sno and the new snolab art mcdonald queen’s university, kingston, ontario, canada
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SNO and the New SNOLAB
Art McDonaldQueen’s University, Kingston, Ontario, Canada
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Bahcall et al.
, SNO
Flavour Change for Solar NeutrinosSolar Model Flux Calculations
CNO
SNO was designed to observe separately e and all neutrino types to determine if low e fluxes come from flavor change or solar models
Previous Experiments Sensitive to Electron Neutrinos
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Unique Signatures in SNO (D2O)
Charged-Current (CC)e+d e-+p+pEthresh = 1.4 MeV
ee onlyonly
Elastic Scattering (ES) (D2O & H2O)x+e- x+e-
x, but enhanced for e
Neutral-Current (NC) x+d x+n+p Ethresh = 2.2 MeV
Equally sensitive to Equally sensitive to e e
3 ways todetect neutrons
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Phase II (salt)July 01 - Sep. 03
Phase III (3He)Nov. 04-Dec. 06
Phase I (D2O)Nov. 99 - May 01
SNO: 3 neutron (NC) detectionmethods (systematically different)
n captures on2H(n, )3H
Effc. ~14.4% NC and CC separation by energy, radial, and
directional distributions
40 proportional counters
3He(n, p)3HEffc. ~ 30% capture
Measure NC rate with entirely different
detection system.
2 t NaCl. n captures on35Cl(n, )36ClEffc. ~40%
NC and CC separation by event isotropy
36Cl
35Cl+n 8.6 MeV
3H
2H+n 6.25 MeV
n + 3He p + 3H
p3H
5 cm
n
3He
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Acrylic vessel (AV) 12 m diameter
1700 tonnes H2O inner shielding
1000 tonnes D2O($300 million)
5300 tonnes H2O outer shielding
~9500 PMT’s
Creighton mineSudbury, CA
The Sudbury Neutrino Observatory: SNO6800 feet (~2km) underground
The heavy water has recently been returned and development work is in progress on SNO+ with liquid scintillator and 150Nd additive.
- Entire detectorBuilt as a Class 2000
Clean room- Low RadioactivityDetector materials
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SNO: One million pieces transported down in the 9 ft x 12 ft x 9 ft mine cage and re-assembled under ultra-clean conditions. Every worker takes a showerand wears clean, lint-free clothing.
Over 70,000Showersto date andcounting
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’s from 8Li, ’s from 16N and t(p,)4He
252Cf neutrons
6.13 MeV
19.8 MeV
Energy calibrated to ~1.5 %
Throughout detector volume
Optical calibration at 5 wavelengths with the “Laserball”
SNO Energy Calibrations: 25% of running time
+ AmBe, 24Na
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)syst.()stat.( 35.2
)syst.()stat.( 94.4
)syst.()stat.( 68.1
15.015.0
22.022.0
38.034.0
21.021.0
08.009.0
06.006.0
ES
NC
CC
)scm10 of units(In 126
029.0031.0)stat.(023.034.0
NC
CC
Electron neutrinos
The Total Flux of Active
Neutrinos is measured
independently (NC) and agrees
well with solar model
Calculations:
5.82 +- 1.3 (Bahcall et al),
5.31 +- 0.6 (Turck-Chieze et al)
CC, NC FLUXESMEASURED
INDEPENDENTLY
Flavor change determined by > 7
Electron neutrinos areOnly about 1/3 of total!
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- The solarresults define themass hierarchy(m2 > m1) through theMatter interaction (MSW)
- SNO: CC/NC fluxdefines tan2 < 1 (ie Non - Maximal mixing)by more than 5standard deviations
SOLAR ONLY
AFTER
SNO SALT
DATA
SOLAR PLUS
KAMLAND (Reactor ’s)
MSW: Large
Mixing Angle
(LMA) Region
LMA for solar predicts very small
spectral distortion, small (~ 3 %) day-night
asymmetry, as observed by SK, SNO
040.0037.0Asym OD salt 2
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SNO Physics Program Solar Neutrinos (5 papers to date)
Electron Neutrino Flux Total Neutrino Flux Electron Neutrino Energy Spectrum Distortion Day/Night effects hep neutrinos hep-ex 0607010 Periodic variations: [Variations < 8% (1 dy to 10 yrs)] hep-ex/0507079
Atmospheric Neutrinos & Muons Downward going cosmic muon flux Atmospheric neutrinos: wide angular dependence [Look above horizon]
Supernova Watch (SNEWS) Limit for Solar Electron Antineutrinos
hep-ex/0407029 Nucleon decay (“Invisible” Modes: N ) Phys.Rev.Lett. 92 (2004) [Improves limit by 1000] Supernova Relic Electron Neutrinos hep-ex 0607010
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Final Phase: SNO Phase III
• Search for spectral distortion
• Improve solar neutrino flux by breaking the CC and NC correlation ( = -0.53 in Phase II):
CC: Cherenkov Signal PMT Array NC: n+3He NCD Array
• Improvement in 12, as
Neutral-Current Detectors (NCD): An array of 3He proportional counters
40 strings on 1-m grid~440 m total active length
Phase III production data taking Dec 2004 to Dec 2006. D2O now removed.
Correlations D2O unconstrained D2O constrained Salt unconstrained NCD
NC,CC -0.950 -0.520 -0.521 ~0
CC,ES -0.208 -0.162 -0.156 ~-0.2
ES,NC -0.297 -0.105 -0.064 ~0
Blind Analysis
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Another analysis is almost complete that combines data fromthe first two SNO Phases and reduces the threshold by > 1 MeV.
This also provides improved accuracy on CC/NC flux ratio and therefore mixing matrix element.
Blind Data
Very low Background. About one count per 2 hours in region of interest. Can be reduced by a factor of more than 20 by pulse shape discrimination.
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New International Underground Facility: SNOLAB
Phase 1 Experimental area: Available 2008Cryopit addition: Excavation nearly completed. Available early 2009. Total additional excavated volume in new lab: 2 times SNO volume.
For Experiments that benefit from a very deep and clean lab:• - less Double Beta Decay
• Dark Matter
• Solar Neutrinos
• Geo – neutrinos
• Supernova `sSUSEL
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SNOLAB (Same depth as SNO: 2 km)
Personnel facilities
SNO Cavern(Existing)
Ladder Labs(2008)
Cube Hall (2008)
Phase IICryopit (2009)
UtilityArea
All Lab Air: Class < 2000
70 to 800 times lower
fluxes than
Gran Sasso, Kamioka.
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Excavation Status
Cryopit Rock RemovalCompleteBolting, Shotcrete andConcrete will be completedin several weeks.
Cube Hall and Ladder LabExcavation complete, walls painted, services being installed.
Cube Hall
Ladder Lab
Cryopit
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Cube Hall
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Letters of Intent/Interest for SNOLAB
Dark Matter:Timing of Liquid Argon/Neon Scintillation: DEAP-1 (7 kg), MINI-CLEAN (360 kg),
DEAP/CLEAN (3.6 Tonne)
Freon Super-saturated Gel: PICASSO
Silicon Bolometers: SUPER-CDMS (25 kg)
Neutrino-less Double Beta Decay:150Nd: Organo-metallic in liquid scintillator in SNO+
136Xe: EXO (Gas or Liquid) (Longer Term)
CdTe: COBRA (Longer Term)
Solar Neutrinos:Liquid Scintillator: SNO+ (also Reactor Neutrinos, Geo-neutrinos)
Liquid Ne: CLEAN (also Dark Matter) (Longer Term)
SuperNovae:SNO+: Liquid scintillator; HALO: Pb plus SNO 3He detectors.
6 th Workshop and Experiment Review Committee
Aug 22, 23, 2007www.snolab.ca
RED IMPLIES APPROVEDFOR SITING
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DEAP/CLEAN: 1 Tonne Fiducial Liquid Argon Dark Matter (WIMP) detector
From simulation, rejection > 108
@ 10 keV
108 simulated e-’s
100 simulatedWIMPs
M.G. Boulay & A. Hime, astro-ph/0411358
- Scintillation time spectrum for Arenables nuclear recoils from WIMP collisions to be separated from betas and gammas from 39Ar background using only scintillation light.
- DEAP and CLEAN collaborationshave come together to build newdetectors with a simple and easily scaled technology at SNOLAB.
Queen’s, Alberta, Carleton, Laurentian, SNOLAB, TRIUMF, LANL, Yale, Boston, South Dakota, New Mexico, North Carolina, Texas, NIST Boulder, MIT
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DEAP-1 discrimination tests using 511 keV gammas
Ran DEAP-1 on surface to background limit ( 6 x 10-8 PSD) , moved to SNOLAB.Now running underground for Pulse Shape Discrimination studies and DM search
PSD agrees withstatistical model over sevenorders of magnitude.
Projection: Light alone issufficient for 109 background reduction neededfor 1 tonne DM experiment with natural Ar.
PSD already OK for 1 tonne fiducial Ar if depleted x 20 in 39Ar. (See Galbiati et al)
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Cube Hall
MiniCLEAN360 kg2009
DEAP/CLEAN3.6 tonne
2010
AssemblyClean Room
DEAP/CLEANProcess Systems
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WIMP Sensitivity with 1 tonne of argon
Schedule: Mini-CLEAN (360 kg): 100 kg Fiducial: 2009,
DEAP/CLEAN (3600 kg): 1000 kg Fiducial: starting 2010
PresentExperimentalLimits~ 5 x 10-44
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• Nd is one of the most favorable double beta decay candidates with large phase space due to high endpoint: 3.37 MeV.
• Ideal scintillator (Linear Alkyl Benzene) has been identified. More light output than Kamland, Borexino, no effect on acrylic.
• Nd metallic-organic compound has been demonstrated to have long attenuation lengths, stable for more than a year.
• 1 tonne of Nd will cause very little degradation of light output.• Isotopic abundance 5.6% (in SNO+ 1 tonne Nd = 56 kg 150Nd) • Collaboration to enrich 150Nd using French laser isotope facility.
Possibility of hundreds of kg of isotope production.• SNO+ Capital proposal to be submitted Oct. 2008. • Plan to start with natural Nd in 2010.• Other physics: CNO solar neutrinos, pep solar neutrinos to
study neutrino properties, geo-neutrinos, supernova search..
SNO+: Neutrino-less Double Beta Decay: 150Nd
Queen’s, Alberta, Laurentian, SNOLAB, BNL, Washington, Penn, Texas, LIP Lisbon, Idaho State, Idaho Nat Lab, Oxford, Sussex, TU Dresden
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AV Hold DownRopes
ExistingAV SupportRopes
The organicliquid is lighterthan water sothe Acrylic Vesselmust be held down.
Main Engineering Changes for SNO+ : Scint. Purification, AV Hold Down
Otherwise, the existing detector, electronics etc. are unchanged.
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0: 1057 events peryear with 500 kg150Nd-loaded liquidscintillator in SNO+.
Simulationassuming lightoutput and backgroundsimilar to Kamland.
SNO+ (150Nd - less Double Beta Decay)
One year of datam= 0.15 eV
Sensitivity Limits (3 yrs): Natural Nd (56 kg isotope): m ~ 0.1 eV 500 kg enriched 150Nd: m ~ 0.04 eV
U Chain Th Chain
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H eliumA ndL eadO bservatory
A lead detector forsupernova neutrinosin SNOLAB
Laurentian, TRIUMF, SNOLAB, LANL, Washington, Duke, Minnesota, Digipen IT HALO-1: 80 tons of existing Pb
& SNO Neutron Detector Array
Pb: Most sensitivity to electron neutrinos.~ 50 events for SN at center of Galaxy.
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Anode PadsMicro-megas
WLS BarElectrode
For 200 kg, 10 bar, box is 1.5 m on a side
Xe GasIsobutaneTEA
. . . . . . . .
. . . . . . . .PMT
Lasers
Grids
Ba Ion
Electrons
R&D in Canada: EXO-gas double beta counter
136Xe decay
EXO-gas Canada: Carleton, Laurentian
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Montreal, Queen’s
Indiana, Pisa, BTI
Fluorine is very sensitive for the spin-dependent interaction
WIMP-Nucleus Spin-Dependent Interaction
AcousticSignal
Up to 2.6 kg being run in 2007-08
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SUMMARY
Scientific:
• SNO is complete, further papers to come over next year.
• SNOLAB excavation is complete, final room outfitting being completed.
• Several experiments are running in existing clean space.
• A number of other experiments have been approved for siting in the near future for neutrinos, double beta decay, Dark Matter.
Personal: Congratulations Frank, Ettore. All the best for the future.
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