Physics using ultra low-energy pulsed antiprotons

一种新的脉冲低能反质子源，AD（反质子减速机），将于1999年在欧洲核子研究中心开始运行。本文从实验和理论两方面进行了研究，以制定利用AD波束的研究方案。在AD，我们在低能反质子环（LEAR）上率先开展的反质子氦原子激光光谱研究将达到更高的精度。此外，还将对质子（反质子和质子的结合态）和反氢等其他奇异体系进行研究。主要研究结果如下：一项在欧洲核子研究中心进行的名为“原子光谱学和慢反质子碰撞（ASACUSA）”的实验提议被提交给欧洲核子研究中心，并获得批准。与欧洲核子研究中心（CERN.3）合作完成了射频四极子（RFQ）反质子减速器的设计研究，该减速器可以将从AD发射的5 MeV束流减速到50 keV左右。对反质子氦激光光谱数据进行了详细的分析，并与最近量子三体理论的高精度结果进行了比较。该协议优于2 ppm，由此可以将反质子质量的精度从目前的50 ppm提高到0.5 ppm。对质子激光光谱学实验进行了概念设计。作为一个二体系统，不需要复杂的三体理论的帮助，应该可以从质子光谱中推断出反质子的质量。提出的方案将使用来自RFQ的低能反质子，使用捕获阱进一步减速，并通过与氢原子碰撞在真空中形成质子。估计精度为10^<-9>或更好。

A new pulsed low-energy antiproton source, AD (antiproton decelerator), will start its operation from 1999 at CERN.This research, both experimental and theoretical, was conducted so as to develop research program using the AD beam. At AD, laser spectroscopy of antiprotonic helium atoms, the work we pioneered at the low energy antiproton ring (LEAR), will reach much higher precision. In addtion, study of other exotic systems such as protonium (bound state of an antiproton and a proton) and anti-hydrogen will be conducted. The major results are as follows :1. A proposal of an experiment at CERN AD, called "Atomic Spectroscopy and Collisions using Slow Antiprotons (ASACUSA)" was submitted to CERN, and was approved.2. The design study of-radio frequency quadrupole (RFQ) antiproton decelerator, which can decelerate the 5 MeV beam from the AD to about 50 keV, was completed in collaboration with CERN.3. Detailed analysis of antiprotonic helium laser spectroscopy data was done, and the results were compared with the high-precision results of recent quantum three-body theory. The agreement was better than 2 ppm, from which we could improve the accuracy of antiproton mass from the present value of 50 ppm to 0.5 ppm.4. A conceptual design of an experiment for protonium laser spectroscopy was done. Being a two-body system, it should be possible to deduce antiproton mass from protonium spectroscopy without the help of complicated three-body theories. The proposed scheme will use the low-energy antiprotons from the RFQ, decelerate them further using a catching trap, and form protoniums in vacuum by collision with atomic hydrogens. The estimated accuracy is 10^<-9> or better.