Broad structure in multiplicity gated proton spectra in 12C+93Nb reaction at E(12C)=42.5 MeV

High-energy proton spectra in the energy range Epc.m.∼8.5-25 MeV are measured in the reaction 12C+93Nb at Elab(12C)=42.5 MeV and at laboratory angles of 130 deg., 145 deg. and 160 deg. The spectra, recorded in coincidence with a gamma ray multiplicity detector array, show a broad structure which becomes more prominent at higher multiplicity. The centroid of the structure shifts with multiplicity. These features could arise from an unusual spin and excitation energy dependence of the nuclear level density in Pd and Ag nuclei with mass around A=104. However, a non-statistical process, viz., the massive cluster transfer, cannot be ruled out