Scattering of the Halo Nucleus Be11 on Au197

Abstract

Angular distributions of the elastic, inelastic, and breakup cross sections of the halo nucleus ^{11}Be on ^{197}Au were measured at energies below (E_{lab}=31.9 MeV) and around (39.6 MeV) the Coulomb barrier. These three channels were unambiguously separated for the first time for reactions of ^{11}Be on a high-Z target at low energies. The experiment was performed at TRIUMF (Vancouver, Canada). The differential cross sections were compared with three different calculations: semiclassical, inert-core continuum-coupled-channels and continuum-coupled-channels ones with including core deformation. These results show conclusively that the elastic and inelastic differential cross sections can only be accounted for if core-excited admixtures are taken into account. The cross sections for these channels strongly depend on the B(E1) distribution in ^{11}Be, and the reaction mechanism is sensitive to the entanglement of core and halo degrees of freedom in ^{11}Be.

Classical dynamical modelling of near-barrier breakup

“…• , and one extending from (θ 12 The previous work [27] illustrated the results of the model by focusing on breakup occuring at fixed distances prior to and after the distance of closest approach, without explicitly considering the lifetime of the 8 Be state involved. Here we show complete Monte Carlo calculations where the impact parameters, reaction distance, the 8 Be excitation energies and lifetimes, and the initial orientation of the α fragments are all stocastically sampled.…”

“…At this conference seen talks experimental measurements of reactions of 7 Be (Mazzocco), 8 B (Kolata [11]), and the halo nucleus 11 Be (Pesudo [12]), in addition to time-dependent Hartree-Fock calculations for exotic calcium isotopes (Vo-Phouc [13]). Innovative technical developments were also presented, such as new methods for extraction of fusion excitation functions with stacked targets, which will soon be utilized in experiments with exotic beams (Di Pietro [14,15]).…”

Elastic scattering measurements for the C10+Pb208 system at ElabLinares1, Sinha2, Cardozo3 et al. 2021Phys. Rev. C10020View full textAdd to dashboardCite

“…Also, the decoupling to the continuum of the single-particle or cluster motion of the valence nucleon(s) with respect to the core has motivated the application of reaction models such as continuum-discretized coupled-channels (CDCC) [6], in which the coupling between the elastic and the breakup channel is explicitly taken into account. The CDCC calculations have been applied to study the elastic scattering of exotic neutron-rich nuclei, such as 6 He, 11 Li, and 11 Be, on several medium to heavy target nuclei and at energies around the Coulomb barrier [7][8][9][10][11][12][13][14][15][16][17]. In some of these works, the 11 Be has been described as 10 Be core and a valence neutron while 6 He has been described as a 4 He core and a paired di-neutron system.…”

Systematic calculations of reactions with exotic and stable nuclei to establish a unified theoretical approach

“…This characteristic favors break-up and, therefore, elastic scattering flux absorption, when interacting with another nucleus. Break-up gives rise to a complex problem of three or more bodies and can be driven by different processes: core excitation, direct excitation of the projectile into continuum states, transfer to bound or unbound states of the target, among others [6][7][8][9][10][11][12][13][14]. Close to or even below the Coulomb barrier, the Coulomb break-up can play an important role.…”

“…The 11 Li ( 9 Li+n+n) represents another neutron rich exotic nucleus with Borromean structure, therefore, the three binary sub-systems, 9 Li-n and n-n, are not bound. The 11 Li decays, by beta minus emission, in 11 Be, with a half-life of 8.75 (14) ms [24]. There is no bound excited states.…”