General characteristics of 5 GeV/c anti-proton interactions with Ag and Br nuclei of nuclear emulsion

In a systematic study of antiproton-heavy nucleus interactions in G5 nuclear emulsions, 1322 stars produced by 5 GeV/c antiprotons with Ag and Br nuclei, have been studied. Mean number of heavily ionizing, grey and shower tracks in these interactions, are found to be Nsub(h)=16.72 +- 0.48, Nsub(g)=3.90 +- 0.11 and nsub(s)=1.44 +- 0.04 respectively. A plot of nsub(s) versus Nsub(h) shows a linear decrease of nsub(s) with increase in Nsub(h), which is just the reverse of what has been observed in proton-nucleon and proton-nucleus collisions. This observation appears to be due to absorption of some pions during the cascade process. Multiple coulomb scattering and grain density measurements have been performed on some selected shower tracks to determine the percentage of π +-, k +- and P-anti P among them, the obtained values being 76%, 8% and 16% respectively. The average energies of evaporated, cascade and pions among the shower particles, have been measured and found to be Esub(b)=(8.8+- 0.9) MeV, Esub(g)=(110 +- 12.5) MeV and Esub(π)=(305 +- 3.8) MeV respectively. The angular distribution of shower particles has been found to fit in with a Gaussian distribution of mean value m = 1.12+- 0.06 and dispersion S = 1.17 +- 0.07. (author)