H.H. Gutbrod

(d, 6Li) reactions on p and sd shell nuclei and their interpretation by finite-range DWBA

Abstract The (d, 6 Li) reaction on 10 B, 11 B, 12 C, 16 O, 19 F, 28 Si and 40 Ca has been investigated with the 19.5 MeV deuteron beam of the MPI Emperor tandem Van de Graaff. The measured angular distributions are analyzed by finite-range DWBA calculations. Spectroscopic factors for the α-cluster transfer have been calculated from shell-model wave functions for the target nuclei. The theoretical cross sections are found to be very sensitive to the choice of the model for 6 Li. The cluster model leads to cross sections which are strongly enhanced compared to the shell-model predictions. They reproduce the absolute experimental cross sections of the ground state transitions for the target nuclei from 12 C to 40 Ca. However, the experimental (d, 6 Li) cross section on the 10 B target is much larger than predicted and the angular distribution cannot be described. This indicates a more complicated reaction mechanism in this case.

Four-nucleon transfer reaction induced by 10B on 12C

Abstract The four-nucleon transfer reaction induced by 10 B on 12 C has been studied above the Coulomb barrier. The population of final states of 16 O is less selective than in other four-nucleon transfer reactions induced by 6 Li, 7 Li, or 16 O. This fact as well as the structureless angular distributions can be explained by the complexity of the structure of the ground state of 10 B, which has large components with a lower degree of symmetry than the α-particle.

Heavy ion transfer reactions with identical initial and final states

Abstract A special type of transfer reaction which has identical initial and final states and which is strongly localized in angular momentum space is discussed. These reactions A(B, A)B are due to exchange effects in elastic scattering A(B, B)A. Examples for α-particle and proton transfer have been measured and analysed.

Elastic and inelastic scattering of16O by12C at forward and backward angles

Angular distributions of the reactions12C(16O,16O)12C and12C(16O,12C)16O have been measured in the angular range of θCM=10 °–60 ° at 65 and 80 MeV to ground states and excited states of both final nuclei. An optical model withl-dependent imaginary potential gives no consistent description of the elastic scattering data. It is shown, however, that the forward angle elastic scattering may be described by strongly absorbing potentials and that the backward rise of the cross sections in both the elastic and inelastic transitions can be explained by a four nucleon transfer12C(16O,12C)16O.

16O and 19F induced multi-nucleon transfer reactions in light nuclei

Abstract Triton, α-particle, five- and nine-nucleon transfer reactions induced by 19 F in 12 C and 16 O in 11 B at incident energies above the Coulomb barrier have been measured in order to study the nuclear structure of 15 N, 16 O and 20 Ne, and the reaction mechanism. The possibility of obtaining spectroscopic information by a comparison of the spectra and cross sections in the different reactions is discussed, DWBA calculations with the fixed-range model show that the strongly absorbing optical potentials extracted from the analysis of the elastic scattering and successfully used for different heavy-ion-induced proton transfer reactions, can be applied to heavy-ion-induced multi-nucleon transfer reactions.

DWBA analysis of the proton transfer 12C(11B, 12C)11B at 28 MeV

Abstract The DWBA analysis of the proton transfer 12 C( 11 B, 12 C) 11 B at an energy well above the Coulomb barrier, based on the theory of Buttle and Goldfarb, gives relative spectroscopic factors for 12 C, which agree with those derived from theory and other experiments. The absolute cross section disagrees with experiment by an order of magnitude.

The compound nucleus reaction 12C(11B, 2α) 15N

Abstract Energy spectra and differential cross sections of nitrogen products formed in the reaction 28 MeV 11 B + 12 C have been measured using a ΔE − E counter telescope. The energy spectra are smooth and therefore indicate that the nitrogen products were formed by a compound nucleus mechanism, via the formation and decay of the compound nucleus 23 Na. The experimental results are compared with statistical model calculations and good agreement is obtained. This result provides further evidence for the importance of the compound nucleus mechanism in heavy ion reactions with light nuclei and also gives added validity to the statistical model for light compound systems.