Beta decay emission, some is a type of radioactive decay that occurs when an unstable atomic nucleus emits beta particles. A positron, which is an 8 letter word, is a type of beta particle with a positive charge. A neutrino, also an 8 letter word, is a type of particle with no charge and very little mass. An alpha particle, a 5 letter word, is a type of particle with a positive charge and relatively large mass. Finally, a Fermi, also a 5 letter word, is a unit of length used to measure nuclear distances.