Transcript Solar Neutrinos – Present and Future

Solar Neutrinos, SNO, and SNOLAB
Art McDonald
For the SNO, SNO+ Collaborations
SNOW 2006,
Stockholm, Sweden
• Ongoing physics motivation for solar neutrino
measurements
• Status of SNO, SNOLAB
• Future solar neutrino experiments, SNO+
Using the oscillation framework for neutrino flavor change:
If neutrinos have mass:
 l  U li  i
For three neutrinos:
 U e1 U e 2 U e3 

 Maki-Nakagawa-Sakata-Pontecorvo (MNSP) matrix
U li  U μ1 U μ 2 U μ 3 
U

(Double b decay only)
 τ1 U τ 2 U τ 3 
0
0  1 0
0   c13 0 s13   1
0
0 
 c12 s12 0   1

 
 
 
 

 i 2 / 2
   s12 c12 0    0 c23 s23    0 1
0  0
1 0 0 e
0 
 0
0 1   0  s23 c23   0 0 e  iδ    s13 0 c13   0
0
e i 3 / 2i 

Solar,Reactor
Atmos., Accel.
CP Violating Phase
Reactor, Accel
Majorana Phases
Range defined for Dm12, Dm23
where cij  cos  ij , and sij  sin  ij
For two neutrino oscillation in a vacuum: (valid approximation in many cases)
Δm L
P(ν μ  νe )  sin 2θ sin ( 1.27
)
E
2
2
2
Matter Effects – the MSW effect
 e 
d  e 
i    H 
dt  x 
 x 
 Δm 2
cos2θ  2G F N e

H   4E
2
Δm

sin2θ

4E
(Mikheyev, Smirnov, Wolfenstein)

Δm 2
sin2θ 
4E

2
Δm
cos2θ

4E
The extra term arises because e have an extra interaction
via W exchange with electrons in the Sun or Earth.
2
sin
2
2
sin 2 m 
(  cos 2 )2  sin 2 2
In the oscillation formula:
   2GF N e E / Dm 2
MSW effect can produce an energy spectrum distortion
and flavor regeneration in Earth giving a Day-night effect
Oscillations for Solar Neutrinos
Solar Model Flux Calculations
, SNO
Bahcall et al. (2001)
CNO
Matter Interaction Effect:LMA
Current Data for e Survival
SAGE
GNO
2005 was a sad year for
solar neutrino physics with
the passing of
Hans Bethe and John Bahcall
Chlorine
7Be
pp
pep
SK,SNO
Future solar neutrino measurements
pp, 7Be, pep, 8B
• NEUTRINO PHYSICS
- Confirm matter effects (MSW).
Vacuum
- Improve Q12, Q13.
pp
7Be
pep
8B
LMA
- Search for effects of sterile ,
Non-Standard Interactions,
Mass-varying neutrinos.
• SOLAR PHYSICS
- Accurate measurement of
neutrino luminosity (pp, pep).
• Compare ES, CC
• Compare ES, SSM
Bahcall & Pena-Garay
hep-ph/0305159
- Observe CNO neutrinos.
Unique Signatures in SNO (D2O)
Charged-Current (CC)
e+d  e-+p+p
Ethresh = 1.4 MeV
e only
Neutral-Current (NC)
x+d  x+n+p
Ethresh = 2.2 MeV
Equally sensitive to e m t
Elastic Scattering (ES)
x+e-  x+ex, but enhanced for e
3 ways to
detect neutrons
Solar Neutrino Physics From SNO
Clear Evidence: Flavor change + active neutrino appearance
June 2001
(with SK)
FCC
FES
=
FCC
FNC
April 2002
Sept. 2003
March 2005
e
e + 0.15 (m + t)
=
e
e + m + t
3.3 s
5.3 s
>7s
With salt
in SNO
Total 8B Solar Neutrino Flux
June 2001
April 2002
Sept. 2003
March 2005
Fx
=
FCC + (FES - FCC) x (1/0.15)
Fx
=
Fnc
~10%
3 neutron (NC) detection
methods (systematically different)
Phase I (D2O)
Phase II (salt)
Nov. 99 - May 01
July 01 - Sep. 03
n captures on
2H(n, g)3H
Effc. ~14.4%
NC and CC separation
by energy, radial, and
directional
distributions
2 t NaCl. n captures on
35Cl(n, g)36Cl
Effc. ~40%
NC and CC separation
by event isotropy
35Cl+n
2H+n
Phase III (3He)
Nov. 04-Dec. 06
40 proportional
counters
3He(n, p)3H
Effc. ~ 30% capture
Measure NC rate with
entirely different
detection system.
5 cm
8.6 MeV
n
6.25 MeV
3H
p
3He
3H
n + 3He  p + 3H
36Cl
Data from Experiments in Operation
The latest SNO data: 391 live days with salt
hep-ex/0502021 March 2005
New Information: Charged Current Energy Spectrum
Day-Night Asymmetry assuming ANC=0
Asalt  D2O  0.037  0.040
Flavor change
determined by > 7 s.
CC, NC FLUXES
MEASURED
INDEPENDENTLY
m ,
The Total Flux of Active
t
Neutrinos is measured
independently (NC) and agrees
Electron neutrinos
CC  1.68
 0.06
0.06
NC  4.94
 0.21
0.21
well with solar model
08
(stat.) 00..09
(syst.)
(stat.)
 0.38
0.34
(syst.)
ES  2.35
(stat.)
(syst.)
(In units of 106 cm2s 1 )
 0.22
0.22
 0.15
0.15
Calculations:
5.82 +- 1.3 (Bahcall et al),
5.31 +- 0.6 (Turck-Chieze et al)
CC
029
 0.34  0.023(stat.) 00..031
 cos4 13 sin2 12
NC
Improved accuracy
for 12.
SOLAR ONLY
AFTER NEW
SNO SALT
DATA
Large mixing
Angle (LMA)
Region only
- The solar
results define the
mass hierarchy
(m2 > m1) through the
Matter interaction (MSW)
- SNO: CC/NC flux
defines tan2  < 1
(ie Non - Maximal mixing)
by more than 5
standard deviations
LMA for solar  predicts very small
spectral distortion, small (~ 3 %) day-night
asymmetry, as observed by SNO, SK
SOLAR PLUS
KAMLAND (assuming CPT)
(Reactor ’s)
Results from SNO -- Salt Phase
Oscillation Parameters,
2-D joint 1-s boundary
Marginalized 1-D 1-s
errors
SNO D2O D/N spectra
SNO Salt D/N spectra
KamLAND 766-day
SK-I zenith spectra
SAGE
Gallex/GNO
Cl/Ar
hep-ex/0507079
Periodicity in Solar Flux?
SNO data 1999-2003
Unbinned Maximum Likelihood
Method compares fit for
Sinusoidal variation with
Expectation for zero amplitude.
Monte Carlo used to estimate
sensitivity shows
35% probability of a larger
likelihood ratio (S) with zero
sinusoidal amplitude than the
maximum S observed in the fits.
Conclusion: No observed
sinusoidal variation at periods
from 1 day to 10 years.
Analysis sensitive to amplitude
of 8-10% at 99% C.L..
Orbital Eccentricity
 = 0.014(9). Actual: 0.0167
SNO: hep-ex/0507079
 = 0.021(3)
SK: hep-ex/0508053
Summary of SNO results
•
Direct observation (7 s) of neutrino flavor change via an
appearance measurement:
Beyond the Standard Model for Elementary Particles.
•
Direct measurement (10 % accuracy) of total flux of
active neutrinos: Strong confirmation of Solar Models.
•
The dominant transformation is to active neutrinos:
Sterile neutrino fraction is restricted (<~ 13%).
•
Clear determination (5.3 s): 12 is non-maximal.
•
With other solar measurements: Strong evidence for
Matter Enhancement in Sun (MSW – LMA solution).
•
With Kamland and CPT: Strong confirmation of neutrino
oscillation due to finite mass (MNSP) as the primary
physics explanation for appearance and disappearance
measurements.
Present Phase: SNO Phase III
Neutral-Current Detectors (NCD):
An array of 3He proportional counters
40 strings on 1-m grid
~440 m total active length
• Search for spectral distortion
• Improve solar neutrino flux by breaking the
CC and NC correlation ( = -0.53 in Phase II):
CC: Cherenkov Signal  PMT Array
NC: n+3He  NCD Array
• Improvement in 12, as
Correlations
D2O unconstrained
D2O constrained
Salt unconstrained
NCD
NC,CC
-0.950
-0.520
-0.521
~0
CC,ES
-0.208
-0.162
-0.156
~-0.2
ES,NC
-0.297
-0.105
-0.064
~0
Blind
Analysis
Phase III production data taking began Dec 2004; completion at the end of 2006
Neutral Current Detector Array deployed by a remotely operated submarine.
Production data and calibrations steadily since Nov. 2004
6.13 MeV
SNO Energy Calibrations: 25% of running time
19.8 MeV
Energy calibrated to ~1.5 %
Throughout detector volume
252Cf
neutrons
+ AmBe, 24Na
b’s from 8Li
g’s from 16N and t(p,g)4He
Optical calibration at 5 wavelengths with the “Laserball”
The objective is for an improved CC/NC ratio measurement compared to the salt phase
SNO Physics Program

Solar Neutrinos
(5 papers to date)
 Electron Neutrino Flux
 Total Neutrino Flux
 Electron Neutrino Energy Spectrum Distortion
 Day/Night effects
 hep neutrinos (paper in progress)
 Periodic variations hep-ex/0507079 [Variations < 8% (1 dy to 10 yrs)]

Atmospheric Neutrinos & Muons
 Downward going cosmic muon flux
 Atmospheric neutrinos: wide angular dependence [Look above horizon]


Supernova Watch (SNEWS)
Limit for Solar Electron Antineutrinos
hep-ex/0407029

Nucleon decay (“Invisible” Modes: N
)
Phys.Rev.Lett. 92 (2004) [Improve limits by 1000]

Supernova Relic Electron Neutrinos
New International Underground Science Facility
At the Sudbury site: SNOLAB
- Underground Laboratory (2 km deep) ($ 38M): Complete mid- 2007
- Surface Laboratory ($ 10 M): Complete September, 2005
To pursue:
• Future observations from a possible SNO+ detector
• Solar Neutrinos
• Geo - neutrinos
• Supernova Neutrinos
• Reactor Neutrinos
• Dark Matter (WIMPS)
• Measurements of nuclear recoils with ultra-low background
• Double Beta Decay:
• Are Neutrinos Majorana particles?
• More accuracy for neutrino masses
The New SNOLAB
New
Excavation
To Date
SNO
Cosmic Ray
Muons
Vs
Depth
Letters of Interest for SNOLAB
Solar Neutrinos:
Liquid Ne: CLEAN (also Dark Matter)
Liquid Scintillator: SNO+ (also Double Beta Decay, Reactor Neutrinos, Geoneutrinos,
Supernovae)
Liquid Helium (also Dark Matter)
Dark Matter:
Silicon Bolometers: CDMS
Liquid Xe: ZEPLIN, XENON
Recent Workshop and
Experiment Review Committee
Aug 14-16, 2005
Gaseous Xe: DRIFT
Freon Super-saturated Gel: PICASSO
Timing of Liquid Argon Scintillation: DEAP
Neutrinoless Double Beta Decay:
Ge Crystals: Individual cryostats (MAJORANA) or Large Liquid Nitrogen bath
Liquid Xe: EXO
CdTe: COBRA
Future low-energy solar 
experiments
*
*
SNOLAB
SNOLAB
Dan McKinsey Talk
+
* funded
[Nakahata@NOON04]
SNO+
• After heavy water is removed from SNO in 2007:
• SNO plus liquid scintillator → physics program
– pep and CNO low energy solar neutrinos (11C: 20 x < Gran Sasso)
• SSM pep flux: uncertainty ±1.5%  allows precision test.
• Comparison with the photon luminosity.
• Tests the neutrino-matter interaction, sensitive to new physics.
–
–
–
–
–
non-standard interactions, mass-varying neutrinos, CPT violation,large 13,
sterile neutrino admixture….
geo-neutrinos
240 km baseline reactor oscillation confirmation
supernova neutrinos
double beta decay (150Nd) ?
Survival Probability Rise
stat + syst + SSM errors estimated
SSM pep flux:
uncertainty ±1.5%
Dm2 = 8.0 × 10−5 eV2
tan2 = 0.45
known source → precision test
improves precision on 12
sensitive to new physics:
• non-standard interactions
• solar density perturbations
• mass-varying neutrinos
• CPT violation
• large 13
• sterile neutrino admixture
SNO CC/NC
pep 
Studying the rise confirms
MSW or perhaps shows us
new physics
New Physics
NC non-standard Lagrangian
Friedland, Lunardini, Peña-Garay, hep-ph/0402266
• non-standard interactions
• MSW is linear in GF and
limits from -scattering
experiments  g2 aren’t
that restrictive
• mass-varying neutrinos
Miranda, Tórtola, Valle, hep-ph/0406280
Sterile Neutrinos:
de Holanda and Smirnov hep-ph/0307266
pep solar neutrinos are at
the “sweet spot” to test
for Huber,
new physics
Barger,
Marfatia, hep-ph/0502196
Event Rates (Oscillated)
7Be
resolution with
450 photoelectrons/MeV
solar neutrinos
3600 pep/year/kton >0.8 MeV
using BS05(OP)
and best-fit LMA
2300 CNO/year/kton >0.8 MeV
11C
Cosmogenic Background
these plots from the KamLAND proposal
muon rate in
KamLAND: 26,000 d−1
compared with
SNO: 70 d−1
KamLAND (7Be  phase)
•Elastic scattering:
 x + e- →  x + e• R&D work focus on
reducing radioactive
backgrounds in the
liquid scintillator.
pep
impurities
present
(3.5 ± 0.5) x 10-18 g/g
232Th (5.2 ± 0.8) x 10-17 g/g
40K
< 2.7 x 10-16 g/g
85Kr ~ 1
Bq/m3
210Pb
~ 10-20 g/g
238U
goal
reduction
10-16 g/g
10-16 g/g
10-18 g/g
~1 mBq/m3
~10-25 g/g
OK
OK
10-2
10-6
10-5
distillation purge
< 10-2
< 10-5
< 10-4
Kamland Purification System to be installed in 2006
< 10-5
Default Scintillator Identified
Like Ivory SNOW
Soap:
(99 + 44/100) %
Pure.
It Floats!
• Linear Alkyl Benzene (LAB) has the smallest
scattering of all scintillating solvents investigated
• LAB has the best acrylic compatibility of all
solvents investigated
• density  = 0.86 g/cm3:Hold down acrylic vessel.
• …default is Petresa LAB with 4 g/L PPO,
wavelength shifter 10-50 mg/L bisMSB
• because solvent is undiluted and SNO
photocathode coverage is high, expect light
output (photoelectrons/MeV) ~3× KamLAND
Geo-Neutrino Signal
terrestrial antineutrino event rates:
• Borexino: 10 events per year (280 tons of C9H12) / 29 events reactor
• KamLAND: 29 events per year (1000 tons CH2) / 480 events reactor
• SNO+: 64 events per year (1000 tons CH2) / 87 events reactor
based on Rothschild, Chen, Calaprice
Geophys. Res. Lett. 25, 1083 (1998)
KamLAND
geo- in
SNO+
SNO+ geo-neutrinos and reactor background
KamLAND geo-neutrino
detection…July 28, 2005 in Nature
SNO++ (Nd Double Beta Decay)
0: 1057 events per
year with 1% natural
Nd-loaded liquid
scintillator in SNO++.
Simulation
assuming light
output similar to
Kamland.
Very preliminary
simulation:
one year of data
m = 0.15 eV
SNO+ Collaboration
Queen’s
M. Chen*, M. Boulay, X. Dai, K. Graham, A. Hallin, C. Hearns, C. Kraus, C.
Lan, J.R. Leslie, A. McDonald, V. Novikov, P. Skensved, A. Wright,
U.
Bissbort, S. Quirk
Laurentian
D. Hallman, C. Virtue
SNOLAB
A subset of the SNO
B. Cleveland, R. Ford, I. Lawson
collaboration will
Brookhaven National Lab
continue with SNO+
A. Garnov, D. Hahn, M. Yeh
Los Alamos National Lab
A. Hime
LIP Lisbon
J. Maneira
* Principal Investigator
•
potential collaborators from outside SNO (Italy, Germany, Russia) have indicated
some interest
new collaborators welcome
We are working on a SNO+ proposal to be submitted this fall.
Some other fun SNOLAB
experiments as time permits
Letters of Interest for SNOLAB
Solar Neutrinos:
Liquid Ne: CLEAN (also Dark Matter)
Liquid Scintillator: SNO+ (also Double Beta Decay, Reactor Neutrinos, Geoneutrinos,
Supernovae)
Liquid Helium (also Dark Matter)
Dark Matter:
Silicon Bolometers: CDMS
Liquid Xe: ZEPLIN, XENON
Recent Workshop and
Experiment Review Committee
Aug 14-16, 2005
Gaseous Xe: DRIFT
Freon Super-saturated Gel: PICASSO
Timing of Liquid Argon Scintillation: DEAP
Neutrinoless Double Beta Decay:
Ge Crystals: Individual cryostats (MAJORANA) or Large Liquid Nitrogen bath
Liquid Xe: EXO
CdTe: COBRA
http://arxiv.org/astro-ph/0411358
scintillation pulseshape analysis for
discrimination of e- vs
nuclear recoils
-> no electron-drift
DEAP : Dark-matter Experiment with Argon PSD
Background rejection with LAr (simulation) [Mark Boulay]
108
From simulation,
rejection > 108
@ 10 keV
(>>!)
simulated e-’s
100 simulated
WIMPs
Discrimination in liquid argon from DEAP-0
<pe> = 60
preliminary
<pe> = 60 corresponds to 10 keV with 75% coverage
•Final analysis and systematics evaluation being done
O(1in 105)
consistent
with room
background
(preliminary)
DEAP-0
DEAP- 1 (2 kg)
Is under
Construction at
Queen’s. To be
Sited in SNOLAB
In 2006
Spin Independent Interaction
} Where we Are
Minimal SuperSymmetric Models
} Some Future
Expts.
Liquid Ar scintillation
M.G. Boulay & A. Hime, astro-ph/0411358
Fluorine is very sensitive for the spin-dependent interaction
Montreal, Queen’s
Indiana, Pisa, BTI
SPIN - DEPENDENT
INTERACTION
20 g: hep-ex/0502028
1 kg
2 kg to be run in 2006
10 kg
100 kg
Conclusions
•The Sudbury Neutrino Observatory (SNO) has provided
fundamental measurements of neutrino and solar properties.
•Neutrino measurements have opened new areas of
investigation for physics beyond the Standard Model of
Elementary Particles.
•With SNO, SNO+ and the deepest international underground
site (SNOLAB) we have an exciting future for sensitive
measurements of solar neutrinos, double beta decay and dark
matter particles.
Another Canada – Sweden connection: Hockey
Mats Sundin
Congratulations to Sweden
Olympic Hockey Champions!