The angular distribution of the recoil protons in neutron-proton scattering at 90 Mev has been measured for angles between 5{sup o} and 65{sup o} from the direction of the neutron beam. The neutrons were produced by stripping 190 Mev deuterons in a 1/2 inch Be target in the 184-inch F.M. cyclotron. R. Serber has calculated the neutron energy distribution; it has a peak at 90 Mev and a half width of 27 Mev. This distributiQn has been checked experimentally for the neutrons by Wilson Powell and by W.Chupp, E.Gardner, and T.B.Taylor for the protons also produced by stripping. The neutrons were collimated by a two-inch hole through 8 feet of concrete. Thin paraffin scatters of known hydrogen and carbon content were used; the number of protons arising from neutron-carbon and neutron-air reactions was determined by using pure carbon scatters and by making blank runs. The scatters were placed in the beam outside of the concrete shielding at a point approximately 52 feet from the cyclotron target. The scattered protons were detected by a telescope of four proportional counters used in coincidence, and set at a constant distance from the scatterer but at a varying angle from the neutron beam. A …

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