Li-11 structural information from inclusive break-up measurements

IWM-EC 2014 – International Workshop on Multi facets of EoS and Clustering.-- et al.Structure information of 11Li halo nucleus has been obtained from the inclusive break-up measurements of the 11Li+208Pb reactions at energies around the Coulomb barrier (Elab = 24.3 and 29.8 MeV). The effective break-up energy and the slope of B(E1) distribution close to the threshold have been extracted from the experimental data.Peer Reviewe

Hints of quasi-molecular states in 13B via the study of 9Li-4He elastic scattering

8 pags., 8 figs., 1 tab.This paper reports on elastic scattering excitation functions for the reaction Li+He measured at backward angles in the centre of mass energy range 5 MeV ≤ E≤c.m.9.5 MeV, with the aim of investigating the possible existence of molecular resonances which have been predicted to exist in the case of neutron-rich B-isotopes. Due to the short lifetime of Li, the experiment necessitated the use of inverse kinematics on a gaseous He target. The Thick Target Inverse Kinematics technique was used which allowed for the measurement of the full excitation function in a single Li run. Broad resonances were observed in the excitation region for B 15 MeV ≤ E≤20 MeV. To understand the nature of such broad structures, various theoretical attempts are reported concerning possible reaction mechanisms for this neutron rich reaction. The most promising approach to interpret the data is within the orbiting reaction scenario.This work was supported by INFN and partially supported by the Ministry of Science, Innovation and Universities of Spain, through the projects PGC2018-096994-B-C21, PID2019-104390GB-I00, PID2020-114687GB-I00 and by the Consejería de Economía, Conocimiento, Empresas y Universidad, Junta de Andalucía (Spain) through the project P20_0124

Scattering of the halo nucleus 11Li and its core 9Li on 208Pb at energies around the Coulomb barrier

The first measurement of the elastic scattering of the halo nucleus 11Li and its core 9Li on 208Pb at energies around the Coulomb barrier is presented. The 11Li reaction showed a large cross section for the breakup channel, even at energies well below the barrier. The analysis of the 11Li + 208Pb scattering data in terms of the continuum-discretized coupled-channel calculations indicates that the effect of the coupling to the breakup channels produces a strong suppression of the elastic cross section at energies above and below the barrier. This effect is mainly due to the strong Coulomb coupling to the dipole states in the low-lying continuum of 11Li

Study of the break-up channel in 11Li+208Pb collisions at energies around the Coulomb barrier

We present a study of 11Li+208 Pb collisions at energies around the Coulomb barrier (Elab = 24.3 and 29.8 MeV), measured at the post-accelerated beam facility, ISAC II, at TRIUMF (Vancouver, Canada). A remarkably large yield of 9Li has been observed, a result that is attributed to the weak binding of the 11Li nucleus. The angular distribution of this 9Li yield, relative to the elastic one, has been analysed in terms of first-order semiclassical calculations as well as four-body and three-body Continuum-Discretized Coupled-Channels (CDCC) calculations, based on a three-body and di-neutron model of the 11Li nucleus, respectively. The calculations reproduce well the trend of the data and support the existence of a large concentration of B (E1) strength at very low excitation energies. The connection of this large B (E1) with a possible low-lying dipole resonance is discussed

Elastic scattering of 9Li on 208Pb at energies around the Coulomb barrier

We have studied the dynamical effects of the halo structure of 11Li on the scattering on heavy targets at energies around the Coulomb barrier. This experiment was performed at ISAC-II at TRIUMF with a world record in production of the post-accelerated 11Li beam. As part of this study we report here on the first measurement of the elastic cross section of the core nucleus, i.e. 9Li on 208Pb, at energies around the Coulomb barrier. A preliminary optical model analysis has been performed in order to extract a global optical potential to describe the measured angular distributions

11Li structural information from inclusive break-up measurements

IWM-EC 2014 – International Workshop on Multi facets of EoS and ClusteringStructure information of 11Li halo nucleus has been obtained from the inclusive break-up measurements of the 11Li+208Pb reactions at energies around the Coulomb barrier (Elab = 24.3 and 29.8 MeV). The effective break-up energy and the slope of B(E1) distribution close to the threshold have been extracted from the experimental dat

Observation of γ-delayed 3α breakup of the 15.11 and 12.71 MeV states in 12C

6 pags., 4 figs., 2 tabs. -- PACS:27.20.+n25.55.Hp23.20.-g29.85.-cThe reactions 10B (3He, p α α α) at 4.9 MeV and 11B (3He, d α α α) at 8.5 MeV have been used to investigate the γ decay of states in 12C. By measuring the four-body final state in complete kinematics we are able to detect γ transitions indirectly. We find γ transitions from the 15.11 MeV state in 12C to the 12.71, 11.83, 10.3 and 7.65 MeV states followed by their breakup into three α particles. The relative γ-ray branching ratios obtained are (1.2 ± 0.3), (0.32 ± 0.12), (1.4 ± 0.2) and (4.4 ± 0.8) %, respectively, with the remaining (92.7 ± 1.0) % of the γ decays going to the bound states. We obtain Γα / Γ = (2.8 ± 1.2) % for the isospin-forbidden α decay of the 15.11 MeV state. From the 12.71 MeV state we find γ transitions to the 10.3 and 7.65 MeV states. The relative γ-ray branching ratios are (0.9- 0.5 + 0.6) and (2.6- 1.2 + 1.6) %, respectively, with the remaining (96.6- 1.3 + 1.7) % of the γ decays going to the bound states. Finally, we discuss the relation between the β decay of 12N and 12B to states in 12C and the γ decay of the 15.11 MeV analog in 12C to the same states. © 2009 Elsevier B.V.We would like to acknowledge the support of the Spanish CICYT research grant FPA2007-62170 and the MICINN Consolider Project CSD 2007-00042 as well as the support of the European Union VI Framework through RII3-EURONS/JRA4-DLEP (contract number 506065). D.G. is a Juan de la Cierva fellow

Astrophysical S factor for the He-4(He-3,gamma)Be-7 reaction at medium energies

3 pags., 1 tab. -- Nuclear Physics in Astrophysics V 3–8 April 2011, Eilat, IsraelThe astrophysical S factor for the He-4(He-3,gamma)Be-7 direct capture reaction plays a major role in the context of solar neutrino flux and primordial Li-7 abundances that demand accurate information on the reaction. We report here our recent cross section measurements using the activation method in the region of E-CM=900-2800 keV, that aim to shed light on the discrepancies in the existing data and lead to a more accurate extrapolation of the S factor

Study of the scattering of halo nuclei around the Coulomb barrier

During the past ten years the present collaboration has carried out several experiments related with the study of radioactive nuclei. One of the topics in which we have centered our research, is the scattering of halo nuclei at energies around the Coulomb barrier. As part of this study, we present in this work a review of the results obtained from the scattering of 6He, 11Be and 11Li. The presence of a "halo" in these exotic nuclei is found to have a striking effect on the dynamics of these reactions, making their study an interesting experimental problem and a challenge for existing reaction theories.Ministerio de Ciencia y Tecnología FPA2005-04460, FPA2005-02379, FPA-2000-1592-C03-02, FPA2003-05958, FPA2002- 04181-C04-02/03, FPA2006-13807-c02-0, FPA2009- 07653Programa Español Consolider-Ingenio 2010 CSD2007-0004

ß-decay studies of states in 12C

5 pags., 1 fig., 1 tab. -- International Symposium on Nuclear Astrophysics - Nuclei in the Cosmos - IX, June 25-30 2006, CERN, Geneva, SwitzerlandThe interest in experimental studies of the 12C nucleus is partly due to the astrophysical interest in its spectroscopic properties, which determine the triple alpha reaction rate, and partly motivated by the structure of this nucleus, which is not fully explained theoretically. Some aspects are described in the shell model and others by a cluster structure of three alpha particles, but both cannot so far be combined in a unified model. New experiments have been performed to address these problems. The focus of this work is on an implantation experiment, which took place in April 2006 at KVI