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Measurement of the He Ground State Lamb Shift Via the Two-Photon 11S - 21S transition
Published
Author(s)
S Bergeson, A Balakrishnan, K G. Baldwin, Thomas B. Lucatorto, J P. Marangos, T J. McIlrath, Thomas R. O'Brian, S L. Rolston, J Wen, N Westbrook, C H. Cheng, E E. Eyler, Craig J. Sansonetti
Abstract
We have extended two-photon Doppler-free spectroscopy to the vacuum ultraviolet spectral region to accurately measure the He 11S - 21S transition at 120 nm. Our result is 4 984 872 315[48] MHz. This yields a ground state Lamb shift of 41104[48] MHz, in fair agreement with theory and other experiments. This approach has the potential for significantly better accuracy once improvements in the laser and the wavelength metrology are implemented.
Bergeson, S.
, Balakrishnan, A.
, Baldwin, K.
, Lucatorto, T.
, Marangos, J.
, McIlrath, T.
, O'Brian, T.
, Rolston, S.
, Wen, J.
, Westbrook, N.
, Cheng, C.
, Eyler, E.
and Sansonetti, C.
(1998),
Measurement of the He Ground State Lamb Shift Via the Two-Photon 1<sup>1</sup>S - 2<sup>1</sup>S transition, Physical Review Letters
(Accessed October 21, 2025)