C-REX (little sister of PREX) : Parity-Violating Measurement of the Weak Charge radius of 48 Ca to 0.03 fm. 1-pass (2.2 GeV) HRS + septum C-REX Workshop at JLab March 17 – 20, Participants from several fields 19 talks & discussions PAC39 result : C2 approval return with stronger case demonstrating how C-REX tests microscopic models (e.g. 3-neutron forces) R. Michaels HA mtg 3/26/13 P1/4

PREX II and C-REX 208 Pb approximates infinite nuclear matter -- ~ a small neutron star 48 Ca smaller, optimizes at higher Q 2 (natural 11 GeV expt). Lots of neutrons, sensitive to 3N force Tests micrscopic models for neutrons. ( PAC39: “explain this !” ) Want doubly-magic nuclei: little coupling to inelastic -- “clean” Want neutrons : weak interaction couples to neutrons 208 Pb 48 Ca P2/4

Interfaces provide crucial clues Interfaces provide crucial clues dimension of the problem Witek Nazarewicz’s talk : Why C-REX after PREX ? 48 Ca: bridge between microscopic and DFT New microscopic theory results were presented at workshop. P3/4

Gandolfi et al. PRC85, (2012) Witek Nazarewicz’s talk : Why C-REX after PREX ? C-REX  3N forces  important for neutron stars Fini