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					          Art McDonald
          SNO Institute
Queen’s University, Kingston, Canada
SOLAR FUSION CHAIN
       Solar Neutrinos
Solar Neutrinos        Experimental Results

                       SAGE+GALLEX/GNO


                       Flux = 0.58 SSM
                       Homestake


                       Flux = 0.33 SSM
                       Kamiokande + Superkamiokande


                       Flux = 0.46 SSM
Figure by J. Bahcall


      Neutrino Flavor Change ?
SSM




Experiments
 Beyond the Standard Model - n mass &
                mixing
Vacuum Oscillations                                 Matter Enhanced
If neutrinos have mass then the lepton
mixing matrix (MNSP) is expressed as                Oscillations (MSW)
    n e        Ue1 Ue2 Ue3  n 1        ns in matter can acquire an
                                       effective mass through scattering
    n                              n
                   U 1 U  2 U 3   2 
                                       (analogous to index of refraction for
    n         U 1 U 2 U 3  n 3 
                                                   light in transparent media)
and flavor eigenstates are a mixture of
mass eigenstates.
                                                   Normal Matter contains many
Then                                               electrons, but no muons or taus, so
        n e  U e1n 1  U e 2n 2  U e3n 3
                                                   ne can undergo both CC and NC
                                                   scattering. Have QM two-state
and the state evolves with time or distance        level crossing and flavor change.
ne  Ue1e iE1tn1  Ue2 e iE2tn2  Ue3e iE3tn3
                                                   MSW Oscillations are dependent
        2   2
where Ei  p  mi
                 2                                 on the n energy and the density of
                                                   the material, hence one can
                                                   observe spectral energy distortions.
         Matter Enhanced n Oscillations
MSW gives a dramatic
extension of oscillation
sensitivity to potential
regions in Dm2
                                            LMA
                            SMA
Solar n data are
consistent with the MSW
hypothesis.
                                            LOW
But only circumstantial
evidence
• Need definitive proof
                            SAGE & GALLEX
• Appearance measurement    Kamiokande
                            Homestake
• Independent of SSM
Solar Model Independent Measurements: SuperKamiokande, SNO
                      (Using 8B Solar Neutrinos)

 SuperKamiokande, SNO
   • MSW Effects
    - Distortion of the spectrum
    - Regeneration in the Earth (Day/Night Effects)
   • Other Time Dependent Effects
    - Seasonal effects (Earth-Sun Distance, Neutrino Magnetic Moments ..)
    - Long Term: Solar cycle … (Neutrino Magnetic Moments …)

  SNO
   • Charged Current to Neutral Current comparisons
    - Electron Neutrino flux compared to Total Active Neutrino flux
Spectral Distortion From
  MSW


    Charged Current (SNO)




Elastic Scattering (SK, SNO)
Superkamiokande
                      Superkamiokande




Also: Limit on Anti-electron neutrinos: few % of Standard Solar Model
                   Including SK
                   Day and Night
                      Spectra


                      Fogli et al.
                   hep-ph/0106247




Active Neutrinos
Solar Model Independent Measurements: SuperKamiokande, SNO
                      (Using 8B Solar Neutrinos)

 SuperKamiokande, SNO
   • MSW Effects
    - Distortion of the spectrum
    - Regeneration in the Earth (Day/Night Effects)
   • Other Time Dependent Effects
    - Seasonal effects (Earth-Sun Distance, Neutrino Magnetic Moments ..)
    - Long Term: Solar cycle … (Neutrino Magnetic Moments …)

  SNO
   • Charged Current to Neutral Current comparisons
    - Electron Neutrino flux compared to Total Active Neutrino flux
                    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
                     n Reactions in SK, SNO

 ES      ν x  e-  ν x  e -
- Both SK, SNO
- Mainly sensitive to ne,, less to n and n
- Strong directional sensitivity


CC     ne  d  p  p  e               -


- Good measurement of ne energy spectrum
- Weak directional sensitivity  1-1/3cos(q)
- ne only.


NC     n x  d  p  n n x
- Measure total 8B n flux from the sun.
- Equal cross section for all n types
Solar Neutrino Physics From SNO
                  Flavor change/oscillations

June 2001    Fcc             ne
                  =
             Fes    ne + 0.154(n + n)
               Fcc           ne
April 2002          =
               Fnc     ne + n + n
April 2002         Fday        vs    Fnight
              Total 8B Solar Neutrino Flux

June 2001    Fx    =   Fcc + (Fes - Fcc) x (1/e)
April 2002                Fx    =   Fnc
                 SNO Run Sequence

   The Three Phases                Neutron Detection Method

Pure D2O Nov. 1999- May 2001      Capture on D
   • Good CC sensitivity         n  d  t  g …  e (Eg = 6.3 MeV)

Added Salt in D2O Counting        Capture on Cl
   • Enhanced NC Since June
     sensitivity            n  35Cl  36Cl  g …  e (Eg = 8.6 MeV)
                    2001


Neutral Current Detectors         Capture on 3He
  • 3He proportional                     n  3He  p  t
     counters in the D2O          Event by event separation of CC
                                    and NC events
Signals in SNO (Monte Carlo, Renormalized)
         Pure D2O
                                     First Analysis:

                     X 0.45
                                     High Threshold,
                     X 1/3
                                     CC, ES only
                                     Jun 2001 PRL 87, 071301
                                      April 2002:
                                      Further Analysis
                                      NC/CC,
                                      Day/Night

                                      Nucl-ex/0204008
                                      Nucl-ex/0204009



                              ~ 9 NHIT/MEV
6.13 MeV   SNO Energy Calibrations
               19.8 MeV




                               252Cf   neutrons




  b’s from 8Li
  g’s from 16N and t(p,g)4He
       Cuts to remove Instrumental Background




                                Mean angle between phototube hits
     Number of phototubes hit                                Fraction of hits in a prompt time window


Signal loss measured with                                           Contamination measured
   calibration sources                                               with independent cuts
              Backgrounds

        Sources               Consequences

High Energy Rock Gammas     Low Energy Threshold
      Uranium Chain
                             Fiducial Volume Cut
      Thorium Chain
 Muon spallation products    Photo Disintegration
         PMT bg               g+ d     p+n
Instrumental Backgrounds           NC Bkg
        Measuring U/Th Content
              Ex-situ
   Ion exchange (224Ra, 226Ra)
   Membrane Degassing (222Rn)
    count daughter product decays
               In-situ
   Low energy data analysis
   Separate 208Tl & 214Bi
       Using Event isotropy




                                              D 2O    H2O/AV
                                    Neutron
                                    Events
                                              44 +8
                                                 -9   27 +8
                                                         -8
   The Pure D2O Phase Dataset
 Livetime: 306.4 days (November 2, 1999             May 27, 2001)
  Day: 128.5 days     Night: 177.9 days

 Energy Threshold: 5 MeV Kinetic

 Fiducial Volume Cut: 550 cm

 Total Number of Events after cuts: 2928
  Neutron Bkg 78 +12 Cherenkov Bkg 45 +18
                  -12                     -12

 The data set is used for a hypothesis test of no neutrino oscillations
 by assuming no MSW distortion and comparing NC and CC. rates
  Nucl-ex/0204008     Nucl-ex/0204009
                Signal Information

Hits and Energy
Direction from Sun
Radial Response
n  d  t  g …  e (Eg = 6.25 MeV)
          Shape Constrained Signal
             Extraction Results
#EVENTS
                       +61.9
          CC 1967.7    +60.9


          ES   263.6 +26.4
                     +25.6

                       +49.5
          NC   576.5   +48.9
    Shape Constrained Neutrino Fluxes
  Signal Extraction in FCC, FNC, FES. ETheshold > 5 MeV

   Fcc(ne) =          +0.06         +0.09
                 1.76 -0.05 (stat.) -0.09 (syst.)     x106 cm-2s-1

   Fes(nx) =          +0.24         +0.12
                 2.39 -0.23 (stat.) -0.12 (syst.)     x106 cm-2s-1

   Fnc(nx) =          +0.44
                 5.09 -0.43
                                      +0.46
                              (stat.) -0.43 (syst.)   x106 cm-2s-1
  Signal Extraction in         Fe, F.
  Fe   =
                +0.05
           1.76 -0.05
                                +0.09
                        (stat.) -0.09 (syst.)   x106 cm-2s-1

  F =        +0.45          +0.48
           3.41 -0.45 (stat.) -0.45   (syst.) x106 cm-2s-1

F is 5.3 sfrom zero ! Clear evidence for Flavour Change !
  Physics Implication Flavor Content
            Fssm = 5.05 +1.01 Fsno = 5.09 +0.44 +0.46
                        -0.81              -0.43 -0.43




F is
5.3 s
from
zero




         Strong evidence of flavor change
              Solar Neutrino Flux
 8B   SSM Flux (BP01)

    F(nx) = 5.05    +1.01
                    -0.81   x106 cm-2s-1

 8B   SSM Flux: First SNO Result (SNO + SK)

    F(nx) =       +0.99
              5.44 -0.99    x106 cm-2s-1

   Signal extraction in R3, cosqSun, Energy (Constrain)

    F(nx) =        +0.44
              5.09 -0.43
                                   +0.46
                           (stat.) -0.43 (syst.)    x106 cm-2s-1

    Signal extraction in R3, cosqSun only

    F(nx) = 6.42    +1.57
                    -1.57   (stat.)
                                      +0.55
                                      -0.58   (syst.) x106 cm-2s-1
           Charged Current Energy Spectrum




CC spectrum derived from    CC spectrum normalized to
fit without constraint on   predicted 8B spectrum.
shape of 8B spectrum         no evidence for shape
above 6.75 MeV              distortion.
       SNO
 Separate Spectra
 For Day and Night




Difference Spectrum
Day - Night                 Ae versus Atotal
Signal Extraction in F CC, F NC, F ES.

    cc = 14.0 + 6.3 +1.5
                -     -1.4

    nc = -20.4 +16.9+2.4
                 -    -2.5

Signal Extraction in F e, F total,


    e     = 12.8 + 6.2 +1.5
                   -     -1.4

    tot = -24.2 + 16.1+2.4
                  -     -2.5

Signal Extraction in F e, F total, A total = 0

                               +1.3
    e     = 7.0 + 4.9
                  -            -1.2

                               +2.0
    esk = 5.3 + 3.7
                -              -1.7
    Physics Interpretation
    Neutrino Oscillations
 SNO Day and Night     Combining All Experimental
Energy Spectra Alone   and Solar Model information
                            LSND
                         ??n >ne
Particle Data
Group 2000
                        Atmospheric
                        n >n


                         Solar
                X        ne >nactive


                    X


                    X
Holanda and Smirnov
                      Less than Maximal Mixing at 3 s
  hep-ph/0205241
Holanda and Smirnov hep-ph/0205241

                        Non-maximal mixing
           Robust under change of other parameters
       STERILE
     NEUTRINOS??


!!
                            4 Neutrino Models
    B. Kayser
  Neutrino 2002

Bahcall, Gonzales-Garcia,
      Pena-Garay
    hep-ph/0204194
  Uncertainty on solar
   Sterile component
         can be
    Reduced to 12%
    By comparison of
   SNO and Kamland
        Other Possible Interpretations
• Flavor-Changing Neutral Currents are still a possibility.
• Resonant Spin-Flavor Precession in the Sun is possible,
but external restrictions on neutrino magnetic moments and
Solar magnetic fields make it improbable.

 Future comparisons of Kamland with solar data will restrict
 the remaining possibilities substantially.
 Note that Kamland uses anti-electron neutrinos so that a
 comparison with solar electron neutrinos is a broader test.
      Future Solar Neutrino Measurements
• SuperKamiokande will be back on line in December, 2002
• Ga experiments will continue to define low energy fluxes.
• SNO will pursue Solar Model Independent measurements
 to define oscillation parameters and neutrino properties:
 * CC-NC comparisons with much improved accuracy
 * Improved spectral shape and Zenith angle information
 * Anti-electron neutrino detection
• Kamland and Borexino will measure 7Be and LOW region.
• Many experiments are in development for pp neutrinos.
        Present and Future of SNO
           The Salt Phase                      Neutral Current Detectors
 n  35Cl  36Cl  g …  e (Eg = 8.6 MeV)          n  3He  p  t

Higher n-capture efficiency                   Event by event separation

Higher event light output

Event isotropy differs from e-

Running since June 2001
Signals in SNO (Monte Carlo, Renormalized)
         Pure D2O   Plus Salt

                                  X 0.45
                                  X 1/3


                        NC Salt
                        (BP98)                     Present Results




                                                   Phase 2:
                                                   Improved NC
                                                   Signal

                                           ~ 9 NHIT/MEV
Signals in SNO (Monte Carlo, Renormalized)
       Pure D2O    Plus 3He Detectors for NC
                                               Phase 3:
                                               • Independent
                                               Signals for NC
                                               • Capture in 3He
                                               Suppresses
                                               6.25 MeV
                                               Gammas from
                                               Capture on D
    NHIT will be lower by 15%   ~ 9 NHIT/MEV
 Restriction of Parameter Space

NC/CC                    DAY/NIGHT (%)




  Holanda and Smirnov hep-ph/0205241
 SUMMARY OF SOLAR NEUTRINO MEASUREMENTS

• SNO shows 5.3 s evidence for neutrino flavor change to active neutrinos.
• Result is consistent with previous SNO-SK comparison that gave
 3.3 sevidence.
• MSW analysis of all experiments strongly favors LMA solution.
• Transformation solely to sterile neutrinos ruled out at more than 5 s.
• Possible Sterile component strongly restricted by comparison with
 Atmospheric n.
• No evidence of regeneration in Earth.
• No evidence for anti-electron neutrinos.
• Time dependence shows only geometric effects.
• Future measurements of solar, reactor neutrinos can restrict parameters
 further.
   New International Underground Science Facility
                 At the Sudbury site
Proposal ($ 30M) submitted to Canada Foundation for Innovation:
                Approved June 19, 2002 !!!

To build on the success of the underground science being done
by SNO and pursue further measurements of:

- Neutrinos from Astrophysical sources
    * The next generation SNO experiment (Wavelength Shifter ?)
    * Lower Energy Solar Neutrinos

- Other Forms of Dark Matter (WIMPS)
    * PICASSO (Bubble Detectors)

- Double Beta Decay

- Low Background Counting Test Facility
14m x 14m x 60m, Clean Area

				
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