Demande ANR STEREO

Pablo DEL AMO SANCHEZHenri PESSARD

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Conseil Labo Demande ANR STEREO Pablo DEL AMO SANCHEZ, LAPP, UniSavoie

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Overview

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• Neutrino anomalies• The STEREO experiment• ANR request• LAPP’s contribution• Conclusions

Conseil Labo Demande ANR STEREO Pablo DEL AMO SANCHEZ, LAPP, UniSavoie

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Open questions inoscillation physics

• Oscillations extremely successful description of ν flavour change during propagation, θ13 just measured!

• Mass hierarchy and leptonic CP in ~ 2025 (LAGUNA/LBNO)• Meanwhile, some open questions:

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Anomaly Type Significance

Gallium νe disappearance 2.7σ

Reactor νe disappearance 3.0σ

LSND νμ → νe 3.8σ

MiniBoone νμ → νe 3.0σ

Conseil Labo Demande ANR STEREO Pablo DEL AMO SANCHEZ, LAPP, UniSavoie

418/12/2012

Gallium anomaly

• GALLEX and SAGE experiments looked for low energy solar neutrinos using Gallium-based detectors (νe+71Ga → e–+71Ge)

Deficit observed during calibration runs:Robs/pred=0.86±0.05 (Bahcall’s σν)

Detectors calibrated with ~MCi νe sources

0.86

Conseil Labo Demande ANR STEREO Pablo DEL AMO SANCHEZ, LAPP, UniSavoie

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Reactor anomaly• Reactor ν spectrum predicted from β spectrum → compare w/ experiment

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Emitted b spectra per fission

ν spectra per fission

THEORY!!!

Comparison

Conseil Labo Demande ANR STEREO Pablo DEL AMO SANCHEZ, LAPP, UniSavoie

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Reactor anomaly

• Reactor antineutrino flux re-evaluated (2011): +3.5%

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•Neutron lifetime decrease → σν(InverseBeta Decay) increase +1%•Previously non-accounted long-livedisotopes in reactors +1%

Phys.Rev. C83 (2011) 054615 & Phys.Rev. C84 (2011) 024617

Conseil Labo Demande ANR STEREO Pablo DEL AMO SANCHEZ, LAPP, UniSavoie

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Reactor anomaly

• → Re-analyse reactor neutrino experiments• Result: 7% less events than expected! (3.0 σ)

• Can be explained with a sterile neutrino with Losc ~ 2-10m

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Robs/pred=0.927±0.023

Phys.Rev. D83 (2011) 073006

Conseil Labo Demande ANR STEREO Pablo DEL AMO SANCHEZ, LAPP, UniSavoie

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Reactor+Ga anomalies fit

• Both reactor and Ga anomalies can be explained by 1 sterile ν

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Δm2 ~ 2 eV2

sin2(2θee) ~ 0.2Losc ~ 7m

Phys.Rev. D83 (2011) 073006

Conseil Labo Demande ANR STEREO Pablo DEL AMO SANCHEZ, LAPP, UniSavoie

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Future experiments• Several reactor (short term), sources (short term) & accelerator

(mid-term) experiments under consideration• Probe Reactor+Ga anomalies and sterile ν at the same time:

– Measure rate of reactor– Look at L/E dependence close to reactor (L ~ Losc ~ 10 m)

• Reactor core size important – large cores wash out oscillation

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Grenoble’s ILL most compact!

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STEREO• 2m3 Gd-doped liquid scintillator detector 8m away of ILL reactor

Conseil Labo Demande ANR STEREO Pablo DEL AMO SANCHEZ, LAPP,

UniSavoie

• Signature: νe+p→e++n• Segmented target to see L/E dependence at different L’s

Conseil Labo Demande ANR STEREO Pablo DEL AMO SANCHEZ, LAPP, UniSavoie

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STEREO• STEREO should see sterile ν oscillation if it’s there• Good performance compared to competition (timing important!)• Liquid scintillator technology well known (DoubleChooz, Nucifer)• Potentially big impact• Cheap : ~ 1,5 M€• Quick experiment!• Timeline:11/2012 ILL Scientific Committee2013-2014 Design & construction2015 Installation at ILL2015-2016 Physics Run

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Conseil Labo Demande ANR STEREO Pablo DEL AMO SANCHEZ, LAPP, UniSavoie

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STEREO Collaboration

• ILL, host laboratory: site characterisation.• Three French laboratories:

– CEA Saclay: Inner detector– LAPP: Radioactive source calibration system + possibility of

mechanics of shielding– LPSC: Acquisition electronics + µ veto + shieldings (workshop)

• Foreign collaborators:– Germany, TUM & Max-Plank-Institut Heidelberg: Liquid scintillator +

LED calibration system– Morocco, University Hassan II & CNESTEN.

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Conseil Labo Demande ANR STEREO Pablo DEL AMO SANCHEZ, LAPP, UniSavoie

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ANR Proposal

• Porteur: David LHUILLIER (CEA Saclay)• 800 k€ + 2 postdocs (+1 ENIGMASS postdoc => 1postdoc/french lab)• Timescale:

04/2013 ANR funding decision2013-2014 Design & constructionLate 2014 Lab tests2015 Installation at ILL2015-2016 Physics Run

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Conseil Labo Demande ANR STEREO Pablo DEL AMO SANCHEZ, LAPP, UniSavoie

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LAPP’s contributionCalibration system with radioactive sources

γ sources (Na, Co, n capture by H & Gd)+ n sources (Am-Be)

• Mechanics + automatism + workshop– In touch with B. Lieunard– ITA manpower under

evaluation, seems feasible

• Possibility of engineeringshielding support under study

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m-veto - water

10 c

m le

ad fr

ont w

all Polyethylene

5 target cells40 cm thick

10 cm lead

~ 3.30 m

20 cm acrylic buffer

Tube

Source

Conseil Labo Demande ANR STEREO Pablo DEL AMO SANCHEZ, LAPP, UniSavoie

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Conclusions

• Strong international interest in neutrino anomalies• Grenoble’s ILL unique for Reactor+Gallium anomalies• STEREO has the potential to address Reactor+Gallium

anomalies in a short (~5yr) timescale; excellent bang for buck!• ANR request (CEA, LAPP, LPSC): 800 k€ + 2 postdocs• LAPP’s rôle : Radioactive source calibration system. Possibility

of mechanics of shielding.Engineering manpower seems available for the requested period

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Conseil Labo Demande ANR STEREO Pablo DEL AMO SANCHEZ, LAPP, UniSavoie

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BACKUPSLIDES

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