A Photographic Apparatus for Angular-Distribution Measurements

A scattering camera was designed and constructed to measure the angular distribution of heavy charged particles emitted from nuclear reactions by means of the tracks which they produce in a photographic emulsion. It uses a single 2-in×4-in. plate to detect particles emitted in the angular range of 25° to 160° to the direction of the incident beam of bombarding particles. The camera has been used to investigate the angular distribution of the alpha-particles from the reaction ${\mathrm{Li}}^7(p,\alpha )\alpha$, the long-range alpha-particles from ${\mathrm{F}}^{19}(p,\alpha ){\mathrm{O}}^{16}$, and the resonance scattering of protons in ${\mathrm{Be}}^9(p,\gamma ){\mathrm{B}}^{10}$. These reactions have been investigated over bombarding proton energies covering the range of interest in each reaction. This apparatus has been found to be effective for detailed measurements of angular distributions, with very high resolution of energy and of angle, even for reactions with very low yield, using thin solid targets. Fogging of the plates by soft x-rays from the target has been reduced by suitable target supports. Some results and conclusions concerning the above reactions are reported.