Light collection as a veto for PICO and SBC dark matter searches
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Authors
Hawley Herrera, Hector
Date
2024-07-29
Type
thesis
Language
eng
Keyword
Dark matter , Single-photon devices , Muon veto , SBC , PICO , SBC-LAr10 , PICO-500 , Silicon photomultipliers , SiPM , Photomulltiplier tubes , PMTs
Alternative Title
Abstract
Bubble chambers are a promising technology for dark matter detection that use a superheated fluid as the detection medium, where only point-like energy depositions can initiate a bubble nucleation event. PICO and the Scintillating Bubble Chamber (SBC) collaborations use bubble chambers with the goal of detecting WIMP-like dark matter ($\sim$1-100~GeV). PICO uses fluorocarbons as the active fluid, while SBC uses liquid noble elements.
PICO-500 is a 250-litre C$_3$F$_8$ bubble chamber located in the Cube Hall at SNOLAB. Muon-induced backgrounds will significantly contribute to the background budget assuming the detector meets its other background goals. The Cherenkov radiation generated by the muons will be used to veto muon-induced backgrounds. The PICO-500 muon veto consists of 48 R1408 photomultiplier tubes (PMTs), a water tank with an average radius of 18’-4.8" and height of 25’-10.5", and 12 LEDs. Geant4 and electronics simulations were developed to determine the efficacy of the muon veto and estimate the impact of noise in the system. These simulations were used to find a compromise between several conflicting components (PMT positions, bill of materials, electronics, etc.). 5,100$\pm$1,300 muons per year are expected to interact with the PICO-500 muon veto. Under the worst-case scenario, the muon veto is expected to have an efficiency of 99.71\% (or $15\pm4$ missed muons per year), which can be increased depending on PICO-500 dead-time requirements.
SBC-LAr10 is a 10~kg bubble chamber filled with liquid argon doped with xenon installed in the MINOS tunnel at Fermilab. The use of liquid noble elements introduces scintillation to the data, which enables vetoing capabilities that previous bubble chambers do not have. The generated light will be collected using 32 UV-sensitive Hamamatsu silicon photomultipliers (SiPMs). A novel characterization technique was developed using dark count data, avoiding the requirement of a single-photon source, and it was compared with the more conventional current vs. voltage characterization. The SiPM parameters (breakdown voltage, single photon gain, dark count rate, and others) were estimated to relative accuracies of approximately 0.5\% or Poissonian limited values (as in the case of dark count rate). The extracted temperature coefficients will aid SBC-LAr10 implementation and future experiments using SiPMs.
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Attribution-NoDerivatives 4.0 International
ProQuest PhD and Master's Theses International Dissemination Agreement
Intellectual Property Guidelines at Queen's University
Copying and Preserving Your Thesis
This publication is made available by the authority of the copyright owner solely for the purpose of private study and research and may not be copied or reproduced except as permitted by the copyright laws without written authority from the copyright owner.
Attribution-NoDerivatives 4.0 International