Applications of the photographic method to problems in nuclear physics. II. The scattering of 8.8 and 13 MeV neutrons by protons

Abstract

A method is described for determining the orientation of proton tracks in a photographic emulsion with an accuracy of ± 1°. This technical development increases the range of application of the photographic method to problems in nuclear physics. The method has been applied to an investigation of the scattering of 8.8 and 13.0 MeV neutrons by protons. If I ( ɸ ) is the intensity per unit solid angle of the scattered neutrons in the centre of mass co-ordinate system of the colliding particles, the measurements give values of I ( ɸ ) in the range from ɸ = π to ɸ = 1/2 π . When this range in the value of ɸ is divided into five equal intervals, the observed numbers of tracks in the different intervals are consistent with the scattering being isotropic in the centre of mass system to within the limits of the statistical error, for the 8.8 MeV group of neutrons. There is some evidence for a periodic fluctuation of high order in the angular distribution of the scattered intensity which remains to be confirmed. For the 13 MeV group the ratio of I ( π )/ I (1/2 π ) is found to be 0.67 ± 0.20. The neutrons employed in this experiment were produced by bombarding boron with 600 keV deuterons and arise from the reaction B 11 ( d, n ) C 12 . There is evidence that the excited state of C 12 at 4.5 MeV is complex.