Direct Dark Matter searches with DEAP Peeters.pdf · Fritz Zwicky. 26 Feb 2013 Simon JM Peeters,...

Simon JM PeetersSimon JM Peeters

Direct Dark Matter searches with DEAPDirect Dark Matter searches with DEAP

2Simon JM Peeters, DEAP-3600 and beyond, Oxford26 Feb 2013

Outline

• The case for Dark Matter

• Direct Dark Matter detection

• Current experiments

• DEAP-3600

• Overview & future experiment (DEAP/CLEAN)


The case for Dark Matter


Rotation of galaxiesVera Rubin

Fritz Zwicky


Much more evidence


ΛCDM

Atoms:

•free H & He: 4%

•stars: 0.5%

•neutrinos: 0.3%

•heavy elements: 0.03%

Dark matter ≈ 24% of the universe!

Credits: NASA/WMAP

WMAP 9 year results


Dark Matter properties

optically dark

density around 0.3 GeV/cm3

dark matter particle mass is not well bound (1 GeV -100 TeV)

interactions: very weak, practically collision-less

15 kpc

150 kpc


Dark Matter properties

Open questions:

Mass?

Interaction cross-section?

Spin? Other quantum numbers?

One particle species or more?

Long-lived or stable?

15 kpc

150 kpc


“The quest to elucidate the nature of dark matter and dark energy is at the heart of particle physics—the study of the basic constituents of nature...”

“An answer to the question [what is dark matter] would mark a major breakthrough in understanding the universe and would open an entirely new feld of research on its own.”

“an area of world leading science opportunity”“signifcant UK leadership”“UK involvement is essential”

Sciene #1 question: what is the Universe made of


The hunt for DMAnnihilation in the cosmosAnnihilation in the cosmos

Direct detectionby scattering interrestrial detectors

Annihilation in the cosmosProduction in colliders

FERMI, Pamela, ATTIC

HESS, VERITAS, Magic

IceCube


Direct Dark Matter Detection


χ χ

��

Direct detectionSignal:

Backgrounds:

v/c ≈ 8 x 10-4

v/c ≈ 0.3

Er


WIMP scatteringSpin Independent:χ scatters coherently off of the entire nucleus A: σ∝ A2

Spin Dependent:only unpaired nucleons contribute to scattering amplitude: σ∝ J(J+1)

D. Z. Freedman, PRD 9, 1389 (1974)


MeasurementRecoil NucleusKinetic Energy

NN

χ

χ


Direct Detection

χHeat

Ionization

Scintillation

A

keVr vs

keVee


Rate change and directionality


Different techniques


Current detectors and

results


Xenon-100 results


Xenon-100•XENON100: a large, homogeneous, scalable detector•Particle interaction in the active volume produces

prompt scintillation light (S1) and ionization electrons•Electrons drift to interface (E= 0.5 kV/cm) where they

are extracted and amplifed in the gas. Detected asproportional scintillation light (S2)

•(S2/S1)WIMP << S2/S1)Gamma•3-D position sensitive detector with particle ID


DAMA/LIBRA• 25 crystals in 5x5 grid (9.7 kg each) = 243 kg• Two light guides + two PMTs on each crystal• PMTs work in coincidence at the single photon electronic threshold

Definite signal: but is it Dark Matter?

There are correlations ...


CoGeNT• P-type point contact• 440 g detector• Low 0.4 keVee threshold• Soudan Mine, Minnesota


CRESST• Use scintillating CaWO4 crystals• Detect both phonon signal and scintillation• Multiple targets per detector

CRESST is not claiming to see WIMPS


Low mass region

Studied in detail:when interpreting the observed excesses as DM, theyare in tension with each other.


DEAP-3600


DEAP collaborationUniversity of AlbertaB. Beltran, R. Chouinard, P. Davis, A. Hallin, P. Gorel, D. Grant, S. Liu, T. McElroy, C. Ng, J. Soukup, R. Soluk, J. Tang, A. Vinagreiro

Carleton UniversityC. Brown, K. Graham, C. Ouellet,

Laurentian UniversityB.T. Cleveland, T. Pollman

Queen’s UniversityM.G. Boulay, B. Broerman, B. Cai, D. Bearse, M. Chen, K. Dering, R. Gagnon P. Harvey, C. Hearns, M. Kuźniak, A.B. McDonald,. C. Nantais, T. Noble, P. Pasuthip, W. Rau, P. Skensved, T. Sonley, L. Veloce

Royal Holloway University of LondonA. Butcher, E. Grace, R. Guenette, J. Monroe, N. Slim,J. Walding, M. Widorski

Rutherford Appleton LaboratoryP. Majewski, R. Shah

SNOLABI. Lawson, F. Duncan, R. Ford, C.J. Jillings, O. Li, E.Vázquez-Jáuregui

University of SussexS. Churchwell, G. Booker, S. J. M. Peeters

TRIUMFP.-A. Amaudruz, D. Bishop, S. Chan, C. Lim, A. Muir, C. Ohlmann, K. Olchanski, F. Retiere, V. Strickland


Scintillation light in LAr


Pulse Shape Discrimination (PSD)

McKinsey & Coakley, Astropart. Phys. 22, 355 (2005)Boulay and Hime, Astropart. Phys. 25, 179 (2006) Lippincott et al., Phys.Rev.C 78:035801 (2008)

identify and reject electronic backgroundsidentify and reject electronic backgroundsImportant for LAr: Important for LAr: 3939Ar beta (1 Bq/kg)Ar beta (1 Bq/kg)

Single-phase LAr detectors possible because of Single-phase LAr detectors possible because of rejection power from timing,rejection power from timing,potential for kT scale detectors.potential for kT scale detectors.

LAr scintillates with a prompt and slow component:LAr scintillates with a prompt and slow component:

Achieved e- leakage <3x10-8 in 120-240 photo-electron window (Jillings, CAP '11)Expected <1x10-10 for DEAP-3600 for the same PE window


Depleted Argon• 39Ar beta decays with 565 keV endpoint, at ~1 Bq/kg with half-life 269 years• 39Ar production supported by cosmogenic activation, underground Ar has less!• low-background Ar sources reduce 39Ar by a factor of 50 at least (counting-only analysis)

A. Wright, arXiv:1109.2979

http://lanl.arxiv.org/abs/1109.2979


39Ar discrimination


Single phase concept

Liquid Argon dark mattertarget (cold! 87 K)LAr scintillates at 128 nm

wavelength shift (TPB) to >400 nm

read out with PMTs, digitize at 250 MHz,maximize PE/keVee with 4π coverage


DEAP/CLEAN family


SNOLAB

@ 6000 mwedeepest and cleanest large-space international facility in the world


SNOLAB


DEAP-3600 design

• Neck• Steel shell• Acrylic vessel (AV)

with TPB scintillator layer

• Acrylic light guide• High density

polyethelyne fller material

• 255 Hamamatsu R5912 HQE PMTs

• 3600 kg LAr

Detector in 8 m water shield,

instrumented withveto PMTs


DEAP-3600 specifcations

ArXiv:1203.0604

Parameters Value

Light yield 8 pe per keVee

Nuclear quenching factor 0.25

Analysis threshold 15 keVee (60 keVr)

Total Argon mass (radius) 3600 kg (85 cm)

Fiducial mass (radius) 1000 kg (60 cm)

Position resolution at threshold (cons, design spec) 10 cm

Position resolution at threshold (ML ftter) < 6.5 cm

Background specifications Target

Radon in Argon< 1.4 nBq/kg

Surfaces α’s (tolerance using cons. pos. res.) < 0.2 μBq/m2

Surfaces α’s (tolerance using ML ftter pos. res.)< 100 μBq/m2

Neutrons (all sources, in fducial volume) < 2 pBq/kg

βγ events, dominated by 39Ar (after PSD) < 2 pBq/kg

Total backgrounds < 0.6 events in 3 tonne-years


Background reduction in prototype

DEAP-1:DEAP-1:7 kg LAr7 kg LAr

By-product: “Surface roughness interpretation of CRESST-II result”:arXiv:1203.1576Accepted for publication in Astropart. Phys.

Demonstrated a Demonstrated a detailed detailed understanding understanding of surface alpha of surface alpha backgrounds:backgrounds:an issue for all dark an issue for all dark matter detectorsmatter detectors

ArXiv:1211.0909


Cavity status at SNOLAB

•Cavity and platform are ready

•Water shield has been installed

•Services areready

Simon JM Peeters, DEAP, DESY 12/11/2012


Cryocooler and LN2 system

Delivery and acceptance Delivery and acceptance at SNOLAB (April 2012)at SNOLAB (April 2012)


Thermoforming vessel

Reynolds polymer,Colorado

R&D fnished 2012 (thickness/radius of curvature radius larger than ever attempted before)


DEAP-3600 vessel DEAP-3600 vessel constructed and delivered toconstructed and delivered toSNOLABSNOLAB


Light guide and PMTsPMT assembly:PMT assembly:components components have beenhave beenprototyped,prototyped,purchased (PMTs,purchased (PMTs,testing is underway),testing is underway),or quotes are or quotes are being received.being received.

Lightguides:Lightguides:Radiopure acrylicRadiopure acrylic

bonded and shipped bonded and shipped to TRIUMF to TRIUMF

Jan 2012Jan 2012for machiningfor machining



Acrylic resurfacer• Being Being

commissioned at commissioned at Queen’s Queen’s University on University on test blockstest blocks

• Resurfacer will Resurfacer will be emanated to be emanated to demonstrate demonstrate radon load radon load before shipping before shipping to SNOLABto SNOLAB



TPB deposition

Deposition source has been successfully Deposition source has been successfully demonstrated at Queen’s University in demonstrated at Queen’s University in evaporation test stand.evaporation test stand.



Steel shell

Steel shell is being constructed in the cube hall at Steel shell is being constructed in the cube hall at SNOLAB SNOLAB

Welded underground Electropolished on the inside(Rn emanation)


Calibration programme

Calibration using internal and external gamma sources (RAL)60Co (1.17 and 1.33 MeV γ) ; 22Na

(e+,1.274 keV γ);137Cs

(0.662 keV γ), 83Krm

(9+32 keV

γ)

Neutron calibration (RHUL)Deployable, pulsed D-D generator

Optical calibration (Sussex)LED/fbre optical injection systemLED ball calibration pre and post TPB deposition 266 nm laser injection via the neck to excite TPB

Characterise the response in energy, Characterise the response in energy, radius and fPromptradius and fPrompt


Understanding TPB

Test TPB response in detail:• intensity• timing• wavelength (modified set-up with spectrometer)

as function • angle• TPB deposition thickness• excitation wavelength

(DM, neutrino, 0νββ relevance)

http://tpb.lns.mit.edu/mediawiki/index.php/Program_and_Talks


http://tpb.lns.mit.edu/mediawiki/index.php/Program_and_Talks


Project overview

20132012

Dec

Dec

Ju

n

Ju

n

Detector assembly and commissioningDetector assembly and commissioning

ResurfacingResurfacing

Apply TPB

Apply TPB

Start of Dark Matter runStart of Dark Matter run

Overview of the timeline for DEAP-3600Overview of the timeline for DEAP-3600



Overview & future detectors


Xenon-100 results


The context


There is a limit ..

Z

N N

ν ν

nuclear recoil fnal state1 event/ton-year =~ 10-48 cm2 limit

in zero-background paradigm...unless you measure

the direction!

impossible to shield a detector from coherent neutrino scattering:Φ(solar B8) = 5.86 x 106 cm-2 s-1

J. Monroe, P. Fisher, PRD76:033007 (2007)


Two phase vs single phase

no electric felds = straightforward scalability1) no pile-up from ms-scale electron drift in E2) no recombination in E (high photons/keVee) but no charge background discrimination either!

background discrimination from prompt scintillation timing...

high light yield and self-shielding of liquid noble target

Xe: demonstrated and no 39Ar


Ultimately

€ & ✴Strong backing

fromCanada

UK ownership of calibration WP


DEAP/CLEAN familyBackground reduction andin-situ measurementplusscalibility


CLEAN£ 7M £ 11M



Initial studies

Where MiniCLEAN and DEAP-3600 need a surface activity near 1 Bq/m2/day

CLEAN limits are based on 180 Bq/m2/hour(6 months of assembly in mine air)


Where MiniCLEAN and DEAP-3600 need a surface activity near 1 Bq/m2/day

CLEAN limits are based on 180 Bq/m2/hour(6 months of assembly in mine air)

Challenges:CalibrationDAQ


Summary

• Science case for Direct Dark Matter detection is very strong and it is a vibrant and exciting feld of research

• DEAP-3600 is a very interesting technique promising to set a world limit and a vital step to the ‘ultimate’ size (non-directional) detector

Direct Dark Matter searches with DEAP Peeters.pdf · Fritz Zwicky. 26 Feb 2013 Simon JM Peeters,...

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