Al-26 was the first cosmic radioactivity ever detected in the galaxy as well as one of the first extinct radioactivity observed in refractory phases of meteorites. Its nucleosynthesis in massive stars is still uncertain mainly due to the lack of nuclear information concerning the Al-26(n,p)Mg-26 and Al-26(n,alpha)Na-23 reactions. We report on a single and coincidence measurement of the Al-27(p,p')Al-27(p)Mg-26 and Al-27(p,p')(27) Al(alpha)Na-23 reactions performed at the Orsay TANDEM facility aiming at the spectroscopy study of Al-27 above the neutron threshold. Fourteen states are observed for the first time within 350 keV above the Al-26+n threshold.

26Al was the first cosmic radioactivity ever detected in the galaxy as well as one of the first extinct radioactivity observed in refractory phases of meteorites. Its nucleosynthesis in massive stars is still uncertain mainly due to the lack of nuclear information concerning the 26Al(n,p)26Mg and 26 Al(n,α)23Na reactions. We report on a single and coincidence measurement of the 27Al(p,p')27Al(p)26Mg and 27Al(p,p')27Al(α)23Na reactions performed at the Orsay TANDEM facility aiming at the spectroscopy study of 27Al above the neutron threshold. Fourteen states are observed for the first time within 350 keV above the 26Al+n threshold.

Direct measurements of nuclear reactions of astrophysical interest can be challenging. Alternative experimental techniques such as transfer reactions and inelastic scattering reactions offer the possibility to study these reactions by using stable beams. In this context, I will present recent results that were obtained in Orsay using indirect techniques. The examples will concern various astrophysical sites, from the Big-Bang nucleo synthesis to the production of radioisotopes in massive stars.

The Al-26 radioisotope is of great importance for understanding the chemical and dynamical evolution of our galaxy. Among the possible stellar sources, massive stars are believed to be the main producer of this radioisotope. Understanding Al-26 nucleosynthesis in massive stars requires estimates of the thermonuclear reaction rates of the Al-26(n, p)Mg-26, Al-26(n, alpha)Na-23, and Na-23(alpha, p)Mg-26 reactions. These reaction rates depend on the spectroscopic properties of Al-27 states above the neutron and alpha thresholds. In this context, the Al-27(p, p')Al-27* reaction was studied at 18 MeV using a high-resolution Enge Split-Pole spectrometer. States from the ground state up to excitation energies of approximate to 14 MeV were populated. While up to the Na-23 + alpha threshold no additional states are observed, we report for the first time 30 new levels above the Na-23 + alpha threshold and more than 30 new states above the Al-26 + n threshold for which excitation energies are determined with an uncertainty of 4-5 keV.