基于Geant4的4π多单元载Gd液闪探测系统的初步设计

Preliminary Design of 4π Multicell Gd-Loaded Liquid Scintillator Detection System Using Geant4 Package

采用基于蒙特卡罗方法的Geant4软件设计了由40个载Gd液闪探测器组成的多单元4π立体角探测系统。该探测系统与置于其几何中心的裂变室构成了一个研究平台,该平台主要用于可裂变核(n,2n)反应截面的测量工作。首先对该系统的物理模型进行了初步检验,然后计算并分析了该探测系统的一些基本性能。通过计算发现,系统空腔半径的变化对中子探测效率的影响十分有限;而探测效率随探测器的厚度增加先是迅速增大,然后逐渐趋于平缓;计算还表明,Gd同位素俘获中子后发射的级联γ射线的能量主要沉积在局部几个相邻的探测器中。基于以上计算,初步确定了系统的厚度以及空腔半径的大小,并对下一步将要开展的工作做了初步规划。

A gadolinium-loaded neutron detection system with 40 liquid scintillators is designed and simulated by using Geant4 Package based on Monte Carlo method. This system with a fission chamber placed in its center is mainly used for the cross section measurement of （n, 2n） reaction of fissile nuclides. We firstly test the physics model, and then calculate and analyze some basic performance of this system. According to the calculation, the detecting efficiency is not sensitive to the inner radius of the detecting system. The efficiency increase with the system thickness at limited thickness value. The calculated results also indicate that the energy of the T rays emitted from Gd isotope after capturing a thermal neutron is mainly deposited in a few adjacent detectors. Based on above calculations, the thickness and inradius of this detecting system have been preliminarily determined.