Spin Dependence of Slow Neutron Scattering by Deuterons

Abstract

The cross section of deuterium gas at liquid air temperature for neutrons of average wavelength 5.43A is found to be 21.3×${10}^{-24\mathrm{}}$ ${\mathrm{cm}}^2$ per molecule. The cross section of deuterium atoms for neutrons of a few volts is found to be 3.44×${10}^{-24\mathrm{}}$ ${\mathrm{cm}}^2$ per atom. These two values are used to obtain information on the spin dependence of the neutron scattering by the deuteron. It is found that the two scattering lengths $a_4$ and $a_2$, corresponding to neutron spin parallel or antiparallel to the deuteron spin, have the same sign but may differ in magnitude by as much as a factor 2.