The Relation of the Positron Energy Spectrum to the Decay Constant and to the Energy of the Bombarding Protons

We have reported(1) approximate energy distributions of the positrons emitted by various substances activated by proton or deuton bombardment. A typical photograph is reproduced in Fig. 1. To find whether a relation exists between the maximum energy of the bombarding particles and the energies of the disintegration positrons we have studied numerous samples of carbon bombarded by protons at peak voltages of 900,000 and 700,000, supplied us by Dr. Lauritsen and Mr. Crane.