Multiple Traversals of High Energy Particles in a Cyclotron Beam through Thin Targets

Abstract

An experimental determination has been made of the average number of times that 340-Mev protons traverse various targets in the Berkeley 184-inch cyclotron. The numbers range from slightly above 1 for a 1-inch thick copper target to about 15 for an aluminum target 0.0015 inch thick. The results are compared with calculated values based on multiple scattering in the target and oscillations of the particles in the cyclotron. It is believed that the results can be adapted to apply to various particles of different energies in the cyclotron. Calculations are made on the energy distribution of beam particles which cause reactions in a target, and distributions are shown for several targets. The selection of targets for the production of high energy neutron beams is discussed. Histograms are presented showing the depth of radial penetration of the 340-Mev proton beam into various targets.