Status of the Sudbury Neutrino Observatory (SNO)

1
Status of the Sudbury Neutrino Observatory (SNO)

• Alan Poon
• for the SNO Collaboration
• Institute for Nuclear and Particle Astrophysics
• Lawrence Berkeley National Laboratory, Berkeley,
  USA

2
Outline

• What we did(Phase I Pure D2O target)
• What we are doing(Phase II D2O NaCl)
• What we will be doing(Phase III Neutral Current
  Detectors)

3
Sudbury Neutrino Observatory
1006 tonnes D2O
17.8m dia. PMT Support Structure 9456 20-cm dia.
PMTs 56 coverage
12.01m dia. acrylic vessel
1700 tonnes of inner shielding H2O
Urylon liner
5300 tonnes of outer shielding H2O
Nucl. Inst. Meth. A449, 127 (2000)
4
Detecting ? at SNO

• Measurement of ne energy spectrum
• Weak directionality

• Measure total 8B n flux from the sun
• s(ne) s(nm) s(nt)

• Low Statistics
• s(ne) ? 6 s(nm) ? 6 s(nt)
• Strong directionality

5
Phase I Extracting the Solar n Flux
CC
NC
ES
Max. Likelihood Fit

• PDFs
• kinetic energy T, event location R3,
• and solar angle correlation cos qsun

6
Phase I Missing Solar ns Found
Null hypothesis of no flavor transformation
rejected at 5.3s
See Phys.Rev.Lett. 89 (2002) 011301
Phys.Rev.Lett. 89 (2002) 011302
Solar Model predictions are verified in 106
cm-2 s-1
8B n shape constrained fit
No 8B n shape constraint
7
Correlation in Signal Extraction (Phase I)
Strong statistical anti-correlation between NC
and CC in the signal extraction
Correlation Matrix
CC ES NC
CC 1.000 -0.162 -0.520
ES -0.162 1.000 -0.105
NC -0.520 -0.105 1.000
8
Phase II (D2O 2 tons NaCl)

• Added 2 tons of salt in June 2001 to enhance NC
  detection efficiency and to improve the
  separability of NC and CC Cherenkov signals
• CC Single electron
• (Cherenkov signal less isotropic)
• NC Multiple gs following n capture on 35Cl
• (Cherenkov signal more isotropic)

Variables CC Stat. Error NC Stat. Error ES Stat. Error
E,R,?sun 3.4 8.6 10
R, ?sun 9.5 24 11
E,R,?sun 4.2 6.3 10
E,R,?sun, Iso. 3.3 4.6 10
R,?sun,Iso. 3.8 5.3 10
Simulation
PRL, 89, No. 1, 011301, (2002)
9
Phase II Blind Analysis

• 280 live days
• Triple blind analysis to ensure independence from
  Phase I

• CC, ES
• data set pre-scaled by an unknown factor of
  8010
• NC
• Leak an unknown number of spallation neutrons
  in the data
• NC interaction cross section in the Monte Carlo
  is spoiled by an
• unknown factor

10
Phase II Analysis Challenges
I. Energy Scale Drift
II. Light Isotropy
Absolute Energy Scale Uncertainty 1.1
(preliminary) c.f. 1.2 in Phase I
Mott scattering missing in EGS4, now added in the
SNO Monte Carlo
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Phase II Analysis Challenges
III. Neutron Efficiency
IV. 24Na

• 23Na (in the plumbing) activated by neutrons
  from the rock wall
• 24Na b decays and emits 2 g (1.37, 2.75 MeV)
• calibrated by controlled activation

Z cm
v(x2y2) cm
v(x2y2) cm
12
Decoupling CC and NC in Phase III

• CC Cherenkov Signal ? PMT Array
• NC n3He ? Neutral Current Detector Array

13
SNO Summary
Phase II (D2ONaCl)

• Final full detector calibration of Phase II
  completed
• Analysis of the blind data is completebox to be
  opened upon completion of internal review
• Other analyses in progress solar anti-neutrino,
  day-night flux, proton decay, atmospheric
  neutrinos, muon spallationStay tuned!

Phase III (Neutral Current Detector)

• All 3He counters have been constructed and
  stored in the underground lab
• All counters are being characterized
• Integration of electronics and DAQ in progress
• Deployment in Fall 2003

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The SNO Collaboration
J.D.Anglin, M.Bercovitch, W.F.Davidson,
R.S.Storey National Research Council of
Canada J.C.Barton, S.Biller, R.A.Black,
R.J.Boardman, M.G.Bowler, J.Cameron,
B.T.Cleveland, X.Dai, G.Doucas,
J.A.Dunmore, A.P.Ferarris, H.Fergani, K.Frame,
N.Gagnon, H.Heron, N.A.Jelley, A.B.Knox, M.Lay,
W.Locke, J.Lyon, S.Majerus, G.McGregor, M.Moorhead
, M.Omori, C.J.Sims, N.W.Tanner,
R.K.Taplin, M.Thorman, P.M.Thornewell, P.T.Trent,
N.West, J.R.Wilson University of
Oxford E.W.Beier, D.F.Cowen, M.Dunford,
E.D.Frank, W.Frati, W.J.Heintzelman, P.T.Keener,
J.R.Klein, C.C.M.Kyba, N.McCauley, D.S.McDonald,
M.S.Neubauer, F.M.Newcomer, S.M.Oser, V.L
Rusu, R.Van Berg, P.Wittich University of
Pennsylvania   R.Kouzes Princeton
University E.Bonvin, M.Chen, E.T.H.Clifford,
F.A.Duncan, E.D.Earle, H.C.Evans, G.T.Ewan,
R.J.Ford, K.Graham, A.L.Hallin, W.B.Handler,
P.J.Harvey, J.D.Hepburn, C.Jillings,
H.W.Lee, J.R.Leslie, H.B.Mak, J.Maneira,
A.B.McDonald, B.A.Moffat, T.J.Radcliffe,
B.C.Robertson, P.Skensved Queens
University D.L.Wark Rutherford Appleton
Laboratory, University of Sussex R.L.Helmer,
A.J.Noble TRIUMF Q.R.Ahmad, M.C.Browne,
T.V.Bullard, G.A.Cox, P.J.Doe, C.A.Duba,
S.R.Elliott, J.A.Formaggio, J.V.Germani, A.A.Hamia
n, R.Hazama, K.M.Heeger, K.Kazkaz, J.Manor,
R.Meijer Drees, J.L.Orrell, R.G.H.Robertson,
K.K.Schaffer, M.W.E.Smith, T.D.Steiger,
L.C.Stonehill, J.F.Wilkerson University of
Washington

• G.Milton, B.Sur
• Atomic Energy of Canada Ltd., Chalk River
  Laboratories
• S.Gil, J.Heise, R.J.Komar, T.Kutter, C.W.Nally,
  H.S.Ng,
• Y.I.Tserkovnyak, C.E.Waltham
• University of British Columbia
• J.Boger, R.L Hahn, J.K.Rowley, M.Yeh
• Brookhaven National Laboratory
• R.C.Allen, G.Bühler, H.H.Chen
• University of California, Irvine
•  
• I.Blevis, F.Dalnoki-Veress, D.R.Grant,
  C.K.Hargrove, I.Levine,
• K.McFarlane, C.Mifflin, V.M.Novikov, M.O'Neill,
  M.Shatkay,
• D.Sinclair, N.Starinsky
• Carleton University
•  
• T.C.Anderson, P.Jagam, J.Law, I.T.Lawson,
  R.W.Ollerhead,

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• The END

16

• Backup Slides

17
Global Solar n Analysis

• Inputs 37Cl, latest Gallex/GNO, new SAGE, SK
  1258-day day night spectra
• SNO day spectrum (total CCNCESbackground)
• SNO night spectrum (total CCNCESbackground)
• 8B floats free in fit, hep n at 1 SSM

Global
SNO data only
18
What will SNO and KamLAND tell us in the future
de Holanda et al., hep-ph/0212270 Barger et al.,
hep-ph/0204253
19
Model Independent Test of MSW

• KamLAND establishes LMA region (Dm2gt10-6 eV2)
• Use CC/NC (solar model independent) to test for
  MSW effect in the Sun

MSW off
MSW On
Fogli et al., hep-ph/0211414