The spectral shapes of high energy gamma rays emitted in the decay of excited ${}_{}{}^{63}{}_{}{}^{}\mathrm{Cu}$, ${}_{}{}^{76}{}_{}{}^{}\mathrm{Kr}$, and ${}_{}{}^{127}{}_{}{}^{}\mathrm{Cs}$ compound nuclei are well reproduced by statistical model calculations which include a giant dipole resonance 1-1.5 MeV lower in energy than the ground-state giant dipole resonance. No evidence is found for a dependence of the giant dipole resonance strength function on spin.

NUCLEAR REACTIONS ${}_{}{}^{12}{}_{}{}^{}\mathrm{C}$+${}_{}{}^{51}{}_{}{}^{}\mathrm{V}$, ${}_{}{}^{64}{}_{}{}^{}\mathrm{Zn}$, ${}_{}{}^{115}{}_{}{}^{}\mathrm{In}$; ${}_{}{}^{18}{}_{}{}^{}\mathrm{O}$+${}_{}{}^{45}{}_{}{}^{}\mathrm{Sc}$, ${}_{}{}^{58}{}_{}{}^{}\mathrm{Ni}$, ${}_{}{}^{109}{}_{}{}^{}\mathrm{Ag}$; $E_{\mathrm{lab}}=42-60\mathrm{}$ MeV. Measured $\gamma$-ray spectra, $E_{\gamma }=6-25\mathrm{}$ MeV; compared with statistical model calculations including the GDR. Deduced $E_{\mathrm{GDR}}$, $\gamma$ for excited state GDR decays. Deduced upper limits for spin dependence of GDR parameters.

• Received 8 August 1983

DOI:https://doi.org/10.1103/PhysRevC.28.2554