Measurements of 525 GeV pion interactions in emulsion.

Abstract

Measurements have been made of inclusive 525 GeV [pi][sup [minus]] interactions in emulsion. The results are compared to proton-emulsion and lower energy pion-emulsion data. Average multiplicities of relativistic shower particles increase with increasing energy, although with a somewhat steeper slope above 60 GeV than at lower energies. The ratio [l angle][ital n][sub [ital s]][r angle][sub [ital p]]/[l angle][ital n][sub [ital s]][r angle][sub [pi]][similar to]1.1 over the energy range 60--525 GeV. The ratio of the dispersion in the multiplicity distribution to the average multiplicity is the same for proton and pion collisions in emulsion, and is independent of projectile energy. The shape of the shower particle multiplicity distribution does not vary significantly with energy, and KNO scaling appears to hold over the energy range 60--525 GeV. The shower particle pseudorapidity distributions are independent of the beam energy in the target and projectile fragmentation regions, and both the pseudorapidity and multiplicity distributions agree reasonably well with the FRITIOF model predictions for 525 GeV pions. The dependence of the shower particle multiplicity [l angle][ital n][sub [ital s]][r angle] on the number of heavy tracks [ital N][sub [ital h]] appraoches saturation as the total shower particle energy becomes a significant fraction of [radical][ital s]more » , and the pseudorapidity distributions shift toward smaller [l angle][eta][r angle] with increasing numbers of grey and black tracks at 525 GeV. Neither the average number [l angle][ital N][sub [ital h]][r angle] nor the multiplicity distributions of the heavily ionizing tracks vary significantly with energy, and the normalized angular distributions of grey and black tracks are independent of the type of projectile or projectile energy.« less