Charged particles and π0 multiplicity distributions and the annihilation properties of anti pp interactions at 70 GeV/c

The elastic and inelastic anti pp cross sections at 70 GeV/c have been determined in an experiment performed at CERN using BEBC equipped with a TST. The topological cross sections were measured and the moments of the inelastic multiplicity distribution are = 6.16 +- 0.09, /D = 2.04 +- 0.05 and f2sup(c)sup(c) = 2.97 +- 0.03. The average number of Dalitz pairs per inelastic event is (3.12 +- 0.09) x 10-2. Assuming that these all arise from π0 decay the average π0 multiplicity is = 2.71 +- 0.14. The anti pp-pp cross section differences lead to an annihilation cross section sigmasub(A) = 4.42 +- 0.41 mb and the moments of the annihilation multiplicity distribution are = 8.0 +- 0.3, /D = 2.5 +- 0.2 and f2sup(A)-- = -1.4 +- 0.3. An independent check of sigmasub(A) was made by investigating fast forward charged and neutral secondary interactions in the TST and in the surrounding neon-hydrogen mixture, and gives a value sigmasub(A) = 5.0 +- 1.6 mb. The ratio of fast anti n to anti p production in non-annihilation interactions at 70 GeV/c is found to be 0.45 +- 0.11. (orig.)