An improved Rossi-alpha formula is derived to consider a delayed-neutron contribution to a conditional counting probability defined in the Rossi-alpha technique. The improved formula has an additional constant term and another additional term proportional to time interval tau to the original formula. For an university training and research reactor of Kindai University, the Rossi-alpha analyses based on the original and the improved formulae are carried out to examine the applicability of these formulae to the subcritical thermal reactor. The original formula results in an inconsistent prompt-neutron decay constant with that determined from a previous Feynman-alpha analysis considering delayed neutrons. This difficulty of the original formula originates from the neglect of delayed neutrons. Applying the improved formula leads to a consistent prompt-neutron decay constant. The additional constant term of the improved formula should be considered to determine accurately the decay constant, while the additional proportional term is much too small to consider. The additional constant term obtained from the present analysis is consistent with that from the previous Feynman-alpha analysis.

Time-sequence count data of a neutron counter were acquired at subcritical states of UTR-KINKI reactor and then a Feynman-alpha analysis considering delayed neutrons was carried out to determine a measured ratio of delayed to prompt neutron contribution to the correlation amplitude Y. The zero-power reactor was driven by a neutron source inherent in highly enriched uranium fuels to reduce any spatial effect. The delayed-to-prompt ratio was also calculated using several sets of delayed-neutron group parameters for thermal fission of U-235 nuclide, to validate these sets by comparing with the measured ratio. The ratios calculated using Keepin's 6-group and Spriggs' 8-group sets agreed very well with the measured ratio. However, the ratios calculated using the other sets were almost the same as each other and in a very poor agreement with the measured ratio.

For an university training and research reactor of Kindai University, the Feynman-alpha analyses based on several formulae are carried out to examine the applicability of these formulae to the subcritical thermal reactor system. The original formula, in which the effect of delayed neutrons is neglected, results in a prompt-neutron decay constant sensitive to an upper limit of the gate time range of the analysis and consequently has difficulty in determining the decay constant. This difficulty originates from the neglect of delayed neutrons. An improved formula, where a term proportional to the gate time is added to the original formula, gives a desirable decay constant insensitive to the upper limit and the insensitive decay constant well agrees with that obtained from the Rossi-alpha analysis. The application of a difference filtering technique also leads to a successful result similar to the above improved formula. An alternative index Z to the traditional index Y of the original formula has been sometimes employed as an indication of the non-Poisson nature of the counting statistics. The Z is defined as dividing the Y by the mean number of neutron counts accumulated in the gate time. The formula for the Z never results in a reasonable decay constant even though the effect of delayed neutrons is considered. This study suggests that the improved formula considering delayed neutrons for the Y and the formula for the difference filtering technique should be employed to determine the prompt-neutron decay constant of thermal reactors.

In these years, reactor noise analysis methods have been studied to apply for the Debris’ criticality management at the Fukushima Daiichi NPP, Japan. The Feynman-α analysis with bunching method is one of the candidate techniques, however the bunching method itself has never been validated in detail. This synthesis technique is useful to reduce a time required for the experiment, however it is known that a non-physical trend unrelated to the state of a nuclear reactor is generated by the multiple use of time series data, and this phenomenon (we call “pseudo trend phenomenon”) has never been systematically studied in detail. In this study, Poisson events, whose statistical characteristics were clarified, were employed to investigate the pseudo trend phenomenon of the bunching method. The time-sequence count data for various statistical parameters were generated by the Monte Carlo time series simulator. Comparing the two results obtained by applying the conventional bunching method and the moving-bunching method for the same Poisson event time series, and it was found that the same pseudo trend component appears in both results of the bunching method and the moving bunching method. In addition, it was also found that the fluctuation width of the pseudo trend component is smaller than the statistical fluctuation range.

For a highly enriched uranium subcritical core driven by an inherent or an external Am-Be source in Kyoto University Critical Assembly (KUCA), a series of the source multiplication measurements, the Feynman-alpha and the Rossi-alpha neutron correlation analyses was carried out to demonstrate quantitatively that the use of the former inherent source had some advantages over that of the latter external source. Under a reactor drive by the external source, the subcriticality obtained by the neutron source multiplication method (NSM) significantly depended on neutron counter position and was consequently in very poor agreement with that calculated by the continuous-energy Monte Carlo code MVP (version 3) with the nuclear data library JENDL-4.0. In contrast to the above drive, the other drive by the inherent source spectacularly reduced the counter-position dependence and lead to a good agreement with the calculation by the MVP. The prompt-neutron decay constant determined from the Feynman-alpha analysis under the external source was also significantly dependent on the counter position. The Rossi-alpha analysis had a relatively slight counter-position dependence of the decay constant to the Feynman-alpha analysis but had a very low S/N ratio, which indicated an inferior applicability of the Rossi-alpha analysis to the reactor drive and enlarged a statistical uncertainty of the decay constant. On the other hand, the reactor drive by the inherent source considerably reduced the counter-position dependence of the Feynman-alpha analysis and spectacularly enhanced the S/N ratio of the Rossi-alpha analysis. An effective strength of the inherent source could be also determined from the S/N ratio. When the prompt-neutron decay constant obtained under this reactor drive was transformed into each subcriticality by the Simmons and King method, where a subcritical dependence of the generation time and the effective delayed-neutron fraction was neglected, the subcriticality transformed seemed to agree well with that calculated by the MVP. When the decay constant was transformed by the inhour method, where the subcritical dependence of these kinetic parameters was considered, a systematic disagreement between the transformed and the calculated subcriticality appeared.

For a subcritical reactor system driven by a periodically pulsed spallation neutron source in Kyoto University Critical Assembly, a series of power spectral analysis on frequency domain is carried out to determine the prompt-neutron decay constant and quantitatively to confirm a non-Poisson characteristics of the neutron source. Not only the cross-power but also the auto-power spectral density has a considerable correlated noise component even at a deeply subcritical state, where no correlated component could be observed under a pulsed DT(14MeV) neutron source. The non-Poisson character of the spallation source must enhance the correlation amplitude of these power spectral densities. Moreover, the Degweker's factor (m (2)-m (1) (2))/m (1) (2) of 0.082 +/- 0.021, which is a quantitative indication of the non-Poisson character, is determined from the present analysis and is consistent with that obtained by a previous Rossi-alpha analysis for the same subcritical system driven by the spallation source. The non-zero value of the factor convinces us again that the present source has a different statistical distribution from the Poisson. The prompt-neutron decay constant obtained from the present analysis well agreed with that done from the above previous Rossi-alpha analysis.

For a subcritical reactor system driven by a periodically pulsed spallation neutron source in Kyoto University Critical Assembly (KUCA), the Feynman-alpha and the Rossi-alpha neutron correlation analyses were carried out to determine the prompt-neutron decay constant and quantitatively to confirm a non-Poisson characteristics of the neutron source. In these correlation analyses, a non-negligible contribution of delayed neutrons and a non-Poisson character of the source were considered, and each pulse was assumed to be a delta function. When a neutron counter was placed closely to the reactor core, the prompt-neutron decay constant determined from the present Feynman-alpha analysis well agreed with that done from a previous analysis for the same subcritical system driven by an inherent neutron source. However, the decay constant determined from the present Rossi-alpha analysis was in poor agreement with that done from the above previous analysis. This disagreement originated from an inevitable excitation of a higher mode. In the Rossi-alpha counting probability distribution, the excitation deformed a sharp cusp arising from the delta function to a smooth convex shape. When the data around the convex top were masked for least-squares fitting of the present Rossi-alpha formula, the disagreement could be successfully resolved. Compared with the previous Feynman-alpha and Rossi-alpha analyses under the Poisson inherent source, the non-Poisson spallation source definitely enhanced the respective prompt-neutron correlation amplitudes. The enhancement rate increased with an increase in subcriticality. Moreover, the Degweker's factor (m(2)-m(1)(2))/m(1)(2)of 0.067 +/- 0.011, which indicated a non-Poisson character of the present spallation source, could be determined from the present correlation analysis and the non-zero value of the factor convinced us that the present source had a different statistical distribution from the Poisson.

Solid-moderated cores of the Kyoto University Critical Assembly (KUCA) have an emergency shutdown system to avoid any reactivity-initiated accidents. When a reactor protection system of KUCA detects some abnormal conditions, the emergency system withdraws downward several fuel and reflector assemblies assigned as a central fuel loading from the core in 10 and several seconds. The withdrawal of the fuel loading inserts a very large negative reactivity into the core. The negative reactivity has been measured by the integral count technique; however, the application of the integral count technique to this measurement must have been impossible in principle. The integral count technique assumes an instantaneous insertion of a large negative reactivity but the assumption must fail for this measurement. An accurate measurement of the negative reactivity is of extreme importance from the viewpoint of reactor safety. In this study, the least-squares inverse kinetics method was employed to determine the negative reactivity from time-sequence counts data of a neutron counter. The negative reactivity determined by this method was in good agreement with that calculated by the continuous-energy Monte Carlo code MVP (version 3) with the nuclear data library JENDL-4.0.

The Feynman-α and the Rossi-α methods have been frequently employed to determine the subcriticality of subcritical reactor systems driven by Poisson source such as Am-Be neutron source. In actual accelerator-driven systems (ADS), a spallation device will be applied as an intense neutron source. This device will be probably operated in a pulse mode and it is impossible to apply a conventional analysis method to determine the subcriticality in any ADS. In previous theoretical studies, some advanced formulae of neutron correlation analysis for spallation neutron source have been presented. However, the experimental study has been hardly reported to date. The major objectives of this study are to examine experimentally an applicability of these complicated formulae to a subcritical reactor system driven by an actual pulsed spallation neutron source and to determine the prompt-neutron decay constant α of the system. To achieve these goals, we constructed an ADS core at the Kyoto University Critical Assembly (KUCA). The core was composed of highly-enriched uranium fuel assemblies surrounded by many polyethylene reflector assemblies. We carried out a series of the Feynman-α and the Rossi-α analyses for the system driven by pulsed spallation source. As a result, the prompt-neutron decay constants were experimentally obtained by using a fitting formula. The prompt-neutron decay constants determined by Feynman-α and Rossi-α analyses agrees with each other within a statistical error range of least-squares fitting.

In a variety of highly enriched uranium cores of Kyoto University Critical Assembly, many different subcriticality measurements have been strenuously performed. However, any influence of neutron source inherent in the highly enriched uranium fuels on these measurements has hardly been studied. This is because the influence has been expected to be negligible in the fuels. In this study, we revaluated the influence on pulsed neutron, accelerator-beam trip and rod drop measurements to reveal an unexpected impact of the weak inherent source. Especially, the inherent source was injurious to most of the beam trip and the rod drop measurements based on the integral count method. The least-squares inverse kinetics analysis also had a significant influence on the inherent source. In the area ratio analysis for a pulsed neutron measurement, a considerable number of neutrons from the inherent source was mixed into delayed-neutron area. When the influence was considered in these data analyses, the subcritical reactivity of the above measurements was in good agreement with that calculated by the continuous-energy Monte Carlo code MVP.

Even a zero-power reactor core containing highly enriched uranium has a weak neutron source inherent in uranium 235, and consequently, a neutron counter placed closely to the core without external neutron source registers a certain counting rate. The study of the counting is very important for zero-power reactor physics experiments with a high precision. In this experimental study, first, at a shutdown state of the UTR-Kinki reactor without start-up neutron source, a pulse height distribution of output signals from a neutron proportional counter was measured to confirm that these signals resulted from neutron detections. At several subcritical states of the UTR, then, the Feynman-alpha analysis was carried out to confirm that the neutrons detected by the counter must be fission neutrons multiplied by fission chain reactions. The correlation amplitude measured in the Feynman-alpha analysis was much higher than that measured in a previous drive by start-up source. Further, it was also confirmed that the subcriticality dependence of neutron counting rate followed the source multiplication formula. This feature indicated that the one-point model was very successful in the subcritical range including the shutdown state.

Feynman-alpha method is used as the representative method in reactor noise analysis for the criticality monitoring. Feynman-alpha analysis needs a large amount of measurement time in its original process, though many researchers use the bunching method and its derived methods for the experimental data processing to shorten the measurement time. However, the detailed characteristics and the application limit of the bunching method have not been researched and discussed enough. This paper shows a possibility that the Bunching method is a method to reduce the probability fluctuation with the Y value only in the appearance. Moreover, the criteria for determining that the Y value is not an accidental product are also provided in this paper.

The objective of this study was to determine experimentally a probability distribution of neutron counts in nuclear reactors. In a subcritical state of the UTR-Kinki, a series of time-sequence count data from a neutron counter was acquired to obtain some frequency histograms of neutron counts. Then the applicability of several probability distributions to the measured histogram was examined by a chi-square test. This examination showed that only the negative binomial distribution was judged to be much acceptable over a certain gate-width range required by the Feynman-α analysis for a thermal reactor system.

The bunching technique has been widely utilized in Feynman- neutron correlation analysis to synthesize neutron counts within longer gate widths by bunching time-sequence neutron counts stored in multichannel scaler channels. An alternative technique referred to as moving-bunching technique was proposed to reduce a statistical scatter of variance-to-mean ratio of neutron counts. The conventional bunching technique has no overlap of adjacent bunches, while the present technique makes adjacent bunches overlap as long as possible similarly to the moving average technique. A Feynman- experiment was performed in the UTR-KINKI, to confirm the advantage of the proposed bunching technique. When a neutron detector was placed far from the core, a Feynman- analysis with the conventional bunching technique led to a scattered variance-to-mean ratio from which the prompt-neutron decay constant was never determinable. However, another analysis with the proposed technique remarkably reduced the above scatter and enabled the determination of the decay constant. For a neutron detector close to the core, the proposed technique also reduced statistical error of the decay constant.

A unique power spectral analysis for a subcritical reactor system driven by a pulsed 14 MeV neutron source was carried out at the Kyoto University Critical Assembly (KUCA). In this analysis, a complex cross-power spectral density between time-sequence signal data from an accelerator beam ammeter and a neutron detector was measured to determine the prompt-neutron decay constant of an accelerator-driven system (ADS) from the phase data of the spectral density. Assuming the one-point kinetics model, in theory, the decay constant can be arithmetically derived from the phase at the integral multiples of the pulse repetition frequency. However, the actual derivation from the phase at a pulse repetition frequency of 20Hz considerably underestimated the prompt-neutron decay constant, compared with that obtained by a previous pulsed neutron experiment, and the derived decay constant apparently decreased with an increase in the multiple of the pulsed repetition frequency. Considering a lag time in detector response, the above underestimation and the above apparent decrease were solved to obtain the consistent decay constant. While both previous power spectral analysis and Feynman-alpha analysis for pulsed neutron source require non-linear least-squares fits of the respective complicated formulae, the present analysis makes the fitting unnecessary except at regular calibration of the lag time. This feature is advantageous for a robust online monitoring of subcritical reactivity of an actual ADS.

This paper describes residual space charge formation after 10 kV of voltage was removed in neutron irradiated 0.1mm thick polyethylene film. The neutron irradiation to polyethylene was performed at Kinki University reactor (UTR-KINKI) in Kindai University Atomic Energy Research Institute. The time of neuron irradiation to polyethylene was changed in the range of 3 hours. After the irradiation treatment, 10kV was applied to polyethylene for 5 minutes. After the voltage was switched off, positive polarity of residual space charge was mainly formed in neutron irradiated polyethylene. On the other hand, a small positive space charge was observed in non-irradiated polyethylene. It was also found that the total amount of residual charge in neuron irradiated polyethylene was larger than that in non-irradiated polyethylene. These results indicate that neuron irradiation to polyethylene enhances space charge accumulation in polyethylene bulk.

The Kinki University Atomic Energy Research Institute investigated radioactive contamination resulting from the Fukushima Daiichi Nuclear Power Plant accident in urban areas of Fukushima City, Fukushima Prefecture, Japan. Activity measurement of the surface soil and a survey of the dose rate distribution in urban areas were performed. From the results of this research, dose rate changes in paved areas became clear, and gradients of the dose rate decrease for different paving materials were measured and analyzed.

In recent years, attention has been focused on radionuclide therapy with α emission nuclides. Research and clinical tests of pharmaceuticals including ²²³Ra, which has short half-life and a number of α & β decays with its decay family, started in Japan in this year. Despite the fact that research on pharmaceuticals including ²²³Ra is continuing, methods and knowledge of ²²³Ra radiation controls have not been researched.
Contamination controls of radioactive pharmaceuticals in clinical sites are very important because of radiation protection, and research on ²²³Ra-contamination controls should be performed as soon as possible before any medical application becomes licensed.
In this work, we performed demonstration experiments of ²²³Ra-contamination with commonly-used survey meters. The results of experiments show that a Geiger-Muller type survey meter(TGS-133:Hitachi Aloka Medical) is effective to find ²²³Ra-contamination, but an NaI(Tl) scintillation type survey meter(TCS-161:Hitachi Aloka Medical) should be used carefully due to the measurement limit in a ²²³Ra-contamination survey.

Large amount of radioactive materials had released by the nuclear power plant accident at Fukushima Daiichi site. The level of radiation dose rate has been raised by the radioactive material on the ground. We measured the dose rates in Kawamata-machi, Fukushima Prefecture, Japan, which is located about 40km from the power plant in north-west direction. We measured the ¹³⁷Cs concentration in soil samples by the Ge diode detector. The result shows more than 90% of ¹³⁷Cs exists the depth from the surface to 10mm. The soil of shallow depth was sieved to 6 series by particle size. The radioactivity of the parts less than 0.5mm diameter accounts for more than 80% of the total.

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  Radioactive materials were released to the general environment due to the accident at the Fukushima Daiichi nuclear power station. The released radioactive materials fell and contaminated the land mainly in the Tohoku and Kanto areas of Japan. We surveyed the air dose rate in relation to the pave condition of the land, and investigated the contamination level in some nonpaved areas at the center of Fukushima City, Koriyama City, and Nasushiobara City. From the survey results, the dose rates of the nonpaved areas were found to be higher than those of the paved areas, and the dose rates of the paved areas depend on the paving materials of the area. The contamination level of the nonpaved area in Nasushiobara City was below the regulation level of specific activities in a radiation-controlled area in Japan. However, the contamination levels in the nonpaved areas in Fukushima City and Koriyama City were above the regulation level.

[Abstract] Residual heat removal system of Fukushima Daiichi Nuclear Plant was down at 11th March 2011, because of the Tohoku Region Pacific Coast Earthquake and the Tsunami come after the earthquake. The system down causes the meltdowns in Reactor 1, Reactor2 and Reactor3. As a result, a large amount of radioactive materials were released to general environment, and dose rates of Tohoku & Kanto area increased with the fallout of the radioactive materials. Kinki University Atomic Energy Research Institute has researched time series variations of dose rate distribution and contamination level in urban distracts of Tohoku Naka-Dori Area from the middle of April 2011. Results of the researches and the analyses are described in this paper.Hohara, Sin-ya

Hohara, Sin-ya[Abstract] In resent years, the performances of new electronic devices, for example FPGA or so on, have been improved, and these devices become more cost-effective ones year by year. Moreover, prices of personal computers have become less expensive, and the programming environment on PC becomes much user-friendly and easy to operate in this decimal year. These advancements have possibilities to provide a great help for self-constructions of radiation measurement equipments, which needed huge cost and work to construct in the past. Then, I tried to construct a reasonable Mulch Channel Analyzer (MCA) with an educational FPGA board named EDX-005 (HuMANDATA ltd.), and conduct test measurements of the MCA. The MCA was constructed in a short period, and its cost was just under 50 thousands yen. The MCA normally works at 200 [cps/ch] count rate with a NaI(T1) scintillation counter. The description of the MCA and some points of self-constructions of radiation measurement equipments are provided in this paper.

Quasi-monochromatic gamma-ray beam produced with the laser-Compton scattering (LCS) in 1-40 MeV has been used for various scientific studies and industrial applications in the National Institute of Advanced Industrial Science and Technology (AIST). We briefly overview the recent research progress in AIST. Since the first observation of the LCS gamma-ray beam in 1984 at AIST, photon generation techniques have been studied and improved. A beamline dedicated for user experiments was installed in FY 2000, and has been used by many users since then. There are many research programs being carried out using the LCS beamline, such as nuclear and atomic physics studies, radiation detector calibration and non-destructive tests. (C) 2009 Elsevier B.V. All rights reserved.

Photoneutron cross sections were measured for Zr91, Zr92, and Zr94 near the neutron separation energy with quasimonochromatic γ rays. The data exhibit some extra components around the neutron threshold. A coherent analysis of the photoneutron data for Zr92 together with the neutron capture on Zr91 based on the microscopic Hartree-Fock-Bogoliubov plus quasiparticle random-phase approximation model for the E1 strength has revealed the presence of an M1 resonance at 9 MeV. The microscopic approach systematically shows the same M1 strength in the photoneutron cross section for Zr91 and Zr94. The total M1 strength is about 75% larger than the strength predicted by the systematics, being qualitatively consistent with the giant M1 resonance observed in the inelastic proton scattering. © 2008 The American Physical Society.

Photoneutron cross sections were measured for 80Se near the neutron separation energy with laser Compton-backscattered γ-ray beams at AIST. Neutron capture rates are evaluated for 79Se with the photoreaction data as experimental constraints on the El γ-strength function, a key parameter in the Hauser-Feshbach statistical model calculation. Solving the set of differential equations under a single neutron exposure, we analyzed the solar abundance ratio of the weak components of 80Kr and 82Kr in terms of the s-process branching at 79Se. We discuss the region of temperature and neutron density allowed for the weak s-process nucleosynthesis.

The cross sections of the 152Sm(gamma,n) and Au-197(gamma,n) reactions have been measured with the laser-Compton scattering (LCS) gamma beam in the 8.3-12.4 MeV energy range. The photon difference method has been used for LCS gamma rays in the data analysis for the first time. The present data for Au-197 measured as the standard are in agreement with the preceding data and the recent recommendation. On the other hand, the preceding data for Sm-152 at 8.3 MeV are twice as large as the present data.

Characteristics of a GSO(Ce) crystal were investigated in terms of the light output response and the peak-to-total efficiency for impinging intermediate-energy a-particles. Experiments were carried out using a-particles of energies ranging from 143 to 718 MeV with primary a beams of 400 and 718 MeV. It has been demonstrated that the experimental results are explained well by calculations in the same manner as for protons and deuterons. In particular, no particle identity dependence of scintillation quenching phenomena have been observed between protons, deuterons and a-particles. Furthermore, good linearity is confirmed in the higher energy range up to 718 MeV. The peak-to-total efficiency was accounted for by calculations using a-nucleus reaction cross-sections. (c) 2006 Elsevier B.V. All rights reserved.

Photoneutron cross sections for Ta181(γ,n)Tam180 were determined from simultaneous measurements of total cross sections (σtot) and ground-state cross sections (σgs) for Ta180 in photodisintegration of Ta181 with laser Compton-backscattered γ rays. Techniques of direct neutron counting and photoactivation were used for the measurement of σtot and σgs, respectively. The partial cross sections for the isomeric state serves as a novel probe of the nuclear level density of Ta180. Implications for the p- and s-process nucleosynthesis of Tam180 are given. © 2006 The American Physical Society.

Photoneutron cross sections were measured for 80Se near the neutron separation energy with the laser Compton scattering γ rays. The stellar neutron capture rate for 79Se was evaluated by using the photodisintegration data as constraints on the E1 γ strength function within the framework of the Hauser-Feshbach statistical model. The result is compared with the model calculation of Bao and Käppeler. © Copyright owned by the author(s).

Partial photoneutron cross sections for 181Ta(gamma;,n) 180Tam(9-) were measured with laser Compton scattering γ rays. The partial cross section, which reflects selective γ transitions in 180Ta leading to the isomeric state, cast new light into the spin- and parity-dependent nuclear level density of 180Ta. Essentially the same selective γ transition is expected in neutron capture on 179Ta leading to 180Ta m(9-). The weak s-process branching to the only naturally occurring isomer 180Tam is discussed. © Copyright owned by the author(s).

Performances of a stacked GSO(Ce) spectrometer were investigated in terms of the light output and the peak-to-tail efficiency for deuterons of intermediate energies. Experiments were conducted at the Research Center for Nuclear Physics (RCNP) of Osaka University by using monoenergetic deuterons from pd and ad scatterings. The results are indispensable to determine energy-angle double differential cross-sections of deuteron production reactions induced by 400 MeV protons. (C) 2004 Elsevier B.V. All rights reserved.

Multistep direct processes in proton production reactions were investigated with proton beam of 300- and 392-MeV bombarding targets nuclei. The targets nuclei are Ta-181, Au-197, and Bi-209 for 392 MeV and Au-197 for 300 MeV protons. Energy spectra were measured at several laboratory angles from 20 degrees to 105 degrees and compared with two theoretical models, the quantum molecular dynamics and the intranuclear cascade model. At intermediate energy, the double differential cross section is sensitive to ground state in codes. We found that a more realistic ground state led better accounting of measured data.

Intermediate-energy nucleon-nucleus interactions were investigated in order to achieve a more comprehensive understanding of spallation reactions. Inclusive C-12(p,p') spectra at 300 MeV were measured in a wide energy range and compared with two theoretical calculations: the quantum molecular dynamics model and the intranuclear cascade model. The calculations are in good agreement with the experimental results ill the quasifree region. In the lower energy domain, however, the calculations underestimated the experimental results by a factor of about 2. The cause of the discrepancy was discussed in terms of a collective excitation process.

We investigated light yield of primary scintillation from interactions of alpha particles and gaseous materials under different conditions. The scintillation lights were detected with photomultiplier tubes. The largest yields were obtained under gas pressure of 200 to 300 hPa. We proposed a simple method to deduce photon numbers of primary scintillation.

The alpha-emitter radium-223 (Ra-223), which has an affinity to the bone, has been introduced into clinical practices as a therapeutic radiopharmaceutical that prolongs overall survival in castration-resistant prostate cancer with bone metastases. In this study, we conducted studies on measurements of photons by various counting devices in order to clarify the physiochemical properties of Ra-223, on decontamination methods assuming contamination of materials, and also appropriate parameters for imaging by gamma camera. We demonstrated the characteristics of GM counters，Na(Tl) scintillation counters, and a ZnS(Ag) counter, the importance of early decontamination of materials, and feasibility of gamma rays and characteristic X rays for imaging.