Changes in r-process abundances at late times -: art. no. 035801

We explore changes in abundance patterns that occur late in the r process. As the neutrons available for capture begin to disappear, a quasiequilibrium funnel shifts material into the large peaks at A = 130 and A = 195, and into the rare-earth bump at A = 160. A bit later. after the free-neutron abundance has dropped and beta decay has begun to compete seriously with neutron capture, the peaks can widen. The degree of widening depends largely on neutron-capture rates in a few nuclei near closed neutron shells and relatively close to stability, We identify particular nuclei whose capture rates should be examined experimentally, perhaps at a radioactive beam facility.