Deuteron Photo-Effect at High Energies

Abstract

The cross section for the photoelectric disintegration of the deuteron by gamma-rays with energies in the range 20 to 140 Mev is calculated for various assumptions as to the interaction between neutron and proton. This interaction is taken to be central, half-exchange and half-direct, of approximately Yukawa and exponential forms, and with two effective ranges; experimental data thus far obtained on neutron-proton processes do not provide a firm basis for distinguishing between these assumptions. Only the electric dipole and electric quadrupole cross sections are found, since the magnetic dipole cross section cannot be obtained reliably without explicit reference to a meson theory of nuclear forces. Use is made of a method for approximating to "long-tailed" potentials in such a way that the deuteron wave equation can be solved in simple analytic form. The results show relatively little difference between Yukawa and exponential potentials of the same effective range, either as to total cross section or angular distribution, but an appreciable difference from earlier calculations with a square-well potential, and a dependence on effective range. In the Appendix, it is shown that at very high energies, each photoelectric multipole cross section depends primarily on the coefficient of the lowest odd power of $r$ in the expansion of the deuteron potential about the origin.