Degree Type

Dissertation

Date of Award

2019

Degree Name

Doctor of Philosophy

Department

Physics and Astronomy

Major

Astrophysics

First Advisor

Frank Krennrich

Abstract

Imaging-Atmospheric Cherenkov Telescopes (IACTs) provide insights into a number of open questions in high energy physics, astroparticle physics, and cosmology. However, due to the indirect detection methods necessary to observe TeV gamma rays, the systematic and statistical errors produce a broad energy resolution of about 15--20\% during analysis. Therefore, investigating and characterizing systematics of IACTs is necessary for producing accurate measurements. This thesis presents an analysis technique developed to characterize VERITAS systematics at TeV energies on blazar spectra arising from saturation of the electronics. The application of this analysis method to two epochs of data from the Crab Nebula, extending above 20\ TeV, determined minimal systematic effects from saturation. Instead, the analysis showed bias arising primarily from the choice of low gain ratio, which lead to further investigation of the correct value to apply for the low gain ratio during analysis. With correct values of the low gain ratio applied, the systematic bias from saturation of the electronics is less than statistical errors out to energies greater than 20\ TeV. Finally, analysis of five blazar spectra extending to multi-TeV energies is presented, with both the nominal low gain ratios and the low gain ratios as determined in this thesis. The updated low gain ratio values demonstrate improved energy reconstruction in a VERITAS analysis, leading to more precise spectral reconstruction with low systematic bias from saturation of the electronics.

Copyright Owner

Rita M Wells

Language

en

File Format

application/pdf

File Size

221 pages

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