EXPERIMENT PREX AT TJNAF: A MODEL-INDEPENDENT MEASUREMENT OF THE NEUTRON RADIUS IN 208Pb

Experiment PREX will take place in Hall A at TJNAF in 2010. It will measure the neutron radius Rn in the 208 Pb nucleus through the measurement of the parity violating asymmetry in electron scattering [Formula: see text], with σR and σL the cross sections for right handed and left handed electrons respectively. The projected accuracy of 1% on Rn constitutes a fundamental test of nuclear theory. This measurement of Rn will provide the best determination of the density dependence of the symmetry energy at the density of ordinary nuclear matter. As a consequence, the PREX result will have a big impact on phenomena like neutron star structure, heavy ion collisions and atomic parity violation.