Interactions of 300-GeV protons with tungsten and chromium

Abstract

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 ${n}_{s}$ and the number of heavily ionizing tracks ${N}_{h}$ were determined, and the production angles of the shower tracks were measured. For 39 chromium events, we find $〈{n}_{s}〉=13.8\ifmmode\pm\else\textpm\fi{}1.2$, $〈{N}_{h}〉=7.2\ifmmode\pm\else\textpm\fi{}0.7$, and $〈\ensuremath{-}\mathrm{ln}tan(\frac{{\ensuremath{\theta}}_{\mathrm{lab}}}{2})〉\ensuremath{\equiv}〈r〉=3.32\ifmmode\pm\else\textpm\fi{}0.07$. For 51 events in tungsten, we find $〈{n}_{s}〉=18.6\ifmmode\pm\else\textpm\fi{}1.5$, $〈{N}_{h}〉=12.9\ifmmode\pm\else\textpm\fi{}1.2$, and $〈r〉=2.83\ifmmode\pm\else\textpm\fi{}0.06$. The ratio $R\ensuremath{\equiv}\frac{〈{n}_{s}〉}{{〈{n}_{s}〉}_{p}}$, where ${〈{n}_{s}〉}_{p}$ is the average charged multiplicity in $p\ensuremath{-}p$ collisions, agrees with the form $R=\frac{1}{2}+\frac{\overline{\ensuremath{\nu}}}{2}$, where $\overline{\ensuremath{\nu}}$ is the mean number of intranuclear collisions. However, no single model adequately explains both the multiplicity and the angular distribution data.