Speaker
Moshe Tessler
(Hebrew University of Jerusalem)
Description
As part of a program of neutron-capture measurements in the regime of the weak s-process, we studied for the first time the 36,38Ar(n,gamma) reactions in the stellar neutron energy regime and their contribution to production of light neutron-rich nuclides.
The experiments were performed with the Liquid-Lithium Target (LiLiT) and the mA-proton beam at 1.92 MeV (2-3 kW) from the Soreq Applied Research Accelerator Facility (SARAF). The facility yields high-intensity quasi-Maxwellian (kT sim 30-50 keV) neutrons (3-5 times10^10 n/s). Gas samples were irradiated at the SARAF-LiLiT neutron source and the 37Ar36Ar and 39Ar/38Ar ratios in the activated gas samples were determined by accelerator mass spectrometry at the ATLAS facility (Argonne National Laboratory).
The 37Ar activity was also measured by low-level counting at the University of Bern. The measured values of the Maxwellian Averaged Cross Sections (MACS) are significantly lower than theoretical and evaluated values published so far. Nucleosynthesis He-burning calculations using the 36,38Ar(n,gamma) experimental MACS show that the residual mass fraction of 36Ar increases by a factor of 10 while the mass fraction of neutron-rich nuclides in the region A=36-48 during the weak s-process is lowered by 10 to 50 %.
Summary
This work was supported in part by Israel Science Foundation (Grant Nr. 1387/15), Pazy Foundation (Israel), the US Department of Energy, Office of Nuclear Physics, under Contract NoDE-AC02-06CH11357. D.S.G. acknowledges the support by the U.S. Department of Energy, Office of Nuclear Physics, under grant No. DE-FG02-96ER40978. This research has received funding from the European Research Council under the European Unions's Seventh Framework Program (FP/2007-2013) /ERC Grant Agreement n. 615126.
Primary authors
Michael Paul
(Hebrew University of Jerusalem)
Moshe Tessler
(Hebrew University of Jerusalem)
Co-authors
Arik Kreisel
(Soreq NRC)
Asher Shor
(Soreq NRC)
Bradley S. Meyer
(Clemson University)
Dani Kijel
(Soreq NRC)
Daniel Baggenstos
(University of Bern)
Daniel Santiago-Gonzalez
(LSU, ANL)
Daniel Veltum
(Goethe University Frankfurt)
Ernst Rehm
(Argonne National Laboratory)
Ido Silverman
(Soreq NRC)
Leo Weissmann
(Soreq NRC)
Melina Avila
(Argonne National Laboratory)
Nir Hazenshprung
(Soreq NRC)
Philippe Collon
(University of Notre Dame)
Rashi Talwar
(Argonne National Laboratory)
Rene Reifarth
(Goethe University Frankfurt)
Richard C. Pardo
(Argonne National Laboratory)
Richard Vondrasek
(Argonne National Laboratory)
Robert H. Scott
(Argonne National Laboratory)
Roland Purtschert
(University of Bern)
Sergio Almaraz
(Argonne National Laboratory)
Shlomi Halfon
(Hebrew University of Jerusalem and Soreq NRC)
Yoav Kashiv
(University of Notre Dame)
