Transcript SNO+ (1000 tonnes highly purified Liquid Scintillator): 2010

Telescopes: SNO and the New SNOLAB
2 km underground in Vale-INCO’s Creighton
Mine near Sudbury, Ontario
Neutrino Telescopes
Venice
March 10, 2009
(Galileo + 400)
Art McDonald
Queen’s University, Kingston
For the SNO Collaboration
The Sudbury Neutrino Observatory: SNO
6800 feet (~2km) underground
Acrylic vessel (AV)
12 m diameter
1000 tonnes D2O
($300 million)
1700 tonnes H2O
inner shielding
5300 tonnes H2O
outer shielding
~9500 PMT’s
Creighton mine
Sudbury, CA
- Entire detector
Built as a Class 2000
Clean room
- Low Radioactivity
Detector materials
The heavy water has been returned and development work is in progress
on SNO+ with liquid scintillator and 150Nd additive.
SNO: Solving the “Solar Neutrino Problem”
Previous Experiments Sensitive
Mainly to Electron Neutrinos
Solar Model Flux Calculations
, SNO
Bahcall et al.
CNO
SNO was designed to observe separately ne and all
neutrino types to determine if low ne fluxes come from
solar models or neutrino flavor change (New Physics)
Unique Signatures in SNO (D2O)
Charged-Current (CC)
ne+d  e-+p+p
Ethresh = 1.4 MeV
ne only
Neutral-Current (NC)
nx+d  nx+n+p
Ethresh = 2.2 MeV
Equally sensitive to ne nm nt
Elastic Scattering (ES) (D2O & H2O)
nx+e-  nx+enx, but enhanced for ne
Events point away from the sun.
3 ways to
detect neutrons
SNO: 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
As of today: Oscillation of 3 massive active neutrinos is clearly the dominant effect:
If neutrinos have mass:
n l  Uli n i
For 3 Active neutrinos. (MiniBoone has recently ruled out LSND result)
 U e1 U e 2 U e3 


Maki-Nakagawa-Sakata-Pontecorvo 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
Atmospheric
?
CP Violating Phase
where cij  cos  ij , and sij  sin  ij
Reactor, Accel.
Majorana Phases
Range defined for Dm12, Dm23
For two neutrino oscillation in a vacuum: (a valid approximation in many cases)
2
Δm
L
2
2
P(ν μ  νe )  sin 2θ sin ( 1.27
)
E
Leptogenesis:  or  phases -> possible matter/antimatter asymmetry in Early Universe
Matter Effects – the MSW effect
n e 
d n e 
i    H 
dt n x 
n 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 solar ne 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.
If observed, matter interactions define the mass heirarchy.
Reactor AntiNeutrinos
(KAMLAND)
Solar
Neutrinos
(SNO plus
others)
-The solar results are best fit
with the MSW effect and
define the mass hierarchy
(m2 > m1) through the Matter
interaction.
-SNO: CC/NC flux defines
tan2 12 < 1 (ie Non - Maximal
mixing) by more than 5
standard deviations
The Total Flux of Active Neutrinos agrees
SNO Results for Salt Phase
CC  1.68
 0.06
0.06
NC  4.94
 0.21
0.21
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
CC
029
 0.34  0.023(stat.) 00..031
NC
reasonably well with solar models:
5.95 (1+- 0.11) [BPS08 (GS)]
4.72 (1+- 0.11) [BPS08 (AGS)]
However, metal abundances, mixing …?
-> CNO measurements: Haxton, Serenelli
Electron Neutrinos are only 1/3 of Total
Flavor change determined by > 7 s.
Final Phase: SNO Phase III
Neutral-Current Detectors (NCD): An array of 3He
proportional counters:40 strings on 1-m grid: ~440 m
Phase III production
data taking Dec 2004
to Dec 2006. D2O and
NCD’s now removed.
NCD’s to be used in
HALO: a lead-based
Supernova detector
for ne
• Improve solar neutrino flux by breaking the
CC and NC correlation:
CC: Cherenkov Signal  PMT Array
NC: n+3He  NCD Array
CC
 sin 2 12
• Improvement in 12, as
 NC
Neutrons from solar neutrino interactions
NC Signal:
983 ± 77
Neutron
background:
185 ± 25
Alphas and
Instrumentals:
6126 ± 250
(0.4 to 1.4 MeV)
SNO PAPER: arXiv:0806.0989v3 [nucl-ex]
Phys.Rev.Lett.101:111301,2008
~ 1 alpha background event
per month per meter of
detector.
full model of detector physics
to simulate pulse shape
characteristics, correlations
Pulse Width (ns)
NCD Simulation Results
data
Pulse Width (ns)
tuned on calibration data
MC
Energy (MeV)
neutron signal
alpha backgrounds:
surface polonium decay
bulk U and Th decay
wire polonium decay
wire bulk decay
insulator polonium decay
insulator bulk U and Th decay
Energy (MeV)
SNO Fluxes: 3 Phases
p-value for consistency of
NC/CC/ES in the salt &
NCD phases + D2O
NC(unconstr) is 32.8%
stat
stat + syst
Solar + KamLAND fit
results
19
Dm2  7.5900..21
105 eV2
8B  4.91106 cm2 s 1 ( ~ 7%)
12  34.4
12  33.9
1.3
1.2
degrees
2.4
2.2
deg (previous)
Neutrino flavour symmetry phenomenology:
(Smirnov summary at Neutrino 2008)
Tri-Bi-Maximal Mixing: 35.2 deg
Quark-Lepton Complementarity: 32.2 deg
(12 + Cabbibo = 45 deg)
The accuracy on 12 and 8B will improve
with new data analysis: SNO LETA
This work:
• SNO NCD results
agree well with previous
SNO phases. Minimal
correlation with CC.
Different systematics.
• New precision on 
Future solar analysis:
• LETA (Low Energy
Threshold Analysis)
• 3-neutrino analysis
• hep flux
• Day-night, other
variations
• Muons, atmospheric n
SNO Physics (Telescope) Program

Solar Neutrinos
(7 papers to date)
 Electron Neutrino Flux
 Total Neutrino Flux
 Electron Neutrino Energy Spectrum Distortion
 Day/Night effects
 hep neutrinos hep-ex 0607010
 Periodic variations: [Variations < 8% (1 dy to 10 yrs)] hep-ex/0507079

Atmospheric Neutrinos & Muons
(arXiv: hep-ex 0902.2776)
 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 nnn)
Phys.Rev.Lett. 92 (2004) [Improves limit by 1000]

Supernova Relic Electron Neutrinos hep-ex 0607010
SNO Muon & Atmospheric Neutrino Analysis
Through-going muons
SNO
X
Super-K
SNO provides a test of the SuperKamiokande oscillation parameters (Dm2 =
2.1 x 10-3 ev2, sin22Q = 1.00 +- 0.032).
SNO: 2.6 x 10-3 ev2
SNO also provides a measure of the
cosmic neutrino flux above the horizon.
Normalization of Bartol 3-D atmospheric
neutrino flux model: 1.22 +- 0.10.
Downward-going Muons
SNO data for
downward-going
muons extends the
previous data to
about 13.5 km of
water equivalent,
where atmospheric
neutrino generated
muons begin to
contribute
significantly.
Also studying
neutron production
From muons.
New SNO paper arXiv: hep-ex 0902.2776
SNO+ : Liquid Scintillator with Nd for Double Beta Decay + Solar, geo - n
The organic
liquid is lighter
than water so
the Acrylic Vessel
must be held down.
1000 tonnes
of liquid
scintillator
(LAB)
New scintillator
purification systems
are required.
(plus 1 tonne
of natural Nd
= 56 kg of
150Nd for
Double Beta
Decay)
Existing
AV Support
Ropes
New AV Hold
Down Ropes
Otherwise, the existing detector, electronics etc. are unchanged.
SNO+: Neutrino-less Double Beta Decay:
150Nd
• Nd is one of the most favorable double beta decay candidates
with large phase space due to high endpoint: 3.37 MeV.
• Ideal scintillator (Linear Alkyl Benzene) has been identified.
More light output than Kamland, Borexino, no effect on acrylic.
• Nd metallic-organic compound has been demonstrated to have
long attenuation lengths, stable for more than 2 years.
• 1 tonne of Nd will cause very little degradation of light output.
(Successful test in 2008 with small chamber in center of SNO)
• Isotopic abundance 5.6% (in SNO+ 1 tonne Nd = 56 kg 150Nd)
• Possible enrichment of 150Nd or increase in the amount of
natural Nd.
• SNO+ Capital proposal submitted, decision June 2009.
• Plan to start with natural Nd in 2011.
• Other physics: CNO solar neutrinos, pep solar neutrinos to
study neutrino properties, geo-neutrinos, supernova search.
(No 11C background at this depth.)
Queen’s, Alberta, Laurentian, SNOLAB, BNL, Washington, Penn, Texas, LIP
Lisbon, Idaho State, Idaho Nat Lab, Oxford, Sussex, TUDresden, Leeds,UCLondon
Capability for 3 Years of Data
Solar Neutrinos
CNO
pep
Backgrounds assumed at Kamland observed values plus their purification
objectives for 210Bi, 40K. Negligible background from 11C at SNOLAB depth.
Measuring Effective n Mass
mnbb = |i Uei ² mi |
mnbb = |m1 cos213cos²12 + m2 e2i cos213sin²12 + m3 e2ib sin²13|
mnbb (eV)
Mass Hierarchies
Present Expts.
Inverted
Degenerate
0.04 eV
Normal
normal hierarchy
Normal
inverted hierarchy
Inverted
SNO+ Sensitivity (3 years):
0.1 eV with 1 tonne natural Nd
0.04 with 500 kg 150Nd.
Lightest neutrino (m1) in eV
SNO+ (150Nd n - less Double Beta Decay)
0n: For example: 1057
events per year with
500 kg 150Nd-loaded
liquid scintillator in
SNO+.
Simulation
assuming light
output and
background
similar to Kamland.
(Borexino has done better)
One year of data
mn = 0.15 eV
U Chain
Th Chain
~Flat 8B Solar n
“background”
Sensitivity Limits (3 yrs):
1000 kg natural Nd (56 kg isotope): mnbb ~ 0.1 eV (start 2011)
With 500 kg enriched 150Nd: mnbb ~ 0.04 eV
Geo-Neutrino Signal
event rates:
• KamLAND: 33 events per year (1000 tons CH2) / 142 events reactor
• SNO+: 44 events per year (1000 tons CH2) / 42 events reactor
- four times smaller reactor
background in the geo-neutrino
region than in KamLAND
- test models in a region
dominated by crustal
components.
- very well characterized local
geology enables residuals to
probe the U and Th content of
the deep Earth
- reactor spectrum “dip” helps
constrain Dm2 and 12
SNO+ geo-neutrinos and reactor background
SNOLAB Construction is complete – Final cleaning occurring
Letters of Intent/Interest (Red implies approval for siting) :
Dark Matter:
Timing of Liquid Argon/Neon Scintillation: DEAP-1 (7 kg), MINI-CLEAN (360 kg),
DEAP/CLEAN (3.6 Tonne)
Freon Super-saturated Gel: PICASSO
Silicon Bolometers: SUPER-CDMS (25 kg)
Double Beta Decay:
150Nd:
In liquid scintillator in SNO+
136Xe:
EXO (Gas or Liquid) (Longer Term)
CdTe: COBRA (Longer Term)
Solar Neutrinos:
Liquid Scintillator: SNO+ (also Reactor Neutrinos, Geo-neutrinos)
SuperNovae:
SNO+: Liquid scintillator;
HALO: Pb plus SNO 3He detectors.
SNOLAB
New large scale
project.
2009: MiniCLEAN 360
2010: DEAP/CLEAN 3600
Phase II
Cryopit
2009: HALO
Cube Hall
Now:PICASSO-II
2010: PICASSO IIB?
2010: EXO-200-Gas?
2011: SuperCDMS ?
Now:DEAP-1
Ladder Labs
Utility
Area
2010: SNO+
SNO Cavern
Personnel
facilities
All Lab Air: Class < 2000
SNOLAB @ Neutrino 2008
Christchurch May 28th, 2008
Personnel
Facility
Lunch
Room
Start of Clean conditions for the new SNOLAB: Feb. 2009
Lunch
Room
Cube Hall
Dark Matter Search with Liquid
Argon: DEAP-1 (7 kg Ar)
(Running); Future: Mini-Clean
(360 kg Ar or Ne) and DEAP3600 (3.6 tonnes Ar)
WIMP-Induced Nuclear recoils
in Ar are discriminated from
beta and gamma radioactivity
(39Ar) by timing of the light
emitted.
MiniCLEAN
360 kg
2009
DEAP/CLEAN
3.6 tonne
2010
Dark Matter Search at SNOLAB with Liquid Argon
Background
suppression
better than
2.6 E-8
demonstrated
to date
Backgrounds (g’s)
Yellow: Prompt light region
Blue: Late light region
DEAP-1 at SNOLAB
For DEAP/CLEAN 3600
suppression of > 10-9
is required.
Signal (nuclear recoil)
Fprompt 
Pr omptPE(150ns)
T otalPE(9ms)
Note also that sources of
Ar depleted x 20 in 39Ar
have been found and are
being developed with the
Princeton group.
Super
CDMS
25 kg
CDMS-II:
~50 kg-days
(Ge)
XENON-10:
~300 kg-days
(Xe)
DEAP- 3600: 1,000,000 kg-days (Ar)
(3 yrs)
PICASSO
Project In CAnada to Search for Supersymmetric Objects
• detectors consist of tiny (5 to 100 mm) halocarbon superheatedliquid droplets (e.g. C3F8, C4F10) embedded in a gel
• WIMP-induced nuclear recoils nucleate a bubble; expanding,
evaporating bubble produces an acoustic signal detected by piezo
microphone
19F
favourable target to search for
“spin-dependent” WIMP scattering
32 detector modules
containing 4 L of gel
insensitive to beta and
gamma radiation; some
discrimination exists for
alphas
SPIN DEPENDENT WIMP INTERACTION: Studied with Fluorine dispersed in
supersaturated gel – WIMP nuclear recoils create bubbles - detected acoustically.
Low response for other radioactivity. Breakthrough this year: alpha discrimination
PICASSO PHASES
Phase 1a: (published in ’05 PLB, NIM)
20g 2kgd
MSSM
Theory
Predictions
Phase Ib:
2.6 kg 700 kgd
Bckg red. 1/6 – 1/10
Phase Ib/100:
2.6 kg 700 kgd
Bckg: red. 1/100
Phase II:
25 kg 7000 kgd
Larger modules 30L
(ongoing)
H elium
A nd
L ead
O bservatory
Pb: Most sensitivity to electron neutrinos.
~ 50 events for SN at center of Galaxy.
A lead detector for
supernova neutrinos
in SNOLAB
Laurentian, TRIUMF,
SNOLAB, LANL, Washington,
Duke, Minnesota, Digipen IT
HALO-1: 80 tons of existing Pb
& SNO Neutron Detector Array
SUMMARY
• SNO operation is complete, further papers to come over next
year.
• SNOLAB construction is complete, final cleanliness in progress.
• Several experiments are already running in existing clean space.
• A number of other experiments have been approved for siting in
the near future for neutrinos, double beta decay, Dark Matter.
• Stay tuned for some exciting future physics results.