Constraining the astrophysical r-process by mass measurements on very neutron-rich isotopes at CARIBU and the N=126 factory*

The Californium Rare Isotope Breeder Upgrade (CARIBU) facility at ANL can provide access to beams of mass separated very neutron-rich isotopes which can then have their mass determined to high-precision with the Canadian Penning Trap (CPT) mass spectrometer or their decay properties studied with the X-array spectrometer. Recent mass measurement results (R. Orford et al, PRL 120, 262702 (2018)) have reached the region of nuclear masses relevant to the formation of the rare-earth abundance peak at A ∼165 by the rapid neutron-capture process. These results are now being completed in his region and will be extended to the region responsible for the formation of the heaviest abundance peak in the r-process at the N=126 factory. The technique and  recent results will be presented, together with the on-going work to help constrain the r-process astrophysical conditions. The additional information coming from the decay studies which significantly expand on the data obtained at fragmentation facilities, will also be presented.