Precision Mass Measurements with the Canadian Penning Trap at CARIBU and the N=126 Factory

Adrian Valverde

13.11.2025

SFB Kolloquium, S2|11, 10

Understanding the reaction rates of nuclei relevant to nucleosynthesis processes relies in part on nuclear masses, often of isotopes far from the valley of stability. The Canadian Penning Trap (CPT) has long measured such masses, and has recently concluded a decade-long campaign at the CARIBU facility, measuring over 200 nuclei produced through the spontaneous fission of 252Cf. One focus of these measurements was masses of interest to understanding the formation of the rare-earth peak in the astrophysical r-process, and another was on measurement of the ground and isomeric states of “astromers” or astrophysically-relevant isomers in neutron-rich nuclei along both the r- and s-process paths. The next step for the CPT will be nuclear mass measurements at the N=126 Factory, which will make use of multi-nucleon transfer reactions to produce previously-unmeasured isotopes far from stability at rates that make Penning trap mass measurements possible. The N=126 Factory, which is currently commissioning, will make use of a large-volume ultra-pure helium gas catcher, dipole separator magnet, cooler-buncher, and MR-TOF mass separator, similar to CARIBU, to convert the wide-angular-distributed, isotopically mixed, continuous, high-emittance MNT reaction products into low-emittance, isotopically-separated, bunched beams suitable for trapping, as well as for delivery to other experiments. While measurements at the N=126 Factory will begin with masses of interest for the formation of the heaviest A∼195 r-process abundance peak, it will also be able to extend the CPT’s rare earth peak campaign farther from stability and to other areas of the chart of the nuclides.