Physics using ultra low-energy pulsed antiprotons

一种新的脉冲低能反质子源AD(反质子减速器)将于1999年在欧洲核子研究中心开始运行。这项研究包括实验和理论两方面，目的是开发利用AD束流的研究计划。在AD，我们在低能反质子环(LEAR)上开创的反质子氦原子激光光谱学将达到更高的精度。此外，还将研究其他奇异系统，如质子(反质子和质子的束缚态)和反氢。主要研究成果如下：1.向欧洲核子研究中心提交了一项名为《原子光谱学与慢反质子碰撞(ASACUSA)》的实验提案，并获得批准。与欧洲核子研究中心合作完成了射频四极(RFQ)反质子减速器的设计研究，该减速器可以将来自AD的5 MeV束流减速到约50keV。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。这种一致性优于2ppm，由此我们可以将反质子质量的准确度从目前的50ppm提高到0.5ppm。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就可以从质子谱中推断出反质子的质量。所提出的方案将使用RFQ中的低能反质子，使用捕获器进一步减速，并在真空中与原子氢碰撞形成质子。估计的精度为10^&lt；-9；或更高。

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.