Origin of correlations between evaporation protons and discrete γ rays in heavy-ion fusion-evaporation reactions

Abstract

We have investigated correlations between evaporated protons and discrete p rays in the heavyion fusion-evaporation reactions Ni( Al, jp) Sr and Ni( Si,4p) Sr. Sp-y and 4p-p coincidences were measured using a 4m charged-particle detector array. The events studied were completely reconstructed kinematically in order to determine the excitation energy of formation of Sr. Correlations arising from well-understood kinematic effects were measured and found to be well reproduced by predictions made by the statistical-model evaporation code PACE2. Dynamical correlations due to nuclear structure effects were searched for by measuring proton spectra in coincidence with discrete p rays from four rotational bands in Sr. Contrary to published results, no significant shifts of the first moment of the spectra were observed.PACS number(s): 25.70. Gh, 24.60.Dr, 27.50.+e