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 18th March 2019

• Dark Matter
• Direct Detection
• DEAP-1 prototype
• DM detection in LAr
• DEAP-3600 detector
• First Results
• Future DEAP-50T
• Projected results

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Outline

DEAP-3600 without steel casing [1]

Dark Matter

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• Dark Matter constitutes 26.8% of total universe
• Candidates:
• Weakly Interacting Massive Particles
• Axions
• Sterile Neutrinos
• And more!

Dark Energy (68.3%) (26.8%) Dark Matter (4.9%) Visible Matter

Dark Matter Direct Detection

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• Direct Detection - elastic scattering on nuclei
• Produces Nuclear Recoil (NR) O(10) keV
• Detect recoil -> Directly detect Dark Matter!

X X N N

Time

DEAP-1 Prototype

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Dark Matter Experiment using Argon Pulse-shape discrimination

[1]

• 7kg Liquid Argon
• Scintillator
• 2km Underground
• Purpose:
• LAr Techniques
• Backgrounds

DM Detection in LAr

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• Biggest background
• e- recoil in ! scattering
• Pulse Shape Discrimination

[2]

(signal)

DM detection in LAr

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• Americium Beryllium

(AmBe) Source

• Electronic + Nuclear
• 0.0 – 0.6 – Electronic
• 0.6 – 0.9 – Nuclear
• DEAP-1 conclusions
• e- suppressed
• Use Fprompt for DM

[2]

DEAP-3600 Detector

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• 3600kg Liquid Argon
• First LAr > 1 tonne
• Acrylic Cryostat
• LAr cryogenic
• PMTs room temp
• Submerged in water
• External ! veto

DEAP-3600 Calibration

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ROI ER NR

AmBe source

• Region Of Interest
• Limits on #PE
• Band crossing
• Surface impurities
• Limits on Fprompt
• 90% NR events

[3]

s

DEAP-3600 First Results

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[3]

• Published 1st Aug 2017
• Data taken during filling
• 4.44 Live days
• 9.87 tonne days
• No events in ROI
• Leakage < 1.2 x 10-7
• Fraction of e- in ROI
• 104 stronger than Xe

DEAP-3600 First Results

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[3]

Cross section<1.2×10−44 cm2 for 100 GeV WIMP (90% CL) Leading Limit in LAr

Future - DEAP-50T

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Water Shield, 44ft diameter Steel Cryostat Acrylic Shielding 4400 PMTs Acrylic Vessel, 17ft diameter

• Single phase LAr
• Easily scaled up
• Large masses
• More exposure
• Impurities suppressed
• High cost

[4]

Future - DEAP-50T Projections

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• Neutrino floor
• Strong PSD in LAr
• Low sensitivity to solar !
• Neutrino floor lower
• Theoretical 100GeV limit
• Xe ~ 10-47 cm2
• Ar ~ 10-48 cm2
• No spin dependency

[4]

projection projection

• DEAP-1 Prototype
• Detection with LAr – Pulse shape discrimination
• DEAP-3600 detector
• Design – First >1 tonne LAr detector
• Cross section <1.2×10−44 cm2 for 100 GeV WIMP
• Future DEAP-50T
• Projected cross section limit ~ 10-48 cm2

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Summary

Thank You

• 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

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References