Energy dependence of the 51V(p,n)51Cr analog transition between 16 and 26 MeV

Utilizing the recently completed cyclograaff facility, we have measured the angular distribution of the ⁵¹V(p, n)⁵¹Cr analog transition between 16 and 26 MeV. Between 21 and 26 MeV the integrated cross section decreases monotonically with increasing energy while between 16 and 21 MeV a broad resonant behavior is observed. Coupled-channel calculations, with isospin strengths linearly scaled up 1.5% per MeV from the optimum values deduced at 26 MeV, provide a good description of the measurements between 21 and 26 MeV. However, in the region of the apparent resonance the measurements are systematically higher than the calculations at the backward angles, implying a correlation between the appearance of the broad structure and the increase of cross section at the backward angles. Similarly, search routines on the isospin strengths produced a significant improvement in the fits only between 21 and 26 MeV. Between 21 and 16 MeV, the isospin strengths increase to account for the increasing total cross section but the quality of the fits is essentially unchanged. Thus, the most likely explanation for the resonant behavior is not an energy dependence of the isospin strengths, but the presence of an additional reaction mechanism which yields either an isotropic or symmetric incoherent contribution to the (p, n) analog transition.