Gamma-ray multiplicity in the decay of residual nuclei from nuclear reactions

A technique was developed for measuring the average number of γ rays, $N_{\gamma }$, emitted in the decay of residual nuclei left by specific nuclear reactions as a function of excitation energy. It was used with (p,p′) reactions induced by 17- and 12-MeV protons, and with (d,p) reactions induced by 12-MeV deuterons, each with seven target nuclei of different types. $N_{\gamma }$ increases with excitation energy up to 10 MeV, and is generally below 4 in this range. Variations between light and heavy nuclei; between (d,p) and (p,p′) reactions; between (p,p′) reactions at 17 and at 12 MeV; between odd-even, even-odd, and even-even nuclei in the same mass and energy regions, etc. were investigated, and their interpretations are discussed.