Study of giant dipole resonance in hot rotating light mass nucleus 31P

An exclusive systematic study of the giant dipole resonance (GDR) parameters has been performed in very light mass nucleus P31 in the temperature range of ∼0.8-2.1MeV and average angular momentum of ∼11-16ħ. The high-energy γ rays from the decay of the GDR, evaporated neutrons and γ-ray multiplicities have been measured. The angular distribution of high-energy γ rays has also been measured at Ebeam=42MeV. The GDR parameters, nuclear level density parameter and nuclear temperature were precisely determined by simultaneous statistical model analysis of high-energy γ ray and evaporated neutron spectra. It is observed that the measured width remains roughly constant up to a temperature of ∼1.6MeV. Moreover, the thermal pairing plays no role in describing the GDR width in this open-shell light nucleus at the above-mentioned temperatures and angular momenta. The present measurements provide an excellent platform to extend the applicability of the existing theoretical models down to the very light mass nuclei.