Transcript Slide 1
The Sudbury Neutrino Observatory and The Bruno Pontecorvo Prize
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
The SNO Collaboration
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 B. Aharmim, J. Bigu, J.H.M. Cowan, J. Farine, F. Fleurot, N. Gagnon, E. D. Hallman, R. U. Haq, J. Hewett, J.G. Hykawy, G. Jonkmans, A. Kruger, S. Luoma, A. Roberge, E. Saettler, M.H. Schwendener, H. Seifert, R. Tafirout, C. J. Virtue Laurentian University Y. D. Chan, X. Chen, C. A. Currat, M.C.P. Isaac, K. M. Heeger, K. T. Lesko, A.D. Marino, E.B. Norman, C.E. Okada, A.W. P. Poon, S. S. E. Rosendahl, A. R. Smith, A. Schuelke, R. G. Stokstad Lawrence Berkeley National Laboratory M. G. Boulay, T. J. Bowles, S. J. Brice, M. R. Dragowsky, S. R. Elliott, M. M. Fowler, A. Goldschmidt, A. Hime, J. Heise, K. Kirch, G. G. Miller, P. Thornewell, R. G. Van de Water, J. B. Wilhelmy, J. M. Wouters. Los Alamos National Laboratory R.G. Allen, G. Buhler, H.H. Chen* University of California, Irvine J. D. Anglin, M. Bercovitch, W. F. Davidson, R. S. Storey* National Research Council of Canada 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 Queen’s 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
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.
“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
?
Solar Model Independent Measurements: SuperKamiokande, SNO (Using
8
B 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 However:
•
Sudbury Neutrino Observatory
Charged Current to Neutral Current comparisons
- Electron Neutrino flux compared to Total Active Neutrino flux
Unique Signatures in SNO (D
2
O)
Charged-Current (CC)
e +d e +p+p E thresh = 1.4 MeV e only
Neutral-Current (NC)
x + d x + n+p E thresh = 2.2 MeV Equally sensitive to e m t
3 ways to detect neutrons Elastic Scattering (ES)
x +e x +e x , but enhanced for e
Solar Neutrino Physics From SNO
Flavor change + active neutrino appearance June 2001 (with SK)
F
CC
F
ES
=
e
+ 0.15 (
e
m
+
t )
3.3 s
April 2002 Sept. 2003
(With salt)
F F
CC NC
=
e
+
e
m
+
t
5.3 s > 7 s
June 2001
F
x
Total
8
B Solar Neutrino Flux =
F
CC
+
(F
ES
-
F
CC )
x
(
1/0.15
)
April 2002 Sept. 2003
F
x
=
F
nc ~10%
1000 tonnes D 2 O
Support Structure for 9500 PMTs, 60% coverage 12 m Diameter Acrylic Vessel 1700 tonnes Inner Shielding H 2 O 5300 tonnes Outer Shield H 2 O Urylon Liner and Radon Seal
Sudbury Neutrino Observatory
One million pieces transported and assembled under ultra-clean conditions.
More than 60,000 showers and counting…
Observables
PMT Measurements
-position -time -charge
Reconstructed event
-vertex -direction -energy -isotropy
3 neutron (NC) detection methods
Phase I (D 2 O) Nov. 99 - May 01 Phase II (salt) July 01 - Sep. 03 Phase III ( 3 He) Summer 04-Dec. 06 n captures on 2 H(n,
g
) 3 H Effc. ~14.4% NC and CC separation by energy, radial, and directional distributions 2 t NaCl. n captures on 35 Cl(n,
g
) 36 Cl Effc. ~40% NC and CC separation by event isotropy 35 Cl+n 8.6 MeV 40 proportional counters 3 He(n, p) 3 H Effc. ~ 30% capture Measure NC rate with entirely different detection system.
5 cm 2 H+n 6.25 MeV n 3 H 3 He p n + 3 He
p + 3 H 3 H 36 Cl
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
Kinetic Energy
Radial Profile Phys.Rev.Lett. 92 (2004) 181301
Results from SNO Salt Phase (2003): Agreement: Pure D
2
O measurements (2001,02)
8 B shape unconstrained
F
II CC
unc
.
1 .
59
0 0 .
.
08 07 (
stat
.)
0 0 .
.
06 08 (
syst
.)
F
II ES
unc
.
F
II NC
unc
.
2 .
21
0 0 .
31 .
26 (
stat
.)
0 .
10 (
syst
.)
5 .
21
0 .
27 (
stat
.)
0 .
38 (
syst
.) 8 B shape constrained
F
II CC
cons
.
1 .
70
0 .
07 (
stat
.)
0 0 .
09 .
10 (
syst
.)
F
II ES
cons
.
F
II NC
cons
.
2 .
13
0 0 .
.
29 28 (
stat
.)
0 .
15 0 .
08 (
syst
.) 4 .
90
0 .
24 (
stat
.)
0 .
29 0 .
27 (
syst
.)
F SSM 5 .
84 1 1 .
.
34 34
(Bahcall et al 2004) Total active neutrino ( 8 B) flux = Solar Model -> Restriction on sterile neutrinos
F
CC
/
F
NC
0 .
306
0 .
026 (
stat
)
0 .
024 (
syst
)
sin 2
12 Clear evidence for Flavor Change (> 7
s
) through independent measurements of
F(
e
)
and
F(
Total Active
)
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.
As proposed originally by Pontecorvo:
If neutrinos have mass:
l
For three neutrinos:
U li
i
U li
U
U U e
1
μ
1
τ
1
U e
2
U μ
2
U τ
2
U e
3
U μ
3
U τ
3
Pontecorvo-Maki-Nakagawa-Sakata matrix (Double
b
decay only)
c
12
s
12 0
s
12
c
12 0
Solar,Reactor
0 1 0 1 0 0 0
c
23
s
23
Atmospheric
0
s
23
c
23 1 0 0
c
13 0
s
13 0 0
?
1 0
e
0
iδ
CP Violating Phase
0
s
13
?
0 1 0
c
13
Reactor,LBL
0 0 1 0
e
i
2 / 2 0
?
Majorana Phases
0 0
e
i
3 / 2
i
where c ij
cos
ij
,
and s ij
sin
ij
Range defined for
D
m 12 ,
D
m 23
For
two neutrino
P(ν μ
oscillation in a vacuum: (valid approximation in many cases)
ν e )
sin 2 2
θ
sin 2
(
1
.
27
Δm E
2
L )
After SNO Salt Data: Closing in on
D
m
12 2
,
12
LMA MSW only at > 99.73 % CL Kamland parameters agree with solar --90% --95% --99% --99.73% Solar Solar + Kamland reactor Maximal Mixing disallowed at 5.4
s :
12 = 32.5 +- 1.7 o MSW: m 2 > m 1 Future SNO (and SNO+) measurements will improve the accuracy further.
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
.
Completion 2007
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 3 He detectors
• •
Proposed neutrino oscillations Proposed oscillations as the explanation for the solar neutrino problem
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 3 He 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
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 3 He 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
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 3 He 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 Pontecorvo’s 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!
First Tennis Champion at Chalk River – 1948 Bruno Pontecorvo
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.