Threshold Pion Production and Multiplicity in Heavy-Ion Collisions

Pion and Proton Multiplicities in Heavy-Ion Reactions at 75-200 MeV/Nucleon

“…In another 45 reactions at 150-200 MeV/ nucleon we did not find any shower particles. Thus also in the energy range 150-200 MeV/nucleon our observations are contrary to the Mc-Nulty et al 1 findings.…”

“…3 and Table I. The calculated multiplicity, percentage of reactions, and distribution are in agreement with the results given by Mc-Nulty et al, 1 provided that the light-track-producing particles in their investigation are projectile-fragmentation protons. Naturally our model does not consider all the production mechanisms but only projectile fragmentation.…”

“…One main purpose of this investigation is to study pion production in reactions at 75-100 MeV/nucleon. Stimulated by the work of McNulty et al 1 we extended the investigation to the energy range 150-200 MeV/nucleon. The gap density was 14.8 gaps per 100 jtxm for a singly charged particle track at minimum ionization.…”

“…We have examined the endpoints of the stopping In the range 100-280 MeV/nucleon McNulty et al 1 report a large pion production cross section (~3 b). For direct comparison with these results, we selected randomly 52 events at 150-200 MeV/nucleon and looked for pions c 376 tracks of singly charged particles were examined: (a) 134 short tracks (range <1 cm) were followed in order to search for characteristic pion decay or capture, (b) 242 long tracks (range > 1 cm) were gap counted in order to determine the number of shower particles (gap density <1.4 times that of a minimum-ionizing particle) i.e 0 , E p > 380 MeV, E^ > 57 MeV.…”

“…McNulty et al 1 have identified pions by inspec-290 tion of tracks close to the interaction vertex. They could not observe the end of the tracks because the stack was not thick enough.…”