Neutrino Physics with SNO+ · Neutrino physics with the SNO+ detector Freija Descamps, 12/09/2014...

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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Intro

✤ What we know:!✤ Neutrinos have mass!✤ Neutrinos oscillate between flavour states!✤ Squared mass differences between mass eigenstates!!

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Intro


✤ 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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Intro


✤ 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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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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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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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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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


SNO+ physics goals

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Geo-neutrinos

SNO+ physics goals

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Reactor neutrinos

Darlington reactor, Canada

Geo-neutrinos

SNO+ physics goals

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Reactor neutrinos


Geo-neutrinos

Supernova!neutrinos

SNO+ physics goals

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Reactor neutrinos


Geo-neutrinos

Supernova!neutrinos

SNO+ physics goals

Solar neutrinos

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Reactor neutrinos


Geo-neutrinos

Supernova!neutrinos

SNO+ physics goals

Solar neutrinos

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neutrino-less double beta

decay

νe


Reactor neutrinos


Geo-neutrinos

Supernova!neutrinos

SNO+ physics goals

Solar neutrinos

invisible nucleon decay

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neutrino-less double beta

decay

νe


SNO+ phases

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SNO+ phases

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Water

Nucleonspring 2015- fall 2015


SNO+ phases

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WaterScintillator

Solar Nucleonspring 2015- fall 2015after 0νββ


SNO+ phases

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WaterScintillator

Scintillator + 130Te

0νββ

Solar Nucleonspring 2015- fall 2015after 0νββ

2016


SNO+ phases

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WaterScintillator

Scintillator + 130Te

0νββ

ReactorGeoSupernova

Solar Nucleon

Background studies

spring 2015- fall 2015after 0νββ

2016


0νββ with the SNO+ detector

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✤ (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:


Loading Te in LAB



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SNO+ approach:Old loading technique


Loading Te in LAB



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✤ Dissolve telluric acid (H6O6Te) in water!✤ Combine with LAB using a surfactant!✤ Good optical properties!✤ Stable > 1 year explicitly demonstrated

for 0.3% loading


Loading Te in LAB



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✤ 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)


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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Backgrounds

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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


Backgrounds

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8B Solar neutrinos Tellurium 2νββ!


LAB+PPO!• 238U, 232Th, 14C!




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


LAB+PPO!• 238U, 232Th, 14C!




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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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





✤ 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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✤ 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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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

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10

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2.3 2.4 2.5 2.6 2.7 2.8

0

2

4

6

8

10

12

14

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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

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8

10

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20

2.3 2.4 2.5 2.6 2.7 2.8

0

2

4

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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

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2.3 2.4 2.5 2.6 2.7 2.8

0

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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

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2.3 2.4 2.5 2.6 2.7 2.8

0

2

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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

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18

20

2.3 2.4 2.5 2.6 2.7 2.8

0

2

4

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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

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2.3 2.4 2.5 2.6 2.7 2.8

0

2

4

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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

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18

20

2.3 2.4 2.5 2.6 2.7 2.8

0

2

4

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14

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18

20

0⌫�� (200 meV)

2⌫��

8B ⌫ ES

(↵, n) �

U Chain

Th Chain

External

CosmogenicInternal!

U Chain

Internal!

Th Chain


0.3% natural Te sensitivity

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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


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


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)

-


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


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+


Cosmogenics

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half-life ~ 106d

Neutrino Physics with SNO+ · Neutrino physics with the SNO+ detector Freija Descamps, 12/09/2014...

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Transcript of Neutrino Physics with SNO+ · Neutrino physics with the SNO+ detector Freija Descamps, 12/09/2014...