Secondary production of antiprotons in cosmic radiation

A reliable representation to the invariant cross-section for the production of antiprotons ( ) in inclusive reactions has been obtained, which fits the data extremely well from threshold to ISR energies. Using this, the production spectrum of by cosmic ray interaction with interstellar gas is calculated and is compared with other existing calculations. The equilibrium spectrum in the Galaxy has been derived from about 100 MeV to a few hundred GeV in kinetic energy using Leaky Box Model for the propagation of cosmic rays, by taking into account all energy loss processes. It is found that /P ratio calculated here is very much smaller than the observed ratio. In view of the fact that this excess of observed /P ratio is much larger than the measured upper limits on the fraction of antimatter in the form of antinuclei, the excess /P ratio has not been attributed to the existence of antimatter. Instead, it is shown that Closed Galaxy Model for the propagation of cosmic rays predicts more antiprotons than observed. Therefore, it is suggested that if cosmic rays contain about 50% new component of local origin, the resulting Closed Galaxy Model explains well the observations. The present calculations also predict too small a flux of below a few hundred MeV to make this energy region ideally suited to look for antiprotons of primordial origin.