The Sudbury Neutrino Observatory and The Bruno Pontecorvo Prize

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The Sudbury Neutrino Observatory and The Bruno
Pontecorvo Prize
2
I am deeply honoured to receive the Bruno
Pontecorvo Prize on behalf of myself and my many
colleagues in the Sudbury Neutrino
Observatory Scientific Collaboration
3
The SNO Collaboration
J. C. Barton, S. D. Biller, R. A. Black, R.
Boardman, M. G. Bowler, J. Cameron, B. T.
Cleveland, G. Doucas, J. A. Dunmore, A. P.
Ferraris, H. Fergani, K.Frame, H. Heron, C.
Howard, N. A. Jelley, A. B. Knox, M. Lay, J. C.
Loach, W. Locke, J. Lyon, N. McCaulay, S.
Majerus, G. McGregor, M. Moorhead, M. Omori, S.
J. M. Peeters, C. J. Sims, N. W. Tanner, R.
Taplin, M. Thorman, P. T. Trent, D. H. Wan Chan
Tseung, N. West, J. R. Wilson, K. Zuber Oxford
University E. W. Beier, D. F. Cowen, J. Deng,
M. Dunford, E. D. Frank, W. Frati, W. J.
Heintzelman, P.T. Keener, C. C. M. Kyba, N.
McCauley,D. S. McDonald, M.S.Neubauer, F. M.
Newcomer,V. L. Rusu, R. Van Berg, P.
Wittich. University of Pennsylvania M.M. Lowry,
Princeton University S.N. Ahmed, E. Bonvin, M.
G. Boulay, M. Chen, E. T. H. Clifford, Y. Dai,
F. A. Duncan, E. D. Earle,H. C. Evans, G.T. Ewan,
R. J. Ford, B. G. Fulsom, K. Graham, W. B.
Handler, A. L. Hallin, A. S. Hamer, P. J.
Harvey, R. Heaton, J. D. Hepburn, C. Jillings, M.
S. Kos, L. L. Kormos, R. Kouzes, C. B. Krauss,
A. V. Krumins, H. W. Lee, J. R. Leslie, R.
MacLellan, H. B. Mak, J. Maneira, A. B.
McDonald, W. McLatchie, B. A. Moffat, A. J.
Noble, C. Ouellet, T. J. Radcliffe, B.C.
Robertson, P. Skensved, B. Sur. Y. Takeuchi, M.
Thomson 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 Q. R. Ahmad,
M. C. Browne, T.V. Bullard, T. H. Burritt, G. A.
Cox, P. J. Doe, C. A. Duba, S. R. Elliott, R.
Fardon, J. A. Formaggio, J.V. Germani, A. A.
Hamian, R. Hazama, K. M. Heeger, M. A. Howe, S.
McGee, R. Meijer Drees, K. K. S. Miknaitis, N. S.
Oblath, J. L. Orrell, K. Rielage, R. G. H.
Robertson, K. Schaffer, M. W. E. Smith, T. D.
Steiger, L. C. Stonehill, B. L. Wall, J. F.
Wilkerson. University of Washington G. Milton,
B. Sur, AECL, Chalk River

deceased

• S. Gil, J. Heise, R.L. Helmer, R.J. Komar, T.
  Kutter,
• S. M. Oser, C.W. Nally, H.S. Ng, R. Schubank,
• Y. Tserkovnyak, T. Tsui, C.E. Waltham, J.
  Wendland
• University of British Columbia
• J. Boger, R. L Hahn, R. Lange J.K. Rowley, M. Yeh
• Brookhaven National Laboratory
• I. Blevis, A. Bellerive, X. Dai, F.
  Dalnoki-Veress, R. S. Dosanjh,
• W. Davidson, J. Farine, D.R. Grant, C. K.
  Hargrove,
• R. J. Hemingway, I. Levine, K. McFarlane, H.
  Mes, C. Mifflin,
• V.M. Novikov, M. O'Neill, E. Rollin, M. Shatkay,
  C. Shewchuk,
• O. Simard, D. Sinclair, N. Starinsky, G. Tesic,
  D. Waller
• Carleton University
• T. Andersen, K. Cameron, M.C. Chon, P. Jagam, J.
  Karn,
• H. Labranche, J. Law, I.T. Lawson,B. G. Nickel,
• R. W. Ollerhead, J. J. Simpson, N. Tagg, J.X.
  Wang
• University of Guelph

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SNO and Bruno Pontecorvo

• We are particularly honored because of the
  strong respect that we have
• for Bruno Pontecorvo and the brilliant insight
  that he brought to the field
• of Neutrino Physics.
• Our experiment was conceived to provide a direct
  test of whether
• neutrinos from the core of Sun undergo flavor
  change before reaching Earth.
• - The concept of flavour change was put forward
  by in a paper by Gribov and
• Pontecorvo in 1967, shortly after the initial
  measurements of Ray Davis
• showed too few neutrinos from the Sun.
• We have provided clear evidence that neutrinos
  change their flavour, confirming
• the proposal of Gribov and Pontecorvo and the
  accuracy of solar models.
• Our measurements can be combined with other
  measurements to confirm
• that the dominant mechanism for neutrino flavour
  change is oscillation of massive
• neutrinos - a mechanism proposed by Bruno
  Pontecorvo in 1957.

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Solar Neutrino Problem
Solar Fluxes Bahcall et al
Experiment vs Solar Models
1970 - 2001
Smaller than expected flux of electron
neutrinos Neutrino Flavor Change or Solar Model
Effects?
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Solar Model Independent Measurements
SuperKamiokande, SNO (Using 8B Solar Neutrinos)
SuperKamiokande Measurements

• Matter-Enhanced Oscillations 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 )

None of the above effects are seen with clear
signals of oscillations
Sudbury Neutrino Observatory
However

• Charged Current to Neutral Current comparisons
• - Electron Neutrino flux compared to Total
  Active Neutrino flux

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Unique Signatures in SNO (D2O)
Charged-Current (CC) ?ed ? e-pp Ethresh
1.4 MeV ?e only
Neutral-Current (NC) ?xd ? ?xnp Ethresh
2.2 MeV Equally sensitive to ?e nm ?t
3 ways to detect neutrons
Elastic Scattering (ES) ?xe- ? ?xe- ?x, but
enhanced for ?e
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Solar Neutrino Physics From SNO
Flavor change active neutrino appearance
FCC
ne
June 2001 (with SK)
3.3 s

FES
ne 0.15 (nm nt)
ne
FCC
5.3 s
April 2002

FNC
ne nm nt
Sept. 2003
gt 7 s
(With salt)
Total 8B Solar Neutrino Flux
June 2001
April 2002
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Sept. 2003
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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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One million pieces transported and assembled
under ultra-clean conditions.
More than 60,000 showers and counting
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Observables
PMT Measurements

• position
• time
• charge

Reconstructed event

• vertex
• direction
• energy
• isotropy

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3 neutron (NC) detection methods
Phase I (D2O) Nov. 99 - May 01
Phase II (salt) July 01 - Sep. 03
Phase III (3He) Summer 04-Dec. 06
n captures on 2H(n, g)3H Effc. 14.4 NC and CC
separation by energy, radial, and directional
distributions
40 proportional counters 3He(n, p)3H Effc. 30
capture Measure NC rate with entirely different
detection system.
2 t NaCl. n captures on 35Cl(n, g)36Cl Effc. 40
NC and CC separation by event isotropy
5 cm
n
3H
p
3He
n 3He ? p 3H
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Signal Extraction for Salt
Blind Analysis performed by adding in an
unknown number of neutrons generated by muons
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
Radial Profile
Phys.Rev.Lett. 92 (2004) 181301
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Results from SNO Salt Phase (2003) Agreement
Pure D2O measurements (2001,02)
8B shape unconstrained
8B shape constrained
Total active neutrino (8B) flux Solar Model -gt
Restriction on sterile neutrinos
(Bahcall et al 2004)
Clear evidence for Flavor Change (gt 7 s)
through independent measurements of F(ne) and
F(nTotal Active)
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Neutrino properties

• The most favored explanation for the data to date
  is Neutrino
• Oscillation of massive neutrinos. (As proposed by
  Pontecorvo)
• Others are ruled out as dominant, but could be
  small sub-dominant
• Flavor Changing Neutral Currents,
• Resonant Spin Flavor Precession for solar
  neutrinos
• Violation of Equivalence Principle, Lorentz
  Invariance
• Sterile neutrinos.

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As proposed originally by Pontecorvo
For three neutrinos
Pontecorvo-Maki-Nakagawa-Sakata matrix
(Double b decay only)
?
?
?
Solar,Reactor
Atmospheric
CP Violating Phase
Reactor,LBL
Majorana Phases
Range defined for Dm12, Dm23
For two neutrino oscillation in a vacuum (valid
approximation in many cases)
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After SNO Salt Data Closing in on Dm122, q12
LMA MSW only at gt 99.73 CL
Kamland parameters agree with solar
Solar
--90 --95 --99 --99.73
Solar Kamland reactor
Maximal Mixing disallowed at 5.4 s q12 32.5
- 1.7 o
MSW m2 gt m1
Future SNO (and SNO) measurements will improve
the accuracy further.
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SNO
SNOLAB 2 km Underground (20 times lower cosmic
ray flux than Gran Sasso) 15 Letters of Interest
from International Community bb decay, Dark
Matter, Solar n. Completion 2007
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Many Connections Between Bruno Pontecorvo And SNO

• Science
• He proposed chlorine as a detection medium for
  reactor and solar neutrinos
• Developed proportional counters used by Davis
  and SNO 3He detectors
• Proposed neutrino oscillations
• Proposed oscillations as the explanation for the
  solar neutrino problem

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Many Connections Between Bruno Pontecorvo And SNO

• Science
• He proposed chlorine as a detection medium for
  reactor and solar neutrinos
• Developed proportional counters used by Davis
  and SNO 3He detectors
• Proposed neutrino oscillations
• Proposed oscillations as the explanation for the
  solar neutrino problem

• Indirectly
• One of the principal scientists developing the
  heavy water nuclear reactor
• Therefore Canadian reserves of heavy water
  available for SNO.
• He developed well logging with neutron sources
• Main SNO calibration 16N produced with a
  neutron source
• developed for well logging

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Many Connections Between Bruno Pontecorvo And SNO

• Science
• He proposed chlorine as a detection medium for
  reactor and solar neutrinos
• Developed proportional counters used by Davis
  and SNO 3He detectors
• Proposed neutrino oscillations
• Proposed oscillations as the explanation for the
  solar neutrino problem

• Indirectly
• One of the principal scientists developing the
  heavy water nuclear reactor
• Therefore Canadian reserves of heavy water
  available for SNO.
• He developed well logging with neutron sources
• Main SNO calibration 16N produced with a
  neutron source
• developed for well logging

• International support
• An important letter of support at a critical
  time for SNO in 1988

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Many Connections Between Bruno Pontecorvo And SNO

• Science
• He proposed chlorine as a detection medium for
  reactor and solar neutrinos
• Developed proportional counters used by Davis
  and SNO 3He detectors
• Proposed neutrino oscillations
• Proposed oscillations as the explanation for the
  solar neutrino problem

• Indirectly
• One of the principal scientists developing the
  heavy water nuclear reactor
• Therefore Canadian reserves of heavy water
  available for SNO.
• He developed well logging with neutron sources
• Main SNO calibration 16N produced with a
  neutron source
• developed for well logging

• International support
• An important letter of support at a critical
  time for SNO in 1988

• Personal
• My first 12 years of basic research were at
  Chalk River.
• I knew many of Pontecorvos Chalk River
  collaborators personally
• - Hanna, Carmichael, Hincks, Sargeant.
• Bruno Pontecorvo and I played tennis on the
  same courts in Deep River
• 30 years separated in time and light years
  separated in ability!

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First Tennis Champion at Chalk River
1948 Bruno Pontecorvo
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I was honored to meet Bruno Pontecorvo at
Neutrino 1992 in Granada, Spain and to provide a
tour of the SNO exhibit at the Canadian
Pavillion at EXPO 1992 in Seville and to have
discussions about his Canadian colleagues. His
science, his sense of humour and his athletic
ability captivated me. Today is a wonderful
honor for me and for our project team to receive
the Bruno Pontecorvo Prize named after such a
great scientist.
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