E. M. Fiore

Test of dynamical effects in the decay of the 59Cu compound nucleus

Abstract The energy spectra of α particles emitted in multiple-α decay chains from 59Cu compound nuclei formed in the reaction of 190 MeV 32S on 27Al have been measured. These spectra are sensitive to different regions of the phase space open to the decay of the compound nucleus. A direct test of dynamical effects related to the shape relaxation is obtained by comparing the experimental spectra with results from Monte Carlo statistical model calculations.

Dynamical effects in the pre-scission neutron emission from 160Yb at Ex∼75 MeV

Abstract Neutron spectra in coincidence with fission fragments have been measured for the 115 MeV 16 O + 144 Sm and 270 MeV 60 Ni + 100 Mo reactions, populating 160 Yb compound nucleus at E x ∼75 MeV excitations energy. The extracted pre-scission multiplicity for the 60 Ni + 100 Mo reaction is substantially larger than the statistical model prediction, demonstrating clearly that dynamical effects dominate even at low excitation energy.

Giant dipole resonance inA ∼ 40 hot nuclei from coincidence measurements

The emission of high-energyγ-rays in the deexcitation of hot40Ca and39K nuclei formed in heavy-ion fusion reactions at excitation energyEx ∼ 90 MeV has been studied. The high energyγ-rays were measured in coincidence with evaporation residues or light charged particles. Theγ spectrum from the self-conjugated compound nucleus40Ca shows an appreciable yield suppression in the Giant Dipole Resonance (GDR) energy region with respect to the39K, due to isospin selection rules in the dipoleγ-decay. The spectral line shapes of theγ spectra are well reproduced by using a statistical code which treats explicitly the isospin quantum number in evaluating level densities and transmission coefficients. The GDR parameters determined from the present coincidence measurements are in good agreement with the systematic in theA ∼ 40 mass region at lower bombarding energy based on the analysis of inclusive spectra.