High energy photonuclear processes in O16, F19, Ca40 and V51

Yields for several photonuclear reactions in O16, F19, Ca40, and V51 have been measured from their thresholds to 300 MeV using bremsstrahlung from the University of Illinois 300 MeV betatron. The reaction yields were determined by investigation of the radioactivities of the product nuclei by using gamma ray spectroscopy techniques. The cross sections above 150 MeV for these reactions were compared with cross sections calculated for a reaction mechanism in which the primary step is the photoproduction of a meson at a single nucleon. The results of this comparison indicate that the main features of high energy photonuclear reactions can be accounted for in terms of such a mechanism. In the case of relatively Simple reactions in which only a few nucleons are emitted, the produced meson escapes and the recoil nucleon is responsible for the emission of other particles. For the more complex reactions in which more than four nucleons are emitted, meson reabsorption appears .to play a significant role.published or submitted for publicationU of I Onlythesi