RADIATIVE PROTON CAPTURE TO DISCRETE STATES IN N-31 AT 98 AND 176 MEV

A high resolution magnetic pair spectrometer for medium energy photons has been used for studies of the exclusive (p,gamma) reaction on C-12 at 98 and 176 MeV, We present angular distributions of the differenti al cross section for transitions to the ground state and the first thr ee excited states of N-13. The distributions from these four states ar e compared with predictions from a microscopic continuum shell model c alculation using a realistic finite-ranged effective interaction with tensor components, In general, reasonable agreement is obtained for re actions to states described by p shell single particle wave functions, but poor agreement is obtained for transitions described by sd shell single particle wave functions. Nevertheless we find, however, that th e dominant reaction mechanism is a direct capture process. We also com pare the (p,gamma) data with existing data on the exclusive (p,pi) rea ction at 185 MeV revealing notable differences between the two reactio ns. (C) 1997 Elsevier Science B.V.