Attempting to Close the Loop on the Oslo Technique at 198Au: Constraining the Nuclear Spin Distribution

Abstract

From simultaneous R-matrix analysis of new and previous neutron total-and capture-cross-section data, we obtained total radiation widths, Γγ, for 77 197 Au+n resonances. Γγ distributions calculated according to the nuclear statistical model using published Oslo nuclear level density and photon strength functions for 198 Au are too narrow and too close together for the two s-wave spins compared to our new data. The calculation can be brought into agreement with the data by substantial modifications to the spin distribution in 198 Au as a function of excitation energy. As far as we know, the spin distribution currently is otherwise poorly constrained. The modified spin distribution changes the shapes of the NLD and PSF extracted using the Oslo technique and so could have broad implications.

The status and future of direct nuclear reaction measurements for stellar burning

“…The time structure for the WNR facility makes it ideal for studies with neutron energies above 1 MeV, so the majority of astrophysical research at A c c e p t e d M a n u s c r i p t LANSCE is performed at the Luján Center. Both the Detector for Advanced Neutron Capture Experiments (DANCE) and the Device for Indirect Capture Experiments on Radionuclides (DICER) are located on Luján Center flightpaths [241,242].…”

“…One example of a detector system upgrade is the Device for Indirect Capture Experiment on Radionuclides (DICER), a newly developed instrument at LANSCE, focused on neutron transmission measurements on extremely small samples [242]. While A c c e p t e d M a n u s c r i p t the concept of neutron transmission measurements is not new, such measurements have typically required gram-sized samples for measurements at keV energies.…”

The Status and Future of Direct Nuclear Reaction Measurements for Stellar Burning

“…The time structure for the WNR facility makes it ideal for studies with neutron energies above 1 MeV, so the majority of astrophysical research at LANSCE is performed at the Luján Center. Both the Detector for Advanced Neutron Capture Experiments (DANCE) and the Device for Indirect Capture Experiments on Radionuclides (DICER) are located on Luján Center flightpaths [241,242].…”

“…One example of a detector system upgrade is the Device for Indirect Capture Experiment on Radionuclides (DICER), a newly developed instrument at LANSCE, focused on neutron transmission measurements on extremely small samples [242]. While the concept of neutron transmission measurements is not new, such measurements have typically required gram-sized samples for measurements at keV energies.…”