Alpha particle angular distributions in weakly bound nuclei reactions

CARNELLI, PATRICIO FRANCISCO FLORENCIO; ARAZI, ANDRÉS; CAPURRO, OSCAR A.; CARDONA, MARÍA ANGÉLICA; FERNÁNDEZ NIELLO, JORGE O.; FIGUEIRA, JUAN MANUEL; FIMIANI, LETICIA; HOJMAN, DANIEL; MARTÍ, GUILLERMO V.; MARTINEZ HEIMANN, DIEGO; NEGRI, AGUSTÍN E.; PACHECO, ALBERTO J.; ZALAZAR, LUIS; ZAVALA CÁRDENAS, WALTER H.

Quito

Simposio; IX Latin American Symposium on Nuclear Physics and Applications; 2011

CLAF

The breakup mechanism is one of the most important reaction channels when light radioactive nuclei are involved. In nuclear astrophysics, these nuclei, such as 6He, 7Be and 8Li, may constitute an alternative to the triple-alpha process in the formation of 12C. It is possible to produce these nuclei with existing facilities. Nevertheless, obtained beams are of very low intensities so a systematic study of their properties is difficult to carry out. Alternatively, these properties may be studied using weakly bound, but stable, nuclei such as 6Li, 7Li and 9Be, which can be produced in conventional accelerators with high intensity beams. Particularly, using the weakly bound projectile 7Li, there is at least three exit channels involving alpha particles: transference, fusion-evaporation and breakup. To distinguish these three processes it is helpful to determine energies, scattering angles and atomic numbers of the reaction products. With this purpose, we designed, assembled and characterized a detection-system consisting of a ionization chamber plus three position sensitive silicon-detectors (PSD). The ionization chamber delivers two partial energy-loss signals, as the three PSDs provide residual energy and scattering angle information. Given that the importance of the mechanisms mentioned depends on the scattering angle of alpha particles, we have measured the corresponding angular distributions using 7Li as a projectile and targets of 12C, 27Al and 144Sm. Beams were provided by 20 UD TANDAR tandem accelerator with energies from 8 to 30 MeV. The covered angular range was between 15 and 140 degrees. In this contribution we present preliminary results which we hope to use, together with preexisting data for the same systems, to formulate an integral description of nuclear reactions involving the weakly bound nucleus 7Li.