The beta-spectrum of P-32 has been examined with a thin-lens spectrometer. The maximum energy of the 14.3-day beta activity, as determined from several Kurie plots, was found to be 1.704 +/- 0.008 Mev. The Kurie plots gave excellent straight lines from the maximum beta-energy to about 0.26 Mev. In phosphorus samples prepared from neutron irradiated sulfur an additional beta-activity was observed having a maximum energy of 0.26 +/- 0.02 Mev and a half-life of 24.8 +/- 0.5 days. This low-energy beta-group was also observed in phosphorus samples prepared from sulfur and lithium chloride irradiated with X-rays having a maximum energy of 68 Mev. The low-energy beta-group was not observed in phosphorus samples prepared from sulfur irradiated with deuterons or phosphorus irradiated with neutrons . The low-energy beta-group is ascribed to P-33.
Jensen, Erling N.; Nichols, R. T.; Clement, J.; and Pohm, A., "The beta-spectra of P-32 and P-33" (1951). Ames Laboratory ISC Technical Reports. 27.