Precision Measurement of 4 and 5 photon decay in positronium

1996年，我们发表了测量正电子正电子5光子衰变的第一批结果。这是第一次在不包含QED低阶的情况下对a的8阶进行测试。在第二篇论文中，我们发表了正电子四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数个光子的衰变。由我们在波兰举行的国际会议上提出并讨论的助学金。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装置。本实验已被批准为实验95-G158。我们在线路的下游安装了多个伽马能谱仪，并通过高真空管连接。为了将光束引入到光谱仪的中心，我们通过磁化线圈和亥姆霍兹线圈产生了磁场。经过准备，我们成功地进行了…测试莫尔将光束传输到分光计的入口处。但是我们没有足够的时间来做实验，因为B工厂的注入器的建造使得慢正电子束线应该移动。然后利用径向磁化的圆柱形永磁体，研究了沿束线交变磁场的正电子束流输运线。初步的实验结果令人鼓舞。与电磁铁相比，它们有一些优势。它们产生的磁场强，漏磁小，无功率耗散，对环境加热，结构紧凑。相关成果已在南非举行的国际会议上作了介绍，并将在第五篇论文中发表。我们已经研究并计划，与现有的配备32个NaI闪烁体的光谱仪相比，新的光谱仪对4和5光子衰变的接受度要大10倍。新的探测器有92个GSO闪烁体来探测光子。密歇根大学小组已经报道了QED和关于正电子素寿命的实验之间的差异。为了解决这个问题，我们研究了一种利用6个GSO闪烁体来探测正电子中衰变的2和3光子的光谱仪，能够很好地分离。通过助学金，我们在英国举行的国际会议上提出并讨论了这一主题。这些内容发表在第四篇论文中。较少

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