The ejection of protons from nitrogen on bombardment with α -particles of short range

Abstract

Using the expansion-chamber method, ninety proton tracks are obtained from 850 photo­graphs showing the disintegration of nitrogen under bombardment by slow α-particles. The number of disintegrations decreases as the energy of the α-particles is reduced, but the photographs show disintegrations occurring for energies less than 1.7 MeV. The angular dis­tribution is approximately isotropic for the protons ejected by α-particles of energy less than 3 MeV, but there is a marked preponderance at about 90° for the protons ejected by α-particles of range about 2 cm. in air at N. T. P. Typical photographs are reproduced.