Cross sections for the 6Li(p,γ)7 Be, 7Li(n,γ)8 Li 8Li(n,γ)9 Li and 8Li(p,γ)9 Be capture reactions have been investigated in the framework of the potential model. The main ingredients of the potential model are the potentials used to generate the continuum and bound-state wave functions and spectroscopic factors of the corresponding bound systems. The spectroscopic factors for the 7Li<img src="../../../../../img/revistas/rmf/v54s3/a11s1.jpg">n=8Li gs, 8Li<img src="../../../../../img/revistas/rmf/v54s3/a11s1.jpg">n=9Li gs bound systems were obtained from a FR-DWBA analysis of neutron transfer reactions induced by 8Li radioactive beam on a 9Be target, while spetroscopic factor for the 8Li<img src="../../../../../img/revistas/rmf/v54s3/a11s1.jpg">p=9Be gs bound system were obained from a proton transfer reaction. From the obtained capture reaction cross section, reaction rate for the 8Li(n, γ)9Li and 8Li(p, γ)9Be direct neutron and proton capture were determined and compared with other experimental and calculated values.

Se hace un estudio de las secciones eficaces de las reacciones de captura para 6Li(p,γ)7 Be, 7Li(n,γ)8 Li, 8Li(n,γ)9 Li y 8Li(p,γ)9 y 8Li(p,γ)9Be en el marco de un modelo de potencial. Los principales ingredientes de este modelo son los potenciales usados para generar las funciones de onda del continuo y para los estados ligados así como los factores espectroscópicos de los sistemas ligados correspondientes. Los factores espectroscópicos de los sistemas ligados para 7Li<img src="../../../../../img/revistas/rmf/v54s3/a11s1.jpg">n=8Li gs, 8Li<img src="../../../../../img/revistas/rmf/v54s3/a11s1.jpg">n=9Li gs fueron obtenidos del análisis con FR-DWBA de la transferencia de un neutrón del proyectil radiactivo 8Li a un núcleo de 9Be, mientras que para el sistema ligado 8Li<img src="../../../../../img/revistas/rmf/v54s3/a11s1.jpg">p=9Be gs, los factores espectroscópicos se obtuvieron de análisis de la transferencia de un protón. De las secciones eficaces de reacciones de captura obtenidas, se determinaron las razones de reacción de captura directa y se compararon con otros valores calculados y experimentales.

The spectroscopic study of unbound states in the 6Li nucleus was performed by measuring the energy spectrum of the alpha-particles emitted from the transfer reaction ³He(7Li, alpha)6Li. The 7Li beam at E Lab = 31.2MeV was produced at the São Paulo Pelletron accelerator. A ³He gas cell was used as target. alpha-Particle spectra were measured from thetaLab = 8º up to thetaLab = 20º with steps of 1º. Due to its positive Q = +13.3MeV, the ³He(7Li, alpha)6Li reaction favours the population of states in 6Li at high excitations energies up to about 20MeV. We observed resonances at 17.29MeV, 15.31MeV, and a new state at 12.45MeV, in addition to all previously known states of 6Li. An <FONT FACE=Symbol>Â</FONT>-Matrix analysis was performed and the positions and widths of these states were extracted.

The study of the so called exotic nuclei constitutes an important field of research in nuclear physics. The possibility of producing secondary beams of unstable nuclei(RIB) allows the investigation of nuclei at extreme conditions as low binding energies, high angular momentum and isospin. More laboratories are going through the process of re-direction of their experimental effort towards this activity. The nuclear physics community in Brazil has enthusiastically decided to join this endeavor to provide the Pelletron/LINAC complex with two superconducting solenoids which will permit the production of secondary beams of radioactive nuclei. A description of this facility and project RIBRAS follows.