Show simple item record

dc.contributor.authorCranshaw, Dereken
dc.date.accessioned2018-01-25T19:56:28Z
dc.date.available2018-01-25T19:56:28Z
dc.identifier.urihttp://hdl.handle.net/1974/23843
dc.description.abstractSeveral lines of astronomical evidence indicate that most of the matter in our universe is made of non-luminous material known as dark matter, the nature of which remains a mystery. DEAP-3600 is a liquid-argon-based scintillation detector located 2 km underground outside Sudbury, Ontario, Canada, purposed towards directly detecting dark matter particles as they pass through the target material. Since the acrylic vessel containing the 3600-kg liquid argon target is not transparent to the 128-nm scintillation light produced during these interactions, a thin layer of 1,1,4,4-tetraphenyl-1,3-butadiene (TPB) was deposited onto the inner surface of the acrylic vessel to shift the wavelength of the scintillation light to the visible range, where is can pass through the transparent acrylic vessel and is more easily detected by the surrounding array of photomultiplier tubes. The dark matter signal in DEAP-3600 is accompanied by a host of other background signals, which must either be suppressed, or identified as background signals and subsequently cut from the analysis. A major anticipated source of background events is alpha decays of radioactive isotopes on the inner surface of the acrylic vessel, near the TPB layer. The potential for these events to generate a background signal depends sensitively on the choice of thickness of the TPB layer. A study of the effects of TPB layer thickness on the background rate of these surface alpha events is presented, and a model for the dominant contributor to these background events is developed to generate estimates of the probability that an event of this type would mimic a dark matter signal. Other effects considered in the choice of TPB layer thickness are presented, and the final decision of a 2.99 +- 0.02 micron TPB layer thickness, along with the TPB deposition campaign, is briefly described.en
dc.language.isoengen
dc.relation.ispartofseriesCanadian thesesen
dc.rightsQueen's University's Thesis/Dissertation Non-Exclusive License for Deposit to QSpace and Library and Archives Canadaen
dc.rightsProQuest PhD and Master's Theses International Dissemination Agreementen
dc.rightsIntellectual Property Guidelines at Queen's Universityen
dc.rightsCopying and Preserving Your Thesisen
dc.rightsThis 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.en
dc.subjectDark Matteren
dc.subjectDEAP-3600en
dc.subjectBackgroundsen
dc.subjectTetraphenyl Butadieneen
dc.subjectTPBen
dc.subjectArgonen
dc.titleAn Investigation of the Effects of Wavelength Shifter Thickness on Backgrounds for the DEAP-3600 Dark Matter Direct Detection Experimenten
dc.typethesisen
dc.description.degreeM.Sc.en
dc.contributor.supervisorBoulay, Marken
dc.contributor.departmentPhysics, Engineering Physics and Astronomyen
dc.degree.grantorQueen's University at Kingstonen


Files in this item

Thumbnail

This item appears in the following Collection(s)

Show simple item record