One example of a halo nucleus is Li, which has a half-life of 8.6 ms. It contains a core of 3 protons and 6 neutrons, and a halo of two independent and loosely bound neutrons. It decays into Be by the emission of an antineutrino and an electron. Its mass radius of 3.16 fm is close to that of S or, even more impressively, of Pb, both much heavier nuclei.