碰撞电离产生Au L3空穴态定向行为的研究

采用一种简单的实验方法测定低能区几种离子与Ａｕ碰撞产生Ａｕ的Ｌ₃空穴态的定向度，及定向度的入射离子能量相关性；同时在平面波玻恩近似理论基础上加上库仑偏转效应的校正进行了理论计算，改善了实验点与平面波玻恩近似理论计算的符合程度，讨论了有关空穴态定向行为。 关键词：     

离子原子近距碰撞过程研究

对在北京大学技术物理系核物理与核技术实验１．７ＭＶ串列加速器上进行的有关离子原子碰撞内壳层电离机制的研究进展作了简介。     

OBSERVATION OF PHOTOREFRACTIVE EFFECT OF KNbO3 CRYSTAL AT μW ILLUMINATION

The photorefractive effects of the as-grown and proton-implanted KNbO₃ crystals were studied by two-wave mixing at 62.2μW/cm² illumination. At this pump power level, the as-grown crystal showed little photorefractive effect, while the proton-implanted crystal showed an obvious effect. Furthermore, there seemed to exist two photorefractive gratings with response times of 22.54 and 1596.30s, at 62.2μW/cm² pump power level, in the proton-implanted sample. This phenomenon has been attributed to the influence of proton-implantation.     

A MICROSCOPIC MECHANISM OF LOW TEMPERATURE HELIUM RELEASE

⁴He ions of various energies and at various doses were implanted into three kinds of samples: TiH₂ films, high purity Ti pieces as-received and after hydrogenation. Thermal release of helium was monitored in situ by proton-enhanced backscattering. Low-temperature helium release was observed at T≤573K. Single jump model was used to calculate the active energies for the release. Based on the observations, a mechanism of helium cluster vacancy complex (He_mV_n-V_i) for low temperature helium release is proposed.     

高能量分辨率的平面晶体位置灵敏谱仪

平面晶体波长色散位置灵敏谱仪是一新型高能量分辨率的X射线分析装置,可用于高能量分辨的元素分析、化学态及原子物理等研究中.这里简要介绍所研制的位置灵敏谱仪装置及其性能,以及位置灵敏谱仪与其核心部件──位置灵敏正比计数器的基本原理.所研制位置灵敏谱仪对55Fe,Ti和Si所达到的能量分辨率(FWHM)分别为25eV,15eV及7eV.因此,它将可以用作高分辨的元素分析.