Antihydrogen and hyperfine structure
This project is part of the physics program of the ASACUSA collaboration at the Antiproton Decelerator of CERN. From 2012-2017 the SMI part was suppported by the Advanced Grant „HBAR-HFS“ no. 291242 of the European Research Council awarded to Prof. Dr. Eberhard Widmann, director of the Stefan Meyer Institute for Subatomic Physics of the Austrian Academy of Sciences, Vienna, Austria. The goal of the project is to study the hyperfine structure of antihydrogen, the simplest antimatter atom, and thus search for a violation of the charge-parity-time (CPT) symmetry of Nature. In parallel activities within the AEgIS collaboration at CERN-AD were pursued to evaluate a different approach of creating a slow beam of antihydrogen atoms needed for the measurement.
Antihydrogen is the simplest atom consisting entirely of antimatter. Since its hydrogen counterpart is one of the most precisely measured atoms in physics, a comparison of antihydrogen and hydrogen offers one of the most sensitive tests of CPT symmetry. This project proposes to measure the ground state hyperfine splitting (HFS) of antihydrogen (HBAR), which is known in hydrogen with relative precision of 10–12. It is the central part of the program of the ASACUSA collaboration at CERN-AD. The experimental method consists of the formation of an antihydrogen beam and a measurement using a spin-flip cavity and a sextupole magnet as spin analyser like it was done initially for hydrogen
A major milestone was achieved in 2010 when antihydrogen was first synthesized by ASACUSA. In the first phase of this project, an antihydrogen beam will be produced and the HBAR-HFS will be measured to a precision of around 10–7 using a single microwave cavity. In a second phase, the Ramsey method of separated oscillatory fields will be used to increase the precision by about one order of magnitude.
