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The $^{8}\mathrm{Li}+^{58}\mathrm{Ni}$ collision is investigated at 23.9, 26.1, 28.7, and 30 MeV bombarding energies. Quasielastic angular distributions and the singles $^{7}\mathrm{Li}$ angular and energy distributions are presented. Coupled-reaction channels (CRC) calculations, which include the coupling of the elastic channel to $^{59}\mathrm{Ni}=^{58}\mathrm{Ni}\phantom{\rule{0.16em}{0ex}}+\phantom{\rule{0.16em}{0ex}}n$ states above and below the neutron threshold, provide a simultaneous description of the quasielastic and transfer distributions and evidence the strong effect of the one-neutron transfer/breakup channels on the quasielastic scattering. The $^{7}\mathrm{Li}$ angular and energy distributions have been also successfully analyzed combining the continuum discretized coupled channels (CDCC) method, for the elastic breakup, and the IAV model of Ichimura, Austern, and Vincent [Phys. Rev. C 32, 431 (1985)], for the nonelastic breakup. These calculations indicate that most of the $^{7}\mathrm{Li}$ yields are due to nonelastic breakup contributions (transfer), whereas elastic breakup plays a minor role.

\textbf{Background:} The influence of halo structure of $^6$He, $^8$B, $^{11}$Be and $^{11}$Li nuclei in several mechanisms such as direct reactions and fusion is already established, although not completely understood. The influence of the $^{10}$C Brunnian structure is less known. \textbf{Purpose:} To investigate the influence of the cluster configuration of $^{10}$C on the elastic scattering at an energy close to the Coulomb barrier. \textbf{Methods:} We present experimental data for the elastic scattering of the $^{10}$C+$^{208}$Pb system at $E_{\rm lab}$ = 66~MeV. The data are compared to the three- and the four-body continuum-discretized coupled-channels calculations assuming $^9$B+$p$, $^6$Be+$\alpha$ and $^8$Be+$p$+$p$ configurations. \textbf{Results:} The experimental angular distribution of the cross sections shows the suppression of the Fresnel peak that is reasonably well reproduced by the continuum-discretized coupled-channels calculations. However, the calculations underestimate the cross sections at backward angles. Couplings to continuum states represent a small effect. \textbf{Conclusions:} The cluster configurations of $^{10}$C assumed in the present work are able to describe some of the features of the data. In order to explain the data at backward angles, experimental data for the breakup and an extension of theoretical formalism towards a four-body cluster seem to be in need to reproduce the measured angular distribution.

Motivated by the strong synergy between structure and nuclear reactions we have performed a phenomenological analysis using available elastic scattering data for collisions of tightly-bound ( $$^{10}\hbox {Be}$$ , $$^{10}\hbox {B}$$ , $$^{10}\hbox {C}$$ , $$^{11}\hbox {B}$$ , $$^{12}\hbox {C}$$ , $$^{16}\hbox {O}$$ ), weakly-bound ( $$^6\hbox {Li}$$ , $$^7\hbox {Li}$$ , $$^8\hbox {Li}$$ , $$^9\hbox {Be}$$ ), and exotic ( $$^6\hbox {He}$$ , $$^{8}\hbox {B}$$ and $$^{11}\hbox {Be}$$ ) nuclei on $$^{58}\hbox {Ni}$$ and $$^{64}\hbox {Zn}$$ targets at energies close to the Coulomb barrier. After a proper reduction, the cluster configuration and dynamics effects in the total reaction cross section are discussed. Also, an approach based on the interaction distances is used to investigate static and dynamic effects in the elastic scattering of light nuclei. A correlation between the critical interaction distance and binding energy for a given configuration is observed.

Experiments with secondary radioactive beams $$^6$$ He, $$^7$$ Be, $$^8$$ Li and $$^8$$ B on several targets have been performed in recent years at the Radioactive Ion Beams facility in Brasil (RIBRAS). We present results of elastic scattering and reaction measurements performed with this facility. A preliminary Coulomb excitation experiment using gamma-particle coincidence technique is described.

In this contribution, we report on effects due to the cluster configuration of boron isotopes, \(^8\)B, \(^{10}\)B, \(^{11}\)B and \(^{12}\)B, in the elastic scattering on \(^{58}\)Ni target at energies close to the Coulomb barrier. The results of coupled channel calculations, where the different configurations of the boron isotopes, \(^8\)B \(=\) \(^7\)Be\(+\)p, \(^{10}\)B \(=\) \(^6\)Li\(+\) \(\alpha \), \(^{11}\)B \(=\) \(^7\)Li\(+\) \(\alpha \) and \(^{12}\)B \(=\) \(^{11}\)B\(+\)n, have been attributed to different effects in the angular distributions for the elastic scattering process, are present.

Alpha particle energy distributions in the 6He+120Sn collision have been measured at 7 bombarding energies above the Coulomb barrier. A phenomenological analysis of the centroids of the experimental distributions was performed and compared with the expected alpha-particle energies from breakup and neutron transfer reactions. Q-optimum conditions were determined using the Brinks formula for the di-neutron transfer reaction. A comparison of the measured alpha-particle production cross-sections with Continuum Discretized Coupled Channels (CDCC) calculations for breakup is presented. Fundacao de Amparo `a Pesquisa no Estado de Sao Paulo 2013/22100-7, 2014/19666-1 Conselho Nacional de Desenvolvimento Cientıfico e Tecnologico 308935/2018-7 Ministerio de Economía y Competitividad FIS2017-88410-P European Union 654002

Elastic scattering and transfer cross sections for the $^{7}\mathrm{Be}+^{9}\mathrm{Be}$ system have been measured at ${E}_{\mathrm{lab}}=23.1\phantom{\rule{0.28em}{0ex}}\mathrm{MeV}$ using the $^{7}\mathrm{Be}$ radioactive secondary beam produced at Radioactive Ion Beams in Brazil facility at the University of S\~ao Paulo. The elastic scattering has been measured by detecting the $^{7}\mathrm{Be}$ scattered at forward angles in the laboratory system. The transfer reaction $^{9}\mathrm{Be}(^{7}\mathrm{Be},^{9}\mathrm{Be})^{7}\mathrm{Be}$ was identified by detecting the $^{9}\mathrm{Be}$ scattered at the same laboratory angles. The elastic angular distribution has been analyzed by optical model calculations using a Woods-Saxon form factor whose parameters have been varied to best reproduce the experimental data at forward angles. Coupled reaction channels calculations (CRC) have been performed to describe the transfer, considering the coupling to the transfer channel and including contributions to the ground state and to the first excited state of $^{7}\mathrm{Be}(1/2\ensuremath{-};429\phantom{\rule{0.16em}{0ex}}\mathrm{keV}$) in the final state. The spectroscopic amplitudes used in the CRC calculation have been derived from shell-model calculations. Similar CRC calculations were applied to existing $^{9}\mathrm{Be}(p,t)^{7}\mathrm{Be}$ data to check the consistency of our results results for the ($^{7}\mathrm{Be},^{9}\mathrm{Be}$) transfer reaction.

Elastic scattering of a radioactive neutron-rich boron isotope, $^{12}\mathrm{B}$, has been measured for the first time. Angular distributions for the elastic scattering of $^{12}\mathrm{B}+^{58}\mathrm{Ni}$ have been measured at ${\mathit{E}}_{\mathrm{Lab}}=30.0$ and 33.0 MeV, which are just above the Coulomb barrier (${\mathit{V}}_{\mathrm{B}}=24$ MeV). The obtained angular distributions were analyzed in terms of the large-scale coupled channel (CC) and coupled reaction channel (CRC) calculations, where several inelastic transitions for the target, as well as the most relevant transfer reactions, have been included in the coupling matrix elements. The roles of the spin reorientation and spin-orbit interaction in the reaction mechanism were also investigated. The one-neutron transfer reaction through a coupled reaction calculation had some effect on the elastic scattering of the system studied.

A large yield of $\ensuremath{\alpha}$ particles produced in the $^{120}\mathrm{Sn}(^{6}\mathrm{He},\ensuremath{\alpha})$ reaction was measured at 20.3-, 22.2-, 22.4-, and 24.5-MeV bombarding energies. The $\ensuremath{\alpha}$ particles are distributed over a broad energy range in the vicinity and below the elastic scattering $^{6}\mathrm{He}$ peak. Energy integrated $\ensuremath{\alpha}$-particle cross sections have been obtained at ${\ensuremath{\theta}}_{\text{lab}}={36}^{\ensuremath{\circ}},{40}^{\ensuremath{\circ}}$, and ${60}^{\ensuremath{\circ}}$. The $\ensuremath{\alpha}$ energy distributions have been analyzed at a fixed laboratory angle $(\ensuremath{\approx}{60}^{\ensuremath{\circ}})$ in terms of the reaction $Q$ value, considering the $2n$-transfer reaction kinematics $^{120}\mathrm{Sn}(^{6}\mathrm{He},\ensuremath{\alpha})^{122}\mathrm{Sn}$. A kinematical analysis of the $Q$-value distribution shows that the recoil system $^{120}\mathrm{Sn}+2n$ is formed in highly excited states in the continuum, at increasing excitation energies as the bombarding energy increases. It is shown that by using Brink's formula, the excitation energy depends on the transferred angular momentum following a linear relation with the square of the angular momentum, indicating that some kind of dinuclear rotating system is formed after the reaction.

A new method to obtain the nuclear radius from low energies total reaction cross section measurements is presented. Elastic scattering angular distributions of \(^6\)He on \(^9\)Be at two energies, namely, E\(_\mathrm {cm}= 9.72\) and 12.78 MeV, were analysed previously and the total reaction cross sections obtained are used to assess the \(^6\)He nuclear interaction radius. A comparison with the radius of the \(^6\)He obtained at higher energies is presented.

A description of the RIBRAS (radioactive ion beams in Brasil) facility is presented and the last experimental developments in the system are reported.

We measured the $^{8}\mathrm{Li}(p,p)^{8}\mathrm{Li}$, $^{8}\mathrm{Li}(p,d)^{7}\mathrm{Li}$, and $^{8}\mathrm{Li}(p,\ensuremath{\alpha})^{5}\mathrm{He}$ reactions at low energies using the thick target inverse kinematics method, with a polyethylene ${[{\mathrm{CH}}_{2}]}_{n}$ target and a radioactive $^{8}\mathrm{Li}$ beam available at the Radioactive Ion Beams in Brazil facility of S\~ao Paulo. By measuring simultaneously several reaction channels $(p,p)$, $(p,d)$, and $(p,\ensuremath{\alpha})$, the still uncertain high-lying resonances of $^{9}\mathrm{Be}$, close to the proton threshold, can be studied and their parameters, such as energy, width, and spin parity can be more reliably determined. The experimental excitation functions of the reactions $^{8}\mathrm{Li}(p,p)^{8}\mathrm{Li}$, $^{8}\mathrm{Li}(p,d)^{7}\mathrm{Li}$, and $^{8}\mathrm{Li}(p,\ensuremath{\alpha})^{5}\mathrm{He}$ were analyzed using the $R$-matrix theory, which allows us to infer the properties of the resonances. Multichannel $R$-matrix analysis provides evidence for a significant clustering in the $(p,d)$ channel. The experimental data and the multichannel $R$-matrix analysis will be presented.

Elastic scattering angular distributions of 6He on light, medium and heavy mass targets have been analysed using a simple diffractive model for the S-matrix. The results show that a very large diffuseness in the angular momentum space is necessary to reproduce the data in the case of scattering on heavy targets.

We present $^{8}\mathrm{B}+^{27}\mathrm{Al}$ elastic scattering angular distributions for the proton-halo nucleus $^{8}\mathrm{B}$ at two energies above the Coulomb barrier, namely ${E}_{\mathrm{lab}}=15.3$ and 21.7 MeV. The experiments were performed in the Radioactive Ion Beams in Brasil facility (RIBRAS) in S\~ao Paulo, and in the TwinSol facility at the University of Notre Dame, USA. The angular distributions were measured in the angular range of 15--80 degrees. Optical model and continuum discretized coupled channels calculations were performed, and the total reaction cross sections were derived. A comparison of the $^{8}\mathrm{B}+^{27}\mathrm{Al}$ total reaction cross sections with similar systems including exotic, weakly bound, and tightly bound projectiles impinging on the same target is presented.

We present angular distributions of the He 6 + Ni 58 scattering measured at three bombarding energies above the Coulomb barrier: E lab = 12.2 MeV , 16.5 MeV , and 21.7 MeV . The angular distributions have been analysed in terms of three- and four-body Continuum-Discretized Coupled-Channels calculations considering the effect of the 6 He breakup. A behaviour in the cross section at large angles has been observed which was reproduced only by the four-body Continuum-Discretized Coupled-Channels calculation.

An overview of the experiments performed at RIBRAS over the last year is presented. Elastic scattering and breakup reactions induced by light exotic projectiles on different targets have been measured and some results are presented here for the 120Sn(6He, α) reaction. Resonant scattering experiments have been performed with 10Be and 12C secondary beams on a CH2 thick target and the well known 12C+p resonance was identified. A gamma-particle experiment using a new system of LYSO scintillators to detect gammas was done.

In this work we present an elastic scattering angular distribution for the 8Li+58Ni system measured at Elab = 26.1 MeV. The 8Li beam was produced in the Radioactive Ion Beams in Brasil (RIBRAS) facility using the 7Li primary beam delivered by the 8-UD Pelletron accelerator. The angular distribution covers the angular range from 20 to 85 degrees in the center of mass frame. The data have been analysed by optical model and coupled channels calculations, including couplings to low-lying states in 8Li and the spin-orbit interaction. Our results indicate that the inclusion of the spin-orbit interaction in the calculations is important to describe the data at backward angles.

We have measured the elastic scattering cross-section for 8Li + 9Be and 8Li + 51V systems at 19.6MeV and 18.5MeV, respectively. We have also extracted total reaction cross sections from the elastic scattering analysis for several light weakly bound systems using the optical model with Woods-Saxon and double-folding-type potentials. Different reduction methods for the total reaction cross-sections have been applied to analyze and compare simultaneously all the systems.

The RIBRAS facility (Radioactive Ion Beams in Brasil) is installed in connection with the 8MV Pelletron tandem of the University of Sao 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 E c m = 0.2 – 2.5 MeV energy range.

A double superconducting solenoid system is installed at the Pelletron Laboratory of the Uni- versity of Sao Paulo, Brazil. This system allows the production of secondary beams of 8 Li, 6 He, 7 Be and others light exotic nuclei. The first results using this facility are presented.

The elastic scattering of the radioactive halo nucleus 6He on 27Al target was measured at four energies close to the Coulomb barrier using the RIBRAS (Radioactive Ion Beams in Brazil) facility. The Sao Paulo Potential(SPP) was used and its diffuseness and imaginary strength were adjusted to fit the elastic scattering angular distributions. Reaction cross-sections were extracted from the optical model fits. The reduced reaction cross-sections of 6He on 27Al are similar to those for stable, weakly bound projectiles as {6,7}Li, 9Be and larger than stable, tightly bound projectile as 16O on 27Al., 7 pages, 1 table, 3 figures

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.j, info:eu-repo/semantics/published

In the last 50 years several studies have been made to understand the relaxation mechanisms of the heavy interstitial atoms present in transition metals and their alloys. Internal friction measurements have been carried out in a Nb–Ti alloy containing 3.1 at.% of Ti produced by the Materials Department of Chemical Engineering Faculty of Lorena (Brazil), with several quantities of oxygen in solid solution using a torsion pendulum. These measurements have been performed by a torsion pendulum in the temperature range from 300 to 700 K with an oscillation frequency between 0.5 and 10 Hz. The experimental results show complex internal friction spectra that have been resolved, into a series of Debye peaks corresponding to different interactions. For each relaxation process it was possible to obtain the height and temperature of the peak, the activation energy and the relaxation time of the process.

Elastic angular distributions of the $^{6}\mathrm{He}$ + $^{9}\mathrm{Be}$ scattering at ${E}_{\mathrm{lab}}=16.2$ and 21.3 MeV have been analyzed in the context of the optical model. The projectile-target optical potential was calculated in a cluster model where the contributions from the fragment target $(\ensuremath{\alpha}{\ensuremath{-}}^{9}\mathrm{Be})$ and the dineutron target $(2n{\ensuremath{-}}^{9}\mathrm{Be})$ are separated and the latter was searched to reproduce the experimental data. The total reaction cross sections for the $^{6}\mathrm{He}$$\phantom{\rule{0.16em}{0ex}}+\phantom{\rule{0.16em}{0ex}}{}^{9}\mathrm{Be}$ system have been obtained, and the error bars have been estimated considering the spread between the present optical model and previous coupled channels and continuum discretized coupled-channels calculations. The cross sections have been reduced and compared in a systematics involving tightly bound, weakly bound, and the exotic $^{6}\mathrm{He}$ projectiles, all on $^{9}\mathrm{Be}$ target. An analysis of the enhancements observed in the total reaction cross section induced by $^{6}\mathrm{He}$ on light, medium mass, and heavy targets is presented.

Elastic scattering angular distributions of the radioactive weakly bound $^{7}\mathrm{Be}$ on $^{27}\mathrm{Al}$ have been measured at energies near the Coulomb barrier. The interaction optical potential is investigated by using different potentials. Total reaction cross sections have also been obtained.

We present the results of experiments using a 6 He beam on a 9 Be target at energies 7 − 9 times the Coulomb barrier. Angular distributions of the elastic, inelastic scattering (target breakup) and the a -particle production in the 6 He+ 9 Be collision have been analysed. Total reaction cross sections were obtained from the elastic scatteringanalyses and a considerable enhancement has been observed by comparing to stable systems.

Measurements of the p({sup 6}He,p) elastic scattering excitation function have been performed in the RIBRAS system using a {sup 6}He secondary beam and a CH{sub 2} polyethylene thick target. The motivation is to observe states of the compound nucleus {sup 7}Li in the excitation energy range of E{sub exc}{sup 7Li} = 10.8-11.8MeV, where the isobaric analog state of {sup 7}He ground state lies. Excitation functions have been obtained at three laboratory angles θ{sub lab} = 0°, 20°, and 25° which correspond to θ{sub c.m} = 180°, 140°, and 130°.

Elastic scattering measurements of 6He + 58Ni system have been performed at the laboratory energy of 21.7 MeV. The 6He secondary beam was produced by a transfer reaction 9Be (7Li, 6He) and impinged on 58Ni and 197Au targets, using the Radioactive Ion Beam (RIB) facility, RIBRAS, installed in the Pelletron Laboratory of the Institute of Physics of the University of Sao Paulo, Brazil. The elastic angular distribution was obtained in the angular range from 15° to 80° in the center of mass frame. Optical model calculations have been performed using a hybrid potential to fit the experimental data. The total reaction cross section was derived.

Elastic scattering angular distribution measurements of 7Be+27Al system were performed at the laboratory energy of 15.6 MeV. The 7Be secondary beam was produced by the proton transfer reaction 3He(6Li,7Be) and impinged on 27Al and 197Au targets, using the Radioactive Ion Beam (RIB) facility, RIBRAS. The elastic angular distribution was obtained within the angular range of 150 - 800 at the center of mass frame. Optical model calculations have been performed using the Woods- Saxon form factors and the Sao Paulo potential to fit the experimental data. The total reaction cross section was derived.

A description of the double solenoid system (RIBRAS) operating since 2004 in one of the beam lines of the Pelletron Laboratory of the Institute of Physics of the University of Sao Paulo is presented. The recent installation of the secondary scattering chamber after the second solenoid is reported and the first experiment in RIBRAS using both solenoids is described.

The reaction of 7Li+120Sn has been measured at bombarding energies of 21, 24 and 27 MeV. The -ray transition in 120Sn was observed and the angular distribution for the 2+ excited state was obtained. Coupled channels and coupled-reaction channels calculations, including the dynamical polarization potential due to the projectile break-up, obtained from continuum discretized coupled channel calculations, were performed. The comparison between the existing experimental elastic angular distribution with the coupled-reaction channels calculations indicates that the 1n stripping transfer is the most intense channel to be coupled and the 2n stripping reaction occurs sequentially rather than directly, however, further data must be analyzed to confirm this indication. The experimental elastic and inelastic scattering data were well described by the calculations, but some discrepancies in these channels may indicate the need for corrections to the nuclear potential and/or the necessity to incorporate further channels.

We present a direct measurement of the low-energy ${}^{8}\mathrm{Li}{(p,\ensuremath{\alpha})}^{5}\mathrm{He}$ cross section, using a radioactive ${}^{8}$Li beam impinging on a thick target. With four beam energies, we cover the energy range between ${E}_{\mathrm{c}.\mathrm{m}.}=0.2$ 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 ${E}_{\mathrm{c}.\mathrm{m}.}=1.69$ MeV and $7/{2}^{+}$ at ${E}_{\mathrm{c}.\mathrm{m}.}=1.76$ MeV). At low energies our data are sensitive to the properties of a subthreshold state (${E}_{x}=16.67$ 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 ${}^{8}\mathrm{Li}{(p,\ensuremath{\alpha})}^{5}\mathrm{He}$ reaction rate and briefly discuss its influence in nuclear astrophysics.

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 Sao 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.

Experiments using secondary beams of light rare isotopes such as 6He, 7Be and 8Li have been performed at the Radioactive Ion Beams Facility (RIBRAS) installed in the University of Sao Paulo, Brazil. A description of some results that have been obtained over the last years is presented.

Elastic scattering angular distributions for ${}^{7}$Be, ${}^{9}$Be, and ${}^{10}$Be isotopes on ${}^{12}$C target were measured at laboratory energies of 18.8, 26.0, and 23.2 MeV, respectively. The analysis was performed in terms of optical model potentials using Woods-Saxon and double-folding form factors. Also, continuum discretized coupled-channels calculations were performed for ${}^{7}$Be and ${}^{9}$Be $+{\phantom{\rule{0.16em}{0ex}}}^{12}$C systems to infer the role of breakup in the elastic scattering. For the ${}^{10}$Be $+{\phantom{\rule{0.16em}{0ex}}}^{12}$C system, bound states coupled-channels calculations were considered. Moreover, total reaction cross sections were deduced from the elastic scattering analysis and compared with published data on other weakly and tightly bound projectiles elastically scattered on the ${}^{12}$C target, as a function of energy.

New data for the $^{6}\mathrm{He}+^{9}\mathrm{Be}$ reaction at ${E}_{\mathrm{lab}}=16.2$ and 21.3 MeV have been taken and analyzed. The effect of the collective couplings to the excited states of the target has been studied by means of coupled-channels calculations, using a double-folding potential for the bare interaction between the colliding nuclei, supplemented with a phenomenological imaginary part of Woods-Saxon type. In addition, three- and four-body continuum-discretized coupled-channels calculations have been performed to investigate the effect of the projectile breakup on the elastic scattering. Both effects, the coupling to target and projectile excited states, are found to affect significantly the elastic scattering. The trivial local polarization potential extracted from the continuum-discretized coupled-channels calculations indicates that continuum couplings produce a repulsive real part and a long-range imaginary part in the projectile-target interaction.

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 CH2 polyethylene target. The complete excitation function was measured between Ecm = 0.4–2.7 MeV, which includes the Gamow peak energy region. The excitation function was reproduced with the R‐matrix theory.

Cross sections of $^{120}\mathrm{Sn}$($\ensuremath{\alpha}$,$\ensuremath{\alpha}$)$^{120}\mathrm{Sn}$ elastic scattering have been extracted from the $\ensuremath{\alpha}$-particle-beam contamination of a recent $^{120}\mathrm{Sn}$($^{6}\mathrm{He}$,$^{6}\mathrm{He}$)$^{120}\mathrm{Sn}$ experiment. Both reactions are analyzed using systematic double-folding potentials in the real part and smoothly varying Woods-Saxon potentials in the imaginary part. The potential extracted from the $^{120}\mathrm{Sn}$($^{6}\mathrm{He}$,$^{6}\mathrm{He}$)$^{120}\mathrm{Sn}$ data may be used as the basis for the construction of a simple global $^{6}\mathrm{He}$ optical potential. The comparison of the $^{6}\mathrm{He}$ and $\ensuremath{\alpha}$ data shows that the halo nature of the $^{6}\mathrm{He}$ nucleus leads to a clear signature in the reflexion coefficients ${\ensuremath{\eta}}_{L}$: The relevant angular momenta $L$ with ${\ensuremath{\eta}}_{L}\ensuremath{\gg}0$ and ${\ensuremath{\eta}}_{L}\ensuremath{\ll}1$ are shifted to larger $L$ with a broader distribution. This signature is not present in the $\ensuremath{\alpha}$-scattering data and can thus be used as a new criterion for the definition of a halo nucleus.

The collision $^{6}\mathrm{He}+^{120}\mathrm{Sn}$ has been investigated at four energies near the Coulomb barrier. A large yield of $\ensuremath{\alpha}$ particles has been detected, with energies around the energy of the scattered $^{6}\mathrm{He}$ beam. The energy and angular distributions of the $\ensuremath{\alpha}$ particles have been analyzed and compared with breakup and neutron transfer calculations.

The elastic scattering of $^{6}\mathrm{He}$ on $^{120}\mathrm{Sn}$ has been measured at four energies above the Coulomb barrier using the $^{6}\mathrm{He}$ beam produced at the RIBRAS (Radioactive Ion Beams in Brasil) facility. The elastic angular distributions have been analyzed with the optical model and three- and four-body continuum-discretized coupled-channels calculations. The total reaction cross sections have been derived and compared with other systems of similar masses.

A part of the research program developed in the RIBRAS facility over the last four years is presented. Experiments using radioactive secondary beams of light exotic nuclei such as 6He, 7Be, 8Li on several targets have been performed. Elastic angular distributions have been analysed by the Optical Model and four body Continuous Discretized Coupled Channels Calculations (4b-CDCC) and the total reaction cross sections have been obtained. A comparison between the reaction cross sections of 6He and other stable projectiles with medium-heavy targets was performed. Measurements of the proton transfer reaction 12C(8Li,9Be)11B are also presented.