Although 79Se represents an important branching in the weak s process, the stellar neutron capture cross sections to this isotope have not yet been measured experimentally. In this case, experimental data is essential for evaluating the important branching in the s-process reaction path at 79Se. The total cross section of 78Se at a stellar energy of kT = 25 keV has been investigated with a combination of the activation technique and accelerator mass spectrometry (AMS), since offline decay counting is prohibitive due to the long terrestrial half life of 79Se (2.80±0.36 ×105 y ) as well as the absence of suitable γ -ray transitions. The preliminary result for the total Maxwellian averaged cross section is 〈 σ 〉30 keV= 60.1±9.6 mbarn, significantly lower than the previous recommended value. In a second measurement, also the partial cross section to the 3.92 minisomer was determined via g -spectroscopy and yielded 〈σ 〉 30 keV(part.)= 42.0±2.0 mbarn.
|Journal||Proceedings of Science|
|Publication status||Published - 2006|
|Event||9th International Symposium on Nuclear Astrophysics - Nuclei in the Cosmos, NIC 2006 - Geneva, Switzerland|
Duration: 25 Jun 2006 → 30 Jun 2006