Transcript SNO Update - Istituto Nazionale di Fisica Nucleare

SNO Review &
Comparisons
NOW 2004
12 September 2004
Mark Chen
Queen’s University &
The Canadian Institute for
Advanced Research
The SNO Collaboration
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
Y.D. Chan, X. Chen, K.M. Heeger, K.T. Lesko, A.D. Marino,
E.B. Norman, C.E. Okada, A.W.P. Poon,
S.S.E. Rosendahl, 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.S. Hamer, J. Heise, A. Hime,
G.G. Miller, R.G. Van de Water, J.B. Wilhelmy, J.M. Wouters
Los Alamos National Laboratory
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
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
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
Sudbury
Neutrino
Observatory
1000 tonnes D2O
12 m diameter Acrylic Vessel
18 m diameter support structure; 9500 PMTs
(~60% photocathode coverage)
1700 tonnes inner shielding H2O
5300 tonnes outer shielding H2O
Urylon liner radon seal
depth: 2092 m (~6010 m.w.e.) ~70 muons/day
Neutrino Reactions in SNO
CC
ne + d  p + p + e−
- Q = 1.445 MeV
- good measurement of ne energy spectrum
- some directional info  (1 – 1/3 cosq)
- ne only
NC
n x + d  p + n +n x
- Q = 2.22 MeV
- measures total 8B n flux from the Sun
- equal cross section for all active n flavors
ES
n x + e−  n x + e−
- low statistics
- mainly sensitive to ne, some n and n
- strong directional sensitivity
SNO Neutral Current Trilogy
Pure D2O
Salt
3He
Nov 99 – May 01
Jul 01 – Sep 03
Fall 04 – Dec 06
n+dt+g
n + 35Cl  36Cl + g n + 3He  t + p
(Eg = 6.25 MeV)
(Eg = 8.6 MeV)
good CC
enhanced NC and
event isotropy
Counters
proportional counters
s = 5330 b
event-by-event
separation
PRL 87, 071301 (2001)
PRL 89, 011301 (2002)
PRL 89, 011302 (2002)
“D2O Archival Long
Paper” in progress
PRL 92, 181301 (2004)
“Long Salt Paper” soon to
be submitted
“First NCD Paper” in the
future
SNO Phase III: 3He Detectors
3He
Proportional Counters (“NC Detectors”)
Detection Principle
2H
+ nx  p + n + nx - 2.22 MeV
3He
(NC)
+ n  p + 3H + 0.76 MeV
40 Strings on 1-m grid
nx
PMT
398 m total active length
Physics Motivation
Event-by-event separation. Measure NC
and CC in separate data streams.
Different systematic uncertainties
than neutron capture on NaCl.
3He
array removes neutrons from CC,
calibrates remainder. CC spectral shape.
NCD
n
Structure of this Talk – Comparison of Phases
signals
 backgrounds
 energy and optics
 flux
 spectral shape
 day-night analysis
 oscillation analysis

Čerenkov Detection
PMT Measurements
-position
-charge
-time
Reconstructed Event
-event vertex
-event direction
-energy
-isotropy
Signal Extraction Pure D2O
• signal PDFs
– energy
– R3 (radius)
– cos qSun
• Monte Carlo
• maximum likelihood
fit with background
amplitudes fixed
Signal Extraction Salt Phase
statistical signal
separation –
extended maximum
likelihood
energy
use R3, cos qSun, b14
perform signal
extraction w/o any
spectral shape
assumptions
R3
event isotropy
cos qSun
b14
NaCl Neutron Detection
• higher capture cross section
• higher energy release
• many gammas
g
n
35Cl
36Cl*
s = 0.0005 b
36Cl
s = 44 b
35Cl+n
8.6 MeV
2H+n
6.3 MeV
3H
36Cl
Neutron Capture Efficiency
35Cl(n,g)36Cl
<e> = 0.399 ± 0.010
Te ≥ 5.5 MeV and
Rg ≤ 550 cm
2H(n,g)3H
<e> = 0.144 ± 0.005
Te ≥ 5.0 MeV and
Rg ≤ 550 cm
252Cf
fission neutron source
2 tonnes of NaCl added to 1000 tonnes heavy water
Simulated Neutron Event in D2O

neutron events in pure D2O look very
similar to single electrons
Simulated Neutron Event in Salt

neutron events in salt are more isotropic
Čerenkov Light and b14
qij
e−
(v > c/n)
bl  Pl  cosqij 
b14 = b1 + 4b4
) 43o
i j
hollow cone of
emitted photons
energy &
direction
sum over all pairs of
PMT hits
Monte Carlo Signal Separation
Neutron Signals from the First NCD



data taken on the J3 string (first 9.5 m long NCD) with the AmBe source
on 12/02/03 at 22:38 EST
bin 135 is about 764 keV
total number of neutrons in the peak roughly matches Monte Carlo
prediction
Comparison of Phases
signals 
 backgrounds
 energy and optics
 flux
 spectral shape
 day-night analysis
 oscillation analysis

Sources of Background
• g + d → p + n, from 214Bi (U chain), 208Tl (Th chain)
• cosmic rays: neutrons, spallation products
• atmospheric neutrinos, reactors, CNO electron capture
• fission (U, Cf)
• (a,n) reactions
• 24Na activation (neck, calibration, recirculation, muons)
• AV events
focus is on neutron backgrounds to the NC
Pure D2O Water Assays
targets are set to reduce b-g
events reconstructing inside 6 m
targets for D2O represent a 5%
background from g + d  n + p
Salt Phase Water Assays
• bottom of vessel
• 2/3 way up
• top of vessel
salted D2O radioactivity should
produce 0.72 ± 0.24 neutrons
per day
• MnOx
• HTiO
pure D2O radioactivity was
estimated at 1.0 ± 0.2 neutrons
per day
the SSM rate of NC events
would produce 13.1 neutrons
per day
• MnOx
• HTiO
New Salt Phase Background
 24Na
activation
 neutrons activate 23NaCl…salty D2O can be
activated outside the detector and brought
in by circulation
g+d→p+n
24Na
2.75 MeV
1.37 MeV
24Mg
t1/2 = 14.95 hr
NC background and
low-energy g’s
External
24Na
Introduced
Salt Injected on
May 28, 2001
The NaCl brine in
the underground
buffer tank was
activated
by neutrons from the
rock wall. We
observed the decay
of 24Na after the
brine is injected in
the SNO detector.
24Na
Background
t1/2=14.95 hrs
External Neutrons
light water g’s photodisintegrate deuteron
 radon daughters deposited on the acrylic
vessel during construction

 210Pb
has t1/2 = 22 years
 feeds 210Po which alpha decays
 (a,n) on 13C, 17O, 18O
 neutrons originate from the AV
pure D2O phase
salt phase
estimated from radioassays,
27 ± 8 events subtracted
was not considered
fit both
Fitting External Neutron Backgrounds
• efficient neutron capture on Cl
improved
separation of
internal and
external
background
neutrons
r=(R [cm]/600)3
Salt Phase Backgrounds Table
Source
deuteron photodisintegration
2H(a,a)pn
17,18O(a,n)
fission, atmospheric n’s
Number of Events
+24.0
73.1
−25.5
2.8 ± 0.7
1.4 ± 0.9
23.0 ± 7.2
terrestrial and reactor n’s
2.3 ± 0.8
neutrons from rock
<1
24Na
activation
neutrons from CNO n’s
total internal neutron background
internal g (fission, atmospheric n)
16N
decays
external-source neutrons (from fit)
8.4 ± 2.3
0.3 ± 0.3
111.3 ± 25
5.2 ± 1.3
< 2.5 (68% CL)
84.5 ± 34
Čerenkov events from PMT b-g
<14.7 (68% CL)
“AV events”
< 5.4 (68% CL)
NCD Backgrounds: Pulse Shape
neutron with p-t track  wire
De-logged current
current preamplifiers digitize
pulse shapes for particle
identification
1.5
1.0
0.5
0.0
-0.5
0
4
6
8
Time (microseconds)
neutron with p-t track || wire
20
14
15
12
10
5
0
0
1
2
3
4
Time (microseconds)
5
De-logged current
De-logged current
a track  wire
2
10
8
6
4
2
0
0
2
4
6
Time (microseconds)
8
Comparison of Phases
signals 
 backgrounds 
 energy and optics
 flux
 spectral shape
 day-night analysis
 oscillation analysis

Optical Calibrations



manipulator
positioning
accuracy: ~2 cm
laserball moved
throughout
detector (in two
planes)
extract optical
parameters (D2O
attenuation, PMT
angular response,
H2O attenuation)
at various
wavelengths
B. Moffat with dye laser and laserball
16N


Calibration Source
internally triggered
used for:
16






N 7.13 s
energy scale
b−
energy drift
detector radial
response
energy resolution
vertex resolution
angular resolution
1%
5%
68%
8.87
7.12
6.13
26%
16O
M. Boulay with
16N
source
Detector Energy Drift
Monitoring Detector Optics

D2O attenuation
increasing

water chemistry
analyses reveal
increasing Mn and
organics

consistent with light
absorption feature
at ~420 nm
Salt Energy Scale Drift
energy scale drift
agrees with MC prediction
coming from slight increase
in D2O photon absorption
over time…
Desalination
reverse osmosis


started 09/09/2003
pass #1 completed 09/14/2003…100x reduction
Pass #1 Stratification
salt probe conductivity measurement
salt water more dense
Salt Conductivity during Desalination
3.5
salt interface
remained solid
throughout
operation
Salt Concentration (mS/cm)
3
Wednesday Down
Wednseday Up
Goal
Thursday
2.5
2
1.5
1
purified D2O floats
0.5
0
-200
0
200
400
600
800
1000
1200
Position of Pivot in AV (cm)
probe z position [cm]
Na and Impurities Removed
Limit Feed
Permeate
Feed:
D-067H
D-065H
D-034H
Permeate:
D-098H
D-050H
Concentrate:
D-070H
D-088H
Loop 2 Permeat
D-069H
10000
<2
ppb
~15
ppb
~0.1 ppb
<1
ppb
~0.6
ppb
~0.04
ppb
<1.5
ppb
<10
ppb
<1.5 ppb
Ni
<20
ppb
<0.8
ppb
<0.08
ppb
Cu
<40
ppb
<3
ppb
<1 ppb
TOC
<10
ppb
~20
ppb
~3-4 ppb
Cr
Fe
feed
1000
100
Na (ppm)
Mn
10
permeate
1
0.1
0.01
9 Sep
10 Sep
11 Sep
12 Sep
14 Sep
Sampling Time
24 Sep
4 Oct
Optics Restored – Confirmation!
salt phase energy drift
−1.8% per year due to
D2O attenuation
desalination pass #1
Mn and/or TOC light absorption removed!
Optics Destroyed! in NCD Phase 



example of a
current NCD
phase optics
calibration
occupancy map
from laserball
source in the
centre of the
detector
working now to
understand the
detector (PMT’s
and NCD’s)
Comparison of Phases
signals 
 backgrounds 
 energy and optics 
 flux
 spectral shape
 day-night analysis
 oscillation analysis

#EVENTS
SNO Pure D2O Results (2002)
CC 1967.7
+61.9
+60.9
ES
263.6 +26.4
+25.6
NC
+49.5
+48.9
576.5
1st
paper
threshold
306.4 days
neutron background: 78 +12
−12
primarily g + d → p + n
+18
Čerenkov background: 45 −12
Constrained Shape Fluxes
Ethreshold > 5 MeV
*En >2.2 MeV
Fcc(ne) = 1.76 −0.05 (stat.) −0.09(syst.) × 106 cm−2s−1
+0.06
+0.09
Fes(nx) = 2.39 −0.23 (stat.) −0.12(syst.) × 106 cm−2s−1
+0.24
+0.12
Fnc(nx) = 5.09 −0.43 (stat.)−0.43(syst.) × 106 cm−2s−1 *
+0.44
Fe
+0.46
+0.05
+0.09
+0.45
+0.48
= 1.76 −0.05 (stat.) −0.09 (syst.) × 106 cm−2s−1
F
= 3.41 −0.45 (stat.) −0.45 (syst.) × 106 cm−2s−1
more than just ne coming from the Sun!
#EVENTS
Salt Phase 254.2 neutrino live-days
Light
Isotropy
CC 1339.6
ES
+63.8
-61.5
Energy
Spectra
170.3 +23.9
-20.1
NC 1344.2
+69.8
-69.0
Sun-angle dist.
Radial
SNO Salt Fluxes
compare with pure D2O
Fcc(ne) = 1.76 −0.05 (stat.)−0.09 (syst.) × 106 cm−2s−1
shape of 8B spectrum +0.06
in CC and ES+0.09
not constrained:
Fes(nx) = 2.39 −0.23 (stat.)−0.12 (syst.) × 106 cm−2s−1
+0.24
+0.12
Fnc(nx) = 5.09 −0.43 (stat.)+0.46
(syst.) × 106 cm−2s−1
−0.43
+0.44
standard (Ortiz et al.) shape of 8B spectrum in CC and ES:
Uncertainties in Fluxes (%)
0
energy scale
resolution
radial accuracy
angular resolution
isotropy mean
isotropy width
radial E bias
internal neutrons
Čerenkov bkds
“AV” events
neutron capture
total
1
2
3
4
5
6
7
8
CC uncert.
NC uncert.
ES uncert.
9
10
Total Active
8B
Fluxes
in units of Bahcall, Pinsonneault, Basu 2001 SSM, 5.05 x 106 cm−2 s−1
BPB01 SSM
1.00
+0.20
−0.16
Junghans et al.
nucl-ex/0308003
1.16 ± 0.16
new S17
BP04 SSM
1.15 ± 0.26
SNO D2O
(constrained)
1.01 ± 0.13
SNO D2O
(unconstrained)
1.27 ± 0.33
SNO Salt
(unconstrained)
1.03 ± 0.09
• results are
consistent with
SSM and with
each other
• uncertainty in
total flux
reduced in the
new salt result,
even while
constraints
were relaxed
Next Salt Paper: Fluxes
254.2 days to 391.4 days, increased
statistics
 improved systematics determinations (does
not mean all systematics have become
smaller!)

NCD Phase: Fluxes



good statistics
CC, NC break
correlations
smaller
systematic
uncertainties
NC,CC
CC,ES
ES,NC
D2O
D2O
Salt
unconstrained
constrained
unconstrained
-0.950
-0.208
-0.297
-0.520
-0.162
-0.105
-0.521
-0.156
-0.064
3
He
~0
~-0.2
~0
Comparison of Phases
signals 
 backgrounds 
 energy and optics 
 flux 
 spectral shape
 day-night analysis
 oscillation analysis

Pure D2O Energy Spectrum
Day Spectrum CC+NC+ES
tan2q
0.9
0.8
0.7
0.6
0.5
0.4
0.3
would be worse with salt
Dm2 = 8 × 10−5 eV2
Salt Extracted CC Spectral Shape
CC Spectral Shape
tan2q
rate/SSM
0.9
0.8
0.7
0.6
0.5
0.4
0.3
recoil electron total energy [MeV]
Dm2 = 8 × 10−5 eV2
Salt CC Spectral Systematics
bin-bin statistical correlations from likelihood
extraction and for various systematics
determined
 most systematics are small for the integrated
CC flux measurement…but, not necessarily
small in each spectral bin
 energy dependence and biases investigated
and understood

to be presented soon in the upcoming paper
NCD Phase Spectra
 3He
counters “soak up” the neutrons
 will allow a cleaner look at low energy CC
events
 will still be some neutron captures by
deuterons in the heavy water; these can be
calibrated and subtracted using the NCD
neutron count rate
Comparison of Phases
signals 
 backgrounds 
 energy and optics 
 flux 
 spectral shape 
 day-night analysis
 oscillation analysis

Pure D2O Day-Night Spectra
night rate: 9.79 ± 0.24 d−1
day rate: 9.23 ± 0.27 d−1
define
asymmetry:
night − day
A = 2 (N – D)
(N + D)
Acc =
+1.5
14.0 ± 6.3 −1.4
Anc = −20.4 ± 16.9
Ae = 7.0 ± 4.9
+1.3
−1.2
+2.4
−2.5
Can SNO Observe Day-Night Effect?
tan2q
0.3
2.5% in CC
0.4
0.5
0.6
0.7
0.8
0.9
+5.7
+1.1
3.3 −1.6 % 0.6 −0.4 %
Bahcall, Gonzalez-Garcia,
Peña-Garay
Comparison of Phases
signals 
 backgrounds 
 energy and optics 
 flux 
 spectral shape 
 day-night analysis 
 oscillation analysis

Oscillations Analysis: Before SNO
this figure updated and upgraded
before SNO
Fogli, Lisi,
Montanino
Palazzo
after SNO
Pure D2O
SNO
Collaboration
Oscillation Analysis: Global Solar
Before Salt
--90%
--95%
--99%
--99.73%
After Salt
Oscillation Analysis Before
solar
LMA
solar plus KamLAND
Bahcall, GonzalezGarcia, Peña-Garay
LMA-II
LOW
LMA-I
pre-salt
Oscillation Analysis After Salt
solar
solar plus KamLAND
−90%
−95%
−99%
−99.73%
global solar finds only LMA
LMA-I only at > 99% CL
Salt PRL Fluxes + New KamLAND
log-log plot in tan2q

including
KamLAND
Neutrino 2004
results
Synopsis of SNO Salt Results
oscillation parameters,
2-D joint 1s boundary
LMA-I favored at >99% C.L.
sin2q12 = 0.29 ± 0.04
marginalized 1-D 1s
errors
maximal mixing rejected at 5.4s
next salt paper oscillation analysis will include
salt day-night, CC spectral shape…
Global Solar NCD Projection with
and w/o KamLAND
lin-lin plot in tan2q
SNO will constrain the mixing angle...
Comparison of Phases
signals 
 backgrounds 
 energy and optics 
 flux 
 spectral shape 
 day-night analysis 
 oscillation analysis 

Summary
1998
1999
2000
2001
2002
2003
2004
2005
2006
NOW
commissioning
Pure D2O
Salt
3He
added 2 ton of NaCl
Counters
Pure D2O
and desalination
• pure D2O phase discovers active solar neutrino flavors that are not ne
• salt phase moves to precision determination of oscillation parameters;
flux determination has no spectral constraint (thus can use it rigorously
for more than just the null hypothesis test)
• NCDs installed and about to begin production data taking; final SNO
configuration offers CC and NC event-by-event separation, for improved
precision and cleaner spectral shape examination
fin