Laser
Trapping and Probing of Exotic Helium Isotopes
Dr. Z.-T. Lu
Physics
Division,
Argonne
National Laboratory
Department
of Physics and Enrico Fermi Institute,
University
of
Chicago
We have succeeded in laser trapping and cooling of the exotic
helium isotopes, both 6He (t1/2 = 0.8 sec) and 8He
(t1/2 = 0.1 sec), and have performed precision laser spectroscopy on
individual trapped atoms. Based on the atomic isotope shifts measured along the
isotope chain 3He – 4He – 6He – 8He,
and on the precise theory of the atomic structure of helium, the nuclear charge
radii of 6He and 8He are determined for the first time in
a method independent of nuclear models. The results are compared with the values
predicted by a number of nuclear structure calculations and test their ability
to characterize these neutron rich, loosely bound halo nuclei. The 6He
measurement was performed at ATLAS of Argonne, and the 8He
measurement at GANIL, France. This work was supported by the U.S. Department of
Energy, Office of Nuclear Physics, under Contract No. DE-AC02-06CH11357.