A source of antihydrogen for in-flight hyperfine spectroscopy

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 2.7m
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