Adiabatic expansion cooling of antihydrogen

Journal Article · 16 September 2024 · Physical Review Research

DOI: https://doi.org/10.1103/PhysRevResearch.6.L032065 · OSTI ID:2474347

Ahmadi, M.; Alves, B. X. R.; Baker, C. J.; Bertsche, W. ; Capra, A. ; Cohen, S.; Torkzaban, C.; Cesar, C. L. ; Charlton, M. ; Collister, R.; Eriksson, S.; Evans, A.; Evetts, N.; Fajans, J. ; Friesen, T.; Fujiwara, M. C.; Granum, P. ; Hangst, J. S.; Hayden, M. E.; Hodgkinson, D. ; Isaac, C. A.; Johnson, M. A. ; Jones, S. A. ; Jonsell, S. ; Kalem, N. ; Madsen, N. ; Maxwell, D.; McKenna, J. T. K. ; Menary, S.; Momose, T. ; Munich, J.; Olchanski, K.; Olin, A. ; Pusa, P.; Rasmussen, C. Ø.; Robicheaux, F. ; Sacramento, R. L.; Sameed, M. ; Sarid, E.; Silveira, D. M.; So, C.; Stutter, G.; Tharp, T. D.; Thompson, R. I.; van der Werf, D. P. ; Wurtele, J. S.

Magnetically trapped antihydrogen atoms can be cooled by expanding the volume of the trap in which they are confined. We report a proof-of-principle experiment in which antiatoms are deliberately released from expanded and static traps. Antiatoms escape at an average trap depth of $0.08\pm 0.01\mathrm{K}$ (statistical errors only) from the expanded trap while they escape at average depths of $0.22\pm 0.01$ and $0.17\pm 0.01\mathrm{K}$ from two different static traps. (We employ temperature-equivalent energy units.) Detailed simulations qualitatively agree with the escape times measured in the experiment and show a decrease of $38\%$ (statistical $\text{error}<0.2\%$ ) in the mean energy of the population after the trap expansion without significantly increasing antiatom loss compared to typical static confinement protocols. This change is bracketed by the predictions of one-dimensional and three-dimensional semianalytic adiabatic expansion models. These experimental, simulational, and model results are consistent with obtaining an adiabatically cooled population of antihydrogen atoms that partially exchanged energy between axial and transverse degrees of freedom during the trap expansion. This result is important for future antihydrogen gravitational experiments which rely on adiabatic cooling, and it will enable antihydrogen cooling beyond the fundamental limits of laser cooling. Published by the American Physical Society 2024

• Sponsoring Organization: USDOE
• OSTI ID: 2474347
• Journal Information: Physical Review Research, Journal Name: Physical Review Research Journal Issue: 3 Vol. 6; ISSN PPRHAI; ISSN 2643-1564
• Publisher: American Physical SocietyCopyright Statement
• Country of Publication: United States
• Language: English