Nuclear Seminar : "s-Process Nuclear Reactions Studied with the High-Intensity SARAF-LiLiT Neutron Source "

Mon, 11/06/201815:30-17:00
Kaplun Building, Seminar room, 2nd floor
Lecturer: Moshe Tessler Abstract: Neutron-induced reactions remain at the forefront of experimental investigations for the understanding of stellar nucleosynthesis and chemical evolution of the Galaxy. We report on experiments, first of their kind, 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 setup yields the highest available 30 keV quasi-Maxwellian neutron intensity (3-5×10^10 n/s). First experiments were dedicated to benchmark the experimental system by measuring the Maxwellian Averaged Cross Section (MACS) of several targets. The MACS of 94Zr and 96Zr, important isotopes for understanding the s-process evolution, were determined based on activation measurements and detailed analysis, in good agreement with previous measurements and with lower uncertainties. Using alpha-, beta-, gamma-spectrometry and atom-counting techniques (accelerator mass spectrometry, atom-trap trace analysis), we are extending our experimental studies to several targets of astrophysical interest: the 36,38Ar(n,gamma) reactions are investigated, for the first time above thermal energies, with 30-keV neutrons as well as neutron capture reactions on important nuclides natKr in the weak s-process regime, and 208Pb and 209Bi at the end of the s-process path. The high neutron intensity enables MACS measurements of low-abundance or radioactive targets and neutron capture reactions on the s-process branching point 171Tm is investigated as well.