Precision Measurement of 4 and 5 photon decay in positronium

1996年，我们发表了第一个测量正电子偶素5光子衰变的结果。这是首次在QED中对α的8阶不包括低阶的实验。在第二篇论文中，我们发表了对正电子偶素4光子衰变的电荷共轭不变性的测量结果。它被电荷共轭不变性所抑制，使偶数个光子衰减。通过赠款援助，我们在波兰举行的国际会议上提出并讨论。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。该实验已被批准为实验95-G158。我们将多道伽马能谱仪设置在管道的下游，通过高真空管道连接。为了将光束引入光谱仪的中心，我们通过硒化线圈和亥姆霍兹线圈产生磁场。经过努力，我们成功地 关于我们 将光束传输到光谱仪的入口。但由于B工厂要建造注入器，慢正电子束线需要移动，我们没有足够的时间进行实验。在此基础上，我们研究了采用径向磁化圆柱形永磁体的正电子束传输线，在束线上施加沿着交变磁场。初步实验结果令人鼓舞。它们比电磁铁有一些优势。它们产生强磁场，漏磁小，没有功率耗散来加热环境，并且结构紧凑。有关结果已在南非举行的国际会议上提出，并将列入第五份文件。我们已经研究和计划，新的光谱仪有10倍以上的接受4和5光子衰变相比，现有的光谱仪配备了32碘化钠闪烁。新的一个有92个GSO探测器来探测光子。密歇根大学研究组报道了量子电动力学与有关正电子素寿命的实验之间的差异。为了解决这一难题，我们研制了一台能谱仪，利用6个GSO双光子源对正电子偶素衰变2和衰变3光子进行分离探测。通过赠款援助，我们在英国举行的国际会议上提出并讨论了这一主题。内容刊登在第四期报纸上。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