Transcript Solar Neutrinos – Present and Future

SNO and the new SNOLAB
Art McDonald,
SNO Institute Director
For the SNO Collaboration
Neutrino Telescopes, Venice, 2007
• SNO: Heavy Water Phase Complete
• Status of SNOLAB
• Future experiments at SNOLAB: (Dark Matter,
Double beta, Solar n, geo-n, supernova n)
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)
nx+e-  nx+enx, but enhanced for ne
3 ways to
detect neutrons
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 - Nov. 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
Sudbury Neutrino Observatory
Support Structure
for 9500 PMTs,
60% coverage
12 m Diameter
Acrylic Vessel
1700 tonnes Inner
Shielding H2O
5300 tonnes Outer
Shield H2O
Urylon Liner and
Radon Seal
1000 tonnes D2O ($300 M)
200 tonnes has been
returned
SALT PHASE (“Near Background-free” analysis)
EVENTS VS VOLUME: Bkg < 10%
ISOTROPY: NC, CC separation
Heavy water
DIRECTION FROM SUN
ENERGY SPECTRUM FROM CC REACTION
Flavor change
determined by > 7 s.
CC, NC FLUXES
MEASURED
INDEPENDENTLY
nm ,
The Total Flux of Active
nt
Neutrinos is measured
independently (NC) and agrees
Electron neutrinos
well with solar model
CC  1.68
 0.06
0.06
NC  4.94
 0.21
0.21
38
(stat.) 00..34
(syst.)
4.7 +- 0.5 (BPS07),
ES  2.35
 0.22
0.22
15
(stat.) 00..15
(syst.)
5.31 +- 0.6 (Turck-Chieze et al 04)
08
(stat.) 00..09
(syst.)
Calculations:
(In unitsof 106 cm2s1 )
CC
029
Pee 
 0.34  0.023(stat.) 00..031
 sin 2 12
NC
Pee  0.45(3.1s )
High accuracy
for 12.
Implies Matter Interactions (Folgi, Lisi 2004)
SOLAR ONLY
AFTER NEW
SNO SALT
DATA
Large mixing
Angle (LMA)
Region: MSW
- SNO: CC/NC flux
defines tan2 12 < 1
(ie Non - Maximal mixing)
by more than 5
standard deviations.
-The mass hierarchy is
defined (m2 > m1)
through the
matter interaction (MSW)
LMA for solar n predicts very small
spectral distortion, small (~ 3 %) day-night
asymmetry, as observed by SNO, SK
SOLAR PLUS KAMLAND
(assuming CPT)
(Reactor n’s)
Final Phase: SNO Phase III
Total Radioactivity similar
To Phase I, II
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; completed November 2006
Another analysis
is almost complete
that combines data
from
the first two SNO
Phases and
reduces the
threshold by ~ 1
MeV.
This also provides
improved accuracy
on CC/NC flux
ratio.
BLIND ANALYSIS:
Add in unknown number
of neutrons from muons
New International Underground Science Facility
At the Sudbury site: SNOLAB
- Underground Laboratory (2 km deep) ($ 38M) funded: Complete end-2007
- Surface Laboratory ($ 10 M) funded: Complete September, 2005
- Cryopit addition underground: Funding support nearly completed ($ 14 M)
Excavation to be completed in early 2008
(Cavity capable of housing 100 tons of liquid cryogen, with an independent
path for venting gas to the surface in case of accident.)
- Total additional excavated volume in new lab: 2 times SNO volume.
To pursue Experiments that benefit from a very deep and clean
lab:
• Direct Observation of Dark Matter (WIMPS) via nuclear recoil
• Neutrino-less Double Beta Decay
• Low Energy Solar Neutrinos
• Particle physics and solar physics
• Geo – neutrinos
• Supernova Neutrinos
• Reactor Neutrinos
To Be Ready for Experiments: 2008
The New SNOLAB
New
Excavation
To Date
Cryopit
2/3
All Lab Air: Class < 2000
SNO
40 to 400 times lower m fluxes than
Gran Sasso, Kamioka.
Total Muon Flux vs Depth Relative to Flat Overburden
Canfranc 2.5 km.w.e.
Frejus 4.8 km.w.e.
D. Mei, A. Hime astro-ph/0512125
Surface Facilities
Control Rooms
Meeting Rooms
Clean Room Laboratories
Dark Matter:
Letters of Interest for SNOLAB
Timing of Liquid Argon/Neon Scintillation: DEAP/CLEAN (1 Tonne)
Freon Super-saturated Gel: PICASSO
Silicon Bolometers: SUPER-CDMS
Liquid Xe: ZEPLIN- III, LUX (1 Tonne)
Gaseous Xe: DRIFT
5 th Workshop and
Experiment Review Committee
Aug 21, 22, 2006
www.snolab.ca
Neutrino-less Double Beta Decay:
150Nd:
76Ge:
Organo-metallic in liquid scintillator in SNO+
MAJORANA or next generation GERDA/MAJORANA
136Xe:
EXO (Gas or Liquid)
CdTe: COBRA
Solar Neutrinos:
Liquid Scintillator: SNO+ (also Reactor Neutrinos, Geo-neutrinos)
Liquid Ne: CLEAN (also Dark Matter)
SuperNovae:
HALO: Pb plus SNO 3He detectors; SNO+
SNO+
Support Structure
for 9500 PMTs,
60% coverage
12 m Diameter
Acrylic Vessel
1700 tonnes Inner
Shielding H2O
5300 tonnes Outer
Shield H2O
Urylon Liner and
Radon Seal
Replace Heavy water with
1000 tonnes Liquid Scintillator
Best Scintillator Identified
• Linear Alkyl Benzene (LAB) has the smallest scattering of
all scintillating solvents investigated and the best acrylic
compatibility.
• density  = 0.86 g/cm3: Ropes to hold down acrylic vessel.
• …default is Petresa LAB with 4 g/L PPO, wavelength
shifter 10-50 mg/L bisMSB
• because LAB solvent is undiluted and SNO photocathode
coverage is high, expect light output (photoelectrons/MeV) ~3×
KamLAND
• Nd metallic-organic compound has been demonstrated to have
long attenuation lengths, stable for more than a year.
• 0.1 % of Nd can be added with little degradation of light output.
Neutrino-less Double Beta Decay Candidate
150Nd




3.37 MeV endpoint
(9.7 ± 0.7 ± 1.0) × 1018 yr
2nbb half-life (NEMO-III)
isotopic abundance 5.6% (in
SNO+ 0.1% loading=56 kg)
Nd is one of the most
favorable double beta decay
candidates with large phase
space due to high endpoint.
table from F. Avignone Neutrino 2004
57
 78
0.73
 35(phase space)  2(nuclear calculation)
SNO+ (150Nd Neutrino-less Double Beta Decay)
0n: 1057 events per
year with 500 kg
150Nd-loaded liquid
scintillator in SNO+.
Simulation
assuming light
output and background
similar to Kamland.
One year of data
mn = 0.15 eV
U Chain
Th Chain
Super-Nemo and SNO+ seek use of Laser Isotope Separation facility in France
to enrich 100’s of kg of 150Nd isotope. CEA has agreed to initial study during 07/08
pep solar n
NC non-standard Lagrangian
• SNO+ (Liquid Scintillator)
• Test the MSW Energy
Dependence, transition from
MSW (8B) to vacuum osc. (pp).
• Look for:
- Non-standard interactions
- Mass-varying neutrinos
Barger, Huber, Marfatia, hep-ph/0502196
Friedland, Lunardini, Peña-Garay, hep-ph/0402266
Miranda, Tórtola, Valle, hep-ph/0406280
The pep solar neutrinos are at a sensitive
energy to test for new physics.
The pep (and CNO) can be observed at
SNO+ depth with no 11C interference.
3 Years of Data
CNO
pep
Assuming U, Th as achieved at Kamland, Bi, K set at Kamland objectives,
Max Likelihood fit extracts pep at +- 4%.
Negligible background from 11C at this depth.
Other Double Beta Decay
Example: Majorana
•
•
•
•
60 to 120 kg enriched 86% 76Ge
many crystals, each segmented
advanced signal processing
require special low background
materials
• deep, clean underground location
• Few keV resolution at Qbb = 2039 keV
• known technology
• sensitivity to few 1027 years
mn <~ 0.1 eV
US, Canada, Japan, Russia collaboration
• MOU for future consideration of >~ 500 kg experiment with GERDA
EXO: Liquid or Gas
(~ 200 kg enriched 136Xe at present)
• EXO-200 Liquid Detector with scintillation and ionization measurement:
To Be Deployed at WIPP in June 2007. (No Ba tagging)
• Independent development of Laser-tagging of single Barium atoms in liquid.
• EXO-Gas: Wire chamber under development in parallel
• Future – much larger mass.
EXO-200: Expected sensitivity < 0.35 eV
(Carleton, Laurentian, SNOLAB,
TRIUMF development work)
Liquid
Gas
Compact detector
No pressure vessel
Small shield -> lower purity reqd.
Energy resolution s < 0.6%
Tracking & multi-site rejection
In-situ Ba tagging
Large Cryostat
Poorer energy, tracking resolution
Ex-situ Ba tagging
Large detector
Needs very large shield
Pressure vessel is massive
DARK MATTER
DEAP/CLEAN:
1 Tonne Fiducial
Liquid Argon
- Scintillation time spectrum for Ar
enables WIMP recoils to be
separated from gammas from
39Ar background.
- Simulation indicates that 39Ar
and other gamma-beta
backgrounds can be discriminated
from WIMPS using only scintillation
light for up to 1 tonne fiducial
Volume of liquid argon.
- DEAP and CLEAN collaborations
have come together to build this
new detector with a simple and easily
scaled technology at SNOLAB.
108 simulated e-’s
From simulation,
g rejection > 108
@ 10 keV
100 simulated
WIMPs
M.G. Boulay & A. Hime, astro-ph/0411358
Discrimination in liquid argon from DEAP-0 (<1 kg)
<pe> = 60
O(1in 105)
consistent
with room
neutrons in
surface lab.
DEAP- 1 (7 kg)
Is in operation
on surface. To be
sited in SNOLAB
in May 2007.
<pe> = 60 corresponds to 10 keV threshold
with 75% coverage
Will test
Discrimination
to 109
DEAP/CLEAN Detector
- 3.5 Tonnes of pure liquid Argon (Neon) in an 85-cm
spherical acrylic vessel, viewed by 200 cold PMT’s through
acrylic light guides. Very high light collection, external H2O
shield.
- Objective: 1 tonne liquid central fiducial volume to eliminate
surface radioactivity and obtain sensitivity to WIMP cross
sections down to 10- 46 cm2. (1000 times better than present
limits for spin-independent cross section).
- SNOLAB depth removes neutrons from cosmic rays.
Residual backgrounds are only few per year.
- Argon with reduced 39Ar is also under investigation.
- $ 3 M of $ 5 M total funding available soon.
- Planned deployment during 2009, operation in 2010.
For Example: Muon-induced Neutron Background for a CDMS-type
Dark Matter Experiment: Mei and Hime: astro-ph/0512125
Spin Independent Interaction
} Where we Are
Minimal SuperSymmetric Models
LUX
Super-CDMS
} Future Expts.
10-46cm2
DEAP/CLEAN
Cryogenic Dark Matter Search: CDMS
Planned start of construction: 2008 assuming funding approval soon.
ZEPLIN-III
8 kg Xe Liquid – gas
Scintillation + Electroluminescence
Ready for Immediate Deployment
WIMP-Nucleus Spin-Dependent Interaction
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
PICASSO
2 kg being run in 2006-07
10 kg
100 kg
Initial Suite of Experiments
Cryopit: 1 of
2008: DEAP/CLEAN
2009: LUX
Future??:Large EXO,
CLEAN, 1-ton
GERDA/MAJORANA
Cube Hall:1 (or 2) of
2008: DEAP/CLEAN
2009: PICASSO-III
2009: LUX (1 ton Xe)
2008:HALO
SNO Utility Rm:
Now: PICASSO-IB (2kg)
Ladder Labs: 2 of
2008: Super-CDMS
2009: PICASSO IIB
2009: EXO-200-Gas
2009: Majorana (TBD)
South Drift:
2008: ZEPLIN-III
SNO Cavern:
2008: SNO+
SNO Control Rm:
2007: DEAP-1
Summary
• SNO is analyzing data from its three phases and will be
providing new publications in the near future with improved
accuracy.
• Underground measurements have opened new areas of
investigation for physics beyond the Standard Model of
Elementary Particles and astrophysical topics.
• With a very deep, clean international underground facility
(SNOLAB) we have an exciting future for sensitive
measurements of solar neutrinos, neutrino-less double beta
decay and dark matter particles.