Simulations of astrophysical processes require a plethora of nuclear physics input. In particular, models of neutron-capture nucleosynthesis like the ??, ??, and ?? processes, require ??-decay information and experimentally constrained neutron-capture reaction rates. Past experiments with the 4?? Summing NaI(Tl) (SuN) total absorption spectrometer provide these physics quantities. Here, we outline an upgrade of SuN to SuN++, where 20 new detectors (12 NaI(Tl) and 8 CeBr3 ) have been integrated into the pre-existing SuN detector to provide increased energy and time resolution in ??-decay experiments. The details of the newly upgraded SuN++ detector are discussed with results from the commissioning experiment using SuN++ at the Facility for Rare Isotope Beams (FRIB) utilizing a 70Cu beam.
Published: December 6, 2025
Citation
Ronning E.K., S. Uthayakumaar, A. Spyrou, A.L. Richard, S.N. Liddick, A. Tsantiri, and R. Ringle, et al. 2026.The Upgraded Summing NaI(Tl) (SuN++) Absorption Spectrometer.Nuclear Instruments and Methods in Physics Research. Section A: Accelerators, Spectrometers, Detectors and Associated Equipment 1082, no. Part 1:Art. No. 170930.PNNL-SA-209405.doi:10.1016/j.nima.2025.170930