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Measurement of fast neutrons with ^(238)U-coated fission chamber

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Radiation Detection Technology and Methods 2019年第3期3卷 187-191页

作者： Yuanfan Guan Herun Yang Limin Duan Junwei Zhang Xiaohua Yuan Zhiyong He Xueying Zhang Rongjian Hu Chengui Lu Peng Ma Xianglun Wei Meng Li Zaiguo Gan Chunli Yang Hongbin Zhang Liang Chen Institute of Modern Physics Chinese Academy of SciencesLanzhou 730000China School of Nuclear Science and Technology University of Chinese Academy of SciencesBeijing 100049China

Purpose Afission chamber with two layers of 238Ufissile materials has been developed for the measurements of fast *** The developed fission chamber has been tested by 60Co gamma source and 252Cf neutron *** The results have indicated that it is very easy to cut off the gamma rays from the neutrons by using a discriminator,when the fission chamber works in the pulse *** detector works well,even if the static air is used as the filling *** To discuss the application of the detector,Monte Carlo simulations have been performed by considering four 238U-coated fission chambers located outside the spallation target for the fast neutron measurement from spallation *** simulation results have indicated that the detector can be used to measure the fast neutron flux and neutron flux ratio of four fission ***,a 238U-coated fission chamber can be used within a reactor for longer time,in comparison with a 235U-coated fission chamber.

关键词： Fission chamber fast neutrons Neutron source Experimental measurement Monte Carlo simulations

THE LATE EFFECTS ON BONE MARROWS IN MICE AFTER TOTAL BODY IRRADIATION BY P(35) BE fast neutrons AND γ RAYS

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Chinese Journal of Cancer Research 1997年第2期9卷 116-118页

作者：孙艳韩树奎徐博张淑惠申文江唐景华常维克 Radiotherapy Department Beijing Institute for Cancer Research Beijing Institute of High Energy Physics Academia Sinica Beijing

Purpose: To understand the late effects on bonemarrow after widefield or total body irrdiation withvarious types of *** and Methods: Total body irradiationwith single dose of P(35) Be fast neutrons and γ raysrespectively have been used in this study. Kunming strainmice were irradiated by fast neutrons produced bybombardment of beryllium target with 35MeV protonsand the dose rate was 0.12 to 0.14 Gy/min. Nine doselevels were used in fast neutrons irradiation from 0.20 to3.50Gy. The dose rate of 60Co γ rays was 0.60Gy/min andirradiation was in the range of 0.25 to 9.00Gy. Sixteendose points were studied. All animals without anesthesiawere irradiated whole body with single doses by fastneutrons and γ rays respectively, One group withoutirradiation was regarded as control group. 90 days afterirradiation all animals were sacrificed. The nucleatedcells of bone marrow and the peripheral blood cellsincluding WBC and lymphocytes were ***: our study shows that the number ofnucleated cells of bone marrow in both fast neutrons andγ ray groups decreased with increase of the doses. Thereare significant differences between irradiated groups andzero line (control group) and the slopes are -1.41 ±0.55(p=0.038) and -0.98 ± 0. 24(P= 0.0015) for fast neutronsand γ rays respectively. There is no significant differencebetween the two kinds of radiation (p>0.05). The lateeffects on peripheral blood cells (WBC and lymphocytes)in mice after irradiation with single doses of neutrons andγ rays were signincantly lower than unirradiated group(Pneutrons and γ ***: Total body irradiation with neutronsor γ rays can suppress marrow in mice in the long-term,and is more obvious with increase of doses. There is nosignificant difference between neutrons and γ rays for thelate effects studied.

关键词： fast neutrons Bone marow Irradiation

Influence of thermal and resonance neutron on fast neutron flux measurement by ^(239)Pu fission chamber

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Chinese Physics C 2015年第1期39卷 50-53页

作者：曾丽娜王强宋凌莉郑春 Institute of Nuclear Physics and Chemistry China Academy of Engineering Physics Key Laboratory of Neutron Physics China Academy of Engineering Physics

The ^239Pu fission chambers are widely used to measure fission spectrum neutron flux due to a fiat response to fast neutrons. However, in the meantime the resonance and thermal neutrons can cause a significant influence on the measurement if they are moderated, which could be eliminated by using ^10B and Cd covers. At a column enriched uranium fast neutron critical assembly, the fission reaction rates of ^239gpu are measured as 1.791 × 10^-16 2.350 × 10^-16 and 1.385×10^-15 per second for 15 mm thick ^10B cover, 0.5 mm thick Cd cover, and no cover respectively, while the fission reaction rate of 239pu is rapidly increased to 2.569×10^-14 for a 20 mm thick polythene covering fission chamber. The average 239pu fission cross-section of thermal and resonance neutrons is calculated to be 500 b and 24.95 b with the assumption of 1/v and 1/E spectra respectively, then thermal, resonance and fast neutron flux are achieved to be 2.30×10^6, 2.24×10^6 and 1.04×10^8 cm^-2·s^-1.

关键词： fission chamber neutron flux thermal and resonance neutrons fast neutrons

Genome-Wide Sequencing of 41 Rice （Oryza sativa L.） Mutated Lines Reveals Diverse Mutations Induced by fast-Neutron Irradiation

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Molecular Plant 2016年第7期9卷 1078-1081页

作者： Li, Guotian Chern, Mawsheng Jain, Rashmi Martin, Joel A. Schackwitz, Wendy S. Jiang, Liangrong Vega-Sanchez, Miguel E. Lipzen, Anna M. Barry, Kerrie W. Schmutz, Jeremy Ronald, Pamela C. Univ Calif Davis Dept Plant Pathol Davis CA 95616 USA Univ Calif Davis Genome Ctr Davis CA 95616 USA Lawrence Berkeley Natl Lab Feedstocks Div Joint BioEnergy Inst Berkeley CA 94720 USA US DOE Joint Genome Inst Walnut Creek CA 94598 USA Xiamen Univ Sch Life Sci Xiamen 361102 Peoples R China HudsonAlpha Inst Biotechnol Huntsville AL 35806 USA Monsanto Co Chesterfield Village Campus Chesterfield MO 63017 USA

fast-neutron （FN） irradiation has been used to create mutagen- ized collections of many plant species （Bolon et al., 2014）, FN- induced mutagenesis has clear advantages： it is an efficient means of saturating the genome, and it does not involve time- consuming plant transformation or tissue culture. In rice, most mutant collections, although highly valuable, were generated us- ing either T-DNA insertion or transposon tagging approaches that often induce mutations unlinked to the insertion and complicating analysis （Wang et al., 2013）. Another disadvantage of some of these collections is that they were created in rice varieties that are photoperiod-sensitive and often have long generation times.

关键词： fast neutrons PLANT DNA

Micro-size picosecond-duration fast neutron source driven by a laser-plasma wakefield electron accelerator

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High Power Laser Science and Engineering 2022年第5期10卷 57-64页

作者： Yaojun Li Jie Feng Wenzhao Wang Junhao Tan Xulei Ge Feng Liu Wenchao Yan Guoqiang Zhang Changbo Fu Liming Chen Key Laboratory of Laser Plasma(MoE) School of Physics and AstronomyShanghai Jiao Tong UniversityShanghaiChina IFSA Collaborative Innovation Center Shanghai Jiao Tong UniversityShanghaiChina Shanghai Advanced Research Institute Chinese Academy of SciencesShanghaiChina Key Laboratory of Nuclear Physics and Ion-beam Application(MoE) Institute of Modern PhysicsFudan UniversityShanghaiChina

A pulsed fast neutron source is critical for applications of fast neutron resonance radiography and fast neutron absorption ***,due to the large transversal source size(of the order of mm)and long pulse duration(of the order of ns)of traditional pulsed fast neutron sources,it is difficult to realize high-contrast neutron imaging with high spatial resolution and a fine absorption ***,we experimentally present a micro-size ultra-short pulsed neutron source by a table-top laser-plasma wakefield electron accelerator driving a photofission reaction in a thin metal converter.A fast neutron source with source size of approximately 500μm and duration of approximately 36 ps has been driven by a tens of MeV,collimated,micro-size electron beam via a hundred TW laser *** micro-size ultra-short pulsed neutron source has the potential to improve the energy resolution of a fast neutron absorption spectrum dozens of times to,for example,approximately 100 eV at 1.65 MeV,which could be of benefit for high-quality fast neutron imaging and deep understanding of the theoretical model of neutron physics.

关键词： fast neutrons high-power laser laser wakefield acceleration photofission reaction

Neutron-induced apoptosis of HR8348 cells in vitro

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World Journal of Gastroenterology 2001年第3期7卷 435-439页

作者： Li Ping Wang~1 Ke Liang~2 Yu Shen~2 Wei Bo Yin~2 G.Hans~3 Yan Jun Zeng~1 ~1Biomechanics & Medical Information Institute,Beijing Polytechnic University,Beijng 100022,China ~2Department of Gastrointestinal Surgery,Aalborg University,Denmark ~3Cancer Institute (Hospital),Chinese Academy of Medical Sciences,Peking Union Medical College,Beijing 100021,ChinaLi Ping Wang graduated from Beijing Polytechnic University in 2000,major in tumor radiotherapy,having 3 papers published. Biomechanics & Medical Information Institute Beijing Polytechnic University No.100 Ping Le Yuan Chao Yang District Beijing 100022 China.

INTRODUCTIONTo date ,the major therapy for rectal carcinoma is extensive abdomino-perineal resection[1]. Unfortunately ,after resection of rectal carcinoma ,many patients still die of blood-borne metastases ,usually in the liver or lungs ,or local prlvic recurrence[2,3],which is the major cause of morbidity and mortality in patients with rectal carcinoma .Pre-or postoperative radiotherapy can reduce the incidence of local rdcurrence[4-7].

关键词： Adenocarcinoma fast neutrons Rectal Neoplasms Apoptosis Dose-Response Relationship, Radiation Humans Immunohistochemistry In Vitro Proto-Oncogene Proteins c-bcl-2 Research Support, Non-U.S. Gov't Tumor Cells, Cultured Tumor Suppressor Protein p53