Much-needed high-Z proton-spallation cross sections for astrophysics and planetary missions

Great advances are happening in our understanding of our Galaxy and its physical phenomena, courtesy of missions such as TIGERISS (Trans-Iron Galactic Element Recorder on the International Space Station), which will be the first single instrument to look at elemental abundances spanning B to Pb. Planetary nuclear spectroscopy has also advanced and missions are visiting planets and asteroids never explored before, to determine the surface composition. However, the accurate interpretation of these advanced observational data is contingent upon accurate cross-section data, which are currently quite lacking and inadequate. There are gaps in data and unreliable measurements abound, and there have been very little drive to address these concerns, especially for proton spallation (p,X) cross-sections in high-Z and high-energy regions, which are imperative to study cosmic ray origins and planetary compositions. To that end, our team at NASA Goddard has established a collaboration with various institutions to perform a series of cross-section experiments for the reaction channels of utmost importance. The first of these experiments was performed in March 2024, at Brookhaven National Lab. Proton beams with energies between 0.2 to 2.5 GeV were irradiated upon a natural Cr and a monoisotopic Mn target, and the cross sections of several natCr(p,X) and 55Mn(p,X) reactions are currently being determined, using known gamma-ray lines of unstable daughter products. The second in this series is a planned experiment at FRIB, where we are currently setting up a 52Cr primary beam, for bombardment on a liquid Hydrogen target to study 52Cr(p,X) reactions. Our team has also become limited members of the NA61 collaboration, which performed a proton-spallation experiment at CERN, where high-Z isotopic beams up to Si were incident on a CH2 target. We will report upon how these experiments will help space missions, and our future plans in this endeavour.