Cross sections for the Ni, Cu, Zn16, 18O, xn) reactions near the Coulomb barrier

Cross sections for neutron emitting reactions induced by 16,18O bombardment of 58,60,61,62,64Ni, 63,65Cu, and 64,66,67,68,70Zn targets have been measured for projectile energies between 36 and 55 MeV by means of a large graphite sphere with embedded 10BF3 detectors. Comparisons were made with the total reaction cross section calculated with (1) the optical model, (2) the sharp cutoff model, and (3) the parabolic-barrier model. The data are generally in good agreement with the optical-model predictions above the Coulomb barrier if the neutrons are assumed to be emitted statistically from a compound nucleus and if fusion is the predominant mechanism. Interaction barriers obtained from the parabolic-barrier model yield interaction radii with values of (1.54 to 1.65) x (A/sub T/ 1/sup /3/ + A/sub P/ 1/sup /3/) fm