一种宽能谱多球中子谱仪能量响应的MC模拟

利用蒙特卡罗程序FLUKA模拟计算了聚乙烯慢化球和辅助材料慢化球对低能中子到高能中子的响应函数曲线。结果表明,对纯聚乙烯球来说,随着聚乙烯层厚度的增加,响应曲线峰逐步右移,峰值在高能区有所下降,对20 Me V以上的中子,无论纯聚乙烯球的尺寸有多大,其响应均下降到很低的程度;对辅助材料慢化球来说,中子能量小于1 Me V时,辅助材料慢化球与聚乙烯慢化球的响应曲线相似,但当中子能量大于20 Me V时,中子与辅助材料层发生(n,xn)反应,慢化球的响应呈显著上升趋势。分析计算结果,最终能够确定宽能谱多球中子谱仪的尺寸组合。

MC Calculation of Neutron Response for an Extended Range Multisphere Neutron Spectrometer

The responses of an extended range Multisphere Neutron Spectrometer as function of neutron energy were calculated by Monte Carlo code，FLUKA. The results show that peak value of the response curve shift to the right with the increasing of polyethylene thickness, but decreases in the high energy region. For neutron with energy >20 MeV, the response of polyethylene moderator will be decreased to be a very low level no matter what size it is. For neutron energies below 1 MeV, the response curve of moderator with auxiliary materials behave like the one of polyethylene moderator, but above 20 MeV the responses increase signi cantly due to increasing (n, xn) cross-sections of auxiliary materials. Based on the present discussion, the size of an extended range multisphere neutron spectrometer can be determined.