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The doubly-
In addition, a thicker neutron skin in Lead means that energy rises rapidly with density and this quickly favors uniform phase and a thinner neutron star crust. At last, a large value of the neutron radius of 208Pb would imply a large value of the symmetry energy S at high density and hence a large proton fraction in neutron stars, that would allow the direct Urca process of rapid neutrino cooling in neutron stars and would explain why some neutron stars appear to be unexpectedly cold. The experiment PREX used a 50 to 70 µA beam of longitudinally polarized 1.06 GeV electrons and a 0.55 mm thick 208Pb target foil. Electrons were detected at a scattered angle of about 5°. A value of A pv equal to 656 ± 60 (stat) ± 14 (syst) ppb was obtained. This value corresponds to a value of the neutron radius of 208Pb equal to