First results from the DEAP-3600 Experiment Josephine Paton - PowerPoint PPT Presentation

First results from the DEAP-3600 Experiment Josephine Paton University of Oxford Denys Wilkinson Building, University of Oxford 18 th March 2019

Outline • Dark Matter • Direct Detection • DEAP-1 prototype • DM detection in LAr • DEAP-3600 detector • First Results • Future DEAP-50T • Projected results DEAP-3600 without steel casing [1] 4/3/19 Josephine Paton, University of Oxford 1

Dark Matter • Dark Matter constitutes 26.8% of total universe • Candidates: • W eakly I nteracting M assive P articles Dark Energy (68.3%) • Axions • Sterile Neutrinos • And more! (26.8%) Dark Matter (4.9%) Visible Matter 4/3/19 Josephine Paton, University of Oxford 2

Dark Matter Direct Detection • Direct Detection - elastic scattering on nuclei • Produces Nuclear Recoil (NR) O(10) keV • Detect recoil -> Directly detect Dark Matter! X X N N Time 4/3/19 Josephine Paton, University of Oxford 3

DEAP-1 Prototype D ark Matter E xperiment using A rgon P ulse-shape discrimination • 7kg Liquid Argon • Scintillator • 2km Underground • Purpose: • LAr Techniques • Backgrounds [1] 4/3/19 Josephine Paton, University of Oxford 4

DM Detection in LAr • Biggest background • e - recoil in ! scattering (signal) • Pulse Shape Discrimination [2] 4/3/19 Josephine Paton, University of Oxford 5

DM detection in LAr • Americium Beryllium (AmBe) Source • Electronic + Nuclear • 0.0 – 0.6 – Electronic • 0.6 – 0.9 – Nuclear • DEAP-1 conclusions • e - suppressed • Use F prompt for DM [2] 4/3/19 Josephine Paton, University of Oxford 6

DEAP-3600 Detector • 3600kg Liquid Argon • First LAr > 1 tonne • Acrylic Cryostat • LAr cryogenic • PMTs room temp • Submerged in water • External ! veto 4/3/19 Josephine Paton, University of Oxford 7

DEAP-3600 Calibration • Region Of Interest NR • Limits on #PE ROI • Band crossing • Surface impurities • Limits on F prompt ER • 90% NR events [3] AmBe source 4/3/19 Josephine Paton, University of Oxford 8

DEAP-3600 First Results • Published 1 st Aug 2017 • Data taken during filling • 4.44 Live days • 9.87 tonne days s • No events in ROI • Leakage < 1.2 x 10 -7 • Fraction of e - in ROI • 10 4 stronger than Xe [3] 4/3/19 Josephine Paton, University of Oxford 9

DEAP-3600 First Results [3] Cross section< 1.2 × 10 − 44 cm 2 for 100 GeV WIMP (90% CL) Leading Limit in LAr 4/3/19 Josephine Paton, University of Oxford 10

Future - DEAP-50T Water Shield, 44ft diameter • Single phase LAr • Easily scaled up Steel Cryostat • Large masses Acrylic Shielding • More exposure • Impurities suppressed 4400 PMTs • High cost Acrylic Vessel, 17ft diameter [4] 4/3/19 Josephine Paton, University of Oxford 11

Future - DEAP-50T Projections Neutrino floor • Strong PSD in LAr • Low sensitivity to solar ! • projection Neutrino floor lower • projection Theoretical 100GeV limit • Xe ~ 10 -47 cm 2 • Ar ~ 10 -48 cm 2 • No spin dependency • [4] 4/3/19 Josephine Paton, University of Oxford 12

Summary • DEAP-1 Prototype • Detection with LAr – Pulse shape discrimination • DEAP-3600 detector • Design – First >1 tonne LAr detector • Cross section < 1.2 × 10 − 44 cm 2 for 100 GeV WIMP • Future DEAP-50T • Projected cross section limit ~ 10 -48 cm 2 4/3/19 Josephine Paton, University of Oxford 13

Thank You

References 1. DEAP-3600 – Dark matter Experiment using Argon Pulse-shape discrimination. (2019). Retrieved from http://deap3600.ca 2. M.G. Boulay, A. Hime. Astroparticle Physics, Volume 25, Issue 3, Pages 179-182. April 2006 3. DEAP-3600 Collaboration. Phys.Rev.Lett. 121, no.7, 071801. Jul 25, 2017 4. DEAP Collaboration. Nucl. Phys. B P.S. Volumes 273–275, Pages 340-346. April–June 2016 4/3/19 Josephine Paton, University of Oxford 15