Towards a Laser Spectroscopic Determination of the $^8$He Nuclear Charge Radius
POSTER
Abstract
We will report on the progress towards a laser spectroscopic determination of the $^8$He nuclear charge radius. $^8$He (t$_{1/2}$ = 119 ms) has the highest neutron to proton ratio of all known isotopes. Precision measurements of its nuclear structure shed light on nuclear forces in neutron rich matter, e.g. neutron stars. The experiment is based on our previous work on high-resolution laser spectroscopy of individual helium atoms captured in a magneto-optical trap. This technique enabled us to accurately measure the atomic isotope shift between $^6$He and $^4$He and thereby to determine the $^6$He rms charge radius to be 2.054(14) fm. We are currently well on the way to improve the overall trapping efficiency of our system to compensate for the shorter lifetime and lower production rates of $^8$He as compared to $^6$He. The $^8$He measurement will be performed on-line at the GANIL cyclotron facility in Caen, France and is planned for late 2006.
*This work is supported by the U.S. Department of Energy, Office of Nuclear Physics, under Contract No. W-31-109-ENG-38.