CARIBU: A New Facility to Access R-Process Nuclei

The r-process, a series of rapid neutron-capture reactions in cataclysmic astrophysical events such as supernovae explosions or neutron star mergers, is responsible for the creation of roughly half of the heavy nuclei in our universe. The conditions present in these events are such that the process proceeds through reactions on very neutron-rich radioactive nuclei, many of which have never been observed in the laboratory. Sensitivity studies have looked at various scenarios for the r-process conditions and identified nuclei whose basic properties would have the largest impact on the distribution of produced nuclei. At ANL, a program centered around the ATLAS facility is aimed at improving access to these nuclei and has developed tools to measure the most critical quantities to constrain r-process scenarios.

The talk will discuss the basic nuclear physics inputs required to understand the r-process and will present the novel CARIBU upgrade of ATLAS that is now providing access to some key nuclei along the r-process path. Recent measurements on nuclei around the N=82 r-process abundance peak, focusing on Penning trap mass measurements on very exotic isotopes, will be discussed. Other applications of these radioactive nuclei to understand, for example, the origin of the reactor neutrino anomaly, will also be presented.