Nonequilibrium contributions to the V51(p,n)Cr51 reaction for 18Ep26 MeV

Neutron spectra from the V51(p,n)Cr51 reaction have been measured at bombarding energies of 18, 20, 22, 24, and 26 MeV. The portion of the spectra corresponding to residual excitations of 10 MeV or less was compared to a shape calculated under the assumption that the residual levels are two exciton proton-particle neutron-hole states. Good agreement was obtained at 22, 24, and 26 MeV, but the spectra at lower bombarding energy could only be fitted with the addition of contributions from four exciton states. The inclusion of pairing effects improved the agreement between the calculation and the data. The data were also compared to a calculation with the hybrid model for preequilibrium reactions; good agreement was observed. [NUCLEAR REACTIONS V51(p,n)Cr51, Ep=18,20,22,24,26 MeV; measured (En,), =24-144.]