Giant quadrupole capture of energetic nucleons by nuclei

This paper is concerned with nucleon radiative capture reactions via giant electric quadrupole (T=0) states in nuclei. The coupling potential between an incident particle and the quadrupole vibrational mode of a target nucleus is described in terms of the hydrodynamic model. A cross section formula for quadrupole capture is derived on the analogy of the collective capture model which has been proposed by Clement et al. Moreover, calculations of the cross section for the 208Pb(n, γ)209Pb reaction with 5- to 20-MeV neutrons are presented for both dipole capture process and quadrupole one. The results show that excitation of the giant quadrupole state by nucleon radiative capture is considerably weak, and so masked by giant dipole resonance (T=1). (auth.)