d e aa pp 3 6 0 0performed with non-thoriated tig welding to reduce radon emanation developed...
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Construction of the DEAP-3600 Dark Matter detector and first commissioning results.
Tina Pollmann for the DEAP collaboration
WIN2015, Heidelberg, June 10 2015
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3 6 0 0D E A PD E A P
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!
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3 6 0 0D E A P
The standard model of astronomy puts the composition of the universe at 23% Dark Matter.
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4% Stars, Gas, Planets, etc.
23% Dark Matter
73% Dark Energy
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3 6 0 0D E A P
DEAP is a direct detection experiment, looking for scintillation light produced when an argon nucleus recoils after scattering on a Dark Matter particle.
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Detector
m�
�n�
liquid argon
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3 6 0 0D E A P
The challenges of direct detection: low energy, small signal rate
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m = 100 GeV σ = 10-7 pb exp = 1 ton year
1
10
100
1000
0 10 20 30 40 50 60 70 80 90 100
Even
ts/k
eV
Recoil Energy [keV]
ArgonXenon
Germanium
DEAP-3600
• 1000 kg fiducial mass target volume
• 8 PE/keV lightyield
• < 0.2 background events/year
α γ μ n
Differential dark matter recoil spectrum.
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The argon scintillation pulseshape differs by exciting particle type, allowing PSD against electron-recoil events projected to reach 10-10 at 60 keVr, 8PE/keV.
promptF0 0.1 0.2 0.3 0.4 0.5 0.6 0.7 0.8 0.9 1
Ev
ents
/0.0
1 w
ide
bin
1
10
210
310
410
510
610
-ray eventsγ 7
10×1.7
100 nuclear recoil events
background-like (electron-recoil)
signal-like (nuclear recoil)
DEAP-1 prototype data
γ
Exploiting the singlet (6 ns) and triplet (1.5 μs) lifetime difference.
background (tagged 22Na)
signal (AmBe neutrons)
arXiv: 0904.2930, M. Kuzniak et al., Nuc Phys B Proc Sup 00 (2014) 1–7
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3 6 0 0D E A P 7
2 km (6800 ft) deep. 0.27 μ/m2/day.
DEAP-3600
SNO+ μ
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Steel shell
Water shielding tank. � 8m
LN2 cryocooler
LAr dewar
Magnetic compensation coils
Calibration source tubes (AmBe, 22Na)
Deck
DAQ racks
Process systems
Calibration source deployment system
μ n
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Liquid Argon (84 K, -188℃) single-phase
3.6 tonnes (total) 1 tonne (fiducial)
Image Credit: Wikipedia
The DEAP-3600 detector.
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Acrylic vessel.
The DEAP-3600 detector.
LAr
n
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AV from clean acrylic, assembled underground.
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Radiopurity of MaterialsRadiopurity of Materials Extensive and enormous effort
Acrylic, polymethal-meth-acrylate, sourced, counted in-situ and followed through every step from distillation to thermoforming pure MMA monomer sheets (Thai MMA)
Electropolishing of metal surfaces including interior of the steel shell to reduce radon emanation
Seamless tubing and where unavoidable welds in process system performed with non-thoriated TIG welding to reduce radon emanation
Developed vaporization system for acrylic assays, ultra low background emanation chamber to qualify process systems materials and cleaning methods
<10-19g/g 210Pb, ~ppt U and Th
α
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12AV annealed at ~85 C, 5 times.
α
Radon reduced air.
Radon monitored and controlled.
20 30 40 50 60 70 80 90
Tem
pera
ture
[C] Air average
2 6
10 14 18
02/0102/0202/0302/0402/0502/0602/0702/08
Rad
on L
evel
[Bq/
m3 ]
Date (2013, month/day)
α
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13Once AV is radon-tight, residual deposits are removed. Resurfacer takes fraction of a mm off the AV's inside.
α
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Acrylic vessel.
The DEAP-3600 detector.
LAr
nTPB wavelength shifter.
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15TPB deposition system being installed.
4π thermal evapo- ration source.TPB under UV and visible light.
~μm thickness.
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Acrylic vessel.
Light guide.
The DEAP-3600 detector.
LAr
n
n
50 c
m
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LG acrylic with best transparency, bonded meticulously.
n
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Specular and white reflector covers all surfaces.
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Acrylic vessel.
Light guide.
Filler block.
The DEAP-3600 detector.
LAr
n
nn
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Filler-blocks for extra neutron and heat shielding. n
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Acrylic vessel.
Light guide.
Filler block.
Photo multiplier.
The DEAP-3600 detector.
LAr
n
nn
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255 Hamamatsu 5912 PMTs, oil coupled to LG faces. 71% coverage.
LG
PMT
Copper thermal short
FINEMET magnetic shield
Mount
T ~ -184 C
T > -40 C
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Acrylic vessel.
Light guide.
Filler block.
Photo multiplier.
Cables, insulation.
The DEAP-3600 detector.
LAr
n
nn
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CAEN V1720 250MHz, V140 digitizers
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Acrylic vessel.
Light guide.
Filler block.
Photo multiplier.
The DEAP-3600 detector.
LAr
n
nn
Cables, insulation.
Steel shell.
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Veto PMTs detect Cherenkov light from muons passing through the water thank.
μ n
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Acrylic vessel.
Light guide.
Filler block.
Photo multiplier.
The DEAP-3600 detector.
LAr
n
nn
Cables, insulation.
Steel shell.
Neck, cooling coil.
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Liquid nitrogen storage, gas scrubber and cooling coil.
α
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3 6 0 0D E A P 29
Charge[pC]0 10 20 30 40 50
eve
nts/
bin
1
10
210
310
410
510PMTID 0
DataFull fitPedestal1 PE contribution2 PE contribution
DEAP0063CommissioningPreliminary
Charge [pC]0 10 20 30 40 50
χ
4−2−024
Charge[pC]0 10 20 30 40 50
eve
nts/
bin
1
10
210
310
410
PMTID 0DataFull fitPedestal1 PE contribution2 PE contribution3 PE contribution4 PE contribution
DEAP0063CommissioningPreliminary
Charge [pC]0 10 20 30 40 50
χ
4−2−024
PMTID0 50 100 150 200 250
Cha
rge
[pC
]
02468
1012
Fit mean SPE charge
DEAP0063CommissioningPreliminary
LED light injection system used to commission PMTs and DAQ system.
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3 6 0 0D E A P
What if we see nothing?
30plot: J Cooley, arXiv: 1410.4960v2 prediction: C. Strege, arXiv:1212.2636v1
1 10 100 1000 10410!5010!4910!4810!4710!4610!4510!4410!4310!4210!4110!4010!3910!3810!37
10!1410!1310!1210!1110!1010!910!810!710!610!510!410!310!210!1
WIMP Mass !GeV"c2#
WIMP!nucleoncrosssection
!cm2 #
WIMP!nucleoncrosssection
!pb#
CDMS II Ge (2009)
Xenon100 (2012)
CRESST
CoGeNT(2012)
CDMS Si(2013)
EDELWEISS (2011)
DAMA SIMPLE (2012)
ZEPLIN-III (2012)COUPP (2012)
LUX (2013)
DAMIC (2012)
CDMSlite (2013)
DarkSide G2
PICO250-C3F8
DarkSide 50
Xenon1TDEAP3600
LZPICO250-CF3I
LUX 300day
SuperCDMS SNOLAB
SuperCDMS S NOLAB
8BNeutrinos
Atmospheric and DSNB Neutrinos
7BeNeutrinos
COHERENT NEUTRIN O SCATTERING COHERENT NEU
TRI NO SCATTERING COHERENT NEUTRINO SCATTERING
Figure 1: A compilation of WIMP-nucleon spin-independent cross section limits (solid
lines) and hints of WIMP signals (closed contours) from current dark matter experiments
and projections (dashed) for planned direct detection dark matter experiments. Also
shown is an approximate band where neutrino coherent scattering from solar neutrinos,
atmospheric neutrinos and di↵use supernova neutrinos will dominate [13].
results from other experiments. At this point, we do not have conclusiveevidence of a dark matter signal. Hence, it is necessary to have experimentsusing several technologies and a variety of targets located in di↵erent loca-tions to maximize the chances of discovery and to confirm any claimed darkmatter signal. Figure 1 presents the current limits and favored regions ofcurrent experiments and projections of the parameter space we will be ableto explore with the next generation of experiments. As we look forward tothe next decade, it is clear that with a diverse portfolio we will be able toexplore parameter space all the way to the neutrino floor [13].
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DEAP-3600
3 year data run projection for DEAP
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