22–26 Nov 2021
AlbaNova Main Building
Europe/Stockholm timezone
Please note: ECTI 2021 will be held as a hybrid event.

Dawn of Precision Measurements with Cold Antihydrogen

22 Nov 2021, 10:25
25m
Tsuzuki Lecture Theatre, St. Anne's college (Oxford + Zoom)

Tsuzuki Lecture Theatre, St. Anne's college

Oxford + Zoom

Speaker

April Cridland (Swansea University)

Description

The ALPHA (Antihydrogen Laser PHysics Apparatus) Collaboration at CERN is engaged in precise measurements of the antihydrogen spectrum with a view to studying the fundamental symmetries between matter and antimatter. In 2018, ALPHA measured the 1S-2S transition to one part in 1012 [1]. Since then, ALPHA has gone on to measure the
transitions between the 1S ground state and the 2P1/2 and 2P3/2 excited states to infer the fine structure splitting in the n=2 manifold [2] and more importantly the very first demonstration of laser cooling of antihydrogen atoms [3] which will improve the precision of all future spectroscopy measurements. ALPHA continues to pursue additional techniques to increase the precision of these frequency measurements by using beryllium ions to sympathetically cool positrons, thereby increasing the number of trapped H̅, and introducing a maser and atomic clock to improve the frequency metrology of the experiment. In the last
two years, it has also been necessary to prepare for the ELENA era of operation in the Antiproton Decelerator. This has required significant upgrades to the structure of the ALPHA experiment to work under different vacuum conditions and with slower moving antiprotons.
Finally, the new experiment, ALPHA-g, has been assembled in its final form to begin moving towards a measurement of the effect of gravity on antihydrogen, which would be a test
Einstein’s equivalence principle. ALPHA-g is currently undergoing commissioning of all its essential systems and will be ready for data taking in 2022.

References
[1] Ahmadi, M., Alves, B.X.R., Baker, C.J. et al. Characterization of the 1S–2S transition in antihydrogen. Nature 557, 71–75 (2018). https://doi.org/10.1038/s41586-018-0017-2
[2] The ALPHA Collaboration. Investigation of the fine structure of antihydrogen. Nature 578, 375–380 (2020). https://doi.org/10.1038/s41586-020-2006-5
[3] Baker, C.J., Bertsche, W., Capra, A. et al. Laser cooling of antihydrogen atoms. Nature 592, 35–42 (2021). https://doi.org/10.1038/s41586-021-03289-6

Primary author

April Cridland (Swansea University)

Co-author

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