Neutron-Proton Angular Distribution at 24 MeV

Proton recoil spectra from $n-p$ elastic scattering were measured with a counter telescope for an incident neutron energy of 24.0 MeV at mean lab proton recoil angles of 8°, 17°, 31°, and 45°, corresponding to c.m. neutron scattering angles of 164°, 146°, 118°, and 89°. The ratio $\frac{\sigma \left(164\mathrm{}°\right)}{\sigma \left(89\mathrm{}°\right)}$ was 1.134±0.016, where the error quoted is based on counting statistics. In order to obtain a differential cross section, the c.m. relative angular distribution was normalized to a total cross section of 397.2 mb using an $A(1+B{cos}^2\theta )$ fit. This gave $A=30.1\mathrm{}\pm 0.3$ mb/sr and $B=0.146\mathrm{}\pm 0.017$.