SuperTIGER Instrument and Galactic Cosmic Ray Abundances from 10Ne to 56Ba

SuperTIGER (Super Trans-Iron Galactic Element Recorder) has had two Antarctic long-duration-balloon flights. The first was a record setting 55 days during the 2012-2013 austral summer at an average float altitude of 125,000 feet, and the second was 32 days during 2019-2020 at an average float altitude of 120,000 feet. SuperTIGER has measured the relative abundances of Galactic cosmic-ray (GCR) nuclei with good statistical precision and well resolved individual element peaks from ₁₀Ne to ₄₀Zr, with further measurements with lower statistics out to ₅₆Ba (Walsh et al., 2022AdSpR). SuperTIGER measurements through ₄₀Zr support a cosmic-ray source model with a significant contribution from OB associations where supernovae accelerate the nucleosynthetic products of preceding massive stars (Murphy et al., 2016ApJ). This model includes preferential acceleration of refractory elements that more readily condense onto interstellar dust grains than volatiles with a charge dependence consistent with grain sputtering cross sections. However, the extended measurements in the Z=41-56 range are inconsistent with this model, suggesting an additional GCR source and/or different acceleration model for Z>40 elements. Recent multi messenger observations have established neutron star (NS) mergers as one of the sites of r-process nucleosynthesis, and they might also be a source of ultra-heavy Galactic cosmic rays (UHGCR) ₃₀Zn and heavier. The relative contributions of supernovae and NS mergers to r-process nucleosynthesis can be addressed with further UHGCR measurements. We report progress in refining the UHGCR analysis of data from the first SuperTIGER flight and the effort to incorporate data from the second flight.