Abstract
Proton halo effects in the 8B+64Zn reaction at an energy around 1.5 times the Coulomb barrier have been studied at HIE-ISOLDE CERN using, for the first time, the only existing postaccelerated 8B beam. This, together with the use of a high granularity and large solid angle detection system, allowed for a careful mapping of the elastic angular distribution, especially in the Coulomb-nuclear interference region. Contrary to what is observed for the one-neutron halo nucleus 11Be on the same target in a similar energy range, the analysis of the elastic scattering angular distribution shows only a modest suppression of the Coulomb-nuclear interference peak, with no remarkable enhancement of the total reaction cross-section. Inclusive angular and energy distributions of 7Be produced in direct reaction processes have also been measured. The comparison of these data with the results of theoretical calculations for the elastic and non-elastic breakup contributions indicate that both processes are important. Overall, the experimental data suggest a 8B collision dynamics at the barrier very different from the one of neutron halo nuclei, showing only modest effects of coupling to continuum. This behaviour can be interpreted as due to the presence of the additional Coulomb interactions halo-core and halo-target together with the presence of the centrifugal barrier felt by the valence proton of 8B.
Highlights
B reaction at energies close to the Coulomb barrier with good energy and angular resolution, is obvious in order to have a clear understanding about the effects of 8 B structure on the reaction dynamics
To this aim we proposed to develop at HIE-ISOLDE CERN a postaccelerated 8 B beam with the goal to measure, using the large solid angle and high granularity detection system GLORIA, more precise angular distribution for elastic scattering and breakup on the medium mass target 64 Zn, that we have already used to perform extensive reaction dynamics studies at barrier energies using the n-halo nuclei 6 He [2,32,33], 11 Be [4,5] and, recently, 11 Li [34]
The following conclusions can be drawn. (i) The comparison of first order (DWBA) with all-orders (CDCC) calculations including only E1 Coulomb couplings confirms the expected deceleration effect predicted by the classical model, suggesting a near-target breakup scenario; (ii) this picture breaks down when higher Coulomb multipoles, as well as nuclear couplings, are considered
Summary
Corresponding author at: Dipartamento di Fisica e Astronomia, Universitá di Catania, via S. B reaction at energies close to the Coulomb barrier with good energy and angular resolution, is obvious in order to have a clear understanding about the effects of 8 B structure on the reaction dynamics To this aim we proposed to develop at HIE-ISOLDE CERN a postaccelerated 8 B beam with the goal to measure, using the large solid angle and high granularity detection system GLORIA, more precise angular distribution for elastic scattering and breakup on the medium mass target 64 Zn, that we have already used to perform extensive reaction dynamics studies at barrier energies using the n-halo nuclei 6 He [2,32,33], 11 Be [4,5] and, recently, 11 Li [34]. A comparison of the deduced σR is often performed in this kind of analysis on a “reduced scale” to eliminate trivial static effects, i.e. those effects on the reaction cross-section due to the different Coulomb bar-
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