direct dark matter searches with deap peeters.pdf · fritz zwicky. 26 feb 2013 simon jm peeters,...
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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)
3Simon JM Peeters, DEAP-3600 and beyond, Oxford26 Feb 2013
The case for Dark Matter
4Simon JM Peeters, DEAP-3600 and beyond, Oxford26 Feb 2013
Rotation of galaxiesVera Rubin
Fritz Zwicky
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Much more evidence
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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
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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
8Simon JM Peeters, DEAP-3600 and beyond, Oxford26 Feb 2013
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
9Simon JM Peeters, DEAP-3600 and beyond, Oxford26 Feb 2013
“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
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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
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Direct Dark Matter Detection
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χ χ
��
Direct detectionSignal:
Backgrounds:
v/c ≈ 8 x 10-4
v/c ≈ 0.3
Er
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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)
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MeasurementRecoil NucleusKinetic Energy
NN
χ
χ
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Direct Detection
χHeat
Ionization
Scintillation
A
keVr vs
keVee
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Rate change and directionality
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Different techniques
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Current detectors and
results
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Xenon-100 results
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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
21Simon JM Peeters, DEAP-3600 and beyond, Oxford26 Feb 2013
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 ...
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CoGeNT• P-type point contact• 440 g detector• Low 0.4 keVee threshold• Soudan Mine, Minnesota
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CRESST• Use scintillating CaWO4 crystals• Detect both phonon signal and scintillation• Multiple targets per detector
CRESST is not claiming to see WIMPS
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Low mass region
Studied in detail:when interpreting the observed excesses as DM, theyare in tension with each other.
25Simon JM Peeters, DEAP-3600 and beyond, Oxford26 Feb 2013
DEAP-3600
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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
27Simon JM Peeters, DEAP-3600 and beyond, Oxford26 Feb 2013
Scintillation light in LAr
28Simon JM Peeters, DEAP-3600 and beyond, Oxford26 Feb 2013
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
29Simon JM Peeters, DEAP-3600 and beyond, Oxford26 Feb 2013
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
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39Ar discrimination
31Simon JM Peeters, DEAP-3600 and beyond, Oxford26 Feb 2013
32Simon JM Peeters, DEAP-3600 and beyond, Oxford26 Feb 2013
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
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DEAP/CLEAN family
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SNOLAB
@ 6000 mwedeepest and cleanest large-space international facility in the world
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SNOLAB
36Simon JM Peeters, DEAP-3600 and beyond, Oxford26 Feb 2013
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
37Simon JM Peeters, DEAP-3600 and beyond, Oxford26 Feb 2013
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
38Simon JM Peeters, DEAP-3600 and beyond, Oxford26 Feb 2013
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
39Simon JM Peeters, DEAP-3600 and beyond, Oxford26 Feb 2013
Cavity status at SNOLAB
•Cavity and platform are ready
•Water shield has been installed
•Services areready
Simon JM Peeters, DEAP, DESY 12/11/2012
40Simon JM Peeters, DEAP-3600 and beyond, Oxford26 Feb 2013
Cryocooler and LN2 system
Delivery and acceptance Delivery and acceptance at SNOLAB (April 2012)at SNOLAB (April 2012)
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Thermoforming vessel
Reynolds polymer,Colorado
R&D fnished 2012 (thickness/radius of curvature radius larger than ever attempted before)
42Simon JM Peeters, DEAP-3600 and beyond, Oxford26 Feb 2013
DEAP-3600 vessel DEAP-3600 vessel constructed and delivered toconstructed and delivered toSNOLABSNOLAB
43Simon JM Peeters, DEAP-3600 and beyond, Oxford26 Feb 2013
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
Simon JM Peeters, DEAP, DESY 12/11/2012
44Simon JM Peeters, DEAP-3600 and beyond, Oxford26 Feb 2013
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
Simon JM Peeters, DEAP, DESY 12/11/2012
45Simon JM Peeters, DEAP-3600 and beyond, Oxford26 Feb 2013
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.
Simon JM Peeters, DEAP, DESY 12/11/2012
46Simon JM Peeters, DEAP-3600 and beyond, Oxford26 Feb 2013
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)
47Simon JM Peeters, DEAP-3600 and beyond, Oxford26 Feb 2013
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
48Simon JM Peeters, DEAP-3600 and beyond, Oxford26 Feb 2013
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
Simon JM Peeters, DEAP, DESY 12/11/2012
49Simon JM Peeters, DEAP-3600 and beyond, Oxford26 Feb 2013
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
Simon JM Peeters, DEAP, DESY 12/11/2012
50Simon JM Peeters, DEAP-3600 and beyond, Oxford26 Feb 2013
Overview & future detectors
51Simon JM Peeters, DEAP-3600 and beyond, Oxford26 Feb 2013
Xenon-100 results
52Simon JM Peeters, DEAP-3600 and beyond, Oxford26 Feb 2013
The context
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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)
54Simon JM Peeters, DEAP-3600 and beyond, Oxford26 Feb 2013
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
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Ultimately
€ & ✴Strong backing
fromCanada
UK ownership of calibration WP
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DEAP/CLEAN familyBackground reduction andin-situ measurementplusscalibility
57Simon JM Peeters, DEAP-3600 and beyond, Oxford26 Feb 2013
CLEAN£ 7M £ 11M
Simon JM Peeters, DEAP, DESY 12/11/2012
58Simon JM Peeters, DEAP-3600 and beyond, Oxford26 Feb 2013
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)
Simon JM Peeters, DEAP, DESY 12/11/2012
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
59Simon JM Peeters, DEAP-3600 and beyond, Oxford26 Feb 2013
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
60Simon JM Peeters, DEAP-3600 and beyond, Oxford26 Feb 2013