Transcript The Odyssey 2002: SNO & KamLAND Alan Poon

The n Odyssey 2002:
SNO & KamLAND
Alan Poon
(for the SNO and KamLAND Collaborations)
Institute for Nuclear and Particle Astrophysics
Lawrence Berkeley National Laboratory, Berkeley, USA
Outline
• Introduction — the Solar Neutrino Problem
• Demonstration of Solar Neutrino Flavour
Transformation (nenm,t):
Sudbury Neutrino Observatory
• Testing Solar Neutrino Oscillation Hypothesis
Using Reactor Anti-Neutrinos:
Kamioka Liquid Scintillator AntiNeutrino Detector
• Outlook
Alan Poon, I.O.P HEPP Particle Physics 2003, Durham
Solar Model Prediction of Solar ne Flux
pp chain:
4p + 2e  4He + 2ne + 26.7 MeV
SuperK, SNO(CC)
SNO( NC)
Gallium
Detailed computer
model of solar
evolution
Standard
Solar
Model
Alan Poon, I.O.P HEPP Particle Physics 2003, Durham
Chlorine
Solar Neutrino Problem (circa 2000)
Ga (n e )
 0.58  0.05
SSM (n e )
Ga (n e )
SAGE :
 0.60  0.05
SSM (n e )
Cl (n e )
Homestake :
 0.34  0.03
SSM (n e )
SK (n x )
Super - K :
 0.4510.017
0.015
SSM (n e )
GALLEX :
Experiment
Homestake
SAGE
Gallex + GNO
Kamiokande +
Super-Kamiokande
Reaction
ne+37Cl37Ar+e
ne+71Ga71Ge+e
ne+71Ga71Ge+e
nx+enx+e
either
Solar modelsare incomplete/incorrect
or
Neutrinos undergo flavor-changing
transformation
Alan Poon, I.O.P HEPP Particle Physics 2003, Durham
A Proposal to Hunt for the Missing n’s
Phys. Rev. Lett. 55, 1534 (1985)
Alan Poon, I.O.P HEPP Particle Physics 2003, Durham
2 km to surface
Sudbury Neutrino Observatory
17.8m dia. PMT Support Structure
9456 20-cm dia. PMTs
56% coverage
1006 tonnes
D2O
12.01m dia. acrylic vessel
1700 tonnes of inner shielding H2O
Urylon
liner
5300 tonnes of outer shielding H2O
Alan Poon, I.O.P HEPP Particle Physics 2003, Durham
Nucl. Inst. Meth. A449, 127 (2000)
Detecting n at SNO
CC
n e  d  p  p  e-
• Measurement of ne energy spectrum
• Weak directionality: 1 0.340 cos 
NC
n x  d  p  n n x
• Measure total 8B n flux from the sun
• s(ne)s(nm)s(nt)
ES
nx  e-  nx  e -
• Low Statistics
• s(ne)  6 s(nm)  6 s(nt)
• Strong directionality: e  18
Alan Poon, I.O.P HEPP Particle Physics 2003, Durham
(Te  10 MeV)
Let’s Go Catch Some Z’s
The physics program at SNO is tailored to measure the total solar n flux via
the Neutral-Current reaction with different systematics:
Phase I
(pure D2O):
Neutron capture on D
Phase II
(dissolved NaCl):
Neutron capture on Cl
Single 6.25 MeV g
gcascade, 8.6 MeV
Statistical separation
(Energy, radius)
Statistical separation
(Light Isotropy)
Phase III
(3He n counters):
n  3He  p  t
Independent
channel
High CC-NC correlation Better CC-NC separation NC uncorrelated to CC
Past
Present
Future
(Nov 99 to May 01)
(since June 01)
(Sep 03 ?)
Alan Poon, I.O.P HEPP Particle Physics 2003, Durham
Analysis Example: Energy Response (SNO Phase I)
Calibration:
• PMT & Optics
• Normalized to 16N [Eg=6.13 MeV]
• Check with
• 8Li [13 MeV b]
• 252Cf [d(n,g), Eg=6.25 MeV]
• 3H(p,g) [19.8 MeV g]
E/E = ± 1.21%
s/s = + 4.5%
Linearity = ±0.23% @ Ee=19.1 MeV
CC/CC
E
s

Linearity

Total

Alan Poon, I.O.P HEPP Particle Physics 2003, Durham
Energy 
NC/NC
6.1
4.3
%
4.2
0.0
%
0.9
%
6.2
4.4
%
0.0

0.1%
0.4%
4.3
%
4.3
7.5
%
6.2


Extracting the Solar n Flux (SNO Phase I)
CC
NC
ES
n Signals
Radioactive
Backgrounds
Amplitudes Free Amplitudes Fixed
Perturb
Observables:
R, u , T

Shift amplitudes
(±1 s)
Max.
Likelihood Fit
 CC  NC  ES
OR
• PDFs:
kinetic energy T, event location R3,
and solar angle correlation cos sun
Alan Poon, I.O.P HEPP Particle Physics 2003, Durham

 e mt
+

Signal Extraction Results (SNO Phase I)
• 306 live days (Nov 1999 to May 2001)
Assume standard 8B n spectrum
Null hypothesis:
no neutrino flavour transformation
CC
1967.7
+61.9
-60.9
events
NC
576.5
+49.5
-48.9
events
ES
263.6
+26.4
-25.6
events
Alan Poon, I.O.P HEPP Particle Physics 2003, Durham
Flux Uncertainties (Shape constrained)
0
5
10
15
20
25
Energy Scale
Energy Resolution
Vertex Accuracy
Vertex Resolution
fcc
CC
Angular Resolution
Neutron backgrounds
Cer. Backgrounds
Neutron Capture
Statistics
Total
Alan Poon, I.O.P HEPP Particle Physics 2003, Durham
cnc
NC
Missing Solar n’s Found
CC (n e )   e
 NC (n x )   e   mt
 ES (n x )   e  0.15 mt


0.05
0.09
e  1.76 0.05
(stat.)
(syst.) 10 6 cm2s 1
0.09
ENull
2.2
MeV
n>
hypothesis of no
0.45
0.48
 mt  3.410.45
(stat.)
(syst.) 10 6 cm2s 1
0.45
(But e = CC was measured
flavour
for transformation
Te > 5 MeV)
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:

Alan Poon, I.O.P HEPP Particle Physics 2003, Durham
1.01
SSM (BP01)  5.05 0.81
0.44
0.46
constrained
SNO
 5.09
unconstrained
SNO
1.57
0.55
 6.42
(stat.)
(sy st.)
1.57
0.58
0.43
(stat.)
0.43
(sy st.)
Corrections Made Accordingly
Alan Poon, I.O.P HEPP Particle Physics 2003, Durham
Corrections Made Accordingly
SuperK, SNO(CC)
SNO( NC)
Gallium
Alan Poon, I.O.P HEPP Particle Physics 2003, Durham
Chlorine
Correlation in Signal Extraction (Phase I)
Strong statistical anti-correlation between NC and CC in the
signal extraction
Correlation Matrix
Alan Poon, I.O.P HEPP Particle Physics 2003, Durham
CC
ES
NC
CC
1.000
-0.162
-0.520
ES
-0.162
1.000
-0.105
NC
-0.520
-0.105
1.000
Light Isotropy in Phase II
• CC and ES signals yield an electron, which produces a single cone of
Cherenkov light
• In Phase I (pure D2O), NC signal yields a single g, whereas in Phase II
(salty D2O) there are multiple g’s following n capture on 35Cl
• We can use light isotropy to help distinguish CC and NC
Alan Poon, I.O.P HEPP Particle Physics 2003, Durham
Light Isotropy in Phase II
{
Simulated
D2O +
NaCl
{
NC
Stat.
Error
8.6%
24%
6.3%
4.6%
ES
Stat.
Error
10%
11%
10%
10%
5.3%
10%
Preliminary
Published
D2O *
Variables CC
Stat.
Error
E,R,sun
3.4 %
R, sun
9.5%
E,R,sun
4.2%
E,R,sun, 3.3%
Iso.
R,sun,Iso. 3.8%
Simulations assume 1 yr of data, with .35 SSM for CC, .5 SSM for ES,
and 1 SSM for NC.
* PRL, 89, No. 1, 011301, (2002)
Alan Poon, I.O.P HEPP Particle Physics 2003, Durham
Decoupling CC and NC in Phase III
• CC: Cherenkov Signal  PMT Array
• NC: n+3He  Neutral Current Detector Array
Phase I
Source
Energy Scale ¶
Energy Resolution ¶
Energy Non-linearity ¶
Vertex Resolution ¶
Vertex Accuracy
Angular Resolution
Internal Source p-d ¶
External Source p-d ¶
D2O Cherenkov ¶
H2O Cherenkov
AV Cherenkov
PMT Cherenkov ¶
Neutron Capture
 Systematic
 Statistical
 Uncertainties
¶ CC NC anti-correlation
Alan Poon, I.O.P HEPP Particle Physics 2003, Durham
NC/NC (%)
-6.2, +6.1
-0.0, +4.4
±0.4
±0.1
±1.8
-0.3, +0.3
-1.5, +1.6
-1.0, +1.0
-2.6, +1.2
-0.2, +0.4
-0.2, +0.2
-2.1, +1.6
-4.0, +3.6
-8.5, +9.1
-8.5, +8.6
12
Phase III
Projected
NC/NC (%)
~0
~0
~0
0.0
0.0
0.0
3.0
1.0
0.0
0.0
0.0
0.0
3.0
4.5
4
6
SNO Summary
Phase II (D2O+NaCl)
• Final full-scale detector calibration before the removal of salt
is in progress
• Salt to be removed in about a month
• Intense analysis activities in progress
Phase III (Neutral Current Detector)
• All 3He counters have been constructed and stored in the
underground lab
• Integration of electronics and DAQ in progress
• Deployment in September 2003
Alan Poon, I.O.P HEPP Particle Physics 2003, Durham
2-Flavor Neutrino Oscillation
Mass states (nM)
mass: m1, m2
n1
n2
Weak states (nW)
(participate in weak
interactions)
ne
Pure ne
nm
Pure ne

n e  cos 
  
n m   sin
sin n 1 
 
cos  n 2 
Pure ne
n1
n2
Time

m 2 [eV2 ] L[m] 
2
2
2
P (n e  n m )  sin 2 sin 1.27
where m  m2  m1

E [MeV]


2
Note:
2
May also have resonant flavor conversion in matter —
Mikheyev-Smirnov-Wolfenstein (MSW) effect
Alan Poon, I.O.P HEPP Particle Physics 2003, Durham
Global Solar n Analysis
Inputs:
• 37Cl, latest Gallex/GNO, new SAGE, SK 1258-day day & night spectra
• SNO day spectrum (total: CC+NC+ES+background)
• SNO night spectrum (total: CC+NC+ES+background)
• 8B floats free in fit, hep n at 1 SSM
SNO data only
Alan Poon, I.O.P HEPP Particle Physics 2003, Durham
Global
If CPT is conserved…(and LMA…)
Predicts deficit in
Solar ne
Reactor ne
~100 to 200 km
Complementary!
Alan Poon, I.O.P HEPP Particle Physics 2003, Durham
Is n Oscillation Really the Solution?
Kamioka Liquid scintillator
Anti-Neutrino Detector
(KamLAND)
(Kamioka, Gifu Prefecture, Japan)
 reactor n@ “right” baseline for
directly testing the currently
favoured LMA region
1 kt liquid scintillator as target
ne  p  n e
2x coincidence

e  e   2g
n  p  d  g (2.2 MeV)
(inverse b decay)

Alan Poon, I.O.P HEPP Particle Physics 2003, Durham
The KamLAND Detector
• 1 kton liquid scintillator
80% mineral oil
20% pseudocumine
1.5 g/L PPO (fluor)
r=0.78 g/cm3
Mineral oil outside a 130-mm thick,
13-m diameter nylon balloon
r=0.76 g/cm3
"Dome" Area
Steel Deck
•
• A 3-mm
thick acrylic radon barrier
at 16.6-m diameter to reduce Rn
Outer Detector
Water Cherenkov
Steel Sphere
Nylon Balloon
•
•
1879 PMT's
1325 17” brand new
544 20” from K-II
34% photocathode coverage
225 Veto 20” PMT's from K-II
Water Cherenkov
Alan Poon, I.O.P HEPP Particle Physics 2003, Durham
Tyvek light
baffle
Photomultipliers
Why Kamioka?
Pn e n m

m 2 [eV2 ] L[m] 
 sin 2 sin 1.27

E
[MeV]


2
2
With L  175 km, E  5 MeV


5
2

Sensitive to m  
2 175, 000 1.27 

 4 10 5 eV2
Alan Poon, I.O.P HEPP Particle Physics 2003, Durham
51 reactors in Japan,
80% of flux (or 68.5 GW of
reactor power) from
baseline of ~140 to 210 km
LMA
KamLAND Construction
Autumn 1999
Summer 2000
Winter 2000
Steel sphere construction
PMT installation
Veto counter installation
February 2001
Balloon insertion
April-May 2001
June-Sept. 2001
Early Sept. 2001
Late Sept. 2001
Jan. 22, 2002
Plumbing for fill
Mineral oil and liquid scintillator fill
Electronics/DAQ integration
First data taking
Production data taking began
Dec. 6, 2002
First paper submitted
Alan Poon, I.O.P HEPP Particle Physics 2003, Durham
Position Reconstruction Uncertainty
1.012 MeV (g + g)
65Zn:
1.116 MeV (g)
60Co:
2.506 MeV (g + g)
AmBe: 2.20, 4.40, 7.6 MeV (g)
68Ge:
FV
-5 m
Position resolution ~ 25 cm.
Vertex reconstruction based on photon arrival times.
Alan Poon, I.O.P HEPP Particle Physics 2003, Durham
+5 m
Energy Calibration
65Zn
(1.115 MeV g)
• Esyst = 1.91% at 2.6 MeV
60Co
(2.505 MeV g+g)
 2.13% for ne
• E/E ~ 7.5% /√E
• Energy varies by < 0.5% within
fiducial volume of R < 5m
Light yield ~ 300 p.e./MeV
Alan Poon, I.O.P HEPP Particle Physics 2003, Durham
Radioactive Background
Requirements for reactor ne detection
238U 232Th ~ 10-14 g/g
40K ~ 10-15 g/g
Alan Poon, I.O.P HEPP Particle Physics 2003, Durham
Reactor Anti-Neutrino Flux Analysis
ne  p  n e 
delayed


Data Sample
prompt
e  e   2g
Mar. 4 – Oct. 6, 2002
162 ton•yr (145.1 days)
~ 370M raw events
n  p  d  g (2.2 MeV)

g
Inverse b-decay selection
• no m veto signals
• Eprompt < 30 MeV
from n12C
• 0.5 < T < 660 msec
• R < 1.6 m, Rd > 1.2 m
• 1.8 < Edelayed< 2.6 MeV
• R < 5 m : 409 ton, 3.46x1031 free
protons
 tagging efficiency 78.3%
Fitted correlation time between prompt and delayed sub-event:
t=188 ± 23 ms  In agreement with expectation for thermal n-capture.
Alan Poon, I.O.P HEPP Particle Physics 2003, Durham
Reactor Anti-Neutrino Flux Results
Eprompt > 2.6 MeV (to remove geo-n)
Observed
Expected
Systematic Uncertainties
54 events
86.8 ± 5.6 events
Background 1 ± 1 events
Detector related
%
Source related
%
Total LS mass
2.1
Reactor power
2.0
Fiducial mass ratio
4.1
Fuel composition
1.0
2.1
Time lag
0.28
2.1
%v spectra
2.5
0.7
Cross section
0.2
Energy threshold
[accidental 0.0086 ± 0.0005
9Li/8He
Cut efficiency
0.94 ± 0.85
fast neutron < 0.5
] Live time
Total
6.4%
Nobserved – NBKG
= 0.611 ± 0.085 (stat) ± 0.041 (syst)
Nno oscillation
Probability that result is consistent with no oscillation hypothesis < 0.05%
Alan Poon, I.O.P HEPP Particle Physics 2003, Durham
Reactor Anti-Neutrino Flux
Nobserved – NBKG
= 0.611 ± 0.085 (stat) ± 0.041 (syst)
Nno oscillation
Nobs/Nno oscillation
First observation of reactor
anti-neutrino deficit
Alan Poon, I.O.P HEPP Particle Physics 2003, Durham
LMA prediction:
m2 = 5.5x10-5 eV2
sin2 2 = 0.833
Prompt Energy Spectrum
Events/0.425 MeV
En(geo) < 2.49 MeV
Alan Poon, I.O.P HEPP Particle Physics 2003, Durham
Spectral Distortion?
2-n oscillation: best-fit
No oscillation, flux suppression
Data and best oscillation fit
Data and scaled no-oscillation
shape consistent at 53% C.L
consistent at 93% C.L.
Need more reactor neutrino and calibration data
Alan Poon, I.O.P HEPP Particle Physics 2003, Durham
KamLAND: Summary
KamLAND reactor antineutrino experiment (1st phase)
• KamLAND detector is routinely taking data since January 2002.
• Detector background and energy resolution are better than expected.
• Analysis of first 145 days of data shows clear event deficit.
 After 50 years, first evidence for reactor ne disappearance.
• Data taking continues.  Probe spectral deformations and perform
precision measurement of neutrino mixing parameters.
KamLAND 7Be solar neutrino and geo-neutrino experiment (2nd phase)
• Will require lower backgrounds, possibly purification and re-circulation
of scintillator and buffer oil
• R&D effort underway at Tohoku U.
Alan Poon, I.O.P HEPP Particle Physics 2003, Durham
2-n Mixing Paremeters
Rate + Shape (>2.6 MeV)
Best Fit:
m2 = 6.9 x 10-5 eV2
sin2 2 = 1.0
Rate + Shape (>0.9 MeV)
fit with the additional free
parameters of geoneutrino backgrounds
are consistent with the
results above
Alan Poon, I.O.P HEPP Particle Physics 2003, Durham
What will SNO and KamLAND tell us in the future?
Alan Poon, I.O.P HEPP Particle Physics 2003, Durham
de Holanda et al., hep-ph/0212270
Barger et al., hep-ph/0204253
Summary
• Solar Neutrino Problem solved, and
much have been learned about neutrino
mixing
Stay Tuned…More have yet to come!
Alan Poon, I.O.P HEPP Particle Physics 2003, Durham
The SNO Collaboration
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,
J.J.Simpson, N.Tagg, J.-X.Wang
University of Guelph
J.Bigu, J.H.M.Cowan, J.Farine, E.D.Hallman, R.U.Haq,
J.Hewett, J.G.Hykawy, G.Jonkmans, S.Luoma, A.Roberge,
E.Saettler, M.H.Schwendener, H.Seifert, R.Tafirout, C.J.Virtue
Laurentian University
Y.D.Chan, X.Chen, M.C.P.Isaac, K.T.Lesko, A.D.Marino,
E.B.Norman, C.E.Okada, A.W.P.Poon, S.S.E Rosendahl,
A.Schülke, A.R.Smith, R.G.Stokstad
Lawrence Berkeley National Laboratory
M.G.Boulay, T.J.Bowles, S.J.Brice, M.R.Dragowsky,
M.M.Fowler, A.S.Hamer, A.Hime, G.G.Miller,
R.G.Van de Water, J.B.Wilhelmy, J.M.Wouters
Los Alamos National Laboratory
Alan Poon, I.O.P HEPP Particle Physics 2003, Durham
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
Queen’s 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.Hamian, 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
The KamLAND Collaboration
K.Eguchi, S.Enomoto, K.Furuno, J.Goldman, H.Hanada,
H.Ikeda, K.Ikeda, K.Inoue, K.Ishihara, W.Itoh, T.Iwamoto,
T.Kawaguchi, T.Kawashima, H.Kinoshita, Y.Kishimoto,
M.Koga, Y.Koseki, T.Maeda, T.Mitsui, M.Motoki, K.Nakajima,
M.Nakajima, T.Nakajima, H.Ogawa, K.Owada, T.Sakabe,
I.Shimizu, J.Shirai, F.Suekane, A.Suzuki, K.Tada, O.Tajima,
T.Takayama, K.Tamae, H.Watanabe
Tohoku University
J.Busenitz, Z.Djurcic, K.McKinny, D-M.Mei, A.Piepke,
E.Yakushev
University of Alabama
B.E.Berger, Y.D.Chan, M.P.Decowski, D.A.Dwyer,
S.J.Freedman, Y.Fu, B.K.Fujikawa, K.M.Heeger,
K.T.Lesko, K.-B.Luk, H.Murayama, D.R.Nygren,
C.E.Okada, A.W.P.Poon, H.M.Steiner, L.A.Winslow
UC Berkeley/ Lawrence Berkeley National Laboratory
G.A.Horton-Smith, R.D.McKeown, J.Ritter, B.Tipton, P.Vogel
California Institute of Technology
C.E.Lane, T.Miletic
Drexel University
Alan Poon, I.O.P HEPP Particle Physics 2003, Durham
P.W.Gorham, J.G.Learned, J.Maricic, S.Matsuno,
S.Pakvasa
University of Hawaii
S.Dazeley, S.Hatakeyama,M.Murakami, R.C.Svoboda
Louisiana State University
B.D.Dieterle, M.DiMauro
University of New Mexico
J.Detwiler, G.Gratta, K.Ishii, N.Tolich, Y.Uchida
Stanford University
M.Batygov, W.Bugg, H.Cohn, Y.Efremenko,
Y.Kamyshkov, A.Kozlov, Y.Nakamura
University of Tennessee
L.DeBraeckeleer, C.R.Gould, H.J.Karwowski,
D.M.Markoff, J.A.Messimore, K.Nakamura, R.M.Rohm,
W.Tornow, A.R.Young
Triangle Universities Nuclear Laboratory
Y-F.Wang
IHEP, Beijing
SNO
Backup Slides
Alan Poon, I.O.P HEPP Particle Physics 2003, Durham
Radioactive Backgrounds
Daughters in U or Th chain
• bdecays
• bg decays
“Photodisintegration” (pd)
g+dn+p
Indistinguishable from NC !
Technique:  Radiochemical assay
 Light isotropy
“Cherenkov Tail”
Cause:  Tail of resolution, or
 Mis-reconstruction
Technique:  U/Th calib. source
 Monte Carlo
Alan Poon, I.O.P HEPP Particle Physics 2003, Durham
Must know U and Th
concentration in D2O
Radioactive Backgrounds (SNO Phase I)
I. Ex-situ (Radiochemical Assays)
• Count daughter product decays:
224Ra, 226Ra, 222Rn
II. In-situ (Low energy physics data)
• Statistical separation of 208Tl and
214Bi using light isotropy
Alan Poon, I.O.P HEPP Particle Physics 2003, Durham
Low E Background Summary
For Te 5 MeV,
pd neutron bkg.
Tail Bkg
(counts)
R<550cm
(counts)
D2O
8
44 9
D2O
13
20 6
H2O+AV
8
27 8
H2O
4
33
4 1
AV

3
6 6


 1
PMT
11
16 8
2.0  0.4
Total
17
45 11

 1
Atmospheric n
235U

spont. fission
2H(a,a)pn
17O(a,n)
Terrestrial &
reactor n

External neutrons
Total
3
11
 1
78 ± 12

 2003, Durham
Alan Poon, I.O.P HEPP Particle Physics


2928 n candidates]
[c.f.:
the number of
12% of
observed NC neutrons
assuming standard solar
model n flux
How Will the Salt Be Removed?
How Will the Salt Be Removed?
The current run plan is to
obtain 9 - 12 months of
livetime prior to salt removal.
• Salt will be removed using a
reverse osmosis unit, which
will produce a concentrated
brine.
• The target is for ~1ppm salt
in the D2O after multiple
passes through the unit.
•At this level salt will not
significantly affect neutron
capture in the heavy water
region.
Alan Poon, I.O.P HEPP Particle Physics 2003, Durham
SNO’s reverse osmosis unit
Once the salt has been removed, SNO
plans to continue with a short pure D2O run
before entering the third phase of neutral
current detection, when an array of 96 3He
proportional counters will be installed into
the detector.
Data Reduction
Nov 2, 1999 to May 28, 2001
306.4 live days  “Day” = 128.5 days, “Night” = 177.9 days
Analysis Step
Total Event Triggers
Neutrino Data Trigger
NHIT •
30
Instrumental Background
Cherenkov "likelihood"
Fiducial Volume (R<550cm)
Energy Threshold (T>5 MeV)
Residual Cosmic Background
Candidate Event Set
Alan Poon, I.O.P HEPP Particle Physics 2003, Durham
Events
450,188,649
191,312,560
10,088,842
7,805,238
3,418,439
67,343
3440
2928
2928
Remove instrumental
background (e.g. PMT
“flasher” using):
• PMT time & charge distribution
• Event time correlation
• Veto PMT tag
Light isotropy measure
Data Reduction Cuts
• Reconstruction information
• Light isotropy & arrival timing
Light arrival timing
0.39
n signal loss: CC : 1.430.21 %
0.40
0.41
ES: 1.46 0.21
% NC : 2.280.23
%
Residual instrumental bkg. contamination:

Alan Poon, I.O.P HEPP Particle Physics 2003, Durham
< 3 events (95% CL)
Event Reconstruction
Given:
Hit PMTs’ positions & timing
Determine event’s: (x,y,z) & (,)
Fiducial
volume
determination
(Ntarget=?)
Separation
of n signals from
background
Tools: Triggered g and b sources
CC/CC NC/NC
Vertex Accuracy
Vertex Resolution
Angular Resolution
Total
2.9
1.8
%
1.8
0.1
%
0.1
0.2
0.3
% 
% 
0.3
0.2

2.9  1.8
%
2.8
0.0
%
0.0
2.8
%
1.8

Alan Poon, I.O.P HEPP Particle Physics 2003, Durham
%

Neutron Calibration
• Calibrate using 252Cf fission source
(~3.8 n per fission)
Capture Efficiency
Total:
29.90 ± 1.10 %
With energy
threshold &
fiducial volume
selections
14.38 ± 0.53 %
(T>5 MeV, R<550 cm)
Alan Poon, I.O.P HEPP Particle Physics 2003, Durham
Response vs 252Cf source position
CC, ES, NC Flux
CC (n e )  1.76
0.06
0.09
(stat.)
(syst.)10 6 cm2s 1
0.05
0.09
ES (n x )  2.39 0.23 (stat.) 0.12 (syst.)10 6 cm2s 1
0.24
NC (n x )
0.12
0.44
0.46
 5.09
(stat.)
(syst.)10 6 cm2s 1
0.43
0.43

Alan Poon, I.O.P HEPP Particle Physics 2003, Durham
KamLAND Backup Slides
KamLAND
Backup Slides
Alan Poon, I.O.P HEPP Particle Physics 2003, Durham
A Candidate Anti-n Event
(colour is time)
Prompt Signal
E = 3.20 MeV
Alan Poon, I.O.P HEPP Particle Physics 2003, Durham
t = 111 ms
R = 34 cm
Delayed Signal
E = 2.22 MeV
Front End Electronics
Waveforms are recorded using Analogue
Transient Waveform Digitizers (ATWDs),
allowing multi p.e. resolution
ADC
Counts
 The ATWDs are self launching
with a threshold ~1/3 p.e.
raw data
pedestal
pedestal subtracted
 Each PMT is connected to 2 ATWDs,
reducing deadtime
 Each ATWD has 3 gains (20, 4, 0.5),
allowing a dynamic range of ~1mV- ~1V
Alan Poon, I.O.P HEPP Particle Physics 2003, Durham
samples (~1.5ns)
Waveform Digitiser
Have full waveform
digitizers on every central
and veto channel
1 p.e.
Data from blue LED
flashers in the detector
 Important for exploring new
physics and reject complex
background signatures
Alan Poon, I.O.P HEPP Particle Physics 2003, Durham
2 p.e.
Reactor Anti-Neutrinos
Fission:
 ~200 MeV / fission (“power”)
• Thermal power is routinely
measured by the reactor operator
in order to adjust the reactor to
the highest licensed power.
Economics ($$) pushes this error
to ~0.6-0.7%
 ~6 n/ fission (“& spectrum”)
• 240Pu & 242Pu: negligible
• 235U, 239Pu, 241Pu n spectrum
derived from b spectroscopy
[Schreckenback et al., Phys. Lett B160 (1985) 325
Hahn et al., Phys. Lett. B218 (1989) 365]
• 238U n from fast-n fission, and
has to be derived from 1st
principles: 1000 channels
(uncertainty~10%), but n yield
from 238U is only 11% of total 
total uncertainty due to 238U ~1%
Alan Poon, I.O.P HEPP Particle Physics 2003, Durham
Source Spectrum
Goesgen
“Standard” anti-neutrino spectral determination
procedures checked with short base-line reactor
anti-neutrino experiments
Alan Poon, I.O.P HEPP Particle Physics 2003, Durham
Introduction to KamLAND
KamLAND follows the long history
of using reactor anti-neutrinos to  Spectral distortions if ne oscillate
 Suppressions ~ factor of 2
investigate neutrino properties
Reactor
ne spectrum
Cross section for
n e + p  e+ + n
Alan Poon, I.O.P HEPP Particle Physics 2003, Durham
Time Variations of Reactor Power and Signals
Alan Poon, I.O.P HEPP Particle Physics 2003, Durham
Radioactivity Inside Scintillator
Alan Poon, I.O.P HEPP Particle Physics 2003, Durham
Muon-Induced Backgrounds
L < 3m
12N
12B
Test energy scale at higher energies.
Alan Poon, I.O.P HEPP Particle Physics 2003, Durham
85Kr
Background
85
Kr coincidence measurement
Dominant low-energy backgrounds:
• 85Kr (Q=687 keV)
• 210Pb, 210Bi (from Rn decays)
We are working on purification to remove such contamination for
detector upgrades for 7Be solar n program
Alan Poon, I.O.P HEPP Particle Physics 2003, Durham
Accidental Background
Ep>2.6 MeV
in delayed time window of 0.2-20 s
Accidental bkgd:
0.0086  0.0005
Alan Poon, I.O.P HEPP Particle Physics 2003, Durham
Vertex Distributions of neutrons & 12B/12N
Fiducial Volume Studies
V/V = 4.06 %
Vfid/Vfid = 4.6 %
Alan Poon, I.O.P HEPP Particle Physics 2003, Durham
Statistical Analysis of Mixing Parameters
Rate-only Analysis

2
0.611Ratio (m


2
, sin 2
2
)
2
0.085 2  0.0412
2 in (m2, sin22) space. Points with  2  3.84 (95% CL) are excluded.

Spectral+Rate Analysis
(
)
2
 2   Rate
m 2 , sin2 2 ,N BG , a 
(
(Rate)
)
2 logLshape m 2 , sin2 2 ,N BG , a 
(Shape)
2
2
 BG
(N BG )  distortion
(a )
(Bckgrd)
2 in (m2, sin22) space. Points with  2  5.99 (95% CL) are excluded.
Alan Poon, I.O.P HEPP Particle Physics 2003, Durham
General n Background Slides
General n Backup
Slides
Alan Poon, I.O.P HEPP Particle Physics 2003, Durham
Remaining Questions…
n: Dirac or Majorana
Absolute n mass scale
13
CP violation in leptonic sector?
n Mass hierarchy
Verify oscillation (strong evidence, no direct
observation yet)
• LSND? Sterile n? CPT violation?
•
•
•
•
•
•
Alan Poon, I.O.P HEPP Particle Physics 2003, Durham
Neutrino Mixing
The general lepton mixing matrix (Maki-Nakagawa-SakataPontecorvo) is expressed as
n e

n m

n t





U e 1 U e 2 U e 3

U m 1 U m 2 U m 3

U t 1 U t 2 U t 3





The Standard Electroweak Model assumes U=I

Alan Poon, I.O.P HEPP Particle Physics 2003, Durham
n 1

n 2

n 3





Neutrino Mixing: What do we “know” now?
1
0

Uai = 0 cos  23

0  sin 23
 cos 
13

0

e iCP sin
13

cos  12

 sin 12

 0

0 

sin 23 

cos  23 
Atmospheric n
0 e
sin 13 

1
0

0
cos  13 

sin 12
cos  12
0
iCP
0 

0 

1
Solar n LMA
Present “thinking”:
Solar ne mix with
Reactor
(CHOOZ)
n m  nt
2
Alan Poon, I.O.P HEPP Particle Physics 2003, Durham
1
0

0 1/ 2

0 1/ 2
0 

1/ 2 

1/ 2 

~1

0

e iCP sin
13

0 e iCP sin 13 

1
0


0
~1

0.85 0.51 0 


0.51
0.85
0




0
1
 0
ne  0.85 n 1  0.51 n 2
n m  0.36 n 1  0.60 n 2  0.71n 3
n t  0.36 n 1  0.60 n 2  0.71n 3
MNSP vs CKM
Contrast between UCKM (quark) and UMNSP (lepton)
U MNSP
UCKM



 




1
1
(1O(  ))
(1O (  ))
2
2
1
1
(1O(  )   )
(1O (  )   )
2
2
1
1
(1O(  )   ) 
(1O (  )   )
2
2

 

1 
2 
1 

2 
~0.2 and  < 0.25
 1
O(  ) O ( 3 ) 


2
 O(  )
1
O (  ) 
O( 3 ) O( 2 )
1 


What is the underlying symmetry (possibly at GUT scale)?
Alan Poon, I.O.P HEPP Particle Physics 2003, Durham
Future Solar n Experiments
Nakahata (LowNu2002 Conference)
Alan Poon, I.O.P HEPP Particle Physics 2003, Durham