The Dynamic Collective Model Interpretation of the Photoneutron Cross Section of 181Ta

Abstract

The cross section for photoneutron production in 181Ta has been measured from threshold to 28· 8 MeV using bremsstrahlung and direct neutron detection. Integrated between these limits, the absolute value of the cross section has been determined to be 2 '47 ±O' 35 MeV. b. An examination of the cross section variation with excitation energy reveals the existence of the giant quadrupole resonance lying on the high excitation edge of the dipole peak. This provides additional evidence for the validity of the dynamic collective model. The present data do not support the existence of extensive fine structure below 17 MeV, as proposed by Ishkhanov et al. (1969).