P. R. Christensen

Coulomb-nuclear interference and nuclear reorientation in the scattering of 16, 18O by 58Ni and 64Ni

Abstract The inelastic scattering of 16 O and 18 O projectiles by 58 Ni and 64 Ni has been studied to investigate the interference between Coulomb and nuclear excitation. The interference minimum for the excitation of the first 2 + state in 18 O is found to be shifted towards forward angles when compared to the excitation of the 2 + state in the Ni target nuclei. This shift could not be reproduced by first order DWBA calculations, but reasonable agreement was obtained in a coupled channel analysis allowing for reorientation effects. The coupled channel results depended sensitively on the values of the static quadrupole moments of the excited 2 + states.

Gamma-ray multiplicity moments from 86Kr reactions on 144, 154Sm at 490 MeV

Abstract Gamma-ray multiplicity moments have been measured for reactions induced in the collision systems 86 Kr + 144 Sm and 86 Kr + 154 Sm at 490 MeV lab bombarding energy. Differential cross sections for reaction products from Fe to In were also measured. Angular momentum distribution moments are derived from the multiplicity moments for deep inelastic collisions. The angular momentum transfer results are discussed in terms of the sticking picture and other models for deep inelastic collisions. It is demonstrated that the measured second moments are larger than expected from the standard sticking prescription and may provide a significant test of other models.

Quasielastic transfer reactions induced byFe56onNi58,Ni64, andSn122

Differential cross sections sigma(Z,A,E,theta) for the quasielastic projectilelike reaction products from the bombardment of /sup 56/Fe on /sup 58,64/Ni and /sup 122/Sn at 5.9 and 8.5 MeV/nucleon have been measured with a channel-plate time-of-flight telescope followed by a ..delta..E-E gas-ionization chamber. Angular intervals of 10/sup 0/--15/sup 0/ centered at the grazing angles were covered. The differential cross sections for one-proton transfer with Q values near zero were analyzed using the distorted-wave Born approximation, which can account for the shape of the angular distributions and, to better than a factor of 5, for the absolute cross sections. At Q values more negative than -10 MeV the measured angular distributions begin to deviate from the distorted-wave Born approximation predictions. Substructures were observed in the energy spectra near Q = -25 MeV. A model for unfolding the effects of particle evaporation from the reaction products is developed. It is shown that, within the limitations of the model, the observed substructures cannot be accounted for by evaporation effects alone but must be present in the primary energy spectra. Finally the optimum Q values are analyzed with a one-body dissipation model. The model is reasonably successful if the concept of a local Fermi momentum ismorexa0» introduced.«xa0less

Transfer reactions for28Si+28Si atElab=151.25MeV

Cross sections of one- and few-nucleon transfers in the reaction /sup 28/Si+ /sup 28/Si at E/sub lab/ -- 151.25 MeV have been measured with a quadrupole-dipole-dipole-dipole magnetic spectrometer. The one-neutron and one-proton transfers to corresponding shell model states in the pairs of mirror nuclei /sup 29/Si-/sup 29/P and /sup 27/Si-/sup 27/Al are found to be approximately equal. The cross sections for few-nucleon transfers to states with excitation energies E/sub x/<5 MeV exhibit a strong enhancement of 1n1p over 2n and 2p and of 2n2p (i.e., 1..cap alpha..) over 2n1p or 1n2p transfers. A distorted-wave Born approximation analysis of the 1n and 1p transfers was performed. The derived spectroscopic factors display a high degree of symmetry with respect to isospin and are consistent with the widely varying values obtained in light ion studies.

Transfer reactions for /sup 28/Si+/sup 28/Si at E/sub lab/ -- 151. 25 MeV

Cross sections of one- and few-nucleon transfers in the reaction /sup 28/Si+ /sup 28/Si at E/sub lab/ -- 151.25 MeV have been measured with a quadrupole-dipole-dipole-dipole magnetic spectrometer. The one-neutron and one-proton transfers to corresponding shell model states in the pairs of mirror nuclei /sup 29/Si-/sup 29/P and /sup 27/Si-/sup 27/Al are found to be approximately equal. The cross sections for few-nucleon transfers to states with excitation energies E/sub x/<5 MeV exhibit a strong enhancement of 1n1p over 2n and 2p and of 2n2p (i.e., 1..cap alpha..) over 2n1p or 1n2p transfers. A distorted-wave Born approximation analysis of the 1n and 1p transfers was performed. The derived spectroscopic factors display a high degree of symmetry with respect to isospin and are consistent with the widely varying values obtained in light ion studies.

Quasielastic transfer reactions induced by /sup 56/Fe on /sup 58/Ni, /sup 64/Ni, and /sup 122/Sn

Differential cross sections sigma(Z,A,E,theta) for the quasielastic projectilelike reaction products from the bombardment of /sup 56/Fe on /sup 58,64/Ni and /sup 122/Sn at 5.9 and 8.5 MeV/nucleon have been measured with a channel-plate time-of-flight telescope followed by a ..delta..E-E gas-ionization chamber. Angular intervals of 10/sup 0/--15/sup 0/ centered at the grazing angles were covered. The differential cross sections for one-proton transfer with Q values near zero were analyzed using the distorted-wave Born approximation, which can account for the shape of the angular distributions and, to better than a factor of 5, for the absolute cross sections. At Q values more negative than -10 MeV the measured angular distributions begin to deviate from the distorted-wave Born approximation predictions. Substructures were observed in the energy spectra near Q = -25 MeV. A model for unfolding the effects of particle evaporation from the reaction products is developed. It is shown that, within the limitations of the model, the observed substructures cannot be accounted for by evaporation effects alone but must be present in the primary energy spectra. Finally the optimum Q values are analyzed with a one-body dissipation model. The model is reasonably successful if the concept of a local Fermi momentum ismorexa0» introduced.«xa0less

Quasielastic transfer reactions induced by Fe-56 on Ni-58, Ni-64, and Sn-122

Differential cross sections sigma(Z,A,E,theta) for the quasielastic projectilelike reaction products from the bombardment of /sup 56/Fe on /sup 58,64/Ni and /sup 122/Sn at 5.9 and 8.5 MeV/nucleon have been measured with a channel-plate time-of-flight telescope followed by a ..delta..E-E gas-ionization chamber. Angular intervals of 10/sup 0/--15/sup 0/ centered at the grazing angles were covered. The differential cross sections for one-proton transfer with Q values near zero were analyzed using the distorted-wave Born approximation, which can account for the shape of the angular distributions and, to better than a factor of 5, for the absolute cross sections. At Q values more negative than -10 MeV the measured angular distributions begin to deviate from the distorted-wave Born approximation predictions. Substructures were observed in the energy spectra near Q = -25 MeV. A model for unfolding the effects of particle evaporation from the reaction products is developed. It is shown that, within the limitations of the model, the observed substructures cannot be accounted for by evaporation effects alone but must be present in the primary energy spectra. Finally the optimum Q values are analyzed with a one-body dissipation model. The model is reasonably successful if the concept of a local Fermi momentum ismorexa0» introduced.«xa0less

ANALYSIS OF ELASTIC SCATTERING OF VERY HEAVY IONS WITH POOR ENERGY AND MASS RESOLUTION

Abstract Recent data on the elastic scattering of 86 Kr on 144 Sm with poor resolution is analysed in terms of the coherent surface excitation model with the ion-ion potential of Christensen and Winther.