 The positron would soon be annihilated by an electron and produce two 0 @.@ 51 MeV gamma rays , while the neutron would be captured by a proton and release a 2 @.@ 2 MeV gamma ray . This would produce a distinctive signature that could be detected . They then realised that by adding cadmium salt to their liquid <unk> to enhance the neutron capture reaction , resulting in a 9 MeV burst of gamma rays . For a neutrino source , they proposed using an atomic bomb . <unk> for this was obtained from the laboratory director , Norris Bradbury . Work began on digging a shaft for the experiment when J. M. B. <unk> convinced them to use a nuclear reactor instead of a bomb . Although a less intense source of neutrinos , it had the advantage in allowing for multiple experiments to be carried out over a long period of time . 
