Recent results with radioactive ion beams in Brasil (RIBRAS)

The RIBRAS facility (Radiactive Ion Beams in Brasil) is installed next to the 8 MV Pelletron Tandem of the Nuclear Physics Laboratory of the Institute of Physics of the University of São Paulo. It consists of two superconducting solenoids with maximum magnetic field of B=6.5T. Light radioactive ion beams are produced through transfer reactions, using solid or gaseous production targets of Be, LiF, 3He etc. The solenoids make a magnetic rigidity selection and the use of the two solenoids with a degrader between them allows the production of quite pure secondary beams. Beams of 6He, 8Li, 7Be, 10Be, 8B, 12B are currently produced and used to study elastic, inelastic, and transfer reactions on a variety of light, medium mass and heavy secondary targets. Some examples of reactions recently studied are presented below. © 2012 American Institute of Physics.SCOPUS: cp.pinfo:eu-repo/semantics/publishe

Recent results on reactions with radioactive beams at RIBRAS (Radioactive Ion Beams in Brazil)

We present a quick description of RIBRAS (Radioactive Ion beams in Brazil), which is a superconducting double solenoid system, installed at the Pelletron Laboratory of the University of São Paulo and extends the capabilities of the original Pelletron Tandem Accelerator of 8MV terminal voltage (8UD) by producing secondary beams of unstable nuclei. The experimental program of the RIBRAS covers the study of elastic and inelastic scattering with the objective to study the interaction potential and the reaction mechanisms between weakly bound (RIB) and halo (6He and 8B) projectiles on light, medium and heavy mass targets. With highly purified beams, the study of resonant elastic scattering and resonant transfer reactions, using inverse kinematics and thick targets, have also been included in our recent experimental program.SCOPUS: cp.jinfo:eu-repo/semantics/publishe

The 8Li(p,α) 5He reaction measured at astrophysical energies at RIBRAS

We present the results of the 8Li(p,α) 5He transfer reaction, measured at the RIBRAS facility. It was performed in inverse kinematics using a thick CH 2 polyethylene target. The complete excitation function was measured between E cm=0.4-2.7 2MeV, which includes the Gamow peak energy region. The excitation function was reproduced with the R-matrix theory. © 2011 American Institute of Physics.SCOPUS: cp.pinfo:eu-repo/semantics/publishe

Study of high lying resonances in 9Be by the Measurement of (p, p), (p,α) and (p, d) reactions

The (p, p), (p, α) and (p, d) reactions on 8Li were measured at low energies. The experiment was performed using a thick [CH2]n target and a radioactive 8Li beam available at the RIBRAS facility of São Paulo. This experiment represents an upgrade of a previous experiment, where only the 8Li(p, a)5He cross section was measured. High lying resonances of 9Be, which are still uncertain, could be studied in this way. The detection of several reaction channels allows a reliable determination of the resonance parameters, such as energy, width and spin-parity. In the deuteron channel we could observe the same resonance decaying to d+7Ligs and to d+7Li&z.ast; The properties of the resonances are determined by a R-matrix analysis, which provides evidence for a significant clustering as well in the (p, α) as in the (p, d) channels. The experimental data and the multi-channel R-matrix analysis will be presented.SCOPUS: cp.pinfo:eu-repo/semantics/publishe

The 8Li(p,α)5He reaction at low energies, and 9Be spectroscopy around the proton threshold

We present a direct measurement of the low-energy 8Li(p ,α)5He cross section, using a radioactive 8Li beam impinging on a thick target. With four beam energies, we cover the energy range between Ec.m.=0.2 and 2.1 MeV. An R-matrix analysis of the data is performed and suggests the existence of two broad overlapping resonances (5/2+ at Ec.m.=1.69 MeV and 7/2+ at E c.m.=1.76 MeV). At low energies our data are sensitive to the properties of a subthreshold state (Ex=16.67 MeV) and of two resonances above threshold. These resonances were observed in previous experiments. The R-matrix fit confirms spin assignments, and provides partial widths. We propose a new 8Li(p,α)5He reaction rate and briefly discuss its influence in nuclear astrophysics. © 2012 American Physical Society.SCOPUS: ar.jinfo:eu-repo/semantics/publishe

Scientific program of the Radioactive Ion Beams Facility in Brasil (RIBRAS)

The RIBRAS facility (Radioactive Ion Beams in Brasil) is installed in connection with the 8MV Pelletron tandem of the University of São Paulo Physics Institute. It consists of two superconducting solenoids which focalize light radioactive secondary beams of low energy, produced by transfer reactions. Recent experimental results include the elastic scattering and transfer reactions of 6He halo nucleus on 9Be, 27Al, 51V and 120Sn targets. The elastic scattering and transfer of 8Li and 7Be on several targets is also being studied. The transfer reaction 8Li(p,α)5He of astrophysical interest was also studied in the Ec m = 0.2 - 2.5 MeV energy range. © 2010 Elsevier B.V. All rights reserved.SCOPUS: ar.jinfo:eu-repo/semantics/publishe

Spectroscopy of high lying resonances in 9Be produced with radioactive 8Li beams

We present the results of the 8Li(p,α)5He and 8Li(p,p)8Li reactions measured at the RIBRAS (Radioactive Ion Beams in Brazil) system. The experiment was realized in inverse kinematics using a thick [CH2]n polyethylene target and an incident 8Li beam, produced by RIBRAS. Using the thick target method, the complete excitation function could be measured between Ecm = 0.2 - 2.1 MeV, which includes the Gamow peak energy region. The excitation function of the 8Li(p,α)5He reaction, populating resonances between 16.888 and 19.0 MeV in 9Be, was obtained[1] and the resonances were fitted using R-matrix calculations. This study shed light on spins, parities, partial widths and isospin values of high lying resonances in 9Be. The measurement of the resonant elastic scattering 8Li(p,p)8Li populating resonances in the same energy region can constrain the resonance parameters. Preliminary results of the elastic scattering are also presented. © Owned by the authors, published by EDP Sciences, 2014.SCOPUS: cp.pinfo:eu-repo/semantics/publishe