Attempt to Determine the Elastic Proton-Nucleon Cross Section at 83 GeV

An attempt has been made to measure the proton-nucleon elastic cross section using primary cosmic-ray protons with a mean energy of 83 GeV. A total of 10 m of primary proton tracks has been line-scanned for stars resulting from elastic scatterings on nucleons bound in emulsion nuclei. The probability of detecting an elastic scatter in emulsion is considered using an analysis similar to that of McCusker. Two elasticlike scatters were found, but these can be shown to be random track-intersection coincidences, consistent with the number of proton recoils expected from neutron stars. No elastic scatters in a path length of 10 m have been found. A Monte Carlo analysis, modeled after the suggestions of Goldberger and the calculations performed by Bernardini, has been used to calculate the probability of obtaining an observable proton associated with an elasticlike event in photographic emulsion. This analysis of the detection probability of an elastic scatter indicates that the proton-nucleon elastic cross section at 83 GeV is no greater than 3 mb with 95% probability.