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Intra-Spur Reactions Studied by Using Positronium Formation

利用正电子形成研究内支线反应

基本信息

批准号：
01540360
负责人：
ITO Yasuo
金额：
$ 1.02万
依托单位：
University of Tokyo
依托单位国家：
日本
项目类别：
Grant-in-Aid for General Scientific Research (C)
财政年份：
1989
资助国家：
日本
起止时间：
1989 至 1990
项目状态：
已结题

项目摘要

Positronium (Ps) is a hydrogen-like atom which is formed between positron (e^+) and electron (e^-). The mechanism of Ps formation is not yet made clear. There are two models of Ps formation. The Ore model assumes that energetic (epithermal) e^+ picks up an electron from the medium, and the spur model assumes that e^+ is nearly thermalized in its own terminal radiation spur and combines with e^- (excess electron) that is ejected by ionization.The head investigator has long been involved in the research of this problem, and has a conclusion that the spur model is a better model than the former at least regarding Ps formation in condensed molecular substances. The precious study aims to advance this viewpoint and hopefully make the "Ps formation experiment" a research tool to study fast intra-spur reactions.The experiments have been to measure Ps yield in various mixtures inert and electrophilic molecules. The importance of the spur process has been confirmed. Moreover a new aspect of Ps formation, namely "Ps formation from excited molecular states" has been found. By the discovery of this new process, the picture of Ps formation has been improved substantially, and we have published a thesis titles "A New Model of Positronium formation".There still remains problems concerning evaluation of mutual relative importance of the Ore model and the spur model. These problems have been summarized in a review article.

正电子 (Ps) 是一种类氢原子，由正电子 (e^+) 和电子 (e^-) 形成。 Ps 的形成机制尚未明确。 Ps 形成有两种模型。 Ore模型假设高能（超热）e^+从介质中拾取电子，而杂散模型假设e^+在其自身的终端辐射杂散中近乎热化，并与电离喷射出的e^-（多余电子）结合。首席研究员长期参与该问题的研究，并得出结论：杂散模型是比前者更好的模型，至少在凝聚态中Ps的形成方面分子物质。这项珍贵的研究旨在推进这一观点，并希望使“Ps形成实验”成为研究快速内支链反应的研究工具。该实验测量了各种惰性和亲电分子混合物中的Ps产量。刺激过程的重要性已经得到证实。此外，还发现了Ps形成的一个新方面，即“从激发分子态形成Ps”。通过这个新过程的发现，Ps形成的图景得到了很大的改善，我们发表了一篇论文，题为“正电子形成的新模型”。 Ore模型和spur模型相互相对重要性的评估仍然存在问题。这些问题已在一篇评论文章中进行了总结。