Low-energy antiproton annihilation in nuclei

The annihilation of 100 MeV antiprotons in atomic nuclei is studied in the frame of an intranuclear cascade model. It is found that the antiproton is annihilated about 1 fm inside the nucleus on the average. The energy released by the annihilation is carried by an average of 5 pions, which cascade throughout the nucleus. About 5% (10%) of the primordial pions are absorbed by the ⁴⁰Ca (¹⁰⁸Ag) target. The pions transfer around 5̃50 MeV (7̃00 MeV) to the nucleons and eject about one-fifth of the nucleons. The pion and proton cross sections are calculated. In particular, the relative transparency of the nucleus to high-energy pions (and not to pions in the Δ-resonance region) gives rise to a peculiar pion emission pattern. The time evolution of the baryon density and of the spectrum of the participant nucleons is investigated. It turns out that the cascade does not generate high energy density.