New positron lifetime spectrometer with the coincidence of energy selected positron and the annihilation photon

新型正电子寿命谱仪，能量选择正电子与湮没光子重合

基本信息

批准号：
07555188
负责人：
SHIRAI Yasuharu
金额：
$ 5.57万
依托单位：
Osaka University (1996)Kyoto University (1995)
依托单位国家：
日本
项目类别：
Grant-in-Aid for Scientific Research (A)
财政年份：
1995
资助国家：
日本
起止时间：
1995 至 1996
项目状态：
已结题

来源：
https://kaken.nii.ac.jp/grant/KAKENHI-PROJECT-07555188/
关键词：
positron beam positron lifetime characterization of materials lattice defect 陽電子消滅熱平衡空孔

项目摘要

In order to achieve in-situ studies of condensed matter under extremeconditions, new beta^+-gamma conicidence lifetime spectrometer with the coincidence of energy-selected positron and the annihilation photon has been constructed. The whole apparatus is desk-top and low cost, since it does not need any accelerators but a small sealed positron-source and a pair of magnetic lenses. Specimens can be exposed to any extreme surrounding conditions without the risk of contamination by radioactive materials, since the specimen part is independent and well-separated from the sealed positron-source. In order to overcome the inevitable deterioration of time resolution due to the spread of TOF (time of flight) of positrons emitted from radioisotopes, positrons in a certain energy band are selected using magnetic field. The total efficiency (more than 10^<-3> of positrons from the source can be focused on a specimen) is much superior to that expected for the case of re-acceleration of moderated positrons. The time resolution of the whole system with a 10mCi^<22> Na positron source is about 385ps (FWHM) as yet, which is worse than that of the conventional gamma-gamma coincidence method (around 200ps FWHM typically) but bears comparison with former beta^+-gamma coincidence lifetime spectrometers using close geometry between the positron source and a specimen.

为了在极端结构下实现对凝结物质的原位研究，已经构建了与能量选择的正电子和歼灭光子一致的新型β+ - 伽马圆锥形寿命光谱仪。整个设备都是台式机顶和低成本，因为它不需要任何加速器，而是一个小的密封正电子源和一对磁性镜头。标本可以暴露于任何极端的周围条件下，而不会受到放射性材料污染的风险，因为样品部分是独立的，并且与密封的正电子源分离。为了克服由于从放射性同位素发出的正上音的TOF（飞行时间）散布而导致的时间分辨率的不可避免的恶化，使用磁场选择了某个能量带中的正上音。总效率（来自源的正电子的10^<-3>可以集中在样品上）要优于重新加速中学正子的预期。迄今为止，使用10MCI^<22> na正电子源的整个系统的时间分辨率迄今为385ps（fwhm），比传统的伽马 - 伽马相吻合方法（通常约为200PS FWHM）更糟糕，但与以前的beta^+-gamma comma cosidence cocividence LifeTime-lifeTime Pecormenters相比，它具有比较，使用了beta^+ - gamma^+ - gamma^+gamma comama cominciential cosivide Lifementers of PositiTron source and PositiTron和A PositiTron之间的comine and和A PositiTron之间。