Calorimetric Experiment on the Radiation Losses of 2-Mev Electrons

Abstract

Various investigators report from cloud-chamber experiments that the energy lost in the scattering of 2-Mev beta-rays is several times the loss calculated from the Bethe-Heitler theory. However, other experimenters have found that the production of x-rays in this range agrees with theory. To account for the extra energy loss, Klarmann and Bothe and Champion have suggested the emission of neutrinos as well as x-rays. To test this hypothesis, a 2-Mev beam of electrons was directed on a target immersed in mercury, the assembly acting as a calorimeter. Experiments using beryllium, gold, and mercury targets show that within the experimental error, which is somewhat less than one percent, no energy is carried out of the calorimeter by neutrinos or other penetrating radiation. It thus appears that the production of such radiations cannot account for the large extra energy losses reported from cloud-chamber experiments.