The beta particle has the form of a high speed negatively charged electron (or a positively charged electron in the case of the positron). In beta decay (electron emission) a neutron in the nucleus is converted to a proton with the release of a high speed electron and an anti neutrino. For example, C-14 decays to N-14 and the atomic number has increased by one whilst the mass number at 14 is unchanged. The beta particle is more penetrating than alpha particles but still much less so than gamma rays or x-rays. For every beta emitter there is a unique energy spectrum characterised by average and maximum beta energy. For Tritium (H-3) this is around 18.5 KeV, for C-14 its 156 KeV and for P-32 it is about 1.7 MeV.