A source of antihydrogen for in-flight hyperfine spectroscopy

Abstract

Antihydrogen, a positron bound to an antiproton, is the simplest antiatom. Its counterpart—hydrogen—is one of the most precisely investigated and best understood systems in physics research. High-resolution comparisons of both systems provide sensitive tests of CPT symmetry, which is the most fundamental symmetry in the Standard Model of elementary particle physics. Any measured difference would point to CPT violation and thus to new physics. Here we report the development of an antihydrogen source using a cusp trap for in-flight spectroscopy. A total of 80 antihydrogen atoms are unambiguously detected 2.7 m downstream of the production region, where perturbing residual magnetic fields are small. This is a major step towards precision spectroscopy of the ground-state hyperfine splitting of antihydrogen using Rabi-like beam spectroscopy.

High-precision comparison of the antiproton-to-proton charge-to-mass ratio

“…In this context, we recently reported the most precise and first direct high-precision measurement of the proton magnetic moment, with a fractional precision of 3.3 parts per billion 18 . Complementary to these efforts, spectroscopic comparisons of hydrogen and antihydrogen are underway; recent progress has been made at CERN 13,19 . The most precise test of CPT invariance with baryons is the comparison of the proton and antiproton charge-to-mass ratios.…”

“…The standard model is the theory that describes particles and their fundamental interactions, although without taking into account gravitation. However, this model is known to be incomplete, which has inspired searches for physics beyond the standard model, such as tests of CPT invariance that compare the fundamental properties of matterto-antimatter equivalents at the lowest energies and with the greatest precision [12][13][14][15] . For leptons, for example, the magnetic anomalies of electron and positron were compared with a fractional uncertainty of about 2 parts per billion 4 , and by applying similar techniques to protons and antiprotons, the resulting g-factor (a proportionality constant which links the spin of a particle to its magnetic moment) comparison reached a precision of 4.4 parts per million 8 .…”

Investigation of two-frequency Paul traps for antihydrogen production

“…Equation (15) is numerically integrated and the stability assessed by the same threshold as in (14). The effect of damping terms is pictured in Fig.…”

“…Typical yields in the ALPHA apparatus are several trapped antiatoms per attempt every ≈15 minutes [10,11]. The ASACUSA experiment has pursued an alternative to spectroscopy on trapped atoms with a CUSP trap [12], which uses an anti-Helmholtz field to generate a beam of spin polarized antihydrogen for eventual microwave spectroscopy atoms [13,14].…”

An atomic hydrogen beam to test ASACUSA’s apparatus for antihydrogen spectroscopy

“…The antihydrogen group within the ASACUSA collaboration focuses its experiments on testing the CPT symmetry by comparing the GS-HFS of the hydrogen and antihydrogen atom [4]. During the Long Shutdown 1 period at CERN antiprotons could not be delivered and therefore noHs could be produced.…”