Search

High-precision mass measurements of 64,65Ge and 66,67As are presented, which were obtained with the LEBIT (Low Energy Beam Ion Trap) facility at NSCL. The rare isotopes were produced by fast beam fragmentation, slowed down with a high-pressure gas stopping cell and analyzed with LEBIT's Penning-trap mass spectrometer. Compared to previous data, the uncertainties of the masses of 67As and 66As were reduced threefold to 550 eV and five-fold to 5.7 keV, respectively. The mass measurements of 64Ge and 65Ge with respective uncertainties of 40 keV and 4 keV confirm previous LEBIT data. The mass value of the superallowed beta emitter 66As leads to a new Q E C value of 9581.5(6.1) keV. Its improvement brings 66As closer to the group of isotopes with well-known Q-values that are used to test the conserved vector current (CVC) hypothesis in searches for physics beyond the Standard Model.

Accelerator-based neutron sources offer many advantages, in particular tunability of the neutron beam in energy and width to match the needs of the application. Using a recently constructed neutron beam line at the 88-Inch Cyclotron at LBNL, tunable high-intensity sources of quasi-monoenergetic and broad spectrum neutrons from deuteron breakup are under development for a variety of applications.