Astrophysics with Radioactive Isotopes

First preliminary results on the s-process branchings 79Se(n,g) and 94Nb(n,g) and future prospects

Not scheduled

20m

Oral Presentation

Speaker

Cesar Domingo Pardo (Univ. of Valencia and CSIC (ES))

Description

The recent upgrade of the CERN n_TOF neutron-spallation target has resulted in improved experimental conditions regarding neutron-energy resolution and background level. A concomitant effort has been also made in terms of detection systems, thereby remarkably improving some limitations of previous set-ups. These upgrades, together with a major effort on sample production at PSI and ILL, have enabled the first direct neutron-capture cross section measurements on the radioactive isotopes 79Se and 94Nb. On one hand, the beta-decay of 79Se shows a prominent thermal dependency, which can be exploited to probe the thermal conditions during core He-burning and shell C-burning in massive stars. On the other hand, the interplay between beta-decay and neutron-capture at 94Nb in AGB stars may influence the production of 94Mo, whose isotopic abundance in presolar SiC grains is yet an important topic of debate. A short summary will be presented on the innovative experimental approaches used to perform these two challenging experiments and first preliminary results will be presented to highlight the quality of the results and to discuss their potential impact on s-process nucleosynthesis.