Speaker
Description
We present measurements of the cyclotron frequency ratios $^{4}$He$^{+}$/D$_{2}^{+}$, $^{4}$He$^{+}$/H$_{2}$D$^{+}$, and $^{4}$He$^{+}$/$^{12}$C$^{3+}$ using a cryogenic Penning ion trap [1,2]. Our results clearly differentiate between an earlier measurement of the mass of $^{4}$He by the University of Washington [3] and a more recent measurement by the LIONTRAP collaboration [4] in favor of the latter. From the $^{4}$He$^{+}$/$^{12}$C$^{3+}$ ratio we obtain an atomic mass of $^{4}$He at 9 x 10$^{-12}$ fractional uncertainty. This result, combined with a sufficiently precise future measurement of the ratio of electron spin-flip frequency to cyclotron frequency of $^{4}$He$^{+}$, will yield a value for the electron atomic mass with uncertainty of ~1 x 10$^{-11}$. Further, the consistency of the 3 ratios and the LIONTRAP result adds validation to all of the more recent measurements of the masses of the long-lived isotopes of hydrogen and helium.
[1] M. Medina Restrepo, M. Fernandez Davila, C. A. Navarro, and E. G. Myers, Phys. Rev. A 112, L040801 (2025).
[2] M. Fernandez Davila, M. Medina Restrepo, C. A. Navarro, and E. G. Myers, submitted to Physical Review Letters.
[3] R. S. Van Dyck, Jr., D. B. Pinegar, S. Van Liew, S. L. Zafonte, Int. J. Mass Spectrom. 251, 231 (2006).
[4] S. Sasidharan, O. Bezrodnova, S. Rau, W. Quint, S. Sturm, and K. Blaum, Phys. Rev. Lett. 131, 093201 (2023).
This work was supported by the National Science Foundation under Grant No. 2409083.
strong text