适用于研究低能裂变碎片电荷分布的探测器装置

为研究²⁵²Cf自发裂变碎片电荷分布，建立了由屏栅电离室和ΔE-E粒子望远镜构成的探测器系统。在该系统中，将薄的屏栅电离室作为碎片的ΔE探测器，E探测器是金硅面垒半导体探测器。通过分析实验测量的4参数关联数据，得到了²⁵²Cf自发裂变碎片质量数、动能及碎片在气体ΔE探测器中的能量沉积分布等物理量。用多高斯（multi-Gaussian）分布函数对ΔE探测器的能量响应函数进行最小二乘法拟合，得到了在固定质量数A^*_L和动能条件下轻碎片的电荷分布。结果表明：该探测器系统的电荷分辨能力Z/ΔZ约为40∶1；建立起来的测量技术可用于测定²³⁵U(n,f)和²³⁹Pu(n,f)反应碎片的电荷分布。

Equipment to Measure Charge Distributions of Fragments in Low Energy Fission

In order to study charge distributions of fragments in spontaneous fission of 252Cf, a detector system, including a typical grid-ionization chamber and a ΔE-E particle telescope in which a thin grid ionization chamber is served as the ΔE-section and the E-section is a surface barrier detector, was built up. From the measured four-parameter correlation data, the physical quantities, such as mass number， kinetic energy of fragments and energy deposited by fragments in the gas ΔE detector can be derived. The charge distributions at the fixed mass number A^*_L and total kinetic energy (TKE) of the light fragments were obtained by the leastsquares fiting of the response functions of ΔE detector with multiGaussian distributions representing all charge states. The results show that the charge resolution of Z/ΔZ≈40∶1 can be given by this detector system. The measured technique in this work can be used to determine the charge distributions of fragments for other low energy fission reactions such as ²³⁵U(n, f) and ²³⁹Pu(n, f).