Charged particle and π multiplicity distributions and the annihilation properties of $$\bar p$$ p interactions at 70 GeV/c.

The elastic and inelastic $$\bar p$$ p 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 〈 n〉=6.16±0.09, 〈 n〉/ D=2.04±0.05 and f=2.97±0.03. The average number of Dalitz pairs per inelastic event is (3.12±0.09)×10. Assuming that these all arise from π decay the average π multiplicity is $$\langle n_{\pi ^0 } \rangle = 2.71 \pm 0.14$$ . The $$\bar p$$ p−pp cross section differences lead to an annihilation cross section σ = 4.42±0.41 mb and the moments of the annihilation multiplicty distribution are 〈 n〉=8.0±0.3, 〈 n〉/ D=2.5±0.2 and f=−1.4±0.3. An independent check of σ 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 σ = 5.0±1.6 mb. The ratio of fast $$\bar n$$ to $$\bar p$$ production in non-annihilation interactions at 70 GeV/c is found to be 0.45±0.11. [ABSTRACT FROM AUTHOR]