Evaporation residue cross sections and average neutron multiplicities in the 64Ni+92Zr and 12C+144Sm reactions leading to 156Er

Evaporation residue cross sections and neutron multiplicity distributions have been measured for the 12 C + 144 Sm and 64 Ni + 92 Zr reactions leading to the same compound nucleous 156 Er. Statistical model calculations can account for the data in the 12 C-induced reaction. In contrast, the inhibition of neutron emission with respect to statistical model predictions seen in 64 Ni + 92 Zr cannot be explained even with the inclusion of the broad angular momentum distributions required to describe the fusion cross section data.