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Am at neutron energies below fission threshold廣瀬 健太郎; 西尾 勝久; 牧井 宏之; 西中 一朗*; 太田 周也*; 永山 達郎*; 田村 信行*; 後藤 真一*; Andreyev, A. N.; Vermeulen, M. J.; et al.
Nuclear Instruments and Methods in Physics Research A, 856, p.133 - 138, 2017/06
被引用回数：5 パーセンタイル：44.54(Instruments & Instrumentation)Fission and capture reactions were simultaneously measured in the neutron-induced reactions of Am at J-PARC. Data were taken with the TOF method in 
= 0.1
20 eV. The fission events were observed by detecting prompt fission neutrons using liquid organic scintillators. The capture reaction was measured by detecting 
rays from the compound nuclei using the same detectors, where the prompt fission neutrons and capture rays were separated by a pulse shape analysis. The cross sections were obtained by normalizing the relative yields at the first resonance to evaluations or other experimental data. The ratio of the fission to capture cross sections at each resonance is compared with those from an evaluated nuclear data library and other experimental data. Some differences were found between the present values and the library/literature values at several resonances.
余語 覚文; 佐藤 克俊; 錦野 将元; 森 道昭; 手島 昭樹*; 沼崎 穂高*; 村上 昌雄*; 出水 祐介*; 赤城 卓*; 永山 伸一*; et al.
Applied Physics Letters, 94(18), p.181502_1 - 181502_3, 2009/05
被引用回数：110 パーセンタイル：94.75(Physics, Applied)We report the demonstrated irradiation effect of laser-accelerated protons on human cancer cells. 
(living) A549 cells are irradiated with quasi-monoenergetic proton bunches of 0.8-2.4 MeV with a single bunch duration of 15 ns. Irradiation with the proton dose of 20 Gy results in a distinct formation of -H2AX foci as an indicator of DNA double-strand breaks generated in the cancer cells. This is a pioneering result in view of future investigations on the radiobiological effects of laser-driven ion beams. Unique high-current and short-bunch features make laser-driven proton bunches an excitation source for time-resolved determination of radical yields.
武久 正昭*; 団野 晧文*; 長山 尚; 大野 新一; 小池 満
放射線化学の歴史と未来; 30年の歩み, p.57 - 67, 1991/00
30年前にわが国における放射線化学の研究が開始した。原研東海研においては10hCiの
Coの線源が設置され、広く共同利用に供されるとともに放射線利用研究室を中心に、高崎研究所設置まで、放射線化学の基礎研究がすすめられた。そのあらましを記した。
村上 昌雄*; 出水 祐介*; 丹羽 康江*; 永山 伸一*; 前田 拓也*; 馬場 理師*; 宮脇 大輔*; 寺嶋 千貴*; 有村 健*; 美馬 正幸*; et al.
no journal, ,
The Hyogo Ion Beam Medical Center was established in May 2001, a leading project of the "Hyogo Cancer Strategy". The accelerator is a synchrotron that can accelerate proton and carbon ion beams at a maximum of 230 and 320 MeV/u, respectively, and the maximum ranges in water are 300 and 200 mm, respectively. Three irradiation rooms installed with 45-degree, horizontal/vertical, and horizontal fixed ports can be used for carbon ion radiation therapy, and 2 gantry rooms can be additionally used for proton beams. Particle beam radiation therapy had been performed in 2,639 patients as of the end of March 2009. The diseases treated were prostate cancer, head and neck tumors, liver cancer, lung cancer, and bone soft tissue tumors, in decreasing order of frequency, and these 5 major diseases accounted for 87% of the cases. As the current problems of particle beam radiation therapy, the effect of the differential use of proton and carbon ion beams is unclear, adverse events, such as skin disorders, may occur due to the limitation of the broad beam method, and the necessity to install large-scale devices is an obstacle to its dissemination. We are aiming at the development and clinical application of a laser-driven proton radiotherapy device in cooperation with the Japan Atomic Energy Agency.
Bolton, P.; 阿部 光幸*; 赤城 卓*; Nuesslin, F.*; 堀 利彦; 岩下 芳久*; 河西 俊一; 近藤 公伯; 前田 拓也; Molls, M.*; et al.
no journal, ,
The rapid advancement of high power laser technology combined with laser-accelerated ion yields from intense laser-plasma interactions sustains a strong interest in the development of integrated laser-driven ion accelerator systems (ILDIAS) that can be used for laser-driven ion beam radiotherapy (L-IBRT). A prime motivation is the promise of significantly reduced size and cost that would afford much greater patient access. Bunch duration of several nanoseconds and high peak current (with a low duty factor) make laser-driven ion irradiation unique. En route to a compact laser-driven "clinical" radiotherapeutic facility it is essential to develop multipurpose "preclinical" or test beamlines that can be used for (1) testing suitable transport optics, diagnostics and control instrumentation, (2) medical and radiobiological studies at the cellular level and in tissue to validate the radiobiological effectiveness of laser-driven ion beam radiotherapy and (3) applications to nonmedical science and technology. Preclinical and clinical beamline development calls for delivering proton energies near 50 MeV and at least 80 MeV respectively with beam energy spread and dose accuracy at one to few percent levels. Control instrumentation and diagnostics capable of single bunch resolution at required repetition rates will be essential to verify and optimize ILDIAS machine performance and capability. In the context of L-IBRT we will discuss the ILDIAS concept as well as beam delivery and instrumentation requirements.
E-E検出器の開発永山 達郎*; 千葉 敏; 西尾 勝久; 西中 一朗; 光岡 真一; 牧井 宏之; 古高 和禎; 若林 泰生; 石井 哲朗; 塚田 和明
no journal, ,
核子移行反応を用いた代理反応により、中性子吸収過程では生成することのできないアクチノイド原子核の核分裂特性を測定することを目的とする。本実験では核子移行反応を測定するためのシリコンE-E検出器の開発を行った。
U標的に
Oビームを照射することで、O+U
O+
U
の核子移行反応をさせ、Oとほかの同位体が分離できるかのテスト実験を行った。
西尾 勝久; 永山 達郎*; 西中 一朗; 光岡 真一; 牧井 宏之; 太田 周也*; 古高 和禎; 塚田 和明; 浅井 雅人; 石井 哲朗; et al.
no journal, ,
代理反応による核分裂断面積の測定結果について報告する。原子力機構タンデム加速器を用い、O+U及びO+
Uの核子移行反応で生成される複合核の核分裂崩壊比を測定し、代理反応比法により
U(半減期23.5分)の中性子入射核分裂断面積を導出した。また、同様の方法で既知のデータが存在する
U(n,f)の核分裂断面積を測定し、成立性について考察を行った。
牧井 宏之; 石井 哲朗; 太田 周也*; 西尾 勝久; 永山 達郎*; 西中 一朗; 古高 和禎; 光岡 真一
no journal, ,
原子力機構タンデム加速器施設を用いて、
Gd(O,O)
Gd及びGd(O,O)
Gd反応の測定を行った。測定で得られた
Gd及び
Gdの中性子捕獲反応断面積比と既知のデータとの比較から、中性子捕獲反応に対して代理反応法が適用可能な中性子エネルギー等について議論を行う。
田村 信行; 西尾 勝久; 廣瀬 健太郎; 西中 一朗; 牧井 宏之; 木村 敦; 太田 周也*; Andreyev, A. N.; Vermeulen, M.*; Gillespire, S.*; et al.
no journal, ,
原子炉の運転に伴って長寿命のマイナーアクチノイド(MA)が生成する。このMAを分離・核変換することで将来にわたる環境への放射線影響を低減することが重要となっている。このための核変換炉を構築するため、MAの中性子入射断面積を高精度で測定する必要がある。本研究では、中性子誘起核分裂および中性子捕獲断面積を同時に測定する方法を開発し、これを用いてAmのデータを取得した。中性子飛行時間分析法を用いた本実験は、J-PARC/MLFのBL04コースで行った。核分裂事象を決定するため、即発中性子を有機液体シンチレータで検出した。この検出器を用いて捕獲反応で放出される線も検出した。線と中性子は、波形弁別法によって区別した。測定で得られた低エネルギー側の3つの共鳴のうち、捕獲断面積は従来の測定によく一致したものの、第2共鳴の核分裂断面積は従来より高い値を得た。核分裂および捕獲断面積を同時に測定する手法を見出したのは本研究が初めてであり、核データの高精度化につながる成果である。
廣瀬 健太郎; 西尾 勝久; L
guillon, R.; 牧井 宏之; 西中 一朗; Orlandi, R.; Smallcombe, J.; 石井 哲朗; 塚田 和明; 浅井 雅人; et al.
no journal, ,
We have developed a measurement system for the multi-nucleon transfer reaction and been studying fission of short-lived minor actinides and neutron-rich nuclides. The experiment was performed at the tandem accelerator facility of Japan Atomic Energy Agency where targets of U, 
Th, 
Cm were irradiated with O beams. In this experiment, more than ten nuclides were excited up to few tens of MeV at a time. Projectile-like scattered particles after the multi-nucleon transfer reaction were detected and identified using a E-E silicon telescope. The mass distribution was deduced from the time difference between two fission fragments from the compound nucleus which were detected using two pairs of multi-wire proportional counters. Neutrons accompanied by fission were also measured using liquid scintillators placed around the reaction chamber. In the nucleon transfer reaction, the axis of the angular-momentum transfer can be determined from the direction of the scattered particle. This is one of the most different point from the neutron/ion-induced fusion-fission reaction where only the plane on which the axis lies can be determined. The fission angular distributions with respect to this axis as well as the mass yield, the prompt neutron multiplicity and so on will be presented.
