A study of anti pp annihilations at 100 GeV/c

Results are presented on a study of anti pp and pp interactions at 100 GeV/c. These results are based on a minimum bias sample of 6888 anti pp and 3078 pp events obtained with the 30 inch bubble chamber at Fermilab. Secondary particles were identified by ionization measurements in the bubble chamber as well as by use of a downstream particle identification system consisting of an ionization sampling detector CRISIS, a Cerenkov detector OSIRIS, and a neutral particle calorimeter. The following results were obtained in this experiment: (1) The anti pp annihilation cross section was determined to be 2.4 ± 1.8 mb. (2) The ratio of the number of n/n secondaries to the number of p/anti p secondaries was determined to be 0.668 ± 0.035 in anti pp and 0.681 ± 0.051 in pp interactions. (3) Inclusive Feynman x distributions are given for the reactions anti pp → π+ + X and pp → π+ + X, as well as the corresponding reactions in which the π+ is replaced by π-, p,anti p and n/n, respectively. (4) Inclusive rapidity distributions are given for the reactions anti pp → π+ + X, anti pp → π- + X, pp → π+ + X and pp → π- + X. While the errors are relatively large, these results favor the conjecture that the differences between anti pp and pp interactions are due to baryon-antibaryon annihilation rather than the annihilation of a single valence quark