Analysis of proton-nucleus and helium-nucleus collisions at energies greater than 10 TeV

We have studied the characteristics of inclusive ..gamma..-ray and charged-meson production in proton-lucite collisions at 20 TeV, and helium-lucite collisions at 7 TeV per nucleon. Characteristics of multiple-production phenomena in these energy regions were fully analyzed and compared with those observed in lower-energy regions. The main results are as follows. (1) A substantial increase of charged secondaries in proton-lucite collisions is observed in the central region as the primary energy increases from 400 GeV to 19 TeV. (2) The average multiplicity in helium-lucite collisions is nearly twice as large as that in proton-lucite collisions at the same energy per nucleon. (3) While no difference is observed of the average values of P/sub T/ and P/sub T/ /sup 2/ for P/sub T/ 1.0 GeV/c) substantially increases above 10 TeV. (4) The fractional-energy distribution of ..gamma.. rays in the range of 0.10.1.