Casting Light on Neutron Halo Nuclei

Laser spectroscopic measurements of atomic isotope shifts provide unique access to the nuclear charge distribution of short-lived isotopes. In this talk, I will present a new high-resolution technique based on laser spectroscopy of single atoms cooled and confined in a magneto-optical trap. The isotopes of interest are $^6$He (t$_{1/2}$ = 807 ms) and $^8$He (t$_{1/2}$ = 119 ms), which exhibit a loosely bound neutron halo around a $^4$He-like core. I will report on our recent high-precision measurement of the $^6$He nuclear charge radius and the progress in extending this investigation to $^8$He. Charge radii measurements of both isotopes provide corroboration for their halo structure and test theoretical models of light nuclei.