Search

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.

We report on systematical optical model (OM) and continuum discretized coupled channel (CDCC) calculations applied to describe the elastic scattering angular distributions of exotic and stable nuclei projectiles on heavy targets. Our optical potential (OP) is composed of the nuclear microscopic double folding São Paulo potential (SPP), derived from the nonlocal nature of the interaction, and the Coulomb dipole polarization (CDP) potential, derived from the semiclassical theory of Coulomb excitation. The OP is compared to the trivial equivalent local potential (TELP), extracted from CDCC calculations. The OM and CDCC predictions corroborate each other and account for important differences in the nuclei reaction mechanisms, which are directly related to their structural properties. Thus, OM and CDCC establish a common basis for analyzing or even predicting exotic and stable nuclei reactions., This work was supported by the Ministry of Science, Innovation and Universities of Spain, through the project PGC2018-096994-B-C21. This work was also partially supported by the Spanish Ministry of Economy and Competitiveness, the European Regional Development Fund (FEDER), under Project No. FIS2017-88410-P and by the European Union's Horizon 2020 research and innovation program, under Grant Agreement No. 654002. J.C. acknowledges support by SID funds 2019 (Investimento Strategico di Dipartimento, Universittí degli Studi di Padova, Italy) under Project No. CASA_SID19_01.

Proton halo effects in the 8B+64Zn reaction at an energy around 1.5 times the Coulomb barrier have been studied at HIE-ISOLDE CERN using, for the first time, the only existing postaccelerated 8B beam. This, together with the use of a high granularity and large solid angle detection system, allowed for a careful mapping of the elastic angular distribution, especially in the Coulomb-nuclear interference region. Contrary to what is observed for the one-neutron halo nucleus 11Be on the same target in a similar energy range, the analysis of the elastic scattering angular distribution shows only a modest suppression of the Coulomb-nuclear interference peak, with no remarkable enhancement of the total reaction cross-section. Inclusive angular and energy distributions of 7Be produced in direct reaction processes have also been measured. The comparison of these data with the results of theoretical calculations for the elastic and non-elastic breakup contributions indicate that both processes are important. Overall, the experimental data suggest a 8B collision dynamics at the barrier very different from the one of neutron halo nuclei, showing only modest effects of coupling to continuum. This behaviour can be interpreted as due to the presence of the additional Coulomb interactions halo-core and halo-target together with the presence of the centrifugal barrier felt by the valence proton of 8B., We wish to thank Dr. A. Bonaccorso for useful discussions and suggestions. This work has been supported by the European Commission Horizon 2020 framework trans-national access program of the EU project ENSAR2 (Grant no. 654002). Some of us acknowledge the support of the Istituto Nazionale di Fisica Nucleare (INFN), the UKRI STFC and the Spanish Funding Agency under the projects: “ELEGANT” PGC2018-095640-B-100, FIS2017-88410-P, PDI2019- 104390GB-100, FPA2016-77689-C2-1-R, PGC2018-096994-B-C21, PGC2018-096994-B-C22, RTI2018-098868-B-I00. L.A. is partially supported by DGAPA PAPIIT-IN107820 and CONACYT 314857. L.M.F is partially supported by the CERN associates program. D.G. is supported by the Portuguese FCT under the project CERN/FISPAR/0005/2017

A specially prepared Si/He thin solid film was investigated as a suitable target for experimental studies on nuclear reactions involving 4He targets. For that purpose, the elastically scattered 4He recoil coming from the reaction 6Li + 4He at incident energy of 5.5 MeV was measured. The differential cross section of 6Li on 4He has been found to be fully consistent with previous measurements in the literature. The prospective advantages of using these solid He targets in experiments at radioactive beam facilities are discussed., This work was supported by the Spanish Ministry of Science, Innovation and Universities and co-financed by EU FEDER funds under the following grants: FPA2016-77689-C2-1-R, RTI2018-098117-B-C21, RTI2018-093871-B-I00, PGC2018-096994-B-C22, PGC2018-096994-B-C21 and US-1261006. CSIC support under grant PIE-201760E002 is also acknowledged.

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.

We present preliminary data of elastic scattering and inclusive breakup cross sections for the 7Li+ 119Sn reaction, recently measured at the Laboratori Nazionali del Sud (LNS-INFN) (Catania, Italy) at energies around the Coulomb barrier (E lab = 21.2 and 26.5 MeV). The experimental data have been analyzed under the Optical Model and Continuum-Discretized Coupled-Channels methods.

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.

New experimental results for the elastic scattering of $^{6}\mathrm{He}$ on $^{64}\mathrm{Zn}$ at incident energies of 15.0 and 18.0 MeV and $^{4}\mathrm{He}$ at 17.5 MeV along with results already published at 10.0 and 13.6 MeV, are presented. Elastic and $\ensuremath{\alpha}$ experimental cross sections are compared with coupled-reaction-channel, continuum-discretized coupled-channel, and DWBA inclusive-breakup models. The large yield of $\ensuremath{\alpha}$ particles observed at all measured energies can be explained by considering a nonelastic breakup mechanism.

The elastic scattering process for the nuclear reactions induced by the Radioactive Ion Beams 7Be and 8B on a 208Pb target was measured for the first time in the energy range around the Coulomb barrier. Extensive theoretical calculations within the framework of the optical model were performed. An excellent agreement between experimental data and theoretical predictions was achieved for the reaction 7Be + 208Pb, while a comprehensive understanding of the reaction dynamics induced by the more exotic projectile 8B is still far to be reached. Predictions of the cross section for the breakup for both systems will also be given., The 8B experiment was performed at RI Beam Factory operated by RIKEN Nishina Center and CNS, University of Tokyo. This work was supported by the Polish National Science Centre under Contract No. 2014/14/M/ST2/00738 (COPIN-INFN Collaboration), by JSPS KAKENHI (Nos. 16K05369, and 19K03883) from the Ministry of Education, Culture, Sports, Science and Technology (MEXT) of Japan and by the projects: CONACyT LN-294537 and DGAPA-PAPIIT IA103218.

6 pags., 5 figs. -- 12th International Spring Seminar on Nuclear Physics, IOP Conf. Series. -- Open Access funded by Creative Commons Atribution Licence 3.0, In order to investigate the existence of molecular and/or exotic cluster configurations in Boron and Carbon n-rich isotopes we undertook two experiments: the first experimental study of exotic 9Li+¿ cluster states in 13B using the resonance scattering method at TRIUMF (Canada), and, with the same technique, the measurement of 10Be+¿ scattering at LNS in Catania, where a 10Be radioactive beam was produced for the first time. In order to measure the excitation function in a wide energy range, the beams were stopped in a Helium-flooded chamber. In the case of 13B, the elastic excitation function shows the presence of various peaks in an excitation energy region never explored before. In the case of 14C, our exclusive measurement of elastic scattering data with a high intensity beam, sheds some light on the contradictory previously published results [1, 2].

Exclusive breakup measurements have been performed for the Li6+p system in inverse kinematics at Li6 incident energies of 25 and 29 MeV. The results are considered in the Continuum Discretized Coupled-Channels framework, together with elastic scattering data at 16, 20, 25, and 29 MeV, obtained simultaneously in the same experiment and reported previously. Good agreement between data and theory is observed, interpreted as evidence for strong coupling to the continuum. The direct and sequential (via the Li631+ resonance) breakup cross sections are found to be equally large at the higher incident energies but the dominant effect on the elastic scattering is due to coupling to the sequential breakup. This effect remains dominant even at the lowest energy of 16 MeV, despite the negligible cross section for excitation of the resonance at this low incident energy.

The angular distributions of the elastic, inelastic scattering and break-up cross sections of the one neutron halo $^{11}$Be on a heavy-mass target ($^{197}$Au) have been measured at laboratory energies below (31.9 MeV) and around (39.6 MeV) the Coulomb barrier ($V_b \sim$ 40 MeV). The elastic, inelastic channel and break-up channels of the $^{11}$Be + $^{197}$Au reaction have been experimentally separated for the first time in this energy range. The experiment was performed at TRIUMF, using four Silicon detectors in telescope configuration to separate the $^{11}$Be from the $^{10}$Be fragments and the High-Purity Germanium Detector Array TIGRESS for $\gamma$-ray detection. The break-up and inelastic scattering contributions are observed to be relevant even at energies well below the Coulomb barrier. Data are compared with different models of increasing degree of sophistication: semiclassical, inert-core continuum discretised coupled channel (CDCC) calculations and CDCC including core deformation and excitations (XCDCC). XCDCC calculations are necessary to reproduce simultaneously elastic, inelastic and break-up scattering data. The results show that the reaction mechanism is sensible to the entanglement of core and halo degrees of freedom in $^{197}$Au.

This paper presents values of complete fusion cross sections deduced from activation measurements for the reactions $\phantom{\rule{0.16em}{0ex}}^{6}\mathrm{Li}+\phantom{\rule{0.16em}{0ex}}^{120}\mathrm{Sn}$ and $\phantom{\rule{0.16em}{0ex}}^{7}\mathrm{Li}+\phantom{\rule{0.16em}{0ex}}^{119}\mathrm{Sn}$, and for a projectile energy range from 17.5 to 28 MeV in the center-of-mass system. A new deconvolution analysis technique is used to link the basic activation data to the actual fusion excitation function. The complete fusion cross sections above the barrier are suppressed by about $70%$ and $85%$ with respect to the universal fusion function, used as a standard reference, in the $\phantom{\rule{0.16em}{0ex}}^{6}\mathrm{Li}$ and $\phantom{\rule{0.16em}{0ex}}^{7}\mathrm{Li}$ induced reactions, respectively. From a comparison of the excitation functions of the two systems at energies below the barrier, no significant differences can be observed, despite the two systems have different $n$-transfer $Q$ values. This observation is supported by the results of coupled reaction channels (CRC) calculations.

6 pags., 4 figs., -- Presented at the Zakopane Conference on Nuclear Physics “Extremes of the Nuclear Landscape”, Zakopane, Poland, August 28–September 4, 2016. -- Open Access funded by Creative Commons Atribution Licence 4.0, The excitation function of the resonant reaction He-4(Li-9,alpha) was measured with the aim of investigating the compound nucleus B-13. These measurements were performed in inverse kinematics at center-of-mass scattering angles close to 180 degrees by using a thick He-4 gas target and a Li-9 beam. The B-13 excitation energy region explored was 14-20 MeV where Li-9-alpha configurations of B-13 are predicted by Antysimmetrised Molecular Dynamics calculations. The measured excitation function at theta(cm) = 180 degrees shows different clear structures in a B-13 excitation energy region which was experimentally unknown.

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.

Ministerio de Economia y Competitividad (Espana) FPA2010-22131- C02-01 (FINURA) FPA2013-47327-C2-1-R

A detailed knowledge of the light ions interaction processes with matter is of great interest in basic and applied physics. As an example, particle therapy and space radioprotection require highly accurate fragmentation cross-section measurements to develop shielding materials and estimate acute and late health risks for manned missions in space and for treatment planning in particle therapy. The Fragmentation of Ions Relevant for Space and Therapy experiment at the Helmholtz Center for Heavy Ion research (GSI) was designed and built by an international collaboration from France, Germany, Italy, and Spain for studying the collisions of a C12 ion beam with thin targets. The collaboration's main purpose is to provide the double-differential cross-section measurement of carbon-ion fragmentation at energies that are relevant for both tumor therapy and space radiation protection applications. Fragmentation cross sections of light ions impinging on a wide range of thin targets are also essential to validate the nuclear models implemented in MC simulations that, in such an energy range, fail to reproduce the data with the required accuracy. This paper presents the single differential carbon-ion fragmentation cross sections on a thin gold target, measured as a function of the fragment angle and kinetic energy in the forward angular region (θ≲6∘), aiming to provide useful data for the benchmarking of the simulation softwares used in light ions fragmentation applications. The C12 ions used in the measurement were accelerated at the energy of 400 MeV/nucleon by the SIS (heavy ion synchrotron) GSI facility.

The reaction dynamics of collisions involving halo or weakly bound nuclei, at energies around the Coulomb barrier, can be strongly affected by the structure of such nuclei. Very strong entrance channel effects have been observed on various reaction pocess such as, elastic scattering, fusion and direct reactions when comparing collision induced by the 6 He and 11 Be halo nuclei with the ones induced by their cores 4 He and 10 Be. Collisions induced by the stable weakly bound nuclei 6 Li, 7 Li show also some peculiarities in comparison to the ones induced by well bound nuclei; coupling with the break-up channel is in fact very important in reproducing low energy data. In this contribution an overview of our present understanding of the discussed topic will be given along with the discussion of some new preliminary results.

Elastic scattering angular distributions for the weakly bound nucleus $^{7}\mathrm{Li}$ on $^{64}\mathrm{Zn}$ have been measured in a wide angular range at energies around the Coulomb barrier. The present experimental data and our previously measured elastic scattering data for the system $^{6}\mathrm{Li}+^{64}\mathrm{Zn}$ have been analyzed within the continuum-discretized coupled-channels method, where the resonant and nonresonant states of the projectile are taken into account. In this theoretical framework, we have also analyzed our previously measured excitation functions of elastic scattering at backward angles and the corresponding barrier distributions for the same systems. A good agreement between the experimental data and the calculations has been observed. The obtained results, besides confirming the importance of the coupling to the breakup channels in collisions with weakly bound nuclei, show that, in the case of $^{6}\mathrm{Li}$, the inclusion of the resonant states of the projectile produces non-negligible effects.

We present a detailed analysis of the elastic scattering and breakup channel for the reaction of Li-11 on Pb-208 at incident laboratory energies of 24.3 and 29.8 MeV, measured at the radioactive ion beam facility of TRIUMF, in Vancouver, Canada. A large yield of Li-9 fragments was detected by four charged particle telescopes in a wide angular range. The experimental angular and energy distributions of these Li-9 fragments have been compared to coupled-reaction-channel and continuum-discretized coupled-channel calculations. The large production of Li-9 fragments at small angles can be explained by considering a direct breakup mechanism, while at medium-large angles a competition between direct breakup and neutron transfer to the continuum of the Pb-208 target was observed.

Elastic-scattering measurements have been performed for the $^{6}\mathrm{Li}+p$ system in inverse kinematics at the energies of 16, 20, 25, and 29 MeV. The heavy ejectile was detected by the large acceptance MAGNEX spectrometer at the Laboratori Nazionali del Sud in Catania, Italy. The results are considered in a Jeukenne-Lejeune-Mahaux and a continuum discretized coupled-channel calculation framework.

Open Access.-- et al., The FIRST (Fragmentation of Ions Relevant for Space and Therapy) experiment at GSI has been designed to study carbon fragmentation, measuring 12C double differential cross sections (∂2σ/∂θ∂E) for different beam energies between 100 and 1000 MeV/u. The experimental setup integrates newly designed detectors in the, so called, Interaction Region around the graphite target. The Interaction Region upstream detectors are a 250 μm thick scintillator and a drift chamber optimized for a precise measurement of the ions interaction time and position on the target. In this article we review the design of the upstream detectors along with the preliminary results of the data taking performed on August 2011 with 400 MeV/u fully stripped carbon ion beam at GSI. Detectors performances will be reviewed and compared to those obtained during preliminary tests, performed with 500 MeV electrons (at the BTF facility in the INFN Frascati Laboratories) and 80 MeV/u protons and carbon ions (at the INFN LNS Laboratories in Catania)., This work has been supported by the European Community FP7 - Capacities, contract ENSAR nº 262010. This work was also supported by Junta de Andalucia and the Spanish Ministerio de Ciencia e Innovacion Contracts P07-FQM-02894, FIS2008-04189 and FPA2008-04972-C03.

We studied the reaction dynamics induced at Coulomb barrier energies by the weakly-bound Radioactive Ion Beam 7Be (Sα = 1.586 MeV) on medium-mass (58Ni) and heavy (208Pb) targets. The experiments were performed at INFN-LNL (Italy), where a 2-3×105 pps 7Be secondary beam was produced with the RIB in-flight facility EXOTIC. Charged reaction products were detected by means of high-granularity silicon detectors in rather wide angular ranges. The contribution presents an up-to-date status of the data analysis and theoretical interpretation for both systems. European Commission, Seventh Framework Programme 600376

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.

We have analyzed elastic scattering angular distributions and total reaction cross sections of the exotic nuclei $^{9,11}\text{Li}$ on $^{208}\text{Pb}$, at energies below and above the Coulomb barrier. For this purpose, we have used an optical potential with no adjustable parameters, composed by the nuclear S\~ao Paulo potential, derived from the nonlocal nature of the interaction, and the Coulomb dipole polarization potential, derived from the semiclassical theory of Coulomb excitation. Within this formalism, we identified an unusual long-range absorption for the $^{11}\text{Li}+^{208}\text{Pb}$ system, which is dominated by the Coulomb interaction. We compare it to the absorption mechanisms observed for $^{6}\text{He}+^{208}\text{Pb}$ which, unlike those of $^{11}\text{Li}+^{208}\text{Pb}$, take place at small interacting distances, where both Coulomb and nuclear interactions are important. The proposed approach shows to be a fundamental basis to study reactions involving exotic nuclei.

The experimental elastic scattering angular distributions for the weakly bound nuclei 6,7Li and for the halo nucleus 6He on the same 64Zn target at several energies around the Coulomb barrier were measured at the Laboratori Nazionali del Sud (LNS, Italy) and at the Cyclotron Research Center, Louvain La Neuve (Belgium), respectively. The measured elastic scattering angular distributions of these three systems at the same center of mass energy have been compared. The experimental data of the 6,7Li+ 64Zn systems have been analyzed within the CDCC method, while the 6He+64Zn data have been compared with both both CDCC and CRC calculations.

Content from this work may be used under the terms of the Creative Commons Attribution 3.0 licence.-- Trabajo presentado al: "International Symposium Entrance Channel Effect on the Reaction Mechanism in Heavy Ion Collisions" (ECHIC), celebrado en Messina (Italia) del 6 al 8 de noviembre de 2013.-- et al., We present a study of 11Li+208Pb 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 discused.

The inclusive breakup for the Li-11 + Pb-208 reaction at energies around the Coulomb barrier has been measured for the first time. A sizable yield of Li-9 following the Li-11 dissociation has been observed, even at energies well below the Coulomb barrier. Using the first-order semiclassical perturbation theory of Coulomb excitation it is shown that the breakup probability data measured at small angles can be used to extract effective breakup energy as well as the slope of B(E1) distribution close to the threshold. Four-body continuum-discretized coupled-channels calculations, including both nuclear and Coulomb couplings between the target and projectile to all orders, reproduce the measured inclusive breakup cross sections and support the presence of a dipole resonance in the Li-11 continuum at low excitation energy.

This work reports on the scattering of 11Be on 197Au at energies around and below the Coulomb barrier. By experimentally identifying the elastic scattering, inelastic scattering and breakup channels, and comparing them with different calculations, valuable information on the 11Be structure and its B(E1) distribution to the continuum are obtained. On top of that, a deeper understanding of the scattering process at low energies is achieved for reactions of this kind, making these studies extendable to other loosely-bound systems like 17,19C Gobierno de España FPA2015-64969-P, FIS2014-53448-C2-1-P, FPA2013-47327-c02-01-R, FPA2012-32443, FIS2013-41994-P, CSD2007-00042 EUROCORES EUI-2009-04162 European Union 654002

In the present paper it is described an analysis procedure suited for experiments where cross-sections strongly varying with energy are measured using beams having large energy dispersion. These cross-sections are typically the sub-barrier fusion excitation function of reactions induced by radioactive beams. The large beam energy dispersion, typical of these experiments, can lead to ambiguities in the association of the effective beam energy to the reaction product yields and consequently to an error in the determination of the excitation function. As a test case, the approach is applied to the experiments 6 Li+120 Sn and 7 Li+119 Sn measured in the energy range 14 MeV ≤ Ec.m. ≤28 MeV. The complete fusion cross sections are deduced from activation measurements using the stacked target technique. The results of these experiments, that employ the two weakly-bound stable Li isotopes, show that the complete fusion cross sections above the barrier are suppressed of about 70% and 85% with respect to the Universal Fusion Function, used as a standard reference, in the 6 Li and 7 Li induced reactions respectively. Moreover, the excitation functions of the two systems at energies below the barrier, do not show significant differences, despite the two systems have different n -transfer Qvalue .

The skin nucleus 8He is investigated by measuring the angular distribution of the elasticly scattered 8He and the 6,4He fragments produced in the collision with a 208Pb target at 22 MeV, just above the Coulomb barrier. The experiment was carried out at SPIRAL/GANIL in 2010. Here we present preliminary results for the elastic scattering.

The inclusive breakup for the (11)Li + (208)Pb reaction at energies around the Coulomb barrier has been measured for the first time. A sizable yield of (9)Li following the (11)Li dissociation has been observed, even at energies well below the Coulomb barrier. Using the first-order semiclassical perturbation theory of Coulomb excitation it is shown that the breakup probability data measured at small angles can be used to extract effective breakup energy as well as the slope of B(E1) distribution close to the threshold. Four-body continuum-discretized coupled-channels calculations, including both nuclear and Coulomb couplings between the target and projectile to all orders, reproduce the measured inclusive breakup cross sections and support the presence of a dipole resonance in the (11)Li continuum at low excitation energy.

This work has been supported by the Spanish MICINN under projects FPA2005-04460, FPA200502379, FPA2006-13807-c02-01, FPA2007-63074, FPA2009-07653, FPA2009-07387 and FPA2010 22131-C02-01, by the Junta de Andalucia project FQM-4964, by the Spanish Consolider-Ingenio 2010 Programme CPAN (CSD2007-00042) and Programme Multi-Dark (CSD2009-00064), by the European Community-Access to Research Infrastructure action of the Improving Human Potential Program Contract, No. HPRI-CT-1999-00110, and by the Belgian Program P5/07 on interuniversity attraction poles of the Belgian-state Federal Services for Scientific, Technical and Cultural Affairs. L. Acosta acknowledges financial support by the Universidad de Huelva.

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. © 2011 American Institute of Physics

We measured the scattering of the halo nucleus 11Li and its core 9Li on the lead target at TRIUMF at energies below and around to the Coulomb barrier. We report here on our preliminary analysis of the inclusive breakup reaction.

El pdf del artículo es la versión pre-print: arXiv:1006.1787v3, The elastic and α-production channels for the 6He+208Pb reaction are investigated at energies around the Coulomb barrier (Elab=14, 16, 18, 22, and 27 MeV). The effect of the two-neutron transfer channels on the elastic scattering has been studied within the Coupled-Reaction-Channels (CRC) method. We find that the explicit inclusion of these channels allows a simultaneous description of the elastic data and the inclusive α cross sections at backward angles. Three-body Continuum-Discretized Coupled-Channels (CDCC) calculations are found to reproduce the elastic data, but not the transfer/breakup data. The trivial local polarization potential (TLP) derived from the CRC and CDCC calculations are found to explain the features found in previous phenomenological optical model calculations for this system. © 2010 Elsevier B.V., This work has been supported by the Spanish Ministerio de Ciencia e Innovación under projects FPA2009-08848, FPA2009-07653, by the local government of Junta de Andalucía under project P07-FQM-02894 and the Spanish Consolider-Ingenio 2010 Programme CPAN (CSD2007-00042).

Presented at the Zakopane Conference on Nuclear Physics “Extremes of the Nuclear Landscape”, Zakopane, Poland, August 27–September 2, 2012.-- et al.

The experimental study of the fusion of light neutron-rich nucleus 8He with 206Pb is reported in this work. A fusion stack of 206Pb targets has been used for this study. The most prominent evaporation residue (210Po), which has half-life of 138 days and decays by alpha emission, is populated in the reaction. Radiochemical analysis technique is used to extract the yield of this evaporation residue. © Owned by the authors, published by EDP Sciences, 2011, This work was partially supported by the Spanish Ministry of Science and Innovation (MICINN) under projects FPA2007-63074 (FINURA) and INGENIO-2010 (CPAN). It has also been supported by the European Union ”SPIRAL2 preparatory phase” Grant agreement 212692, through the FP7 European program