Date of Award


Document Type


Degree Name

Master of Science in Applied Physics


Department of Engineering Physics

First Advisor

Robert D. Loper, PhD


Past studies of heavy ions (Z>2) in large (E>10 MeV/nuc) gradual solar energetic particle (SEP) events have focused on elemental abundances relative to those of a single element, such as Fe or O, and have often neglected ionized H (the primary element used for space weather purposes). This work analyzes SEP abundances in a group of 15 large gradual SEP events from 2000 to 2015 across the energy range of 13.5-50.7 MeV. Hourly flux averages of He, C, O, Mg and Fe from the Advanced Composition Explorer/Solar Isotope Spectrometer (ACE/SIS) are compared to two-hour averages of H flux from the Solar and Heliospheric Observatory/Energetic and Relativistic Nuclei and Electron (SOHO/ERNE) experiment. Event-to-event comparisons reveal order of magnitude variances in all elements studied (with Fe exhibiting variances spanning several orders of magnitude). A strong correlation is seen between abundance enhancement relative to the spectral coronal and linear coronal mass ejection (CME) speeds for He, C, O and Mg. Extreme Fe abundance events are determined to have energy loss rates equal to those of H (the consequences of which are briefly discussed).

AFIT Designator


DTIC Accession Number