Fracture behavior of a Zr-metallic glass under dynamic compression

Dynamic planar compressive experiments on a typical tough Zr-BMG (Bulk Metallic Glass) were carried out under impact velocity of 500-600 m/sec and strain rate of 10(6)/s. The fracture surface of samples exhibits different fracture patterns at different parts of the sample. At a corner close to the front loading boundary, fracture patterns from the free edge toward the centre changed from equiaxial veins in microscale to periodic corrugations in nanoscale; in the middle of the sample, the fracture surface contains glazed zones laid out orderly along the same boundary. FEM simulation was performed to investigate the stress distributions in the impacted sample under a short duration impact loading. It has revealed that the fracture patterns changing from the free edge toward the centre were resulted from the fracture modes' changing from the tensile dominant fracture to the shear dominant fracture. Whereas at the middle part of the sample, fracture initiated from several parallel shear bands propagating close to the same boundary is due to a large strain or much higher shear stress in this area.

基于大功率LED的中子墙光刻度系统

光刻度系统是中子墙探测器系统的重要组成部分,用于中子墙前端电子学的刻度和探测器工作性能变化的监测．通过对基于发光二极管(LED)作为光源的中子墙光刻度系统方案开展了细致的测试研究,确定了基于快脉冲驱动的大功率蓝光LED(3W)的中子墙光刻度系统方案,对中子墙探测单元进行了初步刻度测试,刻度结果能很好地满足光刻度要求,表明对于快塑料闪烁体探测器该方案是一种较为理想的方案．

Alterations of immune functions induced by 12C6+ion irradiation in mice

Purpose: To estimate the biological risks to the immune system of the type of space radiation, 12C6+, encountered by cosmonauts during long-term travel in space. Materials and methods: The Kun-Ming strain mice were whole-body irradiated by 12C6+ ion with 0, 0.01, 0.05, 0.075, 0.2, 0.3, 0.5, 0.75, 1 or 2 Gy, at a dose rate of 1 Gy/min. At 35 days after irradiation, the thymus and spleen weights were measured, the natural killer (NK) cells activity of spleen was determined by 3-(4, 5-dimethylthiazol-2-yl)-2, 5-diphenyl tetrazolium bromide (MTT), and the interferon-gamma (IFN-gamma) levels in serum and thymus were detected with enzyme-linked immunosorbent assays (ELISA). Results: The results showed that the thymus weight, IFN-gamma levels in serum and the activity of splenic NK-cells had significantly increased at a dose of 0.05 Gy. With further dose increase, the weight of spleen continued to increase but the weight of thymus, IFN-gamma level and NK-cells activity declined. Conclusions: These results suggest that the dose of 0.05 Gy irradiation has a stimulatory effect on mouse immunity; this effect declined with increasing dose.

A proposal design of a multi-hit two-dimensional position-sensitive energy spectrum detector

A new non-linear comparison method of charge-division readout scheme is conceived and the first design of a multi-hit two-dimensional position-sensitive energy spectrum Si(Au) surface barrier detector with a continuous sensitive area is proposed.

Study of the LED based light calibration system for neutron wall detector

The light calibration system is one of the key components of Neutron Wall detector. It is used to calibrate the electronics and to monitor the long-term stability of the detector modules. With the detaile investigations, a calibration system with high-power LED (3W) driven by the fast pulses has been carried out. It is also tested together with the detector module of the Neutron Wall and the result of the preliminary calibration demonstrates that it fulfills the needs. It's a new design proposal to the light calibration system of the fast scintillator detector.

GeV能区重离子碰撞中碎片的形成和核穿透效应

分析了从0.4至1.2GeV/u 的Ni+Ni和Pb+Pb重离子碰撞过程中的径向流，核穿透等动力学现象及其对碎片形成的影响，得出如下结果： 实验结果发现，从出射粒子的快度分布可以看出，越重的粒子产额越小，且较容易出现在弹靶核快度区域，并且系统越重越有利于碎片的形成。不同快度区间的出射粒子的平均质量数可以说明，碎片不仅来自于弹靶核的碎裂，同时“火球”区域的轻核子凝聚也是一重要来源，对于不同的系统和不同的入射能量，两者的贡献不同。在某一入射能量的某一碰撞系统，不同质量数的粒子的产额随质量数满足很好的指数下降的关系，其斜率随快度绝对值的变化与系统质量相关，……，说明重碎片可能来自弹靶核的碎裂，而随着系统质量的增加，“火球”区域的轻核子凝聚变得越来越重要。 根据冲击波模型假设的出射粒子的平均动能随粒子的质量数的线性变化关系，提取出径向流，发现径向流随入射能量的增高而增高，并且系统越重，径向流越明显。并且发现出射粒子的横向快度分布比纵向快度分布窄，说明碰撞过程中存在部分穿透，并且穿透对系统的大小和入射能量有很强的依赖关系，经“Vartl”定量的描述，发现随着入射能量升高系统的变轻，穿透现象越明显，并且发现径向流与核阻止有很明显的关联关系。 经过理论结果与实验结果的对比，可以发现例如径向流、核穿透等动力学因素对碎片的形成有很明显的影响。同时为提取核物质状态方程（EOS）提供了有用的数据