Composition of the Secondary Particles Produced in Nuclear Interactions at ∼1012eV

Abstract

Twenty-two proton, neutron, and alpha jets (N h <3, 2X10 11 eV<£< 1.5Xl0 13 eV), found in a 22-liter emulsion stack flown for 13 h at an altitude of 116 000 feet, have been analyzed to identify the nature of the particles emitted in the extreme backward cm. cone. Among 82 tracks analyzed, out of 149 tracks traced (total length of the secondaries traced was 20.4 m and 74 interactions were found), 53 secondaries were attributed to pions, 18 to kaons, 10 to protons, and one to a hyperon. The relative composition of the 82 secondaries has a dependence on the cm. emission angle 0. For 0>175°, there were 7 x, 9 K, 10 p, and 1 Y; for 0<175°, there were 46 TT, 9 K, and no baryons. A similar distinction existed for the average cm. momenta <p> and the average transverse momenta <pt> in the extreme backward cm. emission angle; <p> becomes large and <pt> becomes small. The baryons carried the average fraction 0.5±0.2 of the total available energy in the cm. system. Concerning the K/ir ratio, p t distribution, and <p> at 0<175°, the hydrodynamical theory with a critical temperature kTc^m^c 2 predicts the correct behavior. In this region, the cm. momentum distribution of pions fits the form dNozp n dp with n= -0.8db0.4. But for the extreme backward cm. emission angle region, 0>175°, the smallness of <pt> and concentration of kaons and baryons favor an interpretation in terms of the Heisenberg theory. Rochester, edited by