SNO and the new SNOLAB SNO: Heavy Water Phase Complete Status of SNOLAB Future experiments at...
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SNO and the new SNOLAB • SNO: Heavy Water Phase Complete • Status of SNOLAB • Future experiments at SNOLAB: (Dark Matter, Double beta, Solar , geo-, supernova ) Art McDonald, SNO Institute Director For the SNO Collaboration Neutrino Telescopes, Venice, 2007
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Transcript of SNO and the new SNOLAB SNO: Heavy Water Phase Complete Status of SNOLAB Future experiments at...
SNO and the new SNOLAB
• SNO: Heavy Water Phase Complete• Status of SNOLAB• Future experiments at SNOLAB: (Dark Matter,
Double beta, Solar , geo-, supernova )
Art McDonald,
SNO Institute Director
For the SNO Collaboration
Neutrino Telescopes, Venice, 2007
Unique Signatures in SNO (D2O)
Charged-Current (CC)e+d e-+p+pEthresh = 1.4 MeV
ee onlyonly
Elastic Scattering (ES)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
Phase II (salt)July 01 - Sep. 03
Phase III (3He)Nov. 04 - Nov. 06
Phase I (D2O)Nov. 99 - May 01
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
Sudbury Neutrino Observatory
1700 tonnes InnerShielding H2O
1000 tonnes D2O ($300 M)
5300 tonnes Outer Shield H2O
12 m Diameter Acrylic Vessel
Support Structure for 9500 PMTs, 60% coverage
Urylon Liner andRadon Seal
200 tonnes has been returned
ISOTROPY: NC, CC separation
DIRECTION FROM SUN
EVENTS VS VOLUME: Bkg < 10%
ENERGY SPECTRUM FROM CC REACTIONHeavy water
SALT PHASE (“Near Background-free” analysis)
)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
122029.0
031.0 sin)stat.(023.034.0
NC
CCeeP
High accuracy for
Electron neutrinos
The Total Flux of Active
Neutrinos is measured
independently (NC) and agrees
well with solar model
Calculations:
4.7 +- 0.5 (BPS07),
5.31 +- 0.6 (Turck-Chieze et al 04)
CC, NC FLUXESMEASURED
INDEPENDENTLY
Flavor change determined by > 7
)1.3(45.0 eeP Implies Matter Interactions (Folgi, Lisi 2004)
- SNO: CC/NC fluxdefines tan2 < 1 (ie Non - Maximal mixing)by more than 5standard deviations.
-The mass hierarchy isdefined (m2 > m1) through thematter interaction (MSW)
SOLAR ONLY
AFTER NEW
SNO SALT
DATA
SOLAR PLUS KAMLAND
(assuming CPT)
(Reactor ’s)
Large mixing
Angle (LMA)
Region: MSW
LMA for solar predicts very small
spectral distortion, small (~ 3 %) day-night
asymmetry, as observed by SNO, SK
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 began Dec 2004; completed November 2006
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
Total Radioactivity similarTo Phase I, II
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.
BLIND ANALYSIS:Add in unknown number of neutrons from muons
