New experimental measurement of natSe(n, γ) cross section between 1 eV to 1 keV at the CSNS Back-n facility

The ⁷⁴Se is one of 35 p-nuclei, and ⁸²Se is a r-process only nucleus, and their (n, γ) cross sections are vital input parameters for nuclear astrophysics reaction network calculations. The neutron capture cross section in the resonance range of isotopes and even natural selenium samples has not been measured. Prompt γ-rays originating from neutron-induced capture events were detected by four C₆D₆ liquid scintillator detectors at the Back-n facility of China Spallation Neutron Source (CSNS). The pulse height weighting technique (PHWT) was used to analyze the data in the 1 eV to 100 keV region. The deduced neutron capture cross section was compared with ENDF/B-VIII.0, JEFF-3.2, and JENDL-4.0, and some differences were found. Resonance parameters were extracted by the R-matrix code SAMMY in the 1 eV-1 keV region. All the cross sections of ^natSe and resonance parameters are given in the datasets. The datasets are openly available at http://www.doi.org/10.11922/sciencedb.j00113.00019.     

上海激光电子伽马源(SLEGS)核共振荧光谱仪设计及探测器性能分析

核共振荧光(NRF)实验可对光核反应低激发能级进行研究。上海激光电子伽马源(SLEGS)设计、建造了一组由2台大尺寸同轴高纯锗(HPGe,φ80 mm×70 mm)探测器和2台CLOVER HPGe(4×φ50 mm×70 mm)探测器组成的核共振荧光谱仪,大尺寸HPGe探测器获得了大于100%的相对效率和好于0.3%@1 332keV的能量分辨率。谱仪采用Mesytec MDPP-16数字脉冲处理器及MVME获取系统,以读取和记录HPGe前置放大器输出信号的幅度和时间信息。研究了CLOVER HPGe探测器在加和(Add-back)模式和去除(Reduction)模式下的性能提升,结果表明,Add-back重建可以显著提高全能峰效率和峰总比,在1 460 keV能量处,Addback重建后的全能峰效率可以提高21%以上。由于Add-back重建引入了多个晶体之间的耦合,导致探测器能量分辨稍有下降。而Reduction模式可以降低康普顿峰,提高峰总比,并保持和直接(Direct)工作模式同等水平的能量分辨,但是损失了一定的全能峰效率。     

抛光液酸碱性对固结磨料抛光硫化锌晶体的影响

硫化锌晶体是一种重要的红外光学材料,在红外成像、导弹制导、红外对抗等红外技术领域应用广泛.抛光液能够与工件及抛光垫发生化学反应从而影响工件表面质量和材料去除率.实验采用乙二胺、氢氧化钠、柠檬酸、盐酸分别配制不同的酸碱性抛光液,研究抛光液酸碱性对固结磨料抛光硫化锌晶体材料去除率、表面形貌和表面粗糙度的影响.实验结果表明:酸性抛光液抛光的材料去除率高于碱性抛光液;柠檬酸抛光液可同时获得优表面质量和高加工效率,抛光后的晶体表面粗糙度Sa值为4.22 nm,材料去除率为437 nm/min.