Results from SNO and Other Solar Neutrino Experiments

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Results from SNO and Other Solar Neutrino
Experiments

• R.G. Hamish Robertson
• University of Washington
• for
• The Sudbury Neutrino Observatory Collaboration

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Solar Neutrino Program
Comm.
D2O
Salt
SNO
D2O
3He Counters
SK
Cl-Ar
SAGE, Gallex, GNO
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SAGE (January 1990 March 2003)
With Weight Factors
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GALLEX - GNO Davis plot
GNO 58 solar runs
GALLEX 65 solar runs
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GNO Results
completed 58 solar runs 1713 days still
counting 5 solar runs (30 days) blanks 12
GNO (31/08/2003) 62.9 5.4 2.5 SNU (L 68.
9. K 60. 7.) GALLEX 77.5 6.2 4.3-4.7
SNU GALLEXGNO 69.3 4.1 3.6 SNU
SAGE 69.1 4.3 -4.2 SNU
Further minor improvements expected in a short
time ( analysis of counter calibration data)
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New Low-energy Solar n Detectors
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Recent Super-K Analysis
Full zenith-angle dependence 1496-day
dataset hep-ex/0309011 (Michael Smy, TAUP)
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Sudbury Neutrino Observatory
1000 tonnes D2O
Support Structure for 9500 PMTs, 60 coverage
12 m Diameter Acrylic Vessel
1700 tonnes Inner Shielding H2O
5300 tonnes Outer Shield H2O
Urylon Liner and Radon Seal
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? Reactions in SNO
p

• Gives ne energy spectrum well
• Weak direction sensitivity ? 1-1/3cos(q)
• ne only.

• Measure total 8B n flux from the sun.
• Equal cross section for all n types

• Low Statistics
• Mainly sensitive to ne,, some
• sensitivity to n? and n?
• Strong direction sensitivity

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Neutrino Flavor Composition of 8B Flux
Fluxes (106 cm-2 s-1) ne 1.76(11) nmt
3.41(66) ntotal 5.09(64) nSSM 5.05
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Total spectrum (NC CC ES)
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tan2q12-Dm122
Solar Only
SolarKL rate
SolarKL spect.
de Holanda Smirnov, hep-ph/0205241,
hep-ph/0212270
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Advantages of NaCl for Neutron Detection

• Higher capture cross section
• Higher energy release
• Many gammas

s 44 b
35Cln
s 0.0005 b
8.6 MeV
2Hn
6.0 MeV
3H
36Cl
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Neutron Capture Efficiency in SNO
35Cl(n,g)36Cl Average Eff. 0.399 Te 5.5 MeV
and Rg 550 cm
2H(n,g)3H Average Eff. 0.144 Te 5.0 MeV and
Rg 550 cm
Radial Position of 252Cf Source, cm
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Cherenkov light and b14
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Use of b14 to distinguish neutrons and e-
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Addition of Mott scattering to EGS4
Angular Distribution of 5 MeV electrons after
passing through 1 mm of water
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Blind Analysis

• Three blindfolds for the analysts
• Include unknown fraction of neutrons that follow
  muons
• Spoil the NC cross section in MC
• Veto an unknown fraction of candidate events

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b14 Distributions for SNO Salt Data
Data from July 26, 2001 to Oct. 10, 2002 254.2
live days 3055 candidate events 1339.6 63.8
-61.5 CC 1344.2 69.8 -69.0 NC 170.3 23.9
-20.1 ES
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Sun-angle distributions
Away from sun
Toward sun
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Energy spectra
Electron kinetic energy
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Sources of Background

• 2H(g,n)p by 214Bi, 208Tl
• Cosmic rays neutrons, spallation products
• Atmospheric neutrinos, reactors, CNO
• Fission (U, Cf)
• (a,n) reactions
• 24Na activation (neck, calibration, recirc,
  muons)
• AV events

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Radioassay

• Bottom of vessel
• 2/3 way up
• Top of vessel

• MnOx
• HTiO

• MnOx
• HTiO

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Backgrounds
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Radial distributions
550
600
700 cm
0
(Reconstructed radius, cm/ 600)3
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Uncertainties in Fluxes ()
Internal neutrons
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CC, ES, and NC fluxes from Pure D2O Phase
Shape of 8B spectrum in CC and ES not constrained
Standard (Ortiz et al.) shape of 8B spectrum in
CC and ES
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Salt Phase Box Opened Aug. 13, 2003
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Total Active 8B Fluxes
In units of Bahcall, Pinsonneault, Basu SSM, 5.05
x 106 cm-2 s-1
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2-n oscillation region defined by SNO
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tan2q12-Dm122 before Salt Phase
Solar Only
SolarKL rate
SolarKL spect.
de Holanda Smirnov, hep-ph/0205241,
hep-ph/0212270
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For the unconstrained fits
Correlation coefficients
Ratio
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Closing in on Dm2, q
--90 --95 --99 --99.73
LMA I only at gt 99 CL
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One-dimensional marginalized limits on Dm2 and
q Maximal mixing rejected at 5.4 s
LMA 1
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Results from SNO -- Salt Phase
Oscillation Parameters, 2-D joint 1-s boundary
lt 1 probability of LMA I
Marginalized 1-D 1-s errors
Maximal mixing rejected at 5.4 s
A paper plus a companion guide can be found at
sno.phy.queensu.ca this morning. Submitted to
PRL nucl-ex/0309004.
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SNO gratefully acknowledges
Canada Natural Sciences and Engineering
Research Council Northern Ontario Heritage Fund
Corporation Inco Atomic Energy of Canada,
Ltd. Ontario Power Generation High Performance
Computing Virtual Laboratory National Research
Council Canada Foundation for Innovation US De
partment of Energy UK Particle Physics and
Astronomy Research Council
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The SNO Collaboration
S.D. Biller, M.G. Bowler, B.T. Cleveland, G.
Doucas, J.A. Dunmore, H. Fergani, K. Frame, N.A.
Jelley, S. Majerus, G. McGregor, S.J.M. Peeters,
C.J. Sims, M. Thorman, H. Wan Chan Tseung, N.
West, J.R. Wilson, K. Zuber Oxford
University E.W. Beier, M. Dunford, W.J.
Heintzelman, C.C.M. Kyba, N. McCauley, V.L.
Rusu, R. Van Berg University of
Pennsylvania S.N. Ahmed, M. Chen, F.A. Duncan,
E.D. Earle, B.G. Fulsom, H.C. Evans, G.T. Ewan,
K. Graham, A.L. Hallin, W.B. Handler, P.J.
Harvey, M.S. Kos, A.V. Krumins, J.R. Leslie, R.
MacLellan, H.B. Mak, J. Maneira, A.B. McDonald,
B.A. Moffat, A.J. Noble, C.V. Ouellet, B.C.
Robertson, P. Skensved, M. Thomas,
Y.Takeuchi Queens University D.L.
Wark Rutherford Laboratory and University of
Sussex R.L. Helmer TRIUMF A.E. Anthony, J.C.
Hall, J.R. Klein University of Texas at
Austin T.V. Bullard, G.A. Cox, P.J. Doe, C.A.
Duba, J.A. Formaggio, N. Gagnon, R. Hazama, M.A.
Howe, S. McGee, K.K.S. Miknaitis, N.S. Oblath,
J.L. Orrell, R.G.H. Robertson, M.W.E. Smith,
L.C. Stonehill, B.L. Wall, J.F.
Wilkerson University of Washington

• T. Kutter, C.W. Nally, S.M. Oser, C.E. Waltham
• University of British Columbia
• J. Boger, R.L. Hahn, R. Lange, M. Yeh
• Brookhaven National Laboratory
• A.Bellerive, X. Dai, F. Dalnoki-Veress, R.S.
  Dosanjh, D.R. Grant,
• C.K. Hargrove, R.J. Hemingway, I. Levine, C.
  Mifflin, E. Rollin,
• O. Simard, D. Sinclair, N. Starinsky, G. Tesic,
  D. Waller
• Carleton University
• P. Jagam, H. Labranche, J. Law, I.T. Lawson, B.G.
  Nickel,
• R.W. Ollerhead, J.J. Simpson
• University of Guelph
• J. Farine, F. Fleurot, E.D. Hallman, S. Luoma,
• M.H. Schwendener, R. Tafirout, C.J. Virtue
• Laurentian University

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SNO Phase III (NCD Phase)- Begins 04

• 3He Proportional Counters (NC Detectors)

40 Strings on 1-m grid 440 m total active
length
Detection Principle 2H ?x ? p n ?x - 2.22
MeV (NC) 3He n ? p 3H 0.76 MeV
PMT
Physics Motivation Event-by-event separation.
Measure NC and CC in separate data streams.
Different systematic uncertainties than
neutron capture on NaCl. NCD array removes
neutrons from CC, calibrates remainder. CC
spectral shape.
NCD
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Why Event-by-Event?
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Counts per second
N. Oblath
Time after muon, s
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16N in D2O
Counts per s
A.D. Marino
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(a,n) Reactions
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BOREXINO radiopurity requirements
If secular equilibrium is broken contaminants
such as 210Pb, 210Po may be a serious problem
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GALLEX GNO Seasonal variations
Winter-Summer (statistical error only)
GNO only (58 SRs) Winter (32 SR) 58.77.1-6.8
SNU Summer (26 SR) 69.08.8-8.3 SNU W-S -10
11 SNU
GNO Gallex (123 SRs) Winter (66 SR)
66.55.6-5.4 SNU Summer (57 SR) 74.16.4-6.2
SNU W-S -7.6 9 SNU
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SNO KamLAND
3s
Day Night Contours ()
1s
CC/NC Contours
de Holanda, Smirnov hep-ph/ 0212270
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Neutron Capture Efficiency in SNO
35Cl(n,g)36Cl Average Eff. 0.399 Te 5.5 MeV
and Rg 550 cm
2H(n,g)3H Average Eff. 0.144 Te 5.0 MeV and
Rg 550 cm
Radial Position of 252Cf Source, cm
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Backgrounds
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Uncertainty Budget