The ASACUSA antihydrogen and hydrogen program : results and prospects

TL;DR

The ASACUSA collaboration at CERN has made significant progress in producing and detecting cold antihydrogen atoms, and has performed high-precision measurements of hydrogen hyperfine splitting, aiming to test fundamental symmetries.

Contribution

This paper reports the first detection of cold antihydrogen atoms in a magnetic field free region and the most precise beam measurement of hydrogen hyperfine splitting.

Findings

Detected 80 antihydrogen atoms 2.7 meters from production

Achieved a hydrogen hyperfine splitting measurement with 2.7x10^(-9) precision

Presented initial antihydrogen quantum state scans in 2016

Abstract

The goal of the ASACUSA-CUSP collaboration at the Antiproton Decelerator of CERN is to measure the ground-state hyperfine splitting of antihydrogen using an atomic spectroscopy beamline. A milestone was achieved in 2012 through the detection of 80 antihydrogen atoms 2.7 meters away from their production region. This was the first observation of "cold" antihydrogen atoms in a magnetic field free region. In parallel to the progress on the antihydrogen production, the spectroscopy beamline was tested with a source of hydrogen. This led to a measurement at a relative precision of 2.7x 10^(-9) which constitues the most precise measurement of the hydrogen hyperfine splitting in a beam. Further measurements with an upgraded hydrogen apparatus are motivated by CPT and Lorentz violation tests in the framework of the Standard Model Extension. Unlike for hydrogen, the antihydrogen experiment is complicated by the difficulty of synthesizing enough cold antiatoms in ground-state. The first antihydrogen quantum states scan at the entrance of the spectroscopy apparatus was realized in 2016 and is presented here. The prospects for a ppm measurement are also discussed.