The upgraded summing NaI(Tl) (SuN++) absorption spectrometer
E. K. Ronning, S. Uthayakumaar, A. Spyrou, A. Richard, S. Liddick, A. Tsantiri, R. Ringle, H. Arora, H. C. Berg, J. M. Berkman, D. L. Bleuel, K. Bosmpotinis, S. E. Campbell, X. Chen, B. P. Crider, R. J. Coleman, P. DeYoung, A. A. Doetsch, H. Erington, T. Gaballah, N. D. Gamage, E. C. Good, B. G. Greaves, A. C. Hartley, J. Huffman, C. M. Ireland, C. Izzo, R. Jain, J. E. L. Larsson, R. S. Lubna, F. M. Maier, M. J. Mogannam, M. Mumpower, G. Owens-Fryar, T. H. Ogunbeku, D. P. Scriven, M. K. Smith, C. S. Sumithrarachchi, A. Sweet, K. Taft, M. Wiedeking
Published NIMA (2026)
Simulations of astrophysical processes require a plethora of nuclear physics input. In particular, models of neutron-capture nucleosynthesis like the $s$, $i$, and $r$ processes require $\beta$-decay information and experimentally constrained neutron-capture reaction rates. Past experiments with the $4\pi$ Summing NaI(Tl) (SuN) total absorption spectrometer have provided these physics quantities. Here, we outline an upgrade of SuN to SuN++, where 20 new segments (12 NaI(Tl) and 8 CeBr) have been integrated into the pre-existing SuN total absorption spectrometer to provide increased energy and time resolution in $\beta$-decay experiments. The details of the newly upgraded SuN++ total absorption spectrometer are discussed with results from the commissioning experiment at the Facility for Rare Isotope Beams (FRIB) utilizing a $^{70}$Cu beam.