Interactions of 300-GeV protons with tungsten and chromium

Targets consisting of tungsten and chromium powders imbedded in nuclear emulsion were exposed to the 300-GeV proton beam at the Fermi National Accelerator Laboratory. For each event found, the number of minimum-ionizing (shower) tracks nₛ and the number of heavily ionizing tracks Nₕ were determined, and the production angles of the shower tracks were measured. For 39 chromium events, we find 〈nₛ〉=13.8±1.2, 〈Nₕ〉=7.2±0.7, and 〈-lntan(θlab2)〉≡〈r〉=3.32±0.07. For 51 events in tungsten, we find 〈nₛ〉=18.6±1.5, 〈Nₕ〉=12.9±1.2, and 〈r〉=2.83±0.06. The ratio R≡〈nₛ〉〈nₛ〉ₚ, where 〈nₛ〉ₚ is the average charged multiplicity in p-p collisions, agrees with the form R=1/2+ν2, where ν is the mean number of intranuclear collisions. However, no single model adequately explains both the multiplicity and the angular distribution data.