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Heavy Nuclei and α Particles between 7 and 100 Bev/Nucleon. II. Fragmentations and Meson Production

1959; American Institute of Physics; Volume: 115; Issue: 3 Linguagem: Inglês

10.1103/physrev.115.643

1536-6065

P. L. Jain, E. Lohrmann, M. Teucher,

High-Energy Particle Collisions Research

Three hundred and seventeen heavy-nuclei and 175 $\ensuremath{\alpha}$-particle interactions of more than 7 Bev/nucleon have been found in a systematic way and analyzed. We obtained average values and fluctuations of the individual values for the energy of heavy nuclei as measured by the opening angle of their fragments by comparing with the energy found by scattering measurements. At an average energy of 10 Bev/nucleon and 40 Bev/nucleon the average number of charged mesons produced by $\ensuremath{\alpha}$-particle interactions with emulsion nuclei was found to be 4.6 and 8.2, respectively. About one half of the nucleons of the $\ensuremath{\alpha}$ particle participate in the collision. The meson multiplicities per participating nucleon agree for proton and $\ensuremath{\alpha}$-particle collisions at 10 Bev/nucleon.We measured the angular distribution of the shower particles emitted from the interactions. We calculated the energy of the interactions from the angular distribution by using the median angle formula or equivalent formulas, based on the "meson spectrum independent" approximation. These methods overestimate the true primary energy on the average by a factor of 2 (for interactions with less than 5 heavily ionizing prongs). This is due to the relatively large proportion of slow mesons in the c.m. system. The distribution of primary energy as obtained by this method around the true value is shown for two groups having average energies of 10 Bev/nucleon and 40 Bev/nucleon. Equivalent results are given for the heavy-nuclei interactions.The average number of mesons produced in collisions between heavy nuclei and emulsion nuclei at an average energy of 20 Bev/nucleon is given. It increases with the charge of the incident nucleus in agreement with a crude geometrical model.