Alpha Radiation Studies and Related Backgrounds in the DarkSide-50 Detector

Monte, Alissa Erin

doi:10.2172/1497091

Title: Alpha Radiation Studies and Related Backgrounds in the DarkSide-50 Detector

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Abstract

DarkSide-50 is the current phase of the DarkSide direct dark matter search pro- gram, operating underground at the Laboratori Nazionali del Gran Sasso in Italy. The detector is a dual-phase argon Time Projection Chamber (TPC), designed for direct detection of Weakly Interacting Massive Particles (WIMPs), and housed within a veto system of liquid scintillator and water Cherenkov detectors. Since switching to a target of low radioactivity argon extracted from underground sources in April 2015, the background is no longer dominated by naturally occurring $$^{39}$$Ar. However, alpha backgrounds from radon and its daughters remain, both from the liquid argon bulk and internal detector surfaces. In some cases, the alpha events are a dangerous background in need of mitigation. In others, the alpha events can be used as a tool to deepen our understanding of our detector. We present here several analyses of alpha events in DarkSide-50. An analysis of radon-polonium coincidences is perfo rmed, yielding measurements of ion mobility and charged daughter fraction in liquid argon. These coincidences are also used to place upper limits on XY-resolution and liquid argon motion in the detector. A method for simulating the degraded energy spectra from $$^{210}$$Po events traveling through surface materials is presentedmore »« less

Authors:

Monte, Alissa Erin ^[1]

Massachusetts U., Amherst

Publication Date:: Mon Jan 01 00:00:00 EST 2018

Research Org.:: Fermi National Accelerator Lab. (FNAL), Batavia, IL (United States)

Sponsoring Org.:: USDOE Office of Science (SC), High Energy Physics (HEP)

OSTI Identifier:: 1497091

Report Number(s):: FERMILAB-THESIS-2018-26
1721688

DOE Contract Number:: AC02-07CH11359

Resource Type:: Thesis/Dissertation

Country of Publication:: United States

Language:: English

Subject:: 72 PHYSICS OF ELEMENTARY PARTICLES AND FIELDS

Citation Formats


                    Monte, Alissa Erin. Alpha Radiation Studies and Related Backgrounds in the DarkSide-50 Detector.  United States: N. p., 2018. 
        Web.  doi:10.2172/1497091.

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                    Monte, Alissa Erin. Alpha Radiation Studies and Related Backgrounds in the DarkSide-50 Detector.  United States.  https://doi.org/10.2172/1497091

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                    Monte, Alissa Erin. 2018.  
        "Alpha Radiation Studies and Related Backgrounds in the DarkSide-50 Detector".  United States.  https://doi.org/10.2172/1497091.  https://www.osti.gov/servlets/purl/1497091.

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@article{osti_1497091,

  title        = {Alpha Radiation Studies and Related Backgrounds in the DarkSide-50 Detector},

  author       = {Monte, Alissa Erin},

  abstractNote = {DarkSide-50 is the current phase of the DarkSide direct dark matter search pro- gram, operating underground at the Laboratori Nazionali del Gran Sasso in Italy. The detector is a dual-phase argon Time Projection Chamber (TPC), designed for direct detection of Weakly Interacting Massive Particles (WIMPs), and housed within a veto system of liquid scintillator and water Cherenkov detectors. Since switching to a target of low radioactivity argon extracted from underground sources in April 2015, the background is no longer dominated by naturally occurring $^{39}$Ar. However, alpha backgrounds from radon and its daughters remain, both from the liquid argon bulk and internal detector surfaces. In some cases, the alpha events are a dangerous background in need of mitigation. In others, the alpha events can be used as a tool to deepen our understanding of our detector. We present here several analyses of alpha events in DarkSide-50. An analysis of radon-polonium coincidences is perfo rmed, yielding measurements of ion mobility and charged daughter fraction in liquid argon. These coincidences are also used to place upper limits on XY-resolution and liquid argon motion in the detector. A method for simulating the degraded energy spectra from $^{210}$Po events traveling through surface materials is presented and compared with data from DarkSide-50. Lastly, a pileup background created by the accidental coincidence of scintillation-only $^{210}$Po surface events with random ionization-like pulses is thoroughly discussed. The estimation of this background and its mitigation informed the recent WIMP search analysis performed with 532 live-days of DarkSide-50 data.},

  doi          = {10.2172/1497091},

  url          = {https://www.osti.gov/biblio/1497091},
  journal      = {},
number       = ,

  volume       = ,

  place        = {United States},

  year         = {Mon Jan 01 00:00:00 EST 2018},

  month        = {Mon Jan 01 00:00:00 EST 2018}

}

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