Date of Award

Spring 2024

Project Type

Thesis

Program or Major

Physics

Degree Name

Master of Science

First Advisor

Eberhard Moebius

Second Advisor

Nathan Schwadron

Third Advisor

James Clemmons

Abstract

The Interstellar Boundary Explorer (IBEX) launched in 2008 and has been active for over 15 years. In this thesis, we track the instrument efficiency by taking the ratios of double and triple type events for dozens of orbits spanning those 15 years. Doing this lets us diagnose the instrument response in a way that is irrespective of incoming particle rates and properly shows any potential degradation that could have occurred during IBEX-Lo's lifetime. Ensuring that IBEX-Lo is operating nominally is especially crucial as we move into the era of its successor, IMAP-Lo.

Through our efficiency analysis, we have found that during the post 2013 era of IBEX-Lo observations, the efficiency of the instrument has held relatively constant. Across peak science times as well as over the years themselves, IBEX-Lo has maintained a Time of Flight efficiency of about $50\%$. For the 2009-2013 era, we saw elevated efficiencies during peak observation times that we believe were caused by the telemetry limit of the instrument being reached causing data to be lost.

Understanding the efficiency of IBEX-Lo will be crucial for IMAP-Lo's success. Efficiency analysis should give us a less variant reading of the MCP gain test that is performed every year as well as let us adapt it to determine branching ratios for the incoming particle types. With IMAP-Lo's improved geometric factor and detection capabilities, efficiency analysis should replace count rate as a measure of instrument response.

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