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Si and 
Ca湊 太志; 内藤 智也*; 岩本 修
Physical Review C, 107(5), p.054314_1 - 054314_10, 2023/05
被引用回数：1 パーセンタイル：40.52(Physics, Nuclear)Muon captures on nuclei have provided us a plenty of knowledge of nuclear properties. Recently, this nature attracts attention again in electronics, because it is argued that charged particle emissions following muon capture on silicon triggers non-negligible soft errors in semiconductors. To investigate the particle emissions from nuclear physics point of view, we develop a new approach using a microscopic model of muon capture and an up-to-date particle emission models. We paid attention to the muon capture rates, the particle emission spectra, and the multiplicities that have a close interrelation with each other, and found that the nuclear many-body correlation including two-particle two-hole excitations is a key to explain them simultaneously.
MoCiccarelli, M.*; 湊 太志; 内藤 智也*
Physical Review C, 102(3), p.034306_1 - 034306_9, 2020/09
被引用回数：5 パーセンタイル：48.03(Physics, Nuclear)The isotope 
Mo, the generator of 
Tc used for diagnostic imaging, is supplied by extracting from fission fragments of highly enriched uranium in reactors. However, a reactor-free production method of Mo is searched over the world from the point of view of nuclear proliferation. Recently, 
Mo production through a muon capture reaction was proposed and it was found that about 50% of Mo turned into Mo through Mo
reaction. However, the detailed physical process of the muon capture reaction is not completely understood. We, therefore, study the muon capture reaction of Mo by a theoretical approach. We used the 
QRPA to calculate the muon capture rate. The muon wave function is calculated with considering the electronic distribution of the atom and the nuclear charge distribution. The particle evaporation process from the daughter nucleus is calculated by the Hauser-Feshbach statistical model. From the model calculation, about 38% of Mo is converted to Mo through the muon capture reaction, which is in a reasonable agreement with the experimental data. It is revealed that negative parity states, especially 
state, play an important role in Mo 
Nb. Isotope production by the muon capture reaction strongly depends on the nuclear structure. To understand the mechanism, excitation energy functions have to be known microscopically.
石澤 明宏*; 井戸村 泰宏; 今寺 賢志*; 糟谷 直宏*; 菅野 龍太郎*; 佐竹 真介*; 龍野 智哉*; 仲田 資季*; 沼波 政倫*; 前山 伸也*; et al.
プラズマ・核融合学会誌, 92(3), p.157 - 210, 2016/03
幅広いアプローチ協定に基づいて国際核融合エネルギー研究センター(IFERC)の計算機シミュレーションセンター(CSC)に設置された高性能計算機システムHeliosは、2012年1月に運用を開始し、日欧の磁気核融合シミュレーション研究に供用され、高い利用率の実績を示すとともに、炉心プラズマ物理から炉材料・炉工学にわたる広い分野で多くの研究成果に貢献している。本プロジェクトレビューの目的は、国内の大学や研究機関においてHeliosを利用して進められているシミュレーション研究プロジェクトとその成果を一望するとともに、今後予想される研究の進展を紹介することである。はじめにIFERC-CSCの概要を示した後、各研究プロジェクト毎にその目的、用いられる計算手法、これまでの研究成果、そして今後必要とされる計算を紹介する。
湊 太志; 内藤 智也*; 岩本 修
no journal, ,
ミュオンは大気中で作られる放射線の一つであり、絶えず地上に降り注いでいる。ミュオンが原子核に捕獲されると、原子核は高い励起状態になり、そこからの脱励起に伴って様々な粒子が放出される。特に荷電粒子は回りの物質を電離するなどその影響が大きく、半導体の中で無視できない数のソフトエラーを起こしている可能性が指摘されている。ミュオン捕獲によって放出される粒子のスペクトルは、低エネルギーから高エネルギーに及ぶことが知られているが、その発生メカニズムは理論的に十分に明らかにされていない。そのため本研究では、原子核のミュオン捕獲率を微視的モデルであるSecond Tamm-Dancoff近似法から、放出粒子スペクトルを励起子モデルと統計モデルから計算する理論的枠組みを構築し、そのメカニズムの解明を試みた。得られた計算結果は、シリコンとカルシウムから放出される陽子と中性子のスペクトルをよく再現することができることが分かった。発表では、広いエネルギー範囲に及ぶ粒子スペクトルの発生メカニズムについて、核構造の観点から議論をする。
-decays and muon captures湊 太志; 内藤 智也*
no journal, ,
Nuclei can be at an excited state by beta-decays and muon captures. If the excitation energy is above particle threshold energies, the nuclei emit particles competing with the gamma deexcitation. The typical examples are neutron emissions after beta-decays and muon captures. In addition, it is known that proton and alpha particle emissions occur for a highly excited neutron-deficient nuclei. The information is important not only for estimating delayed neutrons that play an important role for a stable operation of reactors, but also for evaluating radioactivities, soft errors of semi-conductors, and nucleosynthesis in stars. Although experimental data of the particle emissions following after beta-decays and muon captures have been reproduced with some phenomenological models, the detailed mechanism with respect to the nuclear structure is still unclear. In particular, experimentally measured neutron spectra after muon capture cannot be reproduced well with a nuclear structure model. In this work, we go into the investigation on this issue with a microscopic approach of proton-neutron random-phase-approximation and particle evaporation models considering pre-equilibrium and compound process.
湊 太志; 内藤 智也*
no journal, ,
Nuclei can be at an excited state by muon captures. If the excitation energy is above particle threshold energies, the nuclei emit neutrons and other light particles competing with the gamma deexcitation. The information is important for evaluating soft errors of semi-conductors. Although experimental data of the particle emissions following after muon captures have been reproduced with some phenomenological models, the detailed mechanism with respect to the nuclear structure is still unclear. In particular, experimentally measured neutron spectra after muon capture cannot be reproduced well with a nuclear structure model. In this work, we go into the investigation on this issue with a microscopic approach of proton-neutron random-phase-approximation (RPA) and particle evaporation models considering pre-equilibrium and compound process. We discuss an importance of continuum states of outgoing neutrons in the scheme of RPA.
湊 太志*; 内藤 智也*; 岩本 修
no journal, ,
Nuclei are excited by muon capture reactions. If the excitation energy is above particle thresholds, the nuclei emit particles competing with the gamma-ray deexcitation. The typical examples are neutron and proton emissions. Other charged particles emissions, like deuteron-, 
He-, triton-, 
-emissions, also occur if the nuclear excitation energy is very high. Information on these particle emissions is important for evaluating soft errors of semi-conductors and radioactivities of materials after irradiations of muon beams. Although experimental data of the particle emissions following muon captures have been reproduced with some phenomenological models, the detailed mechanism with respect to the nuclear structure is still unclear. In particular, experimentally measured neutron spectra after muon capture cannot be reproduced well. We worked on solving this issue with a microscopic approach of second-order proton-neutron Tamm-Dancoff-approximation and particle evaporation models considering pre-equilibrium and compound process. We found that the two-particle two-hole configurations play an important role to reproduce particle spectra obtained after muon captures.
