液滴室内的氢液滴超冷条件下的结晶(英文)

液滴室内超冷现象的存在使得氢微球在自身温度低于其三相点温度的情况下依然处于液态。这可能导致液滴在真空注入过程中发生碎裂。结合液氢的超冷知识, 对液滴室内的氢液滴进行了热力学模拟, 理论上提出了利于氢液滴尽快冷却成固体小丸的最佳实验条件, 即保持液滴室内氦背景气体和氢蒸汽的压强尽可能低, 并将液滴室长度延长到6 cm以上。Because of the existence of supercooling in a droplet formation chamber, the hydrogen micro spheres are still in liquid phase even though their temperature is lower than the triple point temperature. This may cause the droplets to shatter in the vacuum injection capillary. Based on the knowledge about supercooling of liquid hydrogen, we have done a thermodynamic simulation of the droplets in the droplet formation chamber, and theoretically suggested the optimal working conditions under which the droplets will most properly nucleate to solid pellets. The suggested working conditions are that the helium gas pressure and the hydrogen vapor pressure in the droplet formation chamber are kept as low as possible, and the droplet formation chamber should be no less than 6 cm in the length.     

双面硅多条探测器的测试

介绍了由中国科学院近代物理研究所和北京大学微电子研究院联合研制的双面硅多条探测器的初步测试过程及测试结果。测试内容包括: 探测器的电特性、 能量分辨率、 二维能谱、 条间串扰（crosstalk）。在-25 V全耗尽偏压下, 各条的反向漏电流均小于10 nA, 对于5.486 MeV的α粒子, 正面各条的能力分辨率在1.5%左右, 条间串扰在6%左右; 背面各条能量分辨率稍差, 在3%左右, 其条间串扰在1%左右。同时对进口的Micron BB1直流耦合单边读出的双面硅条探测器做了相同测试, 并进行了性能对比。The testing of a doubled-sided multi-strip silicon detector manufactured by Institute of Modern Physics of CAS and Peking University were introduced. The electrical characteristics and energy resolution, two dimensional spectrum, crosstalk were presented. The reverse leak current of each strip is smaller than 10 nA under bias voltage of 25 V. The energy resolution of strips on the front side is about 1.5%, but a little worse for the backside strips, about 3%. The level of crosstalk is about 6% for the front side, 1% for the backside. Same tests were carried out on the commercial Micron BB1 detector and a comparison was presented.