New Cross-Section Measurements for TIGERISS

The Pioneers mission TIGERISS, planned to launch to the ISS in 2026, will provide, for the first time, single-element resolution Galactic cosmic-ray elemental abundances spanning a wide range in the periodic table, from ₅B up to ₈₂Pb, to further our understanding of the grand cycle of matter in the galaxy. In particular, the ultra-heavy galactic cosmic rays (UHGCRs), whose abundances are sensitive to r-process nucleosynthesis, have not yet been measured with single-element resolution above Ba. Such wide-range, fine-resolution experimental data would be best combined with the latest developments in astrophysical models, but the current accuracy of nuclear isotopic production cross sections is far behind experimental data. GALPROP is updating its current cross section library with newer reaction channels and more accurate data on existing channels. To that end, we are performing experiments at NASA Space Radiation Lab (Brookhaven National Laboratory), in March 2024 to determine proton spallation cross sections for isotopes of Co, Ti, Cr, Sc in the energy range 200-2,000 MeV/nucleon, a region largely lacking in data. These isotopes are important for TIGERISS, because several recent studies have indicated that improvements in the uncertainties of spallation cross section measurements of sub-Fe region isotopes are required for constraining geometric properties of diffusion models. We will present the status of this experiment, future planned experiments, as well as the role of GALPROP for TIGERISS.