Telescopes: SNO and the New SNOLAB

Art McDonaldQueen’s University, Kingston

For the SNO Collaboration

2 km underground in Vale-INCO’s CreightonMine near Sudbury, Ontario

Neutrino TelescopesVenice

March 10, 2009(Galileo + 400)

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 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

Bahcall et al.

, SNO

SNO: Solving the “Solar Neutrino Problem”Solar Model Flux Calculations

CNO

SNO was designed to observe separately e and all neutrino types to determine if low e fluxes come from solar models or neutrino flavor change (New Physics)

Previous Experiments Sensitive Mainly to Electron Neutrinos

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 Events point away from the sun.

Neutral-Current (NC) x+d x+n+p Ethresh = 2.2 MeV

Equally sensitive to Equally sensitive to e e

3 ways todetect neutrons

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

ijijijij

ii

i

τττ

μμμ

eee

li

sandcwhere

e

e

cs

sc

iδecs

sccs

sc

UUU

UUU

UUU

U

sin,cos

00

00

001

0

010

0

00

010

001

0

0

001

100

0

0

2/

2/

1313

1313

2323

23231212

1212

321

321

321

3

2

ilil U If neutrinos have mass:

)E

LΔm.(θ)νP(ν eμ

222 271sin2sin

For 3 Active neutrinos. (MiniBoone has recently ruled out LSND result)

Solar,Reactor Atmospheric

As of today: Oscillation of 3 massive active neutrinos is clearly the dominant effect:

For two neutrino oscillation in a vacuum: (a valid approximation in many cases)

CP Violating Phase Reactor, Accel. Majorana Phases

Range defined for m12, m23

Maki-Nakagawa-Sakata-Pontecorvo matrix

(Double decay only)?

??

Leptogenesis: or phases -> possible matter/antimatter asymmetry in Early Universe

Matter Effects – the MSW effect

x

e

x

e Hdt

di

cos2θ

4E

Δmsin2θ

4E

Δm

sin2θ4E

ΔmNG2cos2θ

4E

Δm

H 22

2

eF

2

2

22

22

/2

2sin)2cos(

2sin2sin

mENG eF

m

The extra term arises because solar e have an extra interaction via W exchange with electrons in the Sun or Earth.

In the oscillation formula:

(Mikheyev, Smirnov, Wolfenstein)

MSW effect can produce an energy spectrum distortion and flavor regeneration in Earth giving a Day-night effect.If observed, matter interactions define the mass heirarchy.

)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

The Total Flux of Active Neutrinos agrees

reasonably well with solar models:

5.95 (1+- 0.11) [BPS08 (GS)]

4.72 (1+- 0.11) [BPS08 (AGS)]

However, metal abundances, mixing …?

-> CNO measurements: Haxton, Serenelli

SNO Results for Salt Phase

Flavor change determined by > 7

Electron Neutrinos are only 1/3 of Total

-The solar results are best fit with the MSW effect and define the mass hierarchy (m2 > m1) through the Matter interaction.

-SNO: CC/NC flux defines tan2 < 1 (ie Non - Maximal mixing) by more than 5 standard deviations

SolarNeutrinos(SNO plus others)

Reactor Anti-Neutrinos(KAMLAND)

Final Phase: SNO Phase III

• Improve solar neutrino flux by breaking the CC and NC correlation:

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

Phase III production data taking Dec 2004 to Dec 2006. D2O and NCD’s now removed.

NCD’s to be used in HALO: a lead-based Supernova detector for e

122sin

NC

CC

Neutrons from solar neutrino interactions

NC Signal:983 ± 77

Neutron background:185 ± 25

Alphas and Instrumentals:6126 ± 250(0.4 to 1.4 MeV)

SNO PAPER: arXiv:0806.0989v3 [nucl-ex] Phys.Rev.Lett.101:111301,2008

~ 1 alpha background event per month per meter of detector.

NCD Simulation Results data

MC Energy (MeV)

Energy (MeV)

Puls

e W

idth

(nns)

Puls

e W

idth

(nns)

full model of detector physicsto simulate pulse shape

characteristics, correlations

tuned on calibration data

neutron signal

alpha backgrounds:surface polonium decaybulk U and Th decay wire polonium decaywire bulk decayinsulator polonium decayinsulator bulk U and Th decay

stat stat + systSNO Fluxes: 3 Phases

p-value for consistency of NC/CC/ES in the salt & NCD phases + D2O NC(unconstr) is 32.8%

This work:• SNO NCD results agree well with previous SNO phases. Minimal correlation with CC. Different systematics.• New precision on

Future solar analysis: • LETA (Low Energy Threshold Analysis)• 3-neutrino analysis• hep flux• Day-night, other variations

• Muons, atmospheric

Solar + KamLAND fit results

519.021.0

2 1059.7 m eV2

degrees3.12.112 4.34

%)7~(1091.4 126

8 scmB

4.22.212 9.33

deg (previous)

Neutrino flavour symmetry phenomenology: (Smirnov summary at Neutrino 2008)Tri-Bi-Maximal Mixing: 35.2 degQuark-Lepton Complementarity: 32.2 deg(12 + Cabbibo = 45 deg)

The accuracy on and 8B will improve with new data analysis: SNO LETA

SNO Physics (Telescope) Program Solar Neutrinos (7 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 (arXiv: hep-ex 0902.2776) 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

X

SNO

Super-K

SNO provides a test of the Super-Kamiokande oscillation parameters (m2 = 2.1 x 10-3 ev2, sin22 = 1.00 +- 0.032). SNO: 2.6 x 10-3 ev2

SNO also provides a measure of the cosmic neutrino flux above the horizon. Normalization of Bartol 3-D atmospheric neutrino flux model: 1.22 +- 0.10.

SNO Muon & Atmospheric Neutrino Analysis

Through-going muons

SNO data for downward-going muons extends the previous data to about 13.5 km of water equivalent, where atmospheric neutrino generated muons begin to contribute significantly.Also studying neutron productionFrom muons.

New SNO paper arXiv: hep-ex 0902.2776

Downward-going Muons

New AV Hold Down Ropes

ExistingAV SupportRopes

The organicliquid is lighterthan water sothe Acrylic Vesselmust be held down.

New scintillator purification systems are required.

SNO+ : Liquid Scintillator with Nd for Double Beta Decay + Solar, geo -

Otherwise, the existing detector, electronics etc. are unchanged.

1000 tonnes of liquid scintillator (LAB)

(plus 1 tonne of natural Nd = 56 kg of 150Nd for Double BetaDecay)

• 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 2 years.

• 1 tonne of Nd will cause very little degradation of light output. (Successful test in 2008 with small chamber in center of SNO)

• Isotopic abundance 5.6% (in SNO+ 1 tonne Nd = 56 kg 150Nd) • Possible enrichment of 150Nd or increase in the amount of natural

Nd.• SNO+ Capital proposal submitted, decision June 2009. • Plan to start with natural Nd in 2011.• Other physics: CNO solar neutrinos, pep solar neutrinos to study

neutrino properties, geo-neutrinos, supernova search.(No 11C background at this depth.)

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, TUDresden, Leeds,UCLondon

Backgrounds assumed at Kamland observed values plus their purificationobjectives for 210Bi, 40K. Negligible background from 11C at SNOLAB depth.

Capability for 3 Years of Data

pep

CNO

Solar Neutrinos

m

(

eV)

Lightest neutrino (m1) in eV

m = |i Uei ² mi |

m = |m1 cos213cos²12 + m2 e2i cos213sin²12 + m3 e2i sin²13|

Measuring Effective Mass

normal hierarchy inverted hierarchy

SNO+ Sensitivity (3 years): 0.1 eV with 1 tonne natural Nd0.04 with 500 kg 150Nd.

Inverted

Normal

Present Expts.

0.04 eV

Mass Hierarchies

Normal Inverted

Degenerate

0: For example: 1057 events per year with 500 kg 150Nd-loaded liquid scintillator in SNO+.

Simulationassuming lightoutput and backgroundsimilar to Kamland.(Borexino has done better)

SNO+ (150Nd - less Double Beta Decay)

One year of datam= 0.15 eV

Sensitivity Limits (3 yrs): 1000 kg natural Nd (56 kg isotope): m ~ 0.1 eV (start 2011)With 500 kg enriched 150Nd: m ~ 0.04 eV

U ChainTh Chain

~Flat 8B Solar “background”

event rates:• KamLAND: 33 events per year (1000 tons CH2) / 142 events reactor• SNO+: 44 events per year (1000 tons CH2) / 42 events reactor

Geo-Neutrino Signal

SNO+ geo-neutrinos and reactor background

- four times smaller reactor background in the geo-neutrino region than in KamLAND- test models in a region dominated by crustal components.- very well characterized local geology enables residuals to probe the U and Th content of the deep Earth- reactor spectrum “dip” helps constrain m2 and 12

Letters of Intent/Interest (Red implies approval for siting) :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)

Double Beta Decay:150Nd: 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)

SuperNovae:SNO+: Liquid scintillator;

HALO: Pb plus SNO 3He detectors.

SNOLAB Construction is complete – Final cleaning occurring

SNOLAB @ Neutrino 2008 Christchurch May 28th, 2008

SNOLAB

Personnel facilities

SNO Cavern

Ladder Labs

Cube Hall

Phase IICryopit

UtilityArea

2009: MiniCLEAN 3602010: DEAP/CLEAN 3600

Now:DEAP-1

2010: SNO+

2009: HALO

Now:PICASSO-II

New large scale project.

2011: SuperCDMS ?

2010: PICASSO IIB?2010: EXO-200-Gas?

All Lab Air: Class < 2000

PersonnelFacility

LunchRoom

LunchRoom

Start of Clean conditions for the new SNOLAB: Feb. 2009

Cube Hall

MiniCLEAN360 kg2009

DEAP/CLEAN3.6 tonne

2010

Dark Matter Search with Liquid Argon: DEAP-1 (7 kg Ar) (Running); Future: Mini-Clean (360 kg Ar or Ne) and DEAP-3600 (3.6 tonnes Ar)

WIMP-Induced Nuclear recoils in Ar are discriminated from beta and gamma radioactivity (39Ar) by timing of the light emitted.

Dark Matter Search at SNOLAB with Liquid Argon

Yellow: Prompt light regionBlue: Late light region

)s9(TotalPE

)ns150(omptPEPrFprompt

Backgrounds (’s)

Signal (nuclear recoil)

DEAP-1 at SNOLAB

Backgroundsuppression better than2.6 E-8 demonstratedto date

For DEAP/CLEAN 3600suppression of > 10-9

is required.

Note also that sources of Ar depleted x 20 in 39Ar have been found and are being developed with the Princeton group.

CDMS-II: ~50 kg-days (Ge)XENON-10: ~300 kg-days (Xe)DEAP- 3600: 1,000,000 kg-days (Ar) (3 yrs)

SuperCDMS25 kg

PICASSO

Project In CAnada to Search for Supersymmetric Objects

• detectors consist of tiny (5 to 100 m) halocarbon superheated-liquid droplets (e.g. C3F8, C4F10) embedded in a gel

• WIMP-induced nuclear recoils nucleate a bubble; expanding, evaporating bubble produces an acoustic signal detected by piezo microphone

insensitive to beta and gamma radiation; some discrimination exists for alphas

19F favourable target to search for “spin-dependent” WIMP scattering

32 detector modulescontaining 4 L of gel

Phase 1a: (published in ’05 PLB, NIM) 20g 2kgd

Phase Ib: (ongoing)2.6 kg 700 kgdBckg red. 1/6 – 1/10 Phase Ib/100:2.6 kg 700 kgdBckg: red. 1/100 Phase II:25 kg 7000 kgdLarger modules 30L

PICASSO PHASES

MSSMTheoryPredictions

SPIN DEPENDENT WIMP INTERACTION: Studied with Fluorine dispersed in supersaturated gel – WIMP nuclear recoils create bubbles - detected acoustically.Low response for other radioactivity. Breakthrough this year: alpha discrimination

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.

SUMMARY

• SNO operation is complete, further papers to come over next year.

• SNOLAB construction is complete, final cleanliness in progress.

• Several experiments are already 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.

• Stay tuned for some exciting future physics results.