Spectroscopy of Antihydrogen

该项目的目标是测试CPT不变性（e。例如，在一个实施例中，利用反氢原子和反质子氦原子的精密谱学方法，详细研究了反氢原子的形成机制，发现：1）三体复合过程占主导地位，2）产生的反氢原子很可能处于高激发态，3）反氢原子的动能比在10 K左右的环境温度下预期的要高得多。换句话说，虽然我们现在可以以几百赫兹的速度产生反氢原子，但它们都不适合高精度光谱学。为了克服这个困难，我们（ALPHAcollaboration）构建了一个新的装置，包括超导潘宁陷阱，超导八极线圈和一对镜像线圈，我们现在试图用它来磁性捕获反氢原子。到目前为止，还没有发现任何一个反质子氦原子的高精度激光光谱学已经相当成功。通过以下方法，我们实现了质子/反质子质量和电荷比较的新CPT限值为2x 10 -9：1）我们通过阻止超低能反质子来消除碰撞效应（由线性反质子减速器减速）的超低密度氦气靶中的激光系统，2）我们发展了一种基于单模连续激光脉冲放大的新激光系统，3）采用光频梳技术对激光频率进行了标定。我们的测量结果在质子与电子的质量比为1836.152674？0.000005。这几乎与已知的质子与电子的质量比1836.15267247一样精确。0.000 000 80（codata 2006）。已经确定了进一步提高精度的方法，因此我们的测量很可能在几年内比质子质量测量更精确。

The goal of this project was to test the CPT invariance (e. g., equality of particle vs antiparticle mass & charge) by means of precision spectroscopy of antihydrogen atoms and antiprotonic helium atoms.We studied in detail the formation mechanism of antihydrogen atoms, and found : 1) the dominance of 3-body recombination process, 2) produced antihydrogen atoms are likely to be in highly excited states, 3) antihydrogen atoms have much higher kinetic energy than was expected from the ambient temperature of some 10 K. In other words, although we can now produce antihydrogen atoms at a rate of a few hundred Hz, none of them is suitable for high-precision spectroscopy. In order to overcome this difficulty, we (ALPHAcollaboration) constructed a new setup comprising a superconducting Penning trap, a superconducting octupole coils and a pair of mirror coils, with which we are now attempting to magnetically trap antihydrogen atoms. As of today, none has been found yet.High-precision laser spectroscopy of antiprotonic helium atoms has been quite successful. We achieved a new CPT limit of proton/antiproton mass and charge comparison of 2x10-9, by the following methods : 1) we eliminated collisional effects by stopping ultra-low-energy antiprotons (decelerated by a linear antiproton decelerator) in an ultra-low-density helium gas target, 2) we developed a new laser system based on pulsed amplification of single-mode cw lasers, 3) the optical frequency comb technology was used to calibrate the laser frequencies. Our measurement resulted in the determination of proton-to-electron mass ratio to be 1836.152 674 ?} 0.000 005. This is almost as precise as the known proton-to-electron mass ratio of 1836.152 672 47 ?} 0.000 000 80 (codata 2006). Methods to further improve the precision have been identified, so that our measurements are likely to become more precise than the proton-mass measurement in a few years.