M. P. Kelly

Giant dipole resonance decay and bremsstrahlung emission as a source of high-energy γ-rays in 12C+24,26Mg and 12C+58,64Ni reactions at 6–11 MeV/u

It is shown that in the mass-asymmetric reaction, 12C+24,26Mg and 12C+58,64Ni, at EpA = 6–11 MeV/u, the two types of γ-ray emission, statistical GDR decay and bremsstrahlung radiation, may be disentangled using angular distribution measurements. The analyzed data give information on the GDR built on excited states as well as on the bremsstrahlung process. The extracted GDR parameters and bremsstrahlung parameters for 12C+24,26Mg are in general in agreement with the systematics. However, the inverse slope parameter. E0, depends on γ-ray energy and as a result the bremsstrahlung cross-section at low and high Eγ energies is lower than expected for constant E0 value.

The GDR width in hot Sn nuclei

Gamma-rays, charged particles and evaporation residue products from 18O+100Mo collisions at E(18O)=125 to 217 MeV have been measured in order to understand better the width evolution of the GDR in hot nuclei. Detailed angular distributions of all reaction products are used to determine important preequilibrium and bremsstrahlung effects and the giant-dipole parameters as a function of temperature. Results show the GDR width increasing with final-state temperature up to T=2.5 MeV, in contrast with previous works which argue for a saturation of the width in this energy range.

Bierman {ital et al.}Reply:

reply to the Comment by C.H.Dasso et al., Phys. Rev. Lett. 78,XXX(1997). A Reply to the Comment by C.H. Dasso and J. Fern{acute a}ndez-Niello. {copyright} {ital 1997} {ital The American Physical Society}

Entrance channel dependent light-charged particle emission of the {sup 156}Er compound

Light-charged particle decay from the {sup 156}Er compound nucleus, populated by {sup 12}C+{sup 144}Sm and {sup 60}Ni+{sup 96}Zr at the same excitation energy, were measured in coincidence with the evaporation residues. The high energy slope of charged particle spectra for the {sup 60}Ni-induced reaction is steeper than for the {sup 12}C-induced reaction. Model calculations including particle evaporation during compound nucleus formation result in good agreement with the data. This suggests that the difference in the charged particle spectra between the two entrance channels is due to a longer formation time in the {sup 60}Ni-induced reaction. 14 refs., 3 figs.