Eli Sarid - Video Lecture

Eli Sarid - Video Lecture

IVS-IPSTA 2020 Online Conference December 13, 2020

Afternoon Plasma Session
Session chair:
Ido Barth 

The Hebrew University of Jerusalem

The quest for precision measurements of antihydrogen atoms

Eli Sarid

Soreq NRC, BGU and ALPHA collaboration CERN


Comparison of the properties of matter and antimatter is an important basic physics problem. Measurements of energy transitions in trapped antihydrogen and their comparison to the transitions in hydrogen atoms can be used as a sensitive test of CPT symmetry. The ALPHA collaboration in CERN was the first to demonstrate trapping [1] and then measurement of resonant transitions between levels of trapped antihydrogen atoms [2,3]. Microwave radiation was first used to induce transitions between the hyperfine levels of the ground state of the antiatoms. Then we performed the first ever measurement of the transition 1S→2S in antihydrogen, using two-photon laser excitation with 243 nm light [3]. These initial measurements indicated that the antihydrogen 1S→2S transition energy is equal to its hydrogen counterpart at the level of about 2×10-10. Recently, ALPHA was able to demonstrate large increases in the number of trapped atoms. Important achievements were obtained in the aim of cooling down the antimatter atoms to lower temperatures than ever before. We successfully implemented a pulsed UV laser (121.5 nm) to interact with the 1S–2P Lyman-α transition in antihydrogen. Even before demonstrating laser cooling with that laser, we were able to obtain important unprecedented measurements of the fine structure of antihydrogen. Finally, we also demonstrated the first introduction of antiprotons and positrons into the new vertical trap ALPHA-g, which will eventually be used for gravitational measurements of antihydrogen atoms.