Transcript Sudbury Neutrino Observatory: Status and Future Plans Mark Chen

Sudbury Neutrino
Observatory: Status
and Future Plans
ICFP2005, Chung-Li, Taiwan
Mark Chen
Queen’s University
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 = 1.44 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
Nov 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)
Pure D2O “archival long
paper” being prepared
PRL 92, 181301 (2004)
nucl-ex/0502021 “salt long NCD data being taken
paper” accepted for
publication in Phys. Rev. C
see Melin Huang’s talk, Thurs afternoon
391-Day Salt Phase
Flux Results
+0.06
+0.08
+0.22
+0.15
CC
+ 0.029
 0.340  0.023 0.031
 NC
Fcc(ne) = 1.68 −0.06 (stat.) −0.09(syst.) × 106 cm−2 s−1
Fes(nx) = 2.35 −0.22 (stat.) −0.15(syst.) × 106 cm−2 s−1
Fnc(nx) = 4.94 −0.21 (stat.)−0.34(syst.) × 106 cm−2 s−1
+0.21
+0.38
BS05(OP) Standard Solar Model Flux Calculation:
(5.69 ± 0.91) × 106 cm−2 s−1
Oscillation Analysis 391-day Salt
global solar plus latest KamLAND and 391-day SNO salt
Oscillation Analysis 391-day Salt
global solar with 391-day SNO salt
SNO Timeline
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
we have learned a lot about
solar neutrinos – but there is
more to study and understand!
• 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) – day/night and spectral shape
are studied as well as the total active 8B solar neutrino flux
• NCDs installed and taking production data; final SNO configuration
offers CC and NC event-by-event separation, for improved precision and
cleaner spectral shape examination
?
Beyond SNO
• Fall 04 to Dec 06: SNO Phase III
– 3He proportional counter array now in place
• dedicated Neutral Current Detectors (NCDs)
• taking production data
– data taking end date: 31 Dec 2006
• will bring total uncertainty on 8B solar n NC signal below 5%
– physics with heavy water will be complete
– in 2007, heavy water will be returned to Atomic
Energy of Canada Limited
what should be done with the detector after?
Fill with Liquid Scintillator
• SNO plus liquid scintillator → physics program
– pep and CNO low energy solar neutrinos
• tests the neutrino-matter interaction, sensitive to
new physics
– geo-neutrinos
– 240 km baseline reactor oscillation confirmation
– supernova neutrinos
– double beta decay?
Low Energy Solar Neutrinos
• complete our understanding
of neutrinos from the Sun
pep, CNO, 7Be
• explore the neutrino-matter
interaction which is
sensitive to new physics
from Peña-Garay
• best-fit oscillation parameters
suggest MSW occurs
• but we have no direct evidence of
MSW
vacuum-matter transition
– day-night effect not observed
– no spectral distortion for 8B n’s
Survival Probability Rise
stat + syst + SSM errors estimated
SSM pep flux:
uncertainty ±1.5%
Dm2 = 8.0 × 10−5 eV2
tan2q = 0.45
known source → precision test
improves precision on q12
sensitive to new physics:
• non-standard interactions
• solar density perturbations
• mass-varying neutrinos
• CPT violation
• large q13
• sterile neutrino admixture
SNO CC/NC
pep n
observing the rise confirms
MSW and that we know what’s
going on
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
New Physics
NC non-standard Lagrangian
 0.25
• non-standard interactions
• MSW is linear in GF and
limits from n-scattering
experiments  g2 aren’t
that restrictive
• mass-varying neutrinos
CHARM limit
Friedland,Miranda,
Lunardini,
Peña-Garay,
hep-ph/0402266
Tórtola,
Valle, hep-ph/0406280
solar density fluctuations:
Guzzo, Reggiani, de Holanda, hep-ph/0302303
also Burgess
et at
al., hep-ph/0310366
pep solarsee
neutrinos
are
the “sweet spot” to test for new physics
Barger, Huber, Marfatia, hep-ph/0502196
11C
Cosmogenic Background
these plots from the KamLAND proposal
muon rate in
KamLAND: 26,000 d−1
compared with
SNO: 70 d−1
Real KamLAND Backgrounds
external
pep window
pep Solar n Backgrounds
• radiopurity requirements
–
–
40K, 210Bi
(Rn daughter)
85Kr, 210Po (seen in KamLAND) not a problem
since pep signal is at higher energy than 7Be
– U, Th not a problem if one can repeat
KamLAND scintillator purity
– 14C not a problem since pep signal is at higher
energy
SNO+ pep
SNOLAB is the only deep site that exists where the pep
solar neutrinos could be measured with precision.
pep solar neutrinos are a known source – enables a
precision measurement (this is not the case with 7Be).
pp solar neutrinos are more difficult and may not reveal as
much as pep (pp survival probability set by the average
vacuum Pee).
First observation of the CNO solar neutrino would be
important for astrophysics.
Geo-Neutrinos
 can
we detect the antineutrinos produced
by natural radioactivity in the Earth?
radioactive decay of heavy
elements (uranium, thorium)
produces antineutrinos
ne
assay the entire Earth by
looking at its “neutrino glow”
Image by: Colin Rose,
Dorling Kindersley
Earth’s Heat Flow
 models
of Earth’s heat sources suggest
that radioactivity contributes 40-100%
towards Earth’s total heat flow
the radiogenic portion is not
that well known!
geophysicists want to
understand Earth’s
thermal history
H.N. Pollack, S.J. Hurter and J.R. Johnson,
Reviews of Geophysics 31(3), 267-280, 1993
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
Rothschild, Chen, Calaprice
(1998)
the above plot is for Borexino…geo/reactor ratio
in SNO+ would be twice as high
KamLAND geo-neutrino
detection…July 28, 2005 in Nature
Fundamental Geophysics
 SNO+
geo-neutrinos: a good follow-up to
KamLAND’s first detection




potential to really constrain the radiogenic
heat flow
potential for geochemistry (U and Th
separation)
tests models of Earth’s chemical origin
simple geological configuration (smaller
uncertainties)
Supernova Neutrinos
• 1 kton organic liquid scintillator would
maintain excellent supernova neutrino
capability
–
–
–
–
–
ne + p
ne + 12C (CC)
ne + 12C (CC)
nx NC excitation of 12C (NC)
nx + p elastic scattering (NC)
[large rate]
[large rate]
see Beacom et al., PRD 66, 033001(2002)
Extension of SNO Science
• leverage existing investment in SNO to get new physics
for relatively low cost
• SNO+ is uniquely positioned to make several
measurements (due to depth, geology, appropriate
distance to reactors, low backgrounds)
• costs are:
–
–
–
–
–
liquid scintillator procurement
mechanics of new configuration, AV certification
fluid handling and safety systems
scintillator purification
electronics/DAQ spares or upgrades?
SNO+ Technical Issues
 liquid


scintillator selection
compatibility with acrylic vessel
high light yield, long attenuation length
 reversing


the acrylic vessel mechanics
SNO: AV contains heavy water, must hold up
SNO+: AV contains scintillator, r < 1 g/cm3,
must hold down
 liquid
scintillator purification
Acrylic Vessel Hold-down
 “rope
net” being designed to hold down
15% density difference (buoyancy)
SNO
SNO+
Scintillator Design
density (>0.85 g/cm3)
 chemical compatibility with acrylic
 high light yield, long attenuation and
scattering lengths
 high
 high
flash point
 low toxicity
 low cost
Linear Alkylbenzene
LAB Advantages
• compatible with acrylic (e.g. Bicron BC-531 is
95% LAB)
– “BC-531 is particularly suited for intermediate sized detectors in
which the containers are fabricated with common plastic
materials such as PVC and acrylics. The scintillator provides
over twice the light output of mineral oil based liquids having
similar plastic compatibility.”
•
•
•
•
1
high flash point 130 °C 1 0
low toxicity
(pseudocumene 2 4 0)
cheap, (common feedstock for LAS detergent)
plant in Quebec makes 120 kton/year, supplier
has been very accommodating
• high purity
SNO+ Monte Carlo
• light yield simulations
KamLAND scintillator in
SNO+
629 ± 25 pe/MeV
above no acrylic
711 ± 27 pe/MeV
KamLAND scintillator
and 50 mg/L bisMSB
826 ± 24 pe/MeV
above no acrylic
878 ± 29 pe/MeV
KamLAND (20% PC in
~300 pe/MeV for 22%
dodecane, 1.52 g/L PPO) photocathode coverage
SNO+ has 54% PMT
coverage; acrylic
vessel only diminishes
light ouput by ~10%
LAB Scintillator Optimization
“safe” scintillators
LAB has 75% greater light yield
than KamLAND scintillator
Light Attenuation Length
Petresa LAB
as received
attenuation
length
exceeds 10 m
preliminary measurement
~10 m
Default Scintillator Identified
• LAB has the smallest scattering of all scintillating
solvents investigated
• LAB has the best acrylic compatibility of all
solvents investigated
• density r = 0.86 acceptable
• …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
SNO+ Status
• SNO+ is an NSERC-funded R&D project
• SNO+ endorsed by the SNOLAB Experiment Advisory Committee
“Exploit low-energy solar neutrinos for precision neutrino physics
and stellar physics”
“We endorse development toward SNO+ for pep solar neutrinos
and geo-neutrinos. We applaud the technical progress in developing
the liquid scintillator and encourage continued R&D, development of
the necessary collaboration and proposal to secure funding. We look
forward to a receiving a full technical proposal.”
SNO+ in 2006
• SNO+ in Fall 2005 “proof of principle”
– liquid scintillator identified
– preliminary design to holddown the acrylic vessel
•
•
•
•
•
need more collaborators
project management
scintillator purification R&D
electronics/DAQ plans…
full TDR by Fall 2006
– including process engineering and AV mechanics
• proposals to funding agencies by Fall 2006
SNO+ in 2007
•
•
•
•
•
start of capital funding
construction of hold-down net
access detector after D2O removed
scintillator procurement contracts
…and on to converting SNO into an
operating, multi-purpose, liquid scintillator
detector with unique physics capabilities
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
B. Cleveland, R. Ford, I. Lawson
only a subset of the
Brookhaven National Lab
SNO collaboration will
A. Garnov, D. Hahn, M. Yeh
continue with SNO+
Los Alamos National Lab
A. Hime
LIP Lisbon
J. Maneira
•
potential collaborators from outside SNO (Italy, Germany, Russia) have indicated
some interest
new collaborators welcome
Double Beta Decay: SNO++
• SNO plus liquid scintillator plus double beta isotopes:
SNO++
• add bb isotopes to liquid scintillator
– dissolved Xe gas (2%)
– organometallic chemical loading (Nd, Se, Te)
– dispersion of nanoparticles (Nd2O3, TeO2)
• enormous quantities (high statistics) and low
backgrounds help compensate for the poor energy
resolution of liquid scintillator
• possibly source in–source out capability
table from F. Avignone Neutrino 2004
150Nd
• 3.37 MeV endpoint
• (9.7 ± 0.7 ± 1.0) × 1018 yr
2nbb half-life
measured by NEMO-III
• isotopic abundance 5.6%
1% natural Nd-loaded liquid scintillator in SNO++ has
560 kg of 150Nd compared to 37 g in NEMO-III
• cost: $1/g for metallic Nd; cheaper as Nd salt…on the web NdCl3
sold in lot sizes of 100 kg, 1 ton, 10 tons
2n bb Background
• good energy resolution needed
• but whopping statistics
helps compensate for poor
resolution and…
turns this into an endpoint
shape distortion measure
rather than a peak search
Test <mn> = 0.150 eV
0n: 1000 events per
year with 1% natural
Nd-loaded liquid
scintillator in SNO++
Klapdor-Kleingrothaus et al.,
Phys. Lett. B 586, 198, (2004)
simulation:
one year of data
maximum likelihood statistical test of the shape to extract
0n and 2n components…~240 units of Dc2 significance after only 1 year!
made by Yeh, Garnov, Hahn at BNL
Nd-carboxylate in Pseudocumene
window with >6 m
light attenuation
length
{
Nd LS Works!
external 241Am a
Compton edge 137Cs
207Bi
conversion
electrons
Underground Facilities
Rectangular Hall
Control Rm
Utility Drift
Staging Area
Rectangular
Hall
60’L x 50’W
50’ (shoulder)
65’ (back)
SNOLAB Workshop IV, 15 Aug 2005
Ladder Labs
Wide Drift
Electrical,
20’x12’
AHUs
(19’ to back)
Wide Drift
25’x17’
(25’ to back)
Access Drift
15’x10’
(15’ to back)
Chemistry
Lab
SNOLAB Workshop IV, 15 Aug 2005
Underground Schedule

Excavation




Entry – now – 1 November
Ladder – now – 1 November
Rectangular hall – 1 November – 9 May
Cryopit – 10 May – 1 December/06
Underground Schedule

Outfitting





Finalize contract package – 30 September
Award contract – 14 January
Entry 14Feb/06 – 13 June
Ladder 14 June – 11 Oct
Rectangular hall 12 Oct – 8 February 07
Surface Facility
SNOLAB Workshop IV, 15 Aug 2005
Experimental Interest in SNOLAB
SNO
SNO + & SNO ++
Lithium Detector
CLEAN
Solar Neutrinos
Solar Neutrinos & Double Beta Decay
Solar Neutrinos
Solar Neutrinos & Dark Matter
Majorana
Double Beta Decay
GerDA
Double Beta Decay
EXO
Double Beta Decay
COBRA
Double Beta Decay
SuperCDMS
Dark Matter
ZEPLIN
Dark Matter
XENON
Dark Matter
DEAP
Dark Matter
PICASSO
Dark Matter
COUPP
Dark Matter
DRIFT
Dark Matter
Noble Liquid Tracking Detectors
Solar Neutrinos
HALO
Supernovae Neutrinos
LENA
Proton Decay, Solar Neutrinos, Supernovae Neutrinos
NOSTOS
TRIGA
Neutrino Oscillations (q13)
Neutron-Antineutron Oscillations
Depth
Matters!
Experiment Advisory Committee
Chair: Barry Barish
Secretary: Andrew Hime
Baha Balantekin (US)
Cliff Burgess (CND)
Ken Ragan (CND)
John Martin (CND)
Kate Scholberg (US)
Takaaki Kajita (Japan)
David Wark (UK)
Scientific Merit
Infrastructure Needs
Progress on R&D
Technical Feasibility
Safety
Funding & Schedule
Participation & Management
Letters-of-Interest (LOI’s) received have undergone EAC review …
Letters-of-Response (LOR’s) have been drafted and distributed to points-of-contact …
LOR’s included a set of “Queries” to which (many) of you have responded …
Preliminary recommendations for the science program have been developed …
New considerations on the table since previous workshop and initial call for LOI’s
Use outcome of this workshop to refine vision and recommendations …
Feed-back Wednesday morning … August 17, 2005 at SNOLAB IV Workshop