Antiproton annihilation on nuclei at intermediate energies resulting from one, two and an infinite number of collisions

Abstract

Antiproton annihilation cross sections on nuclei from 20Ne to 208Pb are calculated in the framework of a microscopic optical model in the kinetic energy range EL = 50 – 2000 MeV both directly in the initial channel and after single quasi-free collision. The part of annihilation yield after one quasi-free nucleon knock-out from the nucleus is 20-25% of the contribution to the annihilation cross section in the initial channel. The sensitivity of this cross section to the parameters of antinucleon-nucleon scattering amplitude is investigated. Calculated ratios of volume to surface annihilation cross sections are compared with experimental ones.