Hi, I am reading in some books that after the [itex]\beta[/itex]-decay of neutrons, the maximum energy of the resulting electron is a bit less than 800 keV. In some cases, however, I see that in e.g. some studies that try to extract the electron energy from [itex]\beta[/itex]-decay of neutrons with some Monte Carlo codes, they allow for the energy of the electron to acquire much higher values. Do I suspect correctly that this possibly due to different frames of reference? How can I calculate the maximum electron energy from a decay of e.g. a 100 MeV neutron in the lab frame?