Novel measurements of the neutron energy spectra of the 9Be(d,n)10B reaction with a thick beryllium target are performed using a fast neutron time-of-flight(TOF)spectrometer for the neutron emission angles θ=0°a...Novel measurements of the neutron energy spectra of the 9Be(d,n)10B reaction with a thick beryllium target are performed using a fast neutron time-of-flight(TOF)spectrometer for the neutron emission angles θ=0°and 45°,and the incident deuteron energies are 250 and 300 keV,respectively.The neutron contributions from the 9Be(d,n)10B reaction are distributed relatively independently for the ground state and the first,second,and third excited states of 10B.The branching ratios of the 9Be(d,n)10B reaction for the different excited states of 10B are obtained for the neutron emission angles θ=0°and 45°,and the incident deuteron energies are 250 and 300 keV,respectively.The branching ratio of the 9Be(d,n)10B reaction for the third excited state decreases with increase in the incident deuteron energy,and the branching ratios for the ground state and the second excited state increase with increase in the neutron emission angle.展开更多
文摘硼中子俘获治疗(Boron Neutron Capture Therapy,BNCT)作为一种有效的治疗癌症的方法,在全世界范围内已被广泛认可。基于^(7)Li(p,n)反应的加速器中子源具有反应阈值低、中子产额高、平均中子能量低、易慢化等优点,是最具潜力实现BNCT的加速器中子源。首先采用蒙特卡罗程序Geant4(GEometry And Tracking)程序模拟了不同能量的质子轰击不同厚度锂靶的中子源特性,提出用3 MeV的质子轰击0.2 mm厚度锂靶的加速器参数设计方案。随后开展了中子慢化体的模拟和优化设计研究,提出了一种“26 cm MgF_(2)+10 cm TiF_(3)”的组合作为慢化层结构,采用0.08 cm的^(6)Li作为热中子吸收层、1.5 cm的Bi作为γ吸收层。在加速器质子束流15 mA的条件下,模拟获得的慢化体出口超热中子注量率达到1.16×10^(9)n·cm^(−2)·s^(−1),快中子与超热中子比率(Φ_(epi)/Φ_(fast))为21.64,热中子与超热中子比率(Φ_(epi)/Φ_(th))为125.23,γ成分(D_(γ)/Φ_(epi))达到1.82×10^(−13)Gy·cm^(2)·n^(−1)(epi),可以满足BNCT的研究需求。
基金Supported by the National Natural Science Foundation of China(11875155,11705071.12075105)the NSFC-Nuclear Technology Innovation Joint Fund(U1867213),the NSAF(U1830102)+1 种基金the Fundamental Research Funds for the Central Universities of China(zujbky-2020-kb09)the Projet of National Defense Science and Technology Industry for Nuclear Power Technology Inovation Center(HDLCXZX-2019-HD-33)。
文摘Novel measurements of the neutron energy spectra of the 9Be(d,n)10B reaction with a thick beryllium target are performed using a fast neutron time-of-flight(TOF)spectrometer for the neutron emission angles θ=0°and 45°,and the incident deuteron energies are 250 and 300 keV,respectively.The neutron contributions from the 9Be(d,n)10B reaction are distributed relatively independently for the ground state and the first,second,and third excited states of 10B.The branching ratios of the 9Be(d,n)10B reaction for the different excited states of 10B are obtained for the neutron emission angles θ=0°and 45°,and the incident deuteron energies are 250 and 300 keV,respectively.The branching ratio of the 9Be(d,n)10B reaction for the third excited state decreases with increase in the incident deuteron energy,and the branching ratios for the ground state and the second excited state increase with increase in the neutron emission angle.
