Neutrino Physics with SNO+Freija Descamps for the SNO+ collaboration
NOW 2014, Otranto, Lecce, Italy September 7-14, 2014
Neutrino physics with the SNO+ detector Freija Descamps, 12/09/2014
Intro
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Neutrino physics with the SNO+ detector Freija Descamps, 12/09/2014
Intro
✤ What we know:!✤ Neutrinos have mass!✤ Neutrinos oscillate between flavour states!✤ Squared mass differences between mass eigenstates!!
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Neutrino physics with the SNO+ detector Freija Descamps, 12/09/2014
Intro
✤ What we know:!✤ Neutrinos have mass!✤ Neutrinos oscillate between flavour states!✤ Squared mass differences between mass eigenstates!!
✤ Challenges:!✤ What is their mass and what is the mass hierarchy?!✤ Majorana vs. Dirac nature of neutrinos!✤ What are the precise oscillation parameters?!✤ What can ν’s tell us about Earth, Sun, Universe?
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Neutrino physics with the SNO+ detector Freija Descamps, 12/09/2014
Intro
✤ What we know:!✤ Neutrinos have mass!✤ Neutrinos oscillate between flavour states!✤ Squared mass differences between mass eigenstates!!
✤ Challenges:!✤ What is their mass and what is the mass hierarchy?!✤ Majorana vs. Dirac nature of neutrinos!✤ What are the precise oscillation parameters?!✤ What can ν’s tell us about Earth, Sun, Universe? }
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Neutrino physics with the SNO+ detector Freija Descamps, 12/09/2014
SNOLAB and SNO+
✤ SNO+ = successor to Sudbury Neutrino Observatory (SNO)!
✤ Located in SNOLAB inside the Creighton mine near Sudbury, Canada!
✤ Depth = 2070m (6000m.w.e)!✤ ~70 muons/day in SNO+!✤ Class-2000 clean room
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Neutrino physics with the SNO+ detector Freija Descamps, 12/09/2014
SNOLAB and SNO+
✤ SNO+ = successor to Sudbury Neutrino Observatory (SNO)!
✤ Located in SNOLAB inside the Creighton mine near Sudbury, Canada!
✤ Depth = 2070m (6000m.w.e)!✤ ~70 muons/day in SNO+!✤ Class-2000 clean room
Deck with DAQ SNO+ operator
~780T LAB liquid organic
scintillator!+ PPO
acrylic vessel!
⌀ 12m!5cm thick
~9500 PMTs!54% coverage
rock
~7kT ultra-pure water
shield
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Neutrino physics with the SNO+ detector Freija Descamps, 12/09/2014
SNOLAB and SNO+
✤ SNO+ = successor to Sudbury Neutrino Observatory (SNO)!
✤ Located in SNOLAB inside the Creighton mine near Sudbury, Canada!
✤ Depth = 2070m (6000m.w.e)!✤ ~70 muons/day in SNO+!✤ Class-2000 clean room
Deck with DAQ SNO+ operator
~780T LAB liquid organic
scintillator!+ PPO
acrylic vessel!
⌀ 12m!5cm thick
~9500 PMTs!54% coverage
rock
~7kT ultra-pure water
shield
3
Neutrino physics with the SNO+ detector Freija Descamps, 12/09/2014
Liquid scintillator ✤ Solvent: Linear AlkylBenzene (LAB)!
✤ Long attenuation length (~20m)!✤ Safe: low toxicity and high flash point!✤ Chemically compatible with acrylic!✤ α-β separation through decay-time!
✤ 2g/L fluor 2,5 diphenyloxazole (PPO)!
✤ High light yield ~10000𝛄/MeV
NIM A640, 119-122 (2011)
Petresa plant!Bécancour, QC
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Neutrino physics with the SNO+ detector Freija Descamps, 12/09/2014
LAB purification plan!
✤ Multi-stage distillation!✤ Removes heavy metals!✤ Improves UV
transparency!✤ Dual-stream PPO
distillation!✤ N2/steam stripping!
✤ Removes Rn, Kr, Ar, O2!✤ Water extraction!
✤ Removes Ra, K, Bi!✤ Metal scavenging!
✤ Removes Bi, Pb!✤ Micro-filtration!
✤ Removes dust
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Target levels:!85Kr! : 10-25 g/g!40K ! : 10-18 g/g!39Ar! : 10-24 g/g! U ! : 10-17 g/g! Th ! : 10-18 g/g
Neutrino physics with the SNO+ detector Freija Descamps, 12/09/2014
SNO+ physics goals
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Neutrino physics with the SNO+ detector Freija Descamps, 12/09/2014
Geo-neutrinos
SNO+ physics goals
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Neutrino physics with the SNO+ detector Freija Descamps, 12/09/2014
Reactor neutrinos
Darlington reactor, Canada
Geo-neutrinos
SNO+ physics goals
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Neutrino physics with the SNO+ detector Freija Descamps, 12/09/2014
Reactor neutrinos
Darlington reactor, Canada
Geo-neutrinos
Supernova!neutrinos
SNO+ physics goals
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Neutrino physics with the SNO+ detector Freija Descamps, 12/09/2014
Reactor neutrinos
Darlington reactor, Canada
Geo-neutrinos
Supernova!neutrinos
SNO+ physics goals
Solar neutrinos
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Neutrino physics with the SNO+ detector Freija Descamps, 12/09/2014
Reactor neutrinos
Darlington reactor, Canada
Geo-neutrinos
Supernova!neutrinos
SNO+ physics goals
Solar neutrinos
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neutrino-less double beta
decay
νe
Neutrino physics with the SNO+ detector Freija Descamps, 12/09/2014
Reactor neutrinos
Darlington reactor, Canada
Geo-neutrinos
Supernova!neutrinos
SNO+ physics goals
Solar neutrinos
invisible nucleon decay
6
neutrino-less double beta
decay
νe
Neutrino physics with the SNO+ detector Freija Descamps, 12/09/2014
SNO+ phases
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Neutrino physics with the SNO+ detector Freija Descamps, 12/09/2014
SNO+ phases
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Water
Nucleonspring 2015- fall 2015
Neutrino physics with the SNO+ detector Freija Descamps, 12/09/2014
SNO+ phases
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WaterScintillator
Solar Nucleonspring 2015- fall 2015after 0νββ
Neutrino physics with the SNO+ detector Freija Descamps, 12/09/2014
SNO+ phases
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WaterScintillator
Scintillator + 130Te
0νββ
Solar Nucleonspring 2015- fall 2015after 0νββ
2016
Neutrino physics with the SNO+ detector Freija Descamps, 12/09/2014
SNO+ phases
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WaterScintillator
Scintillator + 130Te
0νββ
ReactorGeoSupernova
Solar Nucleon
Background studies
spring 2015- fall 2015after 0νββ
2016
Neutrino physics with the SNO+ detector Freija Descamps, 12/09/2014
0νββ with the SNO+ detector
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Neutrino physics with the SNO+ detector Freija Descamps, 12/09/2014
0νββ with the SNO+ detector
✤ (add 0.3% of natural Te = ~800kg of 130Te)
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!✤ Trade-off energy resolution for!
✤ Higher statistics!✤ Low backgrounds!
✤ External shielding!✤ Scintillator self-shielding!✤ LAB purification by
distillation!✤ Re-use existing detector!✤ Scalable
SNO+ approach:
Neutrino physics with the SNO+ detector Freija Descamps, 12/09/2014
Loading Te in LAB
0νββ with the SNO+ detector
✤ (add 0.3% of natural Te = ~800kg of 130Te)
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!✤ Trade-off energy resolution for!
✤ Higher statistics!✤ Low backgrounds!
✤ External shielding!✤ Scintillator self-shielding!✤ LAB purification by
distillation!✤ Re-use existing detector!✤ Scalable
SNO+ approach:Old loading technique
Neutrino physics with the SNO+ detector Freija Descamps, 12/09/2014
Loading Te in LAB
0νββ with the SNO+ detector
✤ (add 0.3% of natural Te = ~800kg of 130Te)
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!✤ Trade-off energy resolution for!
✤ Higher statistics!✤ Low backgrounds!
✤ External shielding!✤ Scintillator self-shielding!✤ LAB purification by
distillation!✤ Re-use existing detector!✤ Scalable
SNO+ approach:Old loading technique
✤ Dissolve telluric acid (H6O6Te) in water!✤ Combine with LAB using a surfactant!✤ Good optical properties!✤ Stable > 1 year explicitly demonstrated
for 0.3% loading
Neutrino physics with the SNO+ detector Freija Descamps, 12/09/2014
Loading Te in LAB
0νββ with the SNO+ detector
✤ (add 0.3% of natural Te = ~800kg of 130Te)
8
!✤ Trade-off energy resolution for!
✤ Higher statistics!✤ Low backgrounds!
✤ External shielding!✤ Scintillator self-shielding!✤ LAB purification by
distillation!✤ Re-use existing detector!✤ Scalable
SNO+ approach:Old loading technique
✤ Dissolve telluric acid (H6O6Te) in water!✤ Combine with LAB using a surfactant!✤ Good optical properties!✤ Stable > 1 year explicitly demonstrated
for 0.3% loadingNew loading technique (M. Yeh et al., paper in progress)
Neutrino physics with the SNO+ detector Freija Descamps, 12/09/2014
130Te advantages
✤ 34% natural abundance!✤ Load high amount of natural isotope!✤ Relatively inexpensive compared to
enriched isotope!✤ 2νββ rate is relatively low
(~100 times lower than 150Nd)!✤ Lower background!✤ Less sensitive to poor energy
resolution!✤ Improved optical properties!
✤ No inherent optical absorption lines!✤ Higher intrinsic light yield!
✤ Nd-LS (0.5%): 8400𝛄/MeV!✤ Te-LS (0.5%): 9400𝛄/MeV
Te loaded LS
Nd loaded LS
scaled PMT response
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Neutrino physics with the SNO+ detector Freija Descamps, 12/09/2014
Backgrounds
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Neutrino physics with the SNO+ detector Freija Descamps, 12/09/2014
Backgrounds
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Tellurium cocktail!• 238U, 232Th, 210Po!
LAB+PPO!• 238U, 232Th, 14C!
Thermal neutrons!• Capture on H: 2.2MeV 𝛾!
Cosmogenic!• 60Co, 131I, 110mAg, 124Sb!• 11C
Neutrino physics with the SNO+ detector Freija Descamps, 12/09/2014
Backgrounds
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8B Solar neutrinos Tellurium 2νββ!
Tellurium cocktail!• 238U, 232Th, 210Po!
LAB+PPO!• 238U, 232Th, 14C!
Thermal neutrons!• Capture on H: 2.2MeV 𝛾!
Cosmogenic!• 60Co, 131I, 110mAg, 124Sb!• 11C
Neutrino physics with the SNO+ detector Freija Descamps, 12/09/2014
Backgrounds
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8B Solar neutrinos Tellurium 2νββ!
External!• 214Bi and 208Tl from AV, PMTs,
H2O, ropes!
Acrylic vessel (AV)!• Radon daughters in AV (210Pb,
210Bi, 210Po)
PMTs
AVFiducial !volume
Tellurium cocktail!• 238U, 232Th, 210Po!
LAB+PPO!• 238U, 232Th, 14C!
Thermal neutrons!• Capture on H: 2.2MeV 𝛾!
Cosmogenic!• 60Co, 131I, 110mAg, 124Sb!• 11C
Neutrino physics with the SNO+ detector Freija Descamps, 12/09/2014
U and Th chains✤ 2.6 MeV gamma from
external 208Tl suppressed by fiducialization!
✤ Purification techniques!✤ LS target levels: !✤ ~2.5 x 10-15 gU/gcocktail!✤ ~3 x 10-16 gTh/gcocktail!
✤ Direct background α and β emissions!
✤ Coincidence techniques are under investigation, ex.:!✤ β-α ⇾ 214Bi-214Po!✤ β-α ⇾ 212Bi-212Po !✤ α-β ⇾ 212Bi-208Tl
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Neutrino physics with the SNO+ detector Freija Descamps, 12/09/2014
Cosmogenic isotopes✤ Short and long living isotopes can be produced by cosmogenic
activation of natural tellurium.!✤ Isotopes (Q> 2 MeV, T1/2 > 20 days) !
✤ Rates from ACTIVIA, sea level (n,p)-flux from Armstrong and Gehrels.!✤ For E<200 MeV: TENDL database for cross-sections.
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V. Lozza, J. Petzoldt, “Cosmogenic activation of a natural tellurium target”, Astropart. Phys. 61, 62-71
Neutrino physics with the SNO+ detector Freija Descamps, 12/09/2014
Cosmogenic isotopes✤ Short and long living isotopes can be produced by cosmogenic
activation of natural tellurium.!✤ Isotopes (Q> 2 MeV, T1/2 > 20 days) !
✤ Rates from ACTIVIA, sea level (n,p)-flux from Armstrong and Gehrels.!✤ For E<200 MeV: TENDL database for cross-sections.
✤ 2 stage - purification:!✤ Above ground: 2 passes!
✤ Dissolve Te(OH)6 in water!✤ Re-crystalize using nitric acid!✤ Rinse with ethanol!
✤ Below ground: 2 passes!✤ Dissolve in 80˚C water!✤ Cool down to re-crystalize thermally!✤ 50% yield!
✤ 3-6 months cool-down
>104 reduction
>102 reduction
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V. Lozza, J. Petzoldt, “Cosmogenic activation of a natural tellurium target”, Astropart. Phys. 61, 62-71
Neutrino physics with the SNO+ detector Freija Descamps, 12/09/2014
Cosmogenic isotopes✤ Short and long living isotopes can be produced by cosmogenic
activation of natural tellurium.!✤ Isotopes (Q> 2 MeV, T1/2 > 20 days) !
✤ Rates from ACTIVIA, sea level (n,p)-flux from Armstrong and Gehrels.!✤ For E<200 MeV: TENDL database for cross-sections.
✤ 2 stage - purification:!✤ Above ground: 2 passes!
✤ Dissolve Te(OH)6 in water!✤ Re-crystalize using nitric acid!✤ Rinse with ethanol!
✤ Below ground: 2 passes!✤ Dissolve in 80˚C water!✤ Cool down to re-crystalize thermally!✤ 50% yield!
✤ 3-6 months cool-down
>104 reduction
>102 reduction
=> Cosmogenic isotopes negligible
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V. Lozza, J. Petzoldt, “Cosmogenic activation of a natural tellurium target”, Astropart. Phys. 61, 62-71
Neutrino physics with the SNO+ detector Freija Descamps, 12/09/2014
SNO+ 0νββ spectrum
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✤ 5 years @ 0.3% natural Te loading!✤ Fiducial volume cut at 3.5m
(20%)!✤ 212BiPo, 214BiPo!
✤ 100% efficient tagging for separate trigger windows!
✤ x 50 for in-window !
T�� (MeV)
2.3 2.4 2.5 2.6 2.7 2.8
Counts/5y/20keV
bin
0
2
4
6
8
10
12
14
16
18
20
2.3 2.4 2.5 2.6 2.7 2.8
0
2
4
6
8
10
12
14
16
18
20
0⌫�� (200 meV)
2⌫��
8B ⌫ ES
(↵, n) �
U Chain
Th Chain
External
8B ⌫ ES
2⌫��
Internal U chain
Internal Th chain
External �
Cosmogenics
(↵, n) �
Optimized ROI: 18.6 events/yrOptimized ROI: 18.6 events/yr
T�� (MeV)
2.3 2.4 2.5 2.6 2.7 2.8
Counts/5y/20keV
bin
0
2
4
6
8
10
12
14
16
18
20
2.3 2.4 2.5 2.6 2.7 2.8
0
2
4
6
8
10
12
14
16
18
20
0⌫�� (200 meV)
2⌫��
8B ⌫ ES
(↵, n) �
U Chain
Th Chain
External
T�� (MeV)
2.3 2.4 2.5 2.6 2.7 2.8
Counts/5y/20keV
bin
0
2
4
6
8
10
12
14
16
18
20
2.3 2.4 2.5 2.6 2.7 2.8
0
2
4
6
8
10
12
14
16
18
20
0⌫�� (200 meV)
2⌫��
8B ⌫ ES
(↵, n) �
U Chain
Th Chain
External
T�� (MeV)
2.3 2.4 2.5 2.6 2.7 2.8
Counts/5y/20keV
bin
0
2
4
6
8
10
12
14
16
18
20
2.3 2.4 2.5 2.6 2.7 2.8
0
2
4
6
8
10
12
14
16
18
20
0⌫�� (200 meV)
2⌫��
8B ⌫ ES
(↵, n) �
U Chain
Th Chain
External
T�� (MeV)
2.3 2.4 2.5 2.6 2.7 2.8
Counts/5y/20keV
bin
0
2
4
6
8
10
12
14
16
18
20
2.3 2.4 2.5 2.6 2.7 2.8
0
2
4
6
8
10
12
14
16
18
20
0⌫�� (200 meV)
2⌫��
8B ⌫ ES
(↵, n) �
U Chain
Th Chain
External
T�� (MeV)
2.3 2.4 2.5 2.6 2.7 2.8
Counts/5y/20keV
bin
0
2
4
6
8
10
12
14
16
18
20
2.3 2.4 2.5 2.6 2.7 2.8
0
2
4
6
8
10
12
14
16
18
20
0⌫�� (200 meV)
2⌫��
8B ⌫ ES
(↵, n) �
U Chain
Th Chain
External
T�� (MeV)
2.3 2.4 2.5 2.6 2.7 2.8
Counts/5y/20keV
bin
0
2
4
6
8
10
12
14
16
18
20
2.3 2.4 2.5 2.6 2.7 2.8
0
2
4
6
8
10
12
14
16
18
20
0⌫�� (200 meV)
2⌫��
8B ⌫ ES
(↵, n) �
U Chain
Th Chain
External
CosmogenicInternal!
U Chain
Internal!
Th Chain
Neutrino physics with the SNO+ detector Freija Descamps, 12/09/2014
0.3% natural Te sensitivity
14
90% confidence level for !5 years:!
! T 1/2 = 9.84 x 1025 yrs!! mββ = 66.5 meV!
1 year:!! T 1/2 = 4.27 x 1025 yrs!! mββ = 101.0 meV
✤ NME = 4.03 (IBM-2)!✤ G = 3.69 x 10-14 y-1!
✤ gA = 1.269
Live time (y)1 2 3 4 5 6 7 8 9
T0⌫
1/2Sen
sitivity
(y)
1026
90% CL
3� CL
Neutrino physics with the SNO+ detector Freija Descamps, 12/09/2014
Conclusion
✤ Water level just below acrylic vessel: now.!✤ Water running: spring 2015.!✤ Scintillator transition: fall 2015.!✤ Introduction of Te: start of 2016.
Schedule
✤ SNO+: a large liquid scintillator detector with broad physics program!✤ 0νββ = primary goal!
✤ Natural Te will be added to the liquid scintillator!✤ 0.3% loading (~800kg 130Te)!✤ Possibility of increased loading in future
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Back-up slides
Neutrino physics with the SNO+ detector Freija Descamps, 12/09/2014
Reactor and geo neutrinos νe
✤ Detection through inverse beta decay!✤ Delayed coincidence e+ annihilation and n
capture!✤ Possible in all SNO+ scintillator phases!✤ Reactor!
✤ 3 nearby reactors dominate flux!✤ Favourable direction and distances!
✤ Geo!✤ U, Th and K in Earth's crust and mantle!✤ Investigate origin of the heat produced within
Earth
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No oscillationAll reactors oscillatedNo BruceAll over 700km distance
Geoneutrinos
Eν (MeV)
SudburyGran Sasso
KamiokaMantle geoneutrino flux (238U + 232Th)
-
Neutrino physics with the SNO+ detector Freija Descamps, 12/09/2014
Supernova neutrinos!
✤ ν-p elastic scattering events (in LAB)!
✤ SNO+ plans to be part of SuperNova Early Warning System (SNEWS)
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Neutrino flux on Earth!10kpc SN, 3x1053erg!
True SN ν-p elastic scattering spectrum
Quenched SN ν-p elastic scattering spectrum
Neutrino physics with the SNO+ detector Freija Descamps, 12/09/2014
Solar Neutrinos
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✤ Solar neutrinos probe astrophysics and elementary particle physics models:!
✤ Solar metallicity (CNO)!✤ Neutrino oscillations (pep)!
✤ SNO+ solar neutrino goal: pep/CNO solar neutrino measurement!
✤ Low 11C background thanks to depth (100 times lower than Borexino)!
✤ Low energy threshold thanks to LAB
SNO
SNO: LETA
SNO+
Figure adapted from Nature 512 383, 2014
Assuming initial Borexino-level backgrounds are reached
Critically dependent on 85Kr and 14C background levels
Borexino / SNO+ signal/bkg comparison
Borexino SNO+
Neutrino physics with the SNO+ detector Freija Descamps, 12/09/2014
Cosmogenics
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half-life ~ 106d
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