Date of Award

Spring 5-15-2023

Author's School

Graduate School of Arts and Sciences

Author's Department


Degree Name

Doctor of Philosophy (PhD)

Degree Type



This work describes the determination of the relative abundances of the Galactic Cosmic-Ray (GCR) nuclei from Z=9 through Z=40, with preliminary measurements up to Z=44, using the Calorimetric Electron Telescope (CALET) on board the International Space Station (ISS). This analysis will compare results with the top-of-atmosphere abundances from the balloon-borne SuperTIGER and top-of-instrument abundances from the space missions, ACE-CRIS and HEAO-3. This analysis also provides insight into the potential opportunities and challenges for a future SuperTIGER-like mission on the ISS.

Our analysis looks at work on two separate but complementary aspects of the Ultra-Heavy (UH) analysis in CALET. CALET has a distinct trigger method for UH events separate from the main High-Energy (HE) trigger. This high-duty cycle UH trigger requires events to only pass through the Charge Detector (CHD) and top half of the Imaging Calorimeter (IMC), foregoing the bottom Total Absorption Calorimeter (TASC). This trigger foregoes an energy determination in exchange for a larger geometry factor, which gives higher statistics. For this an event-by-event angle dependent rigidity cutoff is used to select events above an equivalent minimum energy. This is done in two ways, a quick Størmer approximation and a fourth order Runge-Kutta that iteratively back-traces events over a range of energies from point of detection until the particle's event trajectory leaves the magnetosphere or remains trapped.

The second analysis method is to analyze the events that are captured under a self-imposed HE trigger within the UH-trigger dataset. This smaller subset of events pass through the top of the Total Absorption Calorimeter (TASC), providing energy information. This energy information is used to determine effective analysis screens and improve the charge identification through a binning by energy to correct for energy dependence in CHD signals. The knowledge from this UH TASC analysis can then be leveraged back into the UH trigger analysis to improve on the methods for selecting events.


English (en)

Chair and Committee

Brian F. Rauch James Buckley

Committee Members

Henric Krawczynski, Johanna M. Nagy, Lee G. Sobotka,

Available for download on Wednesday, April 24, 2024