Mechanism of Oxygen Effect on Solid State Nuclear Track Detectors

氧对固态核径迹探测器的影响机制

基本信息

批准号：
02680185
负责人：
MIYAKE Hiroshi
金额：
$ 1.28万
依托单位：
Kobe University of Mercantile Marine
依托单位国家：
日本
项目类别：
Grant-in-Aid for General Scientific Research (C)
财政年份：
1990
资助国家：
日本
起止时间：
1990 至 1991
项目状态：
已结题

来源：
https://kaken.nii.ac.jp/grant/KAKENHI-PROJECT-02680185/
关键词：
Track Detector Oxygen Effect Latent Track CR-39 Dissolved-Oxygen Concentration Diffusion Coeffcient Life Time of Radicals

项目摘要

Solid state nuclear track detectors, especially CR-39 plastic ones, are a useful tool to detect heavy charged particles and applied to many fields, such as radiation protection measurements, nuclear fusion study, space science, etc. However, the storage of these detectors in vacuum causes severe effects on the registration sensitivity. The oxygen dissolved in a detector plays an important role in the latent track formation. The purpose of this project is to clarify the mechanism of the "Oxygen Effect" and to develop improved detectors.The oxygen concentration and the diffusion coefficient in CR-39 plastic were measured, and the relation between the oxygen concentration and the sensitivity of the detector was ascertained. Outgas rates of oxygen and some other components from CR-39 sheets commercially available were measured at room temperature with a quadrupole mass specrometer. Diffusion coefficients and oxygen concentrations dissolved at atmospheric pressure were evaluated to be(4-9)x10^<-9>cm^2/sec and(1-8)x10^<19>molecules/cm^3, respectively. The reduction rates of etch rate ratios through the storage in vacuum were given by a function of local pressures of oxygen dissolved in CR-39. These results supported the "oxygen setting model", quantitatively.The life time of the radicals formed by alpha-particle irradiation in the sufficiently outgassed CR-39 was evaluated on the basis of the examination for etch pit recovery in radius due to the air exposure after the storage in vacuum. Radicals with a life time of about 40 minutes were found to be formed as well as radicals with a life time of less than a few minutes after irradiation. It was also found that the fractions of radicals with different life times depended on the lots of CR-39, the time of storage after production and the energy of incident particles.

固态核轨道探测器，尤其是CR-39塑料探测器，是检测重型电荷颗粒并应用于许多领域的有用工具，例如辐射保护测量，核融合研究，太空科学等。但是，真空中这些检测器的存储对注册敏感性产生严重影响。溶解在检测器中的氧气在潜在轨道形成中起着重要作用。该项目的目的是阐明“氧效应”的机制并发展改进的检测器。测量了CR-39塑料中的氧浓度和扩散系数，并确定了氧浓度与检测器的敏感性之间的关系。在室温下用四极质量质量表测量了CR-39床单的Outgas氧和其他一些成分。在大气压下溶解的扩散系数和氧浓度分别为（4-9）x10^<-9> cm^2/sec和（1-8）x10^<19>分子/cm^3。通过储存真空的蚀刻速率比率的降低速率是通过溶解在CR-39中的局部压力的函数。这些结果支持“氧设置模型”，定量地。根据检查真空吸尘器存储后的空气暴露而导致的半径蚀刻坑恢复的蚀刻坑恢复，评估了α粒子辐照在足够大的CR-39中形成的自由基的寿命。发现寿命约40分钟的自由基以及辐照后不到几分钟的寿命的自由基。还发现，具有不同寿命的自由基的分数取决于很多CR-39，生产后的存储时间和入射颗粒的能量。