Abstract
The isotope shift of the transition in helium has been measured using laser excitation of an atomic beam, yielding 33 668.074(5) MHz. This value, combined with atomic theory and the He nuclear charge radius, gives a He radius of 1.9506(14) fm. This result is over an order of magnitude more precise than previous determinations. It agrees with two recent theoretical values 1.958(6) and 1.954(7) fm from realistic nucleon-nucleon potentials and the He binding energy. Our result provides both a confirmation and a sensitive test of the nuclear theory of few-nucleon systems.
- Received 26 July 1994
DOI:https://doi.org/10.1103/PhysRevLett.74.3553
©1995 American Physical Society