Emission Of Helium-Ions After Antiproton Annihilation In Nuclei

Abstract Spectra of hydrogen and helium ions emitted after stopped antiproton annihilation in nuclei have been measured with a Si-detector telescope. Targets of 12C, 40Ca, 63Cu, 92Mo, 98Mo and 238U were used. The 3He and 4He energy spectra can be fitted with the exponential function e−E/T. The parameter T is essentially independent of the target mass number A. A simple pickup model reproduces the 4He/3He ratios as a function of Z and N (target proton and neutron number). The proton spectra from the 238U target indicate that some protons are also emitted by the fission fragments.