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Precision Measurement of 4 and 5 photon decay in positronium

正电子素中 4 和 5 光子衰变的精确测量

基本信息

批准号：
08454068
负责人：
CHIBA Masami
金额：
$ 4.54万
依托单位：
TOKYO METROPOLITAN UNIVERSITY
依托单位国家：
日本
项目类别：
Grant-in-Aid for Scientific Research (B)
财政年份：
1996
资助国家：
日本
起止时间：
1996 至 1997
项目状态：
已结题

来源：
https://kaken.nii.ac.jp/grant/KAKENHI-PROJECT-08454068/
关键词：
positron positronium higher order QED process charge conjugation GSO scintillator 4 and 5 photon decay positron beam ortho-positronium lifetime

项目摘要

In 1996 we published the first results of the measurement of 5 photon decay from ortho-positronium. This was the first test of the 8th order of a without including the lower order in QED.In the second paper we published the results of the measurement of the charge conjugation invariance in 4 photon decay from ortho-positronium. It is inhibited by charge conjugation invariance to decay even number of photons. By the Grant-in Aid we presented and discussed in the international conference held at Poland. The contents were published in the third paper.In 1997 we prepared to use the slow positron beam facility at the National Laboratory for High Energy Physics. The experiment had been approved as the experiment 95-G158. We set the multi-gamma ray spectrometer at the down stream of the line and connected by high vacuum pipe. In order to introduce the beam to the center of the spectrometer, we generated a magnetic field by selenoidal and Helmholz coils. After the preparetion we succeeded to t … More ransport the beam to the entrance of the spectrometer. But we did not have enough time to do the experiment since the slow positron beam line should to move due to the construction of the injector for the B factory. After that we studied the positron beam transport line with alternating magnetic field along the beam line using radially magnetized cylindrical permanent magnets. The preliminary experimental results are encouraging. They have some advantages over electromagnets. They generate strong magnetic field with small magnetic flux leakage, have no power dissipation to heat the environment and are compact. The relevant results was presented at the international conference held at South Africa andwill appear in the fifth paper. We have studied and planed for the new spectrometer to have 10 times larger acceptance for the 4 and 5 photon-decay compared to the existing spectrometer furnished with 32 NaI scintillators. The new one has 92 GSO scintillators to detect the photons. Discrepancy between QED and experiments concerning to the lifetime of ortho-positronium have been reported by Michigan Univ.group. In order to resolve the puzzle, we have studied a spectrometer to utilize 6 GSO scintillators to detect the decay 2 and 3 photons from ortho-positronium in good separation. By the Grant-in Aid we presented and discussed about the theme in the international conference held at England. The contents were published in the fourth paper. Less

1996年，我们首次发表了对正电子的5个光子衰变的测量结果。这是第一次在QED中不包含低阶a的8阶的测试。在第二篇论文中，我们发表了对正电子偶体4光子衰变中电荷共轭不变性的测量结果。电荷共轭不变性抑制了偶光子的衰减。通过我们在波兰举行的国际会议上提出和讨论的无偿援助。内容发表在第三篇论文中。1997年，我们准备使用国家高能物理实验室的慢正电子束设备。该实验已被批准为实验95-G158。我们将多伽马能谱仪设置在流水线的下游，并通过高真空管连接。为了将光束引入光谱仪的中心，我们利用硒体线圈和亥姆霍兹线圈产生磁场。在准备之后，我们成功地将光束传输到光谱仪的入口。但是我们没有足够的时间做实验，因为B工厂的注入器的建设，慢正电子束线应该移动。在此基础上，利用径向磁化的圆柱形永磁体研究了沿束流线存在交变磁场的正电子束流输运线。初步实验结果令人鼓舞。它们比电磁铁有一些优点。它们产生强磁场，漏磁小，对环境没有散热，结构紧凑。有关结果已在南非举行的国际会议上提出，并将出现在第五篇论文中。我们已经研究并计划使新的光谱仪对4和5光子衰变的接受度比现有的配备32个NaI闪烁体的光谱仪大10倍。新的卫星有92个GSO闪烁体来探测光子。美国密歇根大学研究小组报道了关于正电子离子寿命的QED与实验结果的不一致。为了解决这一难题，我们研究了一种利用6个GSO闪烁体的光谱仪，在良好的分离条件下探测正电子的衰变2和衰变3光子。通过赠款，我们在英国举行的国际会议上提出并讨论了这个主题。内容发表在第四篇论文中。少