BCC金属Nb的重离子辐射损伤研究

采用81 MeV碳离子辐照,模拟中子注量为10~(23)/cm~2的堆中子在Nb中产生的辐射损伤,用时间微分扰动角关联和正电子湮没二种方法研究辐射损伤及其高温退火效应。实验发现经注量2.5×10~(16)/cm~2的碳离子辐照后,在BCC金属Nb中产生单空位和双空位二种缺陷。随退火温度升高,双空位分解,单空位的总浓度逐步减小,经过1058K退火后,在Nb中由辐射损伤造成的缺陷消失。     

模拟裂变中子源能谱测量

一、引言在研究链式反应系统的各种性质时,常常用到具有类似裂变中子能谱的中子源。模拟裂变中子源主要由~(210)Po的α粒子轰击F,Be,Li,B等轻元素产生中子,随着靶元素成份以及结构的差异,中子能谱也不完全相同。应本院同位素处的要求,我们测量了一模拟裂变中子源的能谱,其源强约10~4n/s,靶成份为天然Li 24.16%,F66.14%,B 9.4%,     

FATE OF AFLATOXIN M1 IN KASHAR CHEESE

The distribution and stability of aflatoxin M₁ (AFM₁) in Kashar cheese were investigated. Raw milk samples were spiked with AFM₁ at the levels of 50, 250 and 750 ng/L. Distribution of toxin in milk, cheese curd, whey, kneading brine and cheese, and its stability during ripening were determined by high‐performance liquid chromatography. Concentrations of AFM₁ in curds for each contamination level were 2.93, 3.19 and 3.37 times higher than those in milk. After syneresis, the percentage distribution of AFM₁ was 40–46% in curds and 53–58% in whey indicating that relatively higher concentration of toxin passed to whey. Moreover, by the kneading process approximately 2–5% of AFM₁ passed to kneading brine. Compared to the initial spiking level, the percentage of toxin in cheeses varied between 35–42%. Over a 60‐day storage period, there was no decrease in the concentration of AFM₁, suggesting that the toxin was stable during ripening.     

用^252Cf自发裂变中子源刻度中子探测器效率

使用标准的Ｍｏｎｔｅ－Ｃａｒｌｏ程序计算了几种闪烁中子探测器的效率曲线，同时又用＾２５２Ｃｆ自发裂变中子源中子对效率曲线的低能部分进行了实验刻度。通过实验值对计算值归一把刻度点与计算曲线结合起来，按照实验点的走向修正了计算效率曲线的近阈部分。文章着重叙述实验刻度的技术。     

OCHRATOXIN A IN TURKISH WINES

In this research, 47 wine samples produced from 2001 to 2002 harvest period in four Turkish regions were analyzed for the presence of ochratoxin A (OTA). Based on the results, the OTA levels of red wines are generally higher than those of white and rose wines. However, the wines from two wine regions (Aegean and Thrace) are much more contaminated with OTA compared with the others.     

二维位置灵敏硅探测器性能测试

用＾２３９Ｐｕ α源和４０与７０ＭｅＶ的Ｏ和Ｃ离子在Ａｕ靶上的散射束对二维位置灵敏硅探测器的性能进行测试。结果表明：在这种测试条件下，在计算位置的公式中用能量信号代替４个位置信号之和可获得更好的位置分辨；主放大器的成形时间对探测器的位置分辨有较大的影响。     

18－27MeV中子能区的有机闪烁体探测器的效率刻度

通过对Ｔ（ｄ，ｎ）￣４Ｈｅ反应的中子角分布测量，刻度了芪晶体的探测效率，能量范围为１８—２７ＭｅＶ。