The Trans-Iron Galactic Element Recorder for the International Space Station (TIGERISS) is an
ultra-heavy galactic cosmic ray (UHGCR) detector planned for installation at the Columbus SOX
location of the International Space Station (ISS) in 2027. TIGERISS will improve on previous
instruments by using silicon strip detectors (SSDs) to achieve greater linearity in signal response
over an expanded dynamic range 5B and 82Pb and silicon photomultipliers (SiPMs) for a more
compact readout profile and to avoid the need for a high voltage. A Geant4-based instrument
simulation has been useful in the design phase and in predicting instrument performance and
various measurement corrections. Studies performed include a calculation of the top-of-instrument
survival fraction corrections by element and incident angle, ionization energy loss simulations
with a specific focus on the energy needed to be above threshold in the acrylic (325 MeV/Nuc)
and silica aerogel (2.34 GeV/Nuc) Cherenkov detectors by element and incident angle. Additional
studies focus on the instrument geometry factor, accounting for possible obstructions present in
the instrument field of view on the ISS, as well as simulations of instrument response to isotopes
and energies in preparation for a planned beam test at Brookhaven National Laboratory NASA
Space Research Laboratory facility.

