Graduate Student Seminar with Nicole Osborn on Cosmic rays may not fill a picnic table, but they do fill the periodic table: why the study of ultra-heavy galactic cosmic rays is (just barely) better than Friday BBQ

nstead of BBQ, I present to you the equally exciting world of Galactic cosmic rays (GCRs)! GRCs are mid energy (~10¹⁵ eV/nuc) particles with an isotropic flux incident on the Earth’s atmosphere. GCRs originate from OB associations: groups of young, massive, and short-lived stars in which frequent supernova explosions accelerate GCRs to required energies. Studying ultra-heavy galactic cosmic rays (UHGCRs), GCR nuclei with Z > 30, helps us constrain sources of r-process nucleosynthesis and learn more about GCR production and acceleration. The SuperTIGER (Super Trans-Iron Galactic Element Recorder) balloon borne UHGCR detector directly measures UHGCR nuclei. SuperTIGER had two successful Antarctic flights: SuperTIGER-I in 2012 for 55 days, and SuperTIGER-II in 2019 for 32 days. Stratospheric float altitudes of these flights varied between ∼36 – 40 km. To obtain GCR abundance measurements, SuperTIGER’s measured abundances must be corrected for the residual ~0.5% of atmosphere above the instrument. I present preliminary findings of a Geant4 simulation of GCR nuclei interacting with the atmosphere. Results of these simulations will be used to correct SuperTIGER’s measured abundance to the top of the atmosphere. I will end the talk with future plans and goals for the SuperTIGER-II analysis including galactic propagation corrections.