The giant dipole resonance built on excited states in 113,114Sn and level densities in the vicinity of the neutron separation energy

The statistical decay of the excited state giant dipole resonance induced by capture of 24 and 26 MeV α-particles on 110Cd has been investigated exclusively for events feeding isomeric levels in the final nuclei 113Sn and 114Sn. This was done by measuring coincidences between high-energy α-rays and delayed α-rays depopulating the Jπ=11/2- and Jπ=7- isomers in 113Sn 114Sn, respectively. GDR and level-density parameters were deduced from fits of spectra obtained from statistical-model calculations to the data. The GDR energy (E=15.2±0.5 MeV) and strength (S=0.9±0.1) are close to the values of the ground state GDR. The increase of the width of the GDR (Γ=7±1 MeV) is in agreement with previous measurements at higher excitation energies. The level-density parameters obtained from the fits can be well reconciled with the interpolated Dilg paramters. (orig.)