The protons from the radioactive decay of the neutron have been identified by measuring their charge to mass ratio with an electrostatic field and magnetic lens spectrometer. Coincidences have been obtained between these protons and the corresponding beta-particles from the neutron decay using a second magnetic lens spectrometer to measure the energies of the beta-particles. In this manner the beta-spectrum of the neutron has been measured over the region from 300 kev to the end point and has been found to be consistent with the energy distribution expected for an allowed transition. The end point of the spectrum is 782 kev with a probable error of ±13 kev. The half-life of the neutron is 12.8 minutes with a probable error of ±2.5 minutes.

• Received 5 April 1951

DOI:https://doi.org/10.1103/PhysRev.83.349