Precision Mass Measurements of Heavy 252 Cf Fission Fragments Near the r - process Path

The path of the astrophysical r process and the resulting elemental distribution are dependent on the neutron-separation energies of species far from stability. The mass models used to extrapolate these energies have increasing uncertainties with neutron number. Therefore, precision mass measurements of species near the r-process path are vital to generate more precise predictions of elemental abundances produced by this explosive nucleosynthetic process. As part of an ongoing program, the Canadian Penning Trap mass spectrometer at Argonne National Laboratory is measuring the masses of fission products from a 150-µCi 252 Cf source placed inside a new large-volume He gas catcher. Within the region investigated, new precision mass measurements have been made closer to the r-process path than have previously been published, with precisions near 15 keV/c 2. our results differ from the AME03 [1] by up to 325 keV/c 2. Work will continue with the current fission source until 2009, when measurements of many more neutron-rich isotopes will be made at the CARIBU upgrade to the ATLAS accelerator at ANL. c Copyright owned by the author(s) under the terms of the Creative Commons Attribution-NonCommercial-ShareAlike Licence.