Physics & Astronomy ETDs

Publication Date

Fall 9-28-2017

Abstract

Particle Dark Matter is a hypothesis accounting for a number of observed astrophysical phenomena such as the anomalous galactic rotation curves. From these astronomical observation, about 23% of the universe appears to consist of dark matter. Among the possible candidates for dark matter, a plausible one is a Weakly Interacting Massive Particle (WIMP). A particle with the required properties is beyond the standard model of particle physics. The MiniCLEAN experiment is single-phase liquid-argon detector instrumented with 92 photomultiplier tubes placed inside the cryogenic liquid with 4-pi coverage of a 500 kg (150 kg) target (fiducial) mass. For this experiment, PMT stability and calibration are essential. In-situ optical calibration monitors the PMT stability and the energy calibration. We use LEDs to provide a real-time single photon calibration. The naturally occurring Ar-39 beta-emitting isotope provides another way to calibrate the detector. In data taken in cold gas during liquid argon filling we have measured a triplet lifetime (~ 3.5 us), the longest ever measured and confirming a very high argon purity. This long triplet lifetime in gaseous argon provides improved pulse shape discrimination (PSD) that could be exploited an a possible future gaseous dark matter detector. Low density and large recoil lengths might have other benefits as well for dark matter searches.

Degree Name

Physics

Level of Degree

Doctoral

Department Name

Physics & Astronomy

First Committee Member (Chair)

Michael Gold

Second Committee Member

Rouzbeh Allahverdi

Third Committee Member

Dinesh Loomba

Fourth Committee Member

John Matthews

Fifth Committee Member

Keith Rielage

Language

English

Keywords

Dark Matter, Liquid noble gas, gaseous argon

Document Type

Dissertation

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