Energy dependence of backward particle emission from high-energy Hadron-nucleus collisions

Abstract

Angularand kinetic-energy distributions of protons and pious emitted in laboratory backward direction from collisions of 28.5 GeV/c protons with tan ta lum nuclei, were previously reported (1). There, the increase of invariant cross-section of backward emission of protons and pions with incident energy was also reported, comparing with experimental data at lower energies by BAT.DI~ et al. (2) and BAYUKOV et al. (3). However in the case of proton spectrum, we were obliged to compare between results obtained by different nuclei in a wide range of mass number, because the experiments by BAYUKOV cta l . were carried out with carbon, cupper and xenon as target nuclei. Therefore, in the previous paper we discussed incident-energy dependence of proton spectrum (1), assuming the target nucleus mass number dependence of invar iant cross-section being A! obtained by BAYUKOV et aL (s). This assumption made incident-energy dependence of proton spect rum somewhat uncertain. In the case of pion spectrum, this uncertainty is small enough because the experiments with lead target were available to compare with our results. In this paper results obtained for K--Ta collisions are reported. Because the measurements were carried out for 12.6 GeV/c K.Ta interaction under the same experimental conditions as 28.5 GeV/c P-Ta collisions, incident-energy dependence of both pion and proton emission spectra is derived more definitely between 12.6 and 28.5 GeV/e. The difference of incident particles (Kand P) has only little effect for backward particle emission.