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Studies Secondary Electron Emission in Slow Antiproton-Matter

研究慢反质子物质中的二次电子发射

基本信息

批准号：
03044039
负责人：
YAMAZAKI Yasuhori
金额：
$ 3.2万
依托单位：
College of Arts and Sciences, University of Tokyo
依托单位国家：
日本
项目类别：
Grant-in-Aid for international Scientific Research
财政年份：
1991
资助国家：
日本
起止时间：
1991 至 1992
项目状态：
已结题

项目摘要

In atomic and solid state physics, "heavy" particles with negative charge like antiprotons, negative muons etc., can be fantastic probes to investigate Charge asymmetry effects. Among others, antiproton beams from LEAR at CERN are the best because of its high quality and high intensity.The present research is an extension of the previous project, "Studies on Secondary electron emission in antiproton-foil collisions (#0104403 : 1989-1990). Our first step had been devoted to the investigation on "wake-riding" electrons through measurements of energy spectra of secondary electrons emitted in the forward direction in antiproton-foil collisions. We have performed a couple of experiments degrading 5.9MeV antiproton beams (the lowes possible energy upto now)to several hundred KeV degrader foils, where one can only get a beam of wide energy and angular distribution. Our principal observations have been, (1)the spectra around v_p-v_e, where upsilone is the electron velocity, are rather smooth with very weak indication of an anticusp as opposed to simple-minded predictions, and (2) a small bump is observed at the right energy position with reasonable intensity, which is consistent with theoretical evaluations.As a reference experiment, we have also measured the intensity of ionized electrons emitted in the forward direction in coincidence with primary electrons scattered in the same direction for He gas target, where an anticusp is clearly observed which is in good contrast with antiproton experiment.Recent development of RFQ accelelator technique enables us to get "deccelelated"monoenergetic antiproton beam as low as -200KeV. We are on the way to extend our experiment with this high quality ultra slow beams, which will provide, e.g., the definite answer on the existence of the wake riding electrons, and further the possibility of channeling of slow heavy particles through crystals, etc.

在原子和固体物理学中，带负电荷的“重”粒子，如反质子、负μ子等，可以成为研究电荷不对称效应的奇妙探针。本研究是前一个项目“反质子-箔碰撞中二次电子发射的研究”（#0104403：1989-1990）的延伸。我们的第一步工作是通过测量反质子-箔碰撞中正向发射的次级电子的能谱来研究“尾流驾驭”电子。我们已经进行了几次将5.9MeV的反质子束流（目前可能的最低能量）降能到几百KeV的降能箔的实验，在那里只能得到宽能量和角分布的束流。我们的主要观察结果是：（1）v_p-v_e（其中v是电子速度）附近的谱是相当平滑的，与简单的预测相反，具有非常弱的反尖指示;（2）在正确的能量位置处观察到具有合理强度的小凸起，这与理论评估一致。我们还测量了He气体靶在正向发射的电离电子的强度，在反质子加速器技术的最新发展下，我们可以得到“反尖”的结果。低至-200KeV的单能反质子束。我们正在用这种高质量的超慢光束扩展我们的实验，这将提供，例如，对尾流中存在骑电子的问题给出了明确的回答，并进一步讨论了慢重粒子通过晶体的可能性等。