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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.

Background: Reactions involving exotic and stable weakly bound nuclei have been extensively studied in recent years. Although several models have been successfully used to explain particular reaction outcomes, the answers to many questions remain elusive. In previous works, we presented elastic, inelastic, and transfer angular distributions for the $^{10}\mathrm{B}+^{120}\mathrm{Sn}$ system measured at ${E}_{\mathrm{Lab}}=31.5$, 33.0, 35.0, and 37.5 MeV. The data set was analyzed through coupled reaction channels calculations in the context of the double-folding S\~ao Paulo potential.Purpose: We investigate nuclear reaction mechanisms for systems involving weakly bound projectiles.Method: Angular distributions for several nuclear reaction processes were measured for the $^{10}\mathrm{B}+^{120}\mathrm{Sn}$ system at ${E}_{\mathrm{Lab}}=39.70$ MeV.Results: The new data set involves angular distributions for elastic scattering, projectile and target inelastic excitations, one-neutron pickup transfer, one-proton stripping transfer, deuteron pickup transfer, and $^{3,4}\mathrm{He}$ stripping transfer. We have also observed $^{10}\mathrm{Be}$ nuclei. The effect of the couplings to some nonelastic states on the angular distributions is discussed.Conclusion: The theoretical calculations within the coupled reaction channels formalism provide an overall good agreement with the corresponding inelastic, one-neutron stripping, one-proton pickup, one-deuteron pickup, and $^{3}\mathrm{He}$ stripping transfer data. However, to improve the description of the elastic scattering angular distribution, the inclusion of additional channels in the coupling scheme might be necessary.

The $^{10}\mathrm{B}+^{197}\mathrm{Au}$ reaction has been investigated through cross-section measurements for different channels, such as quasielastic and elastic scattering, inelastic excitation of low-lying $^{197}\mathrm{Au}$ states, and one-neutron pickup and one-proton stripping transfer reactions. Experimental angular distributions were obtained for 20 bombardment energies around the Coulomb barrier: $38\ensuremath{\le}{E}_{lab}\ensuremath{\le}61\phantom{\rule{0.16em}{0ex}}\mathrm{MeV}$. Coupled reaction channels calculations have been performed in the context of the double-folding S\~ao Paulo potential, and details of the data analysis are discussed along the paper. In general, the theoretical calculations provide a satisfactory description of the data.

In a previous work, we presented data for the $^{10}\mathrm{B}+^{197}\mathrm{Au}$ system, corresponding to quasielastic and elastic scattering, $^{197}\mathrm{Au}$ inelastic excitation, and one neutron pickup transfer, measuring the angular distribution of scattered beam-like ejectiles at several energies around the Coulomb barrier. In this paper, we present data for the fusion process of the same system, at several energies around the Coulomb barrier, as well as new data for one neutron pickup and stripping transfer. In this case, we detected offline $\ensuremath{\gamma}$ rays stemming from the $\ensuremath{\beta}$-delayed decay chain of fusion-evaporation residues and heavy transfer products. As in our previous work, we analyzed this data set with coupled reaction channels calculations using the S\~ao Paulo potential. We show that the coupling to the one neutron transfer channel is quite important to describe the fusion data at the sub-barrier energy region. We also provide a comparison of the experimental fusion cross sections obtained for $^{10}\mathrm{B}+^{197}\mathrm{Au}$ with data for several other systems involving the same target nucleus.

Background: Neutron transfer measurements for the $^{18}\mathrm{O}+^{28}\mathrm{Si}$ system have shown that the experimental one-neutron and two-neutron transfer cross sections are well reproduced with spectroscopic amplitudes from two different shell-model interactions for the Si isotopes: psdmod for the two-neutron transfer, and psdmwkpn for the one-neutron transfer.Purpose: The need for two distinct shell-model interactions to reproduce two neutron-transfer processes in the same nuclei may cover a more complex mechanism in the one-neutron transfer that requires the unpairing of neutrons prior to its transfer in the ($^{18}\mathrm{O},^{17}\mathrm{O}$) reaction. Studying a nucleus where this characteristic is absent ($^{13}\mathrm{C}$) should help to elucidate this question.Method: One-neutron transfer cross sections were measured for the $^{13}\mathrm{C}+^{28}\mathrm{Si}$ at ${E}_{lab}=30$ and 34 MeV, and compared with coupled reaction channel calculations using spectroscopic amplitudes derived from the psdmod and psdmwkpn shell-model interactions.Results: The spectroscopic amplitudes from the psdmod interaction for the relevant states in $^{29}\mathrm{Si}$ provide a good description of the experimental data and the corresponding values agree with previous estimates obtained from the $(d,p)$ reaction.Conclusions: The experimental data for the one-neutron transfer to $^{28}\mathrm{Si}$ induced by ($^{13}\mathrm{C},^{12}\mathrm{C}$) reaction is well reproduced using spectroscopic amplitudes from the psdmod.

We present new experimental angular distributions for the elastic scattering of $^{6}\mathrm{Li}+^{120}\mathrm{Sn}$ at three bombarding energies. We include these data in a wide systematic involving the elastic scattering of $^{4,6}\mathrm{He},\phantom{\rule{0.16em}{0ex}}^{7}\mathrm{Li}$, $^{9}\mathrm{Be},\phantom{\rule{0.16em}{0ex}}^{10}\mathrm{B}$, and $^{16,18}\mathrm{O}$ projectiles on the same target at energies around the respective Coulomb barriers. Considering this data set, we report on optical model analyses based on the double-folding S\~ao Paulo potential. Within this approach, we study the sensitivity of the data fit to different models for the nuclear matter densities and to variations in the optical potential strengths.

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.

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.

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.

The (p, p), (p, a) 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 Sao 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∗. The properties of the resonances are determined by a R-matrix analysis, which provides evidence for a significant clustering as well in the (p, a) as in the (p, d) channels. The experimental data and the multi-channel R-matrix analysis will be presented.

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.

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 (RIBRAS) for the production of secondary light exotic nuclear beams was installed at the Sao Paulo Pelletron Laboratory of the University of Sao Paulo, Brazil. The two solenoids are presently operating in one of the beam lines of the 8 MV Tandem Accelerator. Secondary beams of 8 Li and 6 He were produced using a 7 Li primary beam and a production target of 9 Be. These beams were impinged on targets of 27 Al, 51 V and 197 Au and the scattered radioactive nuclei were detected in Si telescopes. Elastic scattering angular distributions were measured at several energies close and above the Coulomb barrier. The angular distributions were analysed with optical potentials and reaction cross sections were obtained from the optical model calculations.

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

The energy-integrated reaction cross-sections of several neutron-rich nuclei ( 17−22 N, 19−24 O, 21−27 F, 23−30 Ne, 26−33 Na, 28−35 Mg, 31−38 Al, 33−40 Si, 36−42 P, 39−44 S, 42−45 Cl, 45,46 Ar), measured at intermediate energy (30–65 A MeV), via direct method, are presented. Silicon detectors have been used as the active target as well as for particles identification. The reduced strong absorption radii r 0 2 are extracted and compared to the data available from the literature. New measurements for 19 nuclei ( 27 F, 27,30 Ne, 33 Na, 28,34–35 Mg, 36−38 Al, 38−40 Si, 41−42 P, 42−44 S, 45 Cl) are revealed. From the study of the isospin dependence of the reduced strong absorption radius, a new quadratic parameterisation of the nuclear radii in the closed shell regions N = 8 and N = 28 , is proposed. According to this parameterisation, the proton/neutron rich nuclei skin effect is well described and a new anomalous structure: halo-structure or large deformation is suggested for 35 Mg and 44 S nuclei.

Recent mass measurements of proton-rich nuclei close to the N=Z line were used for the calculation of the interaction strength δVpn between valence protons and neutrons. When compared with δVpn values calculated from mass values of the AME’95 mass tables, the breaking down of the SU(4) symmetry is verified at Z=32,33,34.

Transfer reactions are verified to be an important tool for the study of light unbound nuclei. We have studied the proton-rich unbound nuclei 15 F and 11 N, 10 N respectively through the 16 O( 14 N, 15 C) 15 F and 12 C( 14 N, 15 C) 11 N, 10 B( 14 N, 13 B) 11 N, 10 B( 14 N, 14 B) 10 N reactions. Resonance energies and width were obtained.

Resonances in 6Be and 5Li have been investigated by deuteron transfer reactions with radioactive ion beams, 2H(8B,α)6Be, 2H(7Be,α)5Li, respectively. There is an indication of a possible resonance at excitation energy of 9.6 MeV in 6Be, just below the 3He+3He threshold. The structure of the 6Li nucleus has been also investigated by the neutron transfer reaction 3He(7Li,α)6Li. In 6Li, a new resonance is observed at about 12.4 MeV in excitation energy and the presence of a resonance at 15.2 MeV is confirmed. The data are preliminary and a detailed analysis is in progress. The instalation of a Radioactive Ion Beam facility in Brazil (RIBRAS) is also reported.

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

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°.

An extension of the time-integrated atomic decoupling technique to measure g -factors of (sub)nanosecond isomers and/or the magnetic hyperfine field induced by highly excited atomic electrons on nuclei recoiling into vacuum is discussed. A high average field B hf =1080 −175 +270 T and an average atomic spin J =2.7(2) is deduced using the known magnetic moment of a 4.05(7) μs isomer in 69 Ge. Such high magnetic fields allow g -factor measurements of (sub)nanosecond states. Ab initio calculations show that the combination of a high average magnetic hyperfine field and a high average atomic spin is only possible if a considerable fraction of the ions is in a metastable excited state.

The reaction cross section for the halo nucleus 6 He on hydrogen has been measured at 36 MeV/nucleon using the transmission method and a value of σ R =409±22 mb was obtained. A coherent analysis within a microscopic model of this result in conjunction with (p,p) and (p,n) angular distributions has allowed the interaction potential to be uniquely determined. This analysis also allowed the 6 He density distribution to be explored.

The spectroscopic quadrupole moment of the high-spin, high- K five-quasiparticle isomer (K(pi) = 35/2(-), T(1/2) = 750(80) ns, E(i) = 3349 keV) in (179)W has been determined using the level mixing spectroscopy method. A value Q(s) = 4.00(+0.83-1.06)e b was derived, which corresponds to an intrinsic quadrupole moment Q0 = 4.73(+0.98-1.25)e b and to a quadrupole deformation beta(2) = 0.185(+0.038-0.049). These values differ significantly from the deduced ground-state quadrupole moments and are in disagreement with the current theoretical predictions in this mass region.

Mass measurements of the N = Z nuclei 80Zr, 76Sr, 68Se were performed for the first time and a new measurement was obtained for 80Y, using the second cyclotron CSS2 of GANIL as a high-resolution spectrometer. Ions around N = Z were produced by fusion-evaporation in the inverse 58Ni (4.32 MeV A) + 24Mg and 12C reactions. New masses were measured by a time-of-flight method, with a precision of 2 · 10-6, by using well-known masses as references. Study of the double binding energy difference δV np is then performed leading to a strong N = Z Wigner effect around N = Z = 40. Knowledge of new masses in this region also plays a crucial role in the modelling of the astrophysical rp process.

The ground state of the proton-rich, unbound nucleus ${}^{11}\mathrm{N}$ was observed, together with six excited states using the multinucleon transfer reaction ${}^{10}\mathrm{B}{(}^{14}\mathrm{N}{,}^{13}\mathrm{B}{)}^{11}\mathrm{N}$ at $30A$ MeV incident energy at Grand Acc\'el\'erateur National d'Ions Lourds. Levels of ${}^{11}\mathrm{N}$ are observed as well defined resonances in the spectrum of the ${}^{13}\mathrm{B}$ ejectiles. They are localized at 1.63(5), 2.16(5), 3.06(8), 3.61(5), 4.33(5), 5.98(10), and 6.54(10) MeV above the ${}^{10}\mathrm{C}+p$ threshold. The ground-state resonance has a mass excess of 24.618(50) MeV; the experimental width is smaller than theoretical predictions.

The structure of the neutron-rich isotopes7He,10Li and11Be has been studied in detail using multi-nucleon transfer reactions. New results have been obtained for7He, where we have evidence for the observation of the first excited state, i.e. the 1/2--resonance, which is of interest for the spin-orbit splitting in these light neutron-rich nuclei. Reactions of distinct selectivity have been chosen to study the states of10Li, which are all unbound. The structure of the eight states found in these reactions is discussed, and the relevance for the decay of11Li resonances is shown. The isotopes10Be and11Be have been investigated to study the α-cluster structure and high-lying states. Nine states of the observed11Be-resonances form a molecu-lar rotational band. The multi-nucleon transfer mechanism has also been applied to study the unbound proton-rich isotope11N, the mirror nucleus of11Be. In this case the12C(14N,15C)11N-reaction has been used. Five resonances have been observed, and the lowest two can be identified as 1/2- -and 5/2+ -states.

Secondary ions of100Ag,100Cd,100In and100Sn were produced via the fusion-evaporation reaction50Cr+58Ni at an energy of 5.1 MeV/nucleon. TheA=100 secondary ions were accelerated in the second cyclotron of GANIL, which was used as a high-resolution mass spectrometer. The masses of the three latter isobars were measured with respect to the abundantly produced100Ag. The known mass of100Cd was very well reproduced and the masses of100In and100Sn were determined for the first time with precisions of 3×10−6 and 10−5, respectively.

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.

The binary decay into strongly damped fragments and the quasielastic reactions of the $^{28}\mathrm{Si}$+ $^{16}\mathrm{O}$ system were measured at ${E}_{\mathrm{lab}}=107.5 \mathrm{and} 139.0$ MeV in the angular range of $30\ifmmode^\circ\else\textdegree\fi{}l~{\ensuremath{\theta}}_{\mathrm{c}.\mathrm{m}.}l~150\ifmmode^\circ\else\textdegree\fi{}$ using kinematic coincidence. The loss in the binary decay cross section due to light particle evaporation by the highly excited fragments was evaluated. The $Q$-value-integrated angular distributions of the primary decay exhibit the $\frac{1}{{sin\ensuremath{\theta}}_{\mathrm{c}.\mathrm{m}.}}$ behavior at backward angles, indicating a long lifetime. Mass distributions and the $^{16}\mathrm{O}$/$^{12}\mathrm{C}$ ratio suggest a noncompound process for the reaction mechanism. Coupled-channels calculations, including a great number of channels populated in the reactions, yield good agreement with the experimental angular distributions.

The elastic scattering p( 6 He, 6 He)p and charge exchange reaction p( 6 He, 6 Li)n have been measured in reverse kinematics with a secondary 6 He beam. The angular distributions for these reactions were obtained. In the case of the charge exchange reaction, the ratio of the cross section for the Gamow-Teller transition to the ground state, and for the Fermi transition to the isobaric analog state is a measure of the relative strength of the two components of the exchange interaction, V στ and V τ . This ratio is found to be compatible with existing systematics for stable T = 1 nuclei, and no clear signature of a halo structure was found in the present data.

The elastic scattering cross section for 16 O ions on 16 O targets has been measured with high accuracy over large angular ranges at incident energies from 250 to 704 MeV. From these data which sample both diffractive and refractive scattering processes, we extract the underlying scattering potentials using model-unrestricted analysis methods. The extracted potentials fit very well into the systematics found in light-ion scattering. The real potential parts also compare very favourably with microscopically calculated folding potentials based on a weak density-dependence of the underlying effective nucleon-nucleon interaction at large overlap densities.

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.

We have carried out a search for double Gamow-Teller excitations, employing the 24 Mg( 18 O, 18 Ne) 24 Ne reaction at 100 and 76 MeV/nucleon at NSCL-MSU and GANIL, respectively. The cross sections for low-lying excitations are typically a few nb/sr, providing evidence for a strong suppression of double Gamow-Teller excitations in heavy-ion double charge exchange, compared to pion-induced reactions. This result does not give good hope that heavy ions at intermediate energies could be used to probe double Gamow-Teller strength.

In a high precision experiment, Mott scattering of the 208Pb+208Pb and elastic scattering of the 208Pb+238U systems was measured at 6 energies near the Coulomb barrier with kinematic coincidences for angle pairs at θlab=30°, 60°. The relative laboratory angle between scattered and recoiling nuclei, measured with an absolute precision of 0.003° provides a measurement of the reaction kinematics and the energy loss in the reaction. The binding energy of internal shells of the quasiatioms formed during the collision can be measured in this way.

We present the results of the 8Li(p, α) 5He reaction of astrophysical interest, measured at the RIBRAS system. It was realized in inverse kinematics and using a thick CH2 polyethylene target. Using the thick target method the complete excitation function could be measured between Ecm = 0.2-2.5 MeV, which includes the Gamow peak energy region. The contribution of contaminating 12C(8Li,4He) 16N and 12C(7Li, 4He) 15N reactions is still under analysis. However, if the cross section is expected to be somewhat reduced, the subtraction of the contamination will not change the general feature of the excitation function.

For studies of astrophysical interest and nuclear reactions with radioactive nuclei, charged particle products emitted from nuclear reactions such as 7Li + 9Be are routinely produced, separated and focused onto a focal spot by ion focusing separators such as a superconducting solenoid. The separation and focusing of desired ion groups onto the focal plane is however not complete, being also accompanied by unwanted ion groups. The mass- and energy-resolving but also the spatial focusing power of these separators are also limited and often spread out. In order to evaluate and determine and minimize these effects we decided to analyze the spectral and spatial distributions of ion reaction products at a superconducting solenoid. For this purpose we use the position-sensitive quantum-counting pixel detector Timepix which provides energy or time sensitivity per pixel. This device resolves different ion groups and measures the spectral and spatial spread distributions. Single ions are detected and individual ion groups can be identified and distinguished by multi-parameter event-by-event and pattern recognition analysis of the characteristic ion signal response in the pixelated detector. We present the capabilities of the technique on the indicated reaction above which is studied at the radioactive ion beam facility RIBRAS in Brazil. Several ion groups arriving at the focal plane are established such as 7,8Li, 4,6He and 3H together with their spatial and spectral distributions. The energy- and spatial-spread of the solenoid resolving power at the focal plane can be thus evaluated with a resolution of tens of keV and few µm, respectively. The detector serves moreover as an online verification and calibration imager for the ion optics separator and beam focusing monitoring. Results are presented for measurements with a 24 MeV 7Li beam and a thin 9Be target with the solenoid tuned for selection and focusing of produced radioactive 8Li.

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.

In a high precision experiment, Mott scattering of the [sup 208]Pb+[sup 108]Pb system was measured at [ital E][sub lab]=873.40 MeV and 1129.74 MeV with kinematic coincidences for angle pairs around [theta][sub lab]=30[degree], 60[degree] and [theta][sub lab]=45[degree], 45[degree]. The observed Mott oscillations exhibit an angular shift with respect to pure Mott scattering. A comparison with the angular shift produced by a color van der Waals force including nuclear polarizability, vacuum polarization, relativistic effects, and electronic screening provides a new upper limit for the strength of this force. Influence of atomic effects other than screening were identified for the first time.

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.

Experimental results on orbiting phenomena in 18 O+ 10,11 B systems at E c.m. =18.8 and 19.9 MeV are presented. We show that all features of the orbiting phenomena of 11 B( 18 O, 18 O) 11 B and related transfer reactions are explained by a complete coupled-channels calculation in the AST framework. It is also shown that the orbiting features and the back-angle anomaly are strongly related and explained by the same channel coupling.