Antihydrogen spectroscopy

On the most fundamental level, we have shown how this experimental scheme might be used for a fundamental test of CPT symmetry violation [8]. While still somewhat hypothetical, at present, this would constitute the most sensitive currently proposed test on CPT symmetry. The sensitivity expressed as a baryon mass difference Am between particles and antiparticles (with mass m) would be of the order of Am/m = 10"30 [8]. The best currently proposed other experiment is on antihydrogen spectroscopy at CERN (not yet carried out) with Am/m = 10 18, and the best existing result for the proton-antiproton pair is Am/m < 10 9 [9]. 

Fig. 8.12. A possible scenario for trapped antihydrogen spectroscopy. The microwaves quench the 28 antihydrogen via the 2P3/2 state, which spontaneously decays by emission of a Lyman-a photon.

Gabrielse, G. (1988). Trapped antihydrogen for spectroscopy and gravitation studies is it possible Hyperfine Interactions 44 349-356. 

Hansch, T.W. and Zimmermann, C. (1993). Laser spectroscopy of hydrogen and antihydrogen. Hyperfine Interactions 76 47-57. 

Continuous wave coherent Lyman-a radiation has recently become available [85] so that laser cooling or sensitive shelving spectroscopy of magnetically trapped hydrogen atoms is coming within reach. The ability to work with a small number of atoms is of particular interest for laser spectroscopy of antihydrogen, a goal pursued by the ATRAP and ATHENA collaborations at CERN [8]. 

Antihydrogen Production and Precision Spectroscopy with ATHENA/AD-1... 

Since the ultimate goal consists of high precision spectroscopy on (trapped) antihydrogen, the main focus of future experiments must be on the production and storage of antihydrogen atoms at very low energies. Thus, the recombination technique used should have the prospect to ... 

The second phase will be designed and constructed based on the results of Phase 1. While the focus is on 2-photon laser spectroscopy of magnetically trapped antihydrogen atoms, other measurements (e.g. a measurement of the hyperfine structure using an atomic antihydrogen beam) are being explored for this program. 

Shelving spectroscopy thus involves many decisions whether the antihydrogen atom has been excited to the metastable 2 2S /2 state or not. These decisions have to be made somewhat quicker than the natural lifetime of the metastable state and are based on the observation or the non-observation of fluorescent light at Lyman-a. The detection efficiency for fluorescent light from an antihydrogen sample in a magnetic trap with superconducting coils is probably rather... 

The production and spectroscopy of antihydrogen (p-e+ = H) is one of the central topics at the Antiproton Decelerator (AD) of CERN. The two other approved experiments, ATHENA [5] and ATRAP [6] are dedicated to antihydrogen... 

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