Ultra-Heavy Cosmic Ray Analysis with CALET on the International Space Station: Established and Developing Procedures

Abstract

The CALorimetric Electron Telescope (CALET) has collected over 60 months of uninterrupted data on the flux and spectrum of the Ultra-Heavy (UH) cosmic rays from Z=30 to 40. Using the latest data provided from CALET’s UH trigger, we present a newly developed UH analysis complementary to the ongoing analysis presented at this conference by Zober et al. This work introduces a new Ultra-Heavy Analysis (UHA) dataset produced from CALET production data allowing for more streamlined analysis. We detail temporal and spatial correction algorithms using both the 26 Fe and 14 Si peaks to improve charge resolution in the Z >= 30 region. Additionally, this work presents a new method for removing the contributions from non-relativistic/lower-Z nuclei using trajectory tracing to compute effective cutoff rigidities in place of the previously used vertical Stoermer approximation. We show that replacing the approximated cutoffs with numerically calculated effective cutoff rigidities, calculated using the IGRF13 and T05 (Tsyganenko 05) geomagnetic field models, leads to fewer events being removed from the dataset while maintaining improved charge resolution for Z > 26. Furthermore, we introduce Tarle function peak fitting to perform charge corrections needed as a result of any quenching effects. We show the most recent CALET UH results incorporating these improvements in the analysis