The analysis of 4.5 BeV negative pion interactions in nuclear emulsion

Abstract

Two hundred nuclear interactions produced in Ilford G5 nuclear emulsion by 4.5 Bev π- mesons have been analysed. The transverse momentum of those secondary shower particles identified as pions has an average value over all angles of 290±50 MeV/C. The mean multiplicity of shower particles from the interactions is 2.0 ± 0.1 and is independent of the number of heavily ionizing prongs N_h . About 90 % of the shower particles were estimated to be pions. The angular distribution in the C-system is anisotropic with a mean value for |cos θ*verbar; of 048 ± 0.03. Assuming that secondary pions are emitted symmetrically backwards and forwards from a single collision system, the observed angular distribution of shower particles has been used to determine the effective mass of the collision partner. It is found to be 1.40^+0.47 _−0.27 proton mass units. If the total distribution is divided into groups with respect to N_h , it is found that events having N_h ≤7 yield a value of 0.77^+0.36 _−0.19 proton mass Units whilst those having N_h 7 yield 2.3^+0.9 _−0.4 proton maas units.