Nuclear Masses in Astrophysics for the Next 25 Years

Understanding the reaction rates of nuclei relevant to nucleosynthesis processes relies in part on nuclear masses, often 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 $^{252}$Cf. One focus of these measurements was masses of interest to understanding the formation of the rare-earth peak in the astrophysical r-process [1,2,3], 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 [4,5]. The future of the CPT's studies for nuclear astrophysics will occur at the currently-commissioning N=126 Factory, where multi-nucleon transfer reactions will produce nuclei further from stability at rates that make Penning trap mass measurements possible. Measurements at the N=126 Factory will begin with masses of interest for the formation of the heaviest $A\sim195$ r process abundance peak, but will also extend the CPT's rare earth peak campaign farther from stability.

This work is supported in part by the U.S. Department of Energy, Office of Nuclear Physics, under Contract No. DE-AC02-06CH11357; by the National Science Foundation under Grant No. PHY-2310059; by the University of Notre Dame; and with resources of ANL’s ATLAS facility, an Office of Science User Facility.

[1] Orford, Vassh, et al., PRL 120 262702 (2018)
[2] Orford, Vassh, et al., PRC 105 L052802 (2022)
[3] Ray, Vassh, et al., arxiv/2411.06310 (2024)
[4] Hoff et al., PRL 131 232701 (2023)
[5] Rivero et al., arxiv/2504.03944