Hyperfine spectroscopy of antihydrogen, hydrogen, and deuterium

Measurement of the hyperfine structure of antihydrogen in a beam

A measurement of the hyperfine structure of antihydrogen promises one of the best tests of CPT symmetry. We describe an experiment planned at the Antiproton Decelerator of CERN to measure this quantity in a beam of slow antihydrogen atoms.

Spectroscopy Apparatus for the Measurement of The Hyperfine Structure of Antihydrogen

The ASACUSA CUSP collaboration at the Antiproton Decelerator (AD) of CERN is planning to measure the ground-state hyperfine splitting of antihydrogen using an atomic spectroscopy beamline. We describe here the latest developments on the spectroscopy apparatus developed to be coupled to the antihydrogen production setup (CUSP).

Observation of Hyperfine Transitions in Trapped Ground-State Antihydrogen

This paper discusses the first observation of stimulated magnetic resonance transitions between the hyperfine levels of trapped ground state atomic antihydrogen, confirming its presence in the ALPHA apparatus. Our observations show that these transitions are consistent with the values in hydrogen to within 4~parts~in~$10^3$. Simulations of the trapped antiatoms in a microwave field are consistent with our measurements.

Rabi Experiments on the $σ$ and $π$ Hyperfine Transitions in Hydrogen and Status of ASACUSA's Antihydrogen Program

We report on the status of the in-beam hyperfine-structure measurements on ground-state antihydrogen by ASACUSA and on recent results obtained in supporting measurements from hydrogen. The $σ_1$ and $π_1$ transitions can now be investigated, which is beneficial from both theoretical and experimental perspectives. We discuss systematic effects from resonance interference originating from the chosen field geometries in the interaction region, and how their impact can be managed by appropriate data-taking or design concepts.

利用适用于反氢实验的新型束内超精细谱学方法进行氢的CPT与洛伦兹对称性检验

CPT and Lorentz symmetry tests with hydrogen using a novel in-beam hyperfine spectroscopy method applicable to antihydrogen experiments

本文通过氢原子束内Rabi型超精细跃迁测量，首次对标准模型扩展的部分CPT与洛伦兹破坏系数给出2.3×10^-21 GeV量级约束，并提出适用于反氢束实验的零场频率确定新方法，将束流氢超精细频率测量精度提升至0.44 ppb，较此前结果提高6倍。

Status Report: A Detector for Measuring the Ground State Hyperfine Splitting of Antihydrogen

The ASACUSA (Atomic Spectroscopy And Collisions Using Slow Antiprotons) collaboration at the Antiproton Decelerator at CERN aims to measure the ground state hyperfine structure of antihydrogen. A Rabi-like spectrometer line has been built for this purpose. A detector for counting antihydrogen is located at the end of the beam line. This contribution will focus on the tracking detector, whose challenging task it is to discriminate between background events and antiproton annihilations originating from antihydrogen atoms which are produced only in small amounts.