Experimental research on fusion-fission and multi-nucleon transfer reactions at JAEA, 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, 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, ARITOMO YOSHIHIRO, HOSODA DAISUKE, CHIBA SATOSHI, 日本原子力学会秋の大会予稿集(CD-ROM),   2014 08 22
  • 動的模型による核分裂機構の系統的研究, HOSODA DAISUKE, ARITOMO YOSHIHIRO, CHIBA SATOSHI, 日本原子力学会秋の大会予稿集(CD-ROM),   2014 08 22
  • 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, HOSODA DAISUKE, ARITOMO YOSHIHIRO, CHIBA SATOSHI, 日本原子力学会春の年会予稿集(CD-ROM),   2014 03 10
  • 核分裂における断裂点付近の形状と分裂モードの解析, 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 10
  • 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,   2014 03 05
  • 動力学模型を用いた核分裂過程のダイナミクス, ARITOMO YOSHIHIRO, HOSODA DAISUKE, CHIBA SATOSHI, IWAMOTO AKIRA, 日本物理学会講演概要集,   2014 03 05
  • Fission process of low excited nuclei with dynamical approach, Aritomo Yoshihiro, Chiba Satoshi, Meeting abstracts of the Physical Society of Japan,   2013 08 26
  • 動力学模型による低励起核分裂の計算, ARITOMO YOSHIHIRO, CHIBA SATOSHI, 日本物理学会講演概要集,   2013 08 26
  • 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, 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 20
  • JAEAにおける代理反応研究の成果(1)全体計画と理論研究, 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 03
  • 20aBH-8 Analysis of surrogate reaction using unified model, Aritomo Y, Chiba S, Hashimoto S, Meeting abstracts of the Physical Society of Japan,   2010 03 01
  • 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,   2006 08 18
  • 23aSC-8 Fission fragment mass distributions in the r-process region II, Samyn M, Goriely S, Meeting abstracts of the Physical Society of Japan,   2006 08 18
  • 23aSC-9 Fission fragment mass distributions in the r-process region, 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 18
  • 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,   2006 03 04
  • Prediction for the maximum cross section of superheavy nuclei II, OHTA M, ARITOMO Y, Meeting abstracts of the Physical Society of Japan,   2003 03 06
  • 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,   2002 08 13
  • Prediction for the maximum cross section of superheavy nuclei II, OHTA M, ARITOMO Y, Meeting abstracts of the Physical Society of Japan,   2002 08 13
  • Analysis of fusion-fission process with neutron evaporation in superheavy mass region, ARITOMO Y, OHTA M, Meeting abstracts of the Physical Society of Japan,   2002 08 13
  • 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,   2001 03 09
  • 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,   1999 03 15
  • 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,   1998 09 05
  • 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,   1998 03 10
  • 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,   1997 09 02
  • 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,   1997 09 02
  • 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,   1997 03 17
  • 6a-F-4 Systematics of Evaporation Residue Cross Section of Superheavy Elements by Diffusion Model, Aritomo Y, Wada T, Ohta M, Abe Y, Abstracts of the meeting of the Physical Society of Japan. Sectional meeting,   1996 09 13
  • 6a-F-3 Cooling Property of Excited Nuclei in Superheavy Mass Region, Tokuda T, Aritomo Y, Wada T, Ohta M, Abstracts of the meeting of the Physical Society of Japan. Sectional meeting,   1996 09 13
  • 30p-SB-10 Estimation of Evaporation Residue Cross Section of Superheavy Elements by Diffusion Model, Aritomo Y, Wada T, Ohta M, Abe Y, Abstracts of the meeting of the Physical Society of Japan. Sectional meeting,   1995 09 12

Misc

  • 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, 0, 195, 195,   2018 , 10.11316/jpsgaiyo.73.1.0_195
  • 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, 0, 181, 181,   2018 , 10.11316/jpsgaiyo.73.1.0_181
  • 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, 0, 179, 179,   2018 , 10.11316/jpsgaiyo.73.1.0_179
  • 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, 0, 180, 180,   2018 , 10.11316/jpsgaiyo.73.1.0_180
  • 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, 0, 178, 178,   2018 , 10.11316/jpsgaiyo.73.1.0_178
  • 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 , 10.11316/jpsgaiyo.73.1.0_171
  • 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 , 10.11316/jpsgaiyo.72.2.0_131
  • 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, 0, 130, 130,   2017 , 10.11316/jpsgaiyo.72.2.0_130
  • 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, 0, 205, 205,   2017 , 10.11316/jpsgaiyo.72.1.0_205
  • 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 , http://jglobal.jst.go.jp/public/201602271718310562
  • 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 , 10.11316/jpsgaiyo.71.2.0_116
  • 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 , 10.11316/jpsgaiyo.71.1.0_230
  • 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 , 10.11316/jpsgaiyo.70.2.0_164
  • 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 , 10.11316/jpsgaiyo.70.2.0_240
  • 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 , 10.11316/jpsgaiyo.70.1.0_137
  • 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 , 10.11316/jpsgaiyo.70.2.0_242
  • 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 , 10.11316/jpsgaiyo.70.2.0_163
  • 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 , 10.11316/jpsgaiyo.69.1.1.0_65_3
  • 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 , 10.11316/jpsgaiyo.68.2.1.0_51_4
  • Fusion of Massive Systems and Superheavy Elements, Hagino Kouichi, Aritomo Yoshihiro, Butsuri, 68, 10, 654, 661,   2013 , 10.11316/butsuri.68.10_654, http://id.ndl.go.jp/bib/024897535
    Summary:On August 12, 2012, the anticipated event for the element 113 (with the atomic number 113 and the mass number 278) was detected in the fusion reaction between ^<70>Zn and ^<209>Bi by the experimental group led by Dr. Kosuke Morita at RIKEN. The potential energy between two colliding nuclei consists of a short range nuclear attraction and the long range Coulomb repulsion, and the potential barrier, which is referred to as the Coulomb barrier, appears due to the strong cancellation between the two interactions. For relatively light systems, such as ^<16>O + ^<209>Bi, fusion takes place once the Coulomb barrier is overcome. In contrast, for massive systems, such as ^<70>Zn + ^<209>Bi used in the experiment by Morita, et al., the quasi-fission process, in which the two nuclei reseparate after the Coulomb barrier is overcome, becomes increasingly dominant, and the fusion cross sections are hindered accordingly. Moreover, even if the fusion is succeeded, the compound nucleus quickly decays by the (ordinary) fission. In this article, we first discuss how it is rare to synthesize a new element by heavy-ion fusion reactions and discuss a significance of the experimental result of Dr. Morita, et al. We also discuss a comparison between the so called hot fusion and cold fusion reactions, a transition of fusion dynamics from light systems to heavy systems, and the role of nuclear structure such as nuclear deformation on fusion of massive systems.
  • 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 , http://jglobal.jst.go.jp/public/201302242961026405
  • 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 , 10.11561/aesj.2012f.0.50.0
  • 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 , 10.11561/aesj.2011f.0.68.0
  • 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 , 10.11561/aesj.2011s.0.45.0
  • 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 , 10.11561/aesj.2010s.0.42.0
  • 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 , 10.11561/aesj.2010s.0.43.0
  • 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 , 10.11561/aesj.2010f.0.87.0
  • 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 , 10.11316/jpsgaiyo.65.1.1.0_36_2
  • 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, 10.24532/soken.115.3_C50, http://jglobal.jst.go.jp/public/200902268061470055
  • 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 , 10.11316/jpsgaiyo.61.1.1.0_41_4
  • 23aSC-9 Fission fragment mass distributions in the r-process region, 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, 61, 0, 24, 24,   2006 , 10.11316/jpsgaiyo.61.2.1.0_24_2
  • 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 , 10.11316/jpsgaiyo.61.2.1.0_24_3
  • 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 , 10.11316/jpsgaiyo.58.1.1.0_38_2
  • 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 , 10.11316/jpsgaiyo.57.2.1.0_23_4
  • 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 , 10.11316/jpsgaiyo.57.2.1.0_24_1
  • 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 , 10.11316/jpsgaiyo.57.2.1.0_24_2
  • 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 , 10.11316/jpsgaiyo.56.1.1.0_22_2
  • Dubna, The Center of Investigation for Superheavy Elements(La Toccata), Aritomo Yoshihiro, Butsuri, 56, 9, 695, 697,   2001 , 10.11316/butsuri.56.9_695, http://id.ndl.go.jp/bib/5902163
  • 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 , 10.11316/jpsgaiyo.54.1.1.0_32_3
  • 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 , 10.11316/jpsgaiyo.53.2.1.0_32_4
  • 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 , 10.11316/jpsgaiyo.53.1.1.0_40_4
  • 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 , 10.11316/jpsgaiyo.52.2.1.0_49_3
  • 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 , 10.11316/jpsgaiyo.52.2.1.0_50_1
  • 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 , 10.11316/jpsgaiyo.52.1.1.0_40_3
  • 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 , 10.11316/jpsgaiyoj.1996.1.0_56_2
  • 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 , 10.11316/jpsgaiyoj.1996.1.0_57_1
  • 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 , 10.11316/jpsgaiyoj.1995.1.0_88_1

Awards & Honors

  •   2003 01 , The Scientific Council of the Joint Institute for Nuclear Research Awarded., The second prize of the Joint Institute for Nuclear Research.

Research Grants & Projects

  • Russia and Germany, No. 04-02-04008