Gamma-Ray Multiplicity in the Decay of Residual Nuclei from Nuclear Reactions

A technique was developed for measuring the average number of $\gamma$ 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 ($p,p^{\prime }$) 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 ($p,p^{\prime }$) reactions; between ($p,p^{\prime }$) 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.