No description available.

<p>In order to determine the parent stellar sites for the presolar grains of potential nova origin, it is crucial to know the rates of the thermonuclear reactions which affect the Si production and destruction in novae. One such reaction is the ²⁹P(p, gamma)³⁰S. This reaction also influences type I X-ray bursts. The energy generation and nucleosynthesis in the burst, along with its duration and light-curve structure, are very sensitive to the reaction flow through a few waiting-point nuclei along the rp- and ap-process paths. In particular, network calculations show that the waiting-point nucleus ³⁰S (t_1/2 = 1175.9(17) ms) is critical.</p> <p>The structure of proton-unbound ³⁰S states strongly determines the thermonuclear ²⁹P(p, gamma)³⁰S reaction rate at temperatures characteristic of explosive hydrogen burning in classical novae and type I X-ray bursts (0.1 ≤ T ≤ 1.3 GK). Specifically, the rate had been previously predicted to be dominated by two low-lying, unobserved, J^pi= 3⁺and 2⁺ levels in the E_x = 4.7 to 4.8 MeV region.</p> <p>The 3⁺resonance was observed a few years ago via a ³²S(p, t)³⁰S measurement. However, the 2⁺resonance remained unobserved. To search for it, we have performed a higher energy resolution charged-particle spectroscopy and an in-beam gamma-ray spectroscopy to investigate the level structure of ³⁰S above the proton threshold via the ³²S(p, t)³⁰S and ²⁸Si(³He, n-gamma)³⁰S reactions, respectively.</p> <p>In this work we provide a description of the experimental setup, data analysis and results of both experiments. Moreover, we have calculated the ²⁹P(p, gamma)³⁰S reaction rate via the state-of-the-art Monte Carlo technique, and have investigated the impact of this updated rate on the abundances of elements synthesized in novae, including those of silicon isotopes.</p> / Doctor of Philosophy (PhD)

Thesis (PhD)--Stellenbosch University, 2015. / ENGLISH ABSTRACT: Please refer to full text. / AFRIKAANSE OPSOMMING: Sien asb volteks vir opsomming

Thesis (MSc (Physics))--University of Stellenbosch, 2008. / Experimental double differential cross sections and analyzing powers for the inclusive 93 Nb(p,α) r and 93 Nb(p, 3He) r reactions have been measured at an incident energy of 160 MeV. The results of this experiment, for emission angles ranging from 15º to 60º as well as previously measured data for 93 Nb(p,α) r at 100 MeV and 59Co(p,α) r at 100 and 160 MeV, have been compared with theoretical calculations based on a direct quasi-free α- cluster knockout mechanism. A computer code has been employed which calculates triple differential cross section and analysing power values using the distorted wave impulse approximation (DWIA). Inclusive double differential cross sections and analysing powers were calculated by integrating over the solid angle of the unobserved proton. It was found that the DWIA is limited in its ability to reproduce the experimental data. Some slight agreements have been observed in the region of large emission energies and small angles. This is consistent with the findings of previous studies based on a direct multi-step analysis which indicated that the first step knock-out reaction dominates in this region.

Dissertation (PhD)--University of Stellenbosch, 2004. / 175 Leaves printed single pages, preliminary pages i-xiii and 147 numberd pages. Includes bibliography. List of figures, List of tables. / ENGLISH ABSTRACT: This study forms part of a larger investigation which has as a primary objective the development of a comprehensive theoretical description of all the processes which contribute to the continuum in the interaction of 12C and 16O with nuclei. Previous investigations of 12C and 16O induced reactions on targets with mass close to A = 100 have shown that the experimental excitation functions and recoil range distributions of heavy residues can be reproduced satisfactorily by means of a theoretical model which takes relatively few dominant reaction mechanisms into account. These include the complete fusion of the projectile with the target, the incomplete fusion of break-up α-type fragments (i.e. single α particles, 8Be fragments and for the 16O induced reactions also 12C fragments) with the target and single-nucleon transfer at incident energies above about 15 MeV/nucleon. The mean-field interaction is mainly responsible for these interactions. The thermalization of the intermediate excited nuclei produced in this first stage of the reaction is described by an intranuclear interaction cascade, during which pre-equilibrium emission of particles and clusters may occur, followed by evaporation after statistical equilibrium has been attained. The model also included the probability that break-up α particles may escape with a large fraction of their initial energy after only a few interactions with individual target nucleons following their initial incomplete fusion. The theory also predicted an enhanced isobaric yield for residues with mass similar or near to that of the target. The subsequent analysis of the emission spectra of intermediate mass fragments in these reactions, however, indicated that two additional aspects need to be considered as well in order to reproduce the experimental data. The first is that the projectile may lose a substantial amount of energy in an initial-state interaction before breaking up, which can be described as a friction dissipative process. The second is that several other incomplete fusion channels of “non-α-cluster”- type fragments should also be included in a more complete description of these reactions as their contributions are not negligible. The present study has two main objectives. Firstly, to investigate the isobaric yield in the neartarget mass region by measuring production cross sections for 103Pd, 103mRh and 103Ru. Previous studies only provided data for 103Ag, which constitute only a few percent of the A = 103 isobaric yield. The new data constitute more than 80% of the A = 103 isobaric yield, which provide experimental confirmation of the enhanced isobaric yield in the near-target mass region. The second objective is to perform extensive new calculations of the excitation functions and recoil ranges in order to investigate the predictive power of the extended model in a priori calculations for the entire available data set. / AFRIKAANSE OPSOMMING: Hierdie studie maak deel uit van ‘n meer omvattende ondersoek wat as ‘n primêre doelwit die beskrywing van al die bydraende prosesse tot die kontinuum in die interaksie van 12C en 16O met kerne behels. In vorige ondersoeke van 12C en 16O geïnduseerde reaksies op skywe met massa naby A = 100 kon die eksperimentele opwekkrommes van swaar reskerne en reikwydte distribusies van terugslagkerne bevredigend gereproduseer word met behulp van ‘n teoretiese model wat slegs enkele dominante reaksiemeganismes in berekening bring. Hierdie sluit in die volledige versmelting van die projektiel met die skyfkern, die onvolledige versmelting van opbreek α-tipe fragmente (d.w.s. α- deeltjies, 8Be fragmente, en in die geval van 16O geïnduseerde reaksies ook 12C fragmente) met die skyfkern, en enkel-nukleon oordrag by invalsenergië wat hoër is as ongeveer 15 MeV/nukleon. Die gemiddelde-veld interaksie is hoofsaaklik verantwoordelik vir bogenoemde reaksie meganismes. Die oorgang na termiese ewewig van die opgewekte tussenkerne wat in hierdie eerste stadium van die reaksie gevorm word, word beskryf deur ‘n intrakern interaksie kaskade wat gekenmerk word deur die voorewewigs emissie van deeltjies en klonte van deeltjies, gevolg deur verdamping nadat statistiese ewewig bereik is. Dié model sluit ook die waarskynlikheid in dat opbreek α-deeltjies kan ontsnap met ‘n betekenisvolle fraksie van hul aanvanklike energie na slegs enkele interaksies met individuele skyfnukleone nadat hulle aanvanklik onvolledig versmelt het. In latere studies van die emissiespektra van intermediêre massa fragmente in hierdie reaksies het dit egter geblyk dat twee addisionele aspekte ook in berekening geneem moet word om die eksperimentele data te reproduseer. Eerstens kan die projektiel ‘n substansiële hoeveelheid energie verloor in ‘n aanvangstoestand interaksie voordat dit opbreek, wat beskryf kan word as ‘n wrywingdissipatiewe proses. Tweedens kan verskeie ander onvolledige versmeltingskanale van fragmente met ‘n nié-α-karakter ook betekenisvol bydra en kan hulle dus nie verwaarloos word in ‘n meer volledige beskrywing van hierdie reaksies nie. Die huidige studie het twee hoofdoelwitte. Eerstens word die isobariese opbrengs in die nabyskyfgebied ondersoek deur die produksie kansvlakke van 103Pd, 103mRh en 103Ru te meet. In vorige studies is slegs data verkry vir 103Ag, wat net ‘n klein persentasie van die A = 103 isobariese opbrengs verteenwoordig. Die nuwe data verteenwoordig meer as 80% van die A = 103 isobariese opbrengs, wat eksperimetele bevestiging verleen dat ‘n verhoging in die isobariese opbrengs in die nabyskyfgebied bestaan. Die tweede doelwit is om ‘n volledige stel nuwe a priori berekeninge te doen vir al die opwekkrommes van reskerne en reikwydte distribusies van terugslagkerne wat tans beskikbaar is om sodoende die voorspellings van die nuwe uitgebreide teoretiese model te toets.

Thesis (PhD (Physics))--University of Stellenbosch, 2011. / ENGLISH ABSTRACT: In this dissertation we present, for the first time, a relativistic distorted wave impulse approximation formalism to describe quasielastic proton-nucleus scattering. We start from a full many-body description of the transition matrix element and show systematically how to derive the equivalent two-body form. This procedure allows for a clear and unambiguous method to introduce relativistic distorted waves. It is shown that the polarized double differential cross section may be written as the contraction of two tensors namely, the hadronic tensor (describing the projectile and ejectile), and the polarization tensor describing the target nucleus. The basic nucleon-nucleon (NN) interaction is described by the SPVAT or IA1 representation of the NN scattering matrix. Analytical expressions are derived for the polarization tensor using a Fermi gas model for the target nucleus. The nuclear distortion effects on the projectile and ejectile are described using the relativistic eikonal formalism. The expression for the double differential cross section is a nine dimensional oscillatory integral and an efficient procedure is developed to calculate this quantity. Comparison of Gaussian, Monte Carlo and quasi-Monte Carlo numerical integration schemes reveal that for this work, Gaussian quadrature is best suited for this problem. Traditional Gaussian quadrature is used to generate single variable functions whereby these functions are used in combination with modern software such as MATLAB to complete the computation of the full multidimensional integral in a reasonable amount of time. Even though the calculation of the cross section for a single value of the energy transfer is still time consuming, the computational time can be decreased by spreading the calculational burden across a number of nodes in a cluster computing system. A test calculation is performed whereby a proton with incident laboratory energy of 400 MeV is scattered off a 40Ca target nucleus at θcm = 40◦. For this reaction we calculate the unpolarized double differential cross section, as well as a complete set of spin observables namely Ay, Dℓ′,ℓ, Ds′s, Dnn,Ds′ℓ and Dℓ′s. We find that the distortions lead to a reduction of the unpolarized double differential cross section. On the other hand the spin observables are complex entities which show no uniformity in behaviour. However, the differences between the distorted wave spin observables and that of the plane wave observables are minor and we conclude that distortions have little effect on spin observables. / AFRIKAANSE OPSOMMING: Hierdie proefskrif bevat, vir die eerste keer, ’n relatiwistiese vervormdegolf impuls benadering formalisme vir die beskrywing van kwasielastiese proton-kern verstrooiing. Daar word aangetoon hoe om stapsgewys te gaan vanaf ’n veel-deeltjie beskrywing van die oorgangsmatriks element na die ekwivalente twee-deeltjie vorm. Hierdie metode laat toe dat die vervormde golwe op ’n duidelike en ondubbelsinnige manier ingevoer kan word. Daar word aangetoon dat die gepolariseerde dubbele differensiële kansvlak geskryf kan word as die kontraksie van twee tensore naamlik, die hadroniese tensor (wat die projektiel en uitgaande nukleon beskryf), sowel as die polarisasie tensor wat die kern beskryf. Die basiese kern-kern (NN) wisselwerking word beskryf deur gebruik te maak van die SPVAT of IA1 daarstelling van die NN verstrooiingsmatriks. Analitiese uitdrukkings word ook afgelei vir die polarisasie tensor binne die Fermi gas model. Die vervormdegolf beskrywing van die projektiel en uitgaande deeltjie word gedoen deur gebruik te maak van die eikonal vervormdegolf benadering. Die uitdrukking vir die ongepolariseerde dubbele differsieële kansvlak bevat ’n nege dimensioneële ossilatoriese integraal en ’n prakties-effektiewe prosedure is ontwikkel om hierdie waarneembare te bereken. Vegelyking van Gauss, Monte Carlo en kwasi-Monte Carlo numeriese integrasie tegnieke het uitgewys dat die Gauss integrasie tegniek die beste geskik is om die probleem op te los. Die gebruik van Gauss integrasie om funksies te bereken wat afhanklik is van net een veranderlike en dit te kombineer met moderne sagteware programme soos MATLAB laat ons toe om die gepolariseerde dubbele differensieële kansvlak te bekeren in ’n redelike tyd. Alhoewel die berekening van die kansvlak vir een waarde van die energie-oordrag nogsteeds tydrowend is, word dit bespoedig deur die berekeningslas te versprei oor ’n aantal nodusse in ’n rekenaarbondel sisteem. ’n Toets berekening word gedoen waarby ’n proton met inkomende laboratoriese energie van 400 MeV vanaf ’n 40Ca kern verstrooi word teen ’n hoek van θcm = 400. Vir hierdie reaksie word die ongepolariseerde dubbele differensieële kansvlak bereken sowel as ’n volledige stel spin waarneembares naamlik Ay, Dℓ′,ℓ, Ds′s, Dnn, Ds′ℓ en Dℓ′s. Daar word gevind dat die versteurings lei tot ’n afname in die differensieële kansvlak. Die spin waarneembares egter, is komplekse hoeveelhede wat geen univorme gedrag toon nie. Die verskil tussen die vervormde golf spin waarneembares en die van vlak golf waarneembares is minimaal en ons lei daarvan af dat spin waarneembares onsensitief is teen oor versteurings.

This dissertation describes our efforts to use the assembly of matter on nuclear scales as a probe of the assembly of matter on Galactic scales. To investigate the former, we characterize the detailed abundance patterns of the heaviest elements found in ancient, metal-poor stars in the Galaxy. In particular, we place new constraints on and identify several new correlations among the nuclei produced by the rapid nucleosynthetic process, which we use to refine current models of the physical conditions of this process. To investigate the latter, we apply our knowledge of stellar nucleosynthesis to examine correlations between the space motions of stars and their compositions, which retain a record of the composition of the interstellar medium where they formed many billions of years ago. Using new high quality stellar spectra collected from McDonald Observatory and Las Campanas Observatory, we confirm the relative chemical homogeneity of a well-known stellar stream and identify several chemical differences between the two major components of the stellar halo of the Galaxy. Each of these results has significant implications for our understanding of how the Galactic halo formed, grew, and evolved. More profoundly, these results indicate that we have not yet fully characterized the cosmic origins of the heaviest elements in the universe and that we will likely need to examine large samples of metal-poor stars at great distances from the Sun to potentially do so. / text

No presente trabalho medimos e analisamos distribuições angulares para o processo de espalhamento elástico do núcleo radioativo de 12B em alvo de 58Ni. As medidas foram realizadas nas energias de Elab=30.0 e 33.0 MeV no laboratório do acelerador Pelletron. Essas energias são próximas a barreira Coulombiana (VB=28.0 MeV) para esse sistema. Para a produção do feixe radioativo de 12B utilizamos o sistema RIBRAS instalado nesse laboratório. As distribuições angulares foram analisadas com o modelo ótico, utilizando potenciais de Woods-Saxon e Potencial de São Paulo. Para uma interpretação física mais consistente e um estudo da influência de outros canais de reação no espalhamento elástico analisamos também considerando o método de canais acoplados. Considerando o acoplamento dos canais de espalhamento inelásticos, reorientação e spin-órbita pudemos descrever a distribuição angular na energia de 30.0 MeV. No entanto esses canais não foram suficientes para descrever a distribuição angular na energia de 33.0 MeV, indicando que outros canais como de transferência e/ou break-up possam ser importes. A partir da análise das distribuições angulares com modelo ótico obtivemos também a seção de choque total de reação. Essas seções de choque foram comparadas com a de outros sistemas utilizando métodos de redução, indicando que o projétil 12B segue uma sistemática intermediária entre núcleos fortemente ligados e fracamente ligados. Finalmente, discutimos a sistemática dos resultados de canais acoplados para o espalhamento elásticos dos isótopos de Boro 8,10,11,12B no alvo 58Ni em termos da configuração de clusters dos projéteis. / In the present work we measure and analyzed angular distributions for the process of elastic scattering of the radioactive nucleus of 12B in a target of 58Ni. The measurements were performed in the energies of Elab = 30.0 and 33.0 MeV in the Pelletron accelerator laboratory. These energies are close to the Colombian barrier (VB = 28.0 MeV) for this system. For the production of the radioactive beam of 12B we used the RIBRAS system installed in this laboratory. The angular distributions were analyzed with the optical model, using potentials of Woods-Saxon and Potential of São Paulo. For a more consistent physical interpretation and a study of the influence of other reaction channels in the elastic scattering we also analyze the coupled channel method. Considering the coupling of the inelastic scattering channels, reorientation and spin-orbit we could describe the angular distribution in the energy of 30.0 MeV. However, these channels were not enough to describe the angular distribution in the energy of 33.0 MeV, indicating that other channels as transfer and / or break-up can be amounts. From the analysis of the angular distributions with optical model we also obtained the section of total reaction shock. These cross sections were compared with those of other systems using reduction methods, indicating that projectile 12B follows a systematic intermediate between tightly bound and weakly bonded cores. Finally, we discuss the systematics of the results of elastic scattering channels of the Boron isotopes 8,10,11,12B in the 58Ni target in terms of the cluster configuration of the projectiles.

Neste trabalho obtivemos o coeficiente de normalização da parte não ressonante da reação de captura 3H(alpha,gama)7Li (ou alternativamente, o fator S astrofísico) aplicando o método indireto ANC (Coeficientes de Normalização Assintótica) para a reação de transferência elástica do sistema 7Li + 4He. Essa reação de captura é de suma relevância na nucleosíntese de elementos leves no Universo primordial. Nesse método, o fator espectroscópico (ou alternativamente, o ANC) é obtido pela investigação de uma reação de transferência periférica que contenha como vértice a correspondente reação de captura. Reações de transferência têm normalmente dois vértices e um deles deve ser conhecido para que possamos obter o outro. No caso de uma transferência elástica, cuja característica é que o canal de saída elástico e de transferência são os mesmos, existe a vantagem da necessidade de consideração de apenas um vértice. Assim, uma análise combinada da distribuição angular para o espalhamento elástico 4He(7Li,7Li)4He, e para a reação de transferência 4He(7Li,4He)7Li, permitiu a extração do fator espectroscópico e consequentemente do ANC para o estado ligado <3He|4He>=7Li de uma forma única. As distribuições angulares para esses processos foram medidas no Laboratório Pelletron de São Paulo em duas energias de centro de massa 9.67 MeV e 10.62 MeV. Utilizamos nessas medidas feixes de 7Li obtidos no acelerador Pelletron com as energias de laboratório de 26.6 e 29.2 MeV. Empregamos um alvo gasoso de 4He e um sistema de colimadores de dupla-fenda na detecção. As partículas de 7Li espalhadas elasticamente e as partículas alfa da reação de transferência foram ambas detectadas em ângulos de laboratório diânteiros por um sistema de telescópios delta E - E com detectores de silício. Um código de simulação de Monte Carlo foi desenvolvido para calcular o ângulo sólido para esse sistema de fendas em ângulos próximos de zero grau. Um conjunto de parâmetros globais do Modelo Óptico foi obtido da análise das distribuições angulares do espalhamento elástico do sistema 7Li + 4He, juntamente com outras distribuições angulares obtidas da literatura em diferentes energias (~ 7-32 MeV). Os parâmetros do potencial óptico encontrados foram usados em uma análise de DWBA (Aproximação de Born de Ondas Distorcidas) para descrever a contribuição da reação de transferência de um tritio nas distribuições angulares. O fator espectroscópico obtido para o sistema ligado <3He|4He>=7Li foi S = 0.55+-0.03 e o coeficiente ANC C2 = 17.5 +- 1.0 fm-1. Com estes resultados, a seção de choque de captura para a reação 3H(alpha,gama)7Li e o respectivo fator S astrofísico foram calculados. / The normalization coefficient for the non-resonant part of the 3H(alpha,gama)7Li capture reaction (or alternately, the astrophysical S-factor) was obtained with the indirect method ANC (Asymptotic Normalization Coefficients). In this method the spectroscopic factor (or alternately, the ANC) is extracted from the investigation of a peripheral transfer reaction, which involves the same vertex as the corresponding capture reaction. Usually transfer reactions have two vertexes and the spectroscopic factor for one of them has to be known to obtain the other. In this work we investigate the 4He(7Li,4He)7Li elastic transfer reaction to obtain the spectroscopic factor and ANC for the 4He + t = 7Li bound system. The elastic transfer process, where the elastic and transfer exit channels are the same, has the advantage of having only one unknown vertex. Thus, the combined analysisof the angular distribution for elastic 4He(7Li,7Li)4He, and transfer process 4He(7Li,4He)7Li, allowed the extraction of the spectroscopic factor (and ANC) for the <3H|4He>=7Li bound system in an unique way. Angular distributions for these processes were measured at the Pelletron Laboratory at the center of mass energies of 9.67 MeV and 10.62 MeV. In these measurements, the 7Li beams with 26.6 MeV and 29.2 MeV were obtained from the Sao Paulo Pelletron accelerator. A 4He gas target and a double-slit collimator system were used. The 7Li scattered particles and alpha particles from transfer reaction were both detected at forward angles by a set of delta E - E silicon detectors telescopes. A Monte Carlo simulation code was developed to calculate the solid angle for the collimator system near the zero degree. A global optical potential parameters set for the 7Li + 4He system were defined using the measured elastic scattering angular distribution and other angular distributions obtained from the literature at different energies (from ~ 7-32 MeV). These optical potential parameters were used in the DWBA (Distorted Wave Born Approximation) analysis to describe the tritium transfer reaction contribution in the angular distributions. The obtained spectroscopic factor for the <3H,4He>=7Li bound system is S = 0.55+-0.03 and the ANC coefficient C2 = 17.5+-1.0 fm-1. With these results, the 3H(alpha,gama)7Li direct capture cross sections and astrophysical S-factor were calculated.

A espectroscopia de núcleos leves como ANTPOT. 6,7 Li e outros no contínuo é ainda um campo relativamente pouco explorado, e a possibilidade de se produzir esses núcleos a partir de canais de entrada envolvendo núcleos exóticos é relativamente recente. Em particular, o estudo do ANTPOT. 7 Li em energias de excitação em torno do limiar ANTPOT. 6 He+p é interessante pois corresponde a uma região próxima ao estado fundamental do exótico análogo isobárico ANTPO. 7 He. Neste trabalho, apresentamos resultados de um estudo do espalhamento ressonante ANTPOT. 6 He+p utilizando feixe de ANTPOT. 6 He. As medidas da função de excitação ANTPOT. 6 He+p foram realizadas no sistema RIBRAS (\"Radioactive Ion Beams in Brasil\") do Instituto de Física da Universidade de São Paulo. O feixe secundário foi produzido mediante a reação primária ANTPOT. 9 Be(ANTPOT. 7 Li, ANTPOT. 6 He). Fez-se pela primeira vez, uso do conjunto de dois solenóides do sistema RIBRAS para purificar o feixe secundário de ANTPOT. 6 He, que incide em um alvo sólido de CH IND. 2, grosso o bastante para parar o feixe incidente de ANTPOT. 6 He. Assim, somente as partículas leves de recuo foram detectados, as quais levam a informação do sistema composto ANTPOT. 7 Li. Dessa forma foram analisados os espectros obtidos das reações p(ANTPOT. 6 He,p) e p(ANTPOT. 6 He,). Além disso realizamos um estudo da reação ANTPOT. 3 He(ANTPOT. 7 Be, )ANTPOT. 6 Be. A experiência foi realizada no CRIB-RIKEN fazendo uso de um feixe puro de ANTPOT. 7 Be e um alvo gasoso de ANTPOT. 3 He. O feixe de ANTPOT. 7 Be tem uma energia de laboratório de E IND. lab= 53.4 MeV e foi produzido pela reação primária de ANTPOT. 7 Li(p, n)ANTPOT. 7 Be usando um alvo criogênico H IND. 2. Existem na literatura estados excitados identificados nos núcleos ANTPOT. 6 Li e ANTPOT. 6 He, mas apenas poucos estados no ANTPOT 6 Be. Além do interesse na estrutura nuclear, a importância destes estados no ANTPOT. 6 Be próximos ao limiar de ANTPOT. 3 He ANTPOT. 3 He a 11.48MeV está principalmente na astrofísica. A possível existência de ressonâncias perto deste limiar poderia trazer fortes implicações na queima próton-próton em estrelas. / The spectroscopy in the continuum of light nuclei such as 6,7 Li and others still remains a relatively unexplored field, and the ability to produce these nuclei from entrance channels involving exotic nuclei is relatively recent. In particular, the study of 7Li at excitation energies around the 6He+p threshold is interesting since it corresponds to a region near to the ground state of the exotic analog isobaric 7He. In this work we present the results of the study of the resonant scattering p+6He. The measurements of the excitation function of the system p+6He have been performed in the RIBRAS system (\"Radioactive Ion Beams in Brasil\") of the Institute of Physics of the University of São Paulo. The secondary beam has been produced by the primary reaction 9Be(7Li,6 He). For the first time, the two solenoids of the RIBRAS system have been used to purify the secondary 6He beam, which collides into a solid CH2, thick enough to stop the incident 6He beam. Only the light recoil particles have been detected, which provide information of the compound system 7Li. We analyzed the spectrum obtained from the p(6He,p) and p(6He,) reactions. In addition, we performed a study of the 3He(7Be, )6Be reaction. The experiment has been performed at the CRIB-RIKEN laboratory (Japan), using a pure 7Be beam and a 3He gas target. The 7Be beam had an energy of Elab = 53.4MeV and has been produced by the 7Li(p, n)7Be primary reaction, using a H2 cryogenic target. There are in the literature, excited states identified in the nuclei 6Li and 6He but only a few states in 6Be. Besides the interest in nuclear structure, the importance of these states at 6Be near the threshold of 3He3He at 11.48MeV lies mainly in astrophysics. The possible existence of resonances near this threshold could bring strong implications for proton-proton burning in stars.