An experimental test of the weak equivalence principle for antihydrogen at the future FLAIR facility

Abstract

We present new experimental ideas to investigate the gravitational interaction of antihydrogen. The experiment can first be performed in an off-line mirror measurement on hydrogen atoms, as a testing ground for our methods, before the implementation with antihydrogen atoms. A beam of hydrogen atoms is formed by launching a cold beam of protons through a cloud of trapped electrons in a nested Penning trap arrangement. In the next step, the atoms are stopped in a series of pulsed electromagnetic coilsso-called atomic coilgun. The stopped atoms are confined in a magnetic quadrupole trap and cooled by single-photon laser cooling. We intend to employ the method of Raman interferometry to study the gravitational interaction of atomic hydrogen -and later on antihydrogen at the FLAIR facility -with high sensitivity.

Gravity effects on antimatter in the standard-model extension

“…While the above tests with ordinary, neutral matter yield numerous sensitivities to Lorentz violation, versions of the tests highlighted above performed with antimatter, charged particles, and second-and third-generation particles can yield sensitivities to Lorentz and CPT violation that are otherwise impossible or difficult to achieve. Reference 12 considers gravitational experiments with antihydrogen, 22,23,24,25,26,27,28,29 charged-particle interferometry, 30,26 ballistic tests with charged particles, 31 and signals in muonium free fall. 32 Positronium may also offer an interesting possibility.…”

Special issue on antihydrogen and positronium

“…The antihydrogen positive ion, H + should, like its matter counterpart H − have a single bound state. The GBAR collaboration aims to produce this entity via H-Ps interaction (see e.g., [48]), though direct radiative capture of the positron via interaction with ground state H as e h H H…”

“…Measuring the gravitational interaction of systems containing antiparticles has emerged as an area of current interest, and experiments are planned on Ps [53][54][55], H [48,56] (where a methodolgy has already been developed [57]) and muonium (Mu, the e --positive muon bound state) [58]. These are all challenging: Ps and Mu have finite lifetimes, and though this does not apply to H, the anti-atom is, for obvious reasons, in much shorter supply than either of the other two systems.…”