Speaker
Rodney Orford
(McGill University)
Description
The astrophysical rapid neutron capture process (r process) of nucleosynthesis is thought to be responsible for the production of roughly half of the elements heavier than iron. Despite its large influence in explaining the observed abundance of heavy elements, much of the r process is still poorly understood. A more thorough library of nuclear data, including masses, of neutron-rich nuclei is needed to improve the accuracy and progression of r-process calculations. The Canadian Penning trap mass spectrometer (CPT) is located in the CARIBU facility at Argonne National Laboratory where intense radioactive beams of neutron-rich nuclei are produced from the spontaneous fission of 252Cf. The scope of the CPT experiment at CARIBU is to perform direct mass measurements of isotopes which play a role in the r process. Since moving to CARIBU in 2010, the CPT has successfully measured the masses of more than 110 isotopes to a typical precision of 15 keV/c2 by measuring the cyclotron frequency of ions through a time-of-flight (TOF) technique. An upgrade to a position- sensitive microchannel plate detector at the CPT has facilitated a novel phase-imaging technique, and a multi-reflection time-of-flight mass separator (MR-TOF) has been commissioned at CARIBU which provides fast isobar separation with mass resolving power surpassing 100,000. These two upgrades allow for the CPT to probe shorter- lived nuclei further from stability than has previously been achievable at CARIBU. To illustrate the advantages of phase-imaging over the more commonly used TOF technique, the mass measurement of three previously unresolved nuclear isomers will be discussed.
Primary author
Rodney Orford
(McGill University)
