SoLi - Wright Laboratory · SoLi∂ detectors Friday, 6 February 15. SoLid Technology development...
Transcript of SoLi - Wright Laboratory · SoLi∂ detectors Friday, 6 February 15. SoLid Technology development...
Search for oscillations with 6Li detector at short distance from the BR2 MTR
reactorAntonin Vacheret
for the SoLid collaboration
SoLi∂
Friday, 6 February 15
Outline
• Anomalies in neutrino sector
• SoLid experiment overview
• SoLid technology
• recent developments
Friday, 6 February 15
Recent anomalous results
Giunti Laveder 1006.3244J. Kopp et al., hep/ph:1303.3011
⌫̄e + p ! e+ + n
+4%
+1.5%+1%
• re-analysis of calibration source data • (L/E ~1m/0.1MeV)
• rate deficit of 14 ± 6 %
• Gallium anomaly
• 2011 re-evalatation of reactor antineutrino flux and update on cross-section parameters
• 3.5% new conversion of ILL beta spectra• 1.5% off-equilibrium• 1.5% neutron lifetime τn
• rate deficit 6.5 %• Reactor anomaly
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2011 Reactor anomaly
• Oscillation in a new kind of matter ?
4
10 100distance from reactor [m]
0.7
0.8
0.9
1
1.1ob
serv
ed /
no o
sc. e
xpec
ted
ILL
Bug
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2.7σ deficit
?
PredictionActualOscillation into new state
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Deficit explained : solar neutrinos oscillates into other neutrinos !
Are we in a similar situation ?
1988 Solar anomaly
5
~6σ deficit
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Sterile neutrino hypothesis
• current rate anomalies due to unknown effect or to new physics ?
• additional(s) light fermion mixing with active neutrinos could be one explanation
• a generic extension of SM
• help with phenomenology (connection to DM is possible)
• tension exists between oscillation data sets
• in modest tension with PLANCK data
Energy2 3 4 5 6 7 8 9 10
A. U
.
00.20.40.60.81
1.21.41.61.82
Energy2 3 4 5 6 7 8 9
Ratio
Osc
/non
-Osc
0.5
0.6
0.7
0.8
0.91
1.1
[MeV]
J. Kopp et al., hep/ph:1303.3011
Δm2 ~ 1 eV2νe → νs
Pee = 1 − 2|Ue4|2(1 − |Ue4|2)
Effect as a function of distance
Δm2=2.35 eV2
sin22θee = 0.165
Effect as a function of energy
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Allowed region
• Combined no oscillation disfavored at more than 99.9% C.L. (3.3σ)
• Two techniques in νe disappearance to address this on a short timescale:
• 1. Large source, large detector experiments
• 2. very short baseline [5-20] m reactor experiments
J. Kopp et al., hep/ph:1303.3011Sterile neutrino white paper arXiv:1204.5379
90, 95, 99 % CL.
Friday, 6 February 15
Look for rate and energy variations
Need better experiments !
Energy2 3 4 5 6 7 8 9 10
A. U
.
00.20.40.60.81
1.21.41.61.82
Energy2 3 4 5 6 7 8 9
Ratio
Osc
/non
-Osc
0.5
0.6
0.7
0.8
0.91
1.1
[MeV]
Δm2=2.35 eV2
sin22θee = 0.165
Effect as a function of energy
8
Data scarce at short distance :
Control of background is key for best sensitivity
10 100distance from reactor [m]
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0.8
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Gos
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Rat
e/10
0 ke
V
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Recent reactor data
• Total rate measurements compatible with other experiments
• 2.4σ sigma deficit including Daya Bay nu2014 result
• Deviation in e+ spectrum observed at all three experiments (D-CHOOZ, RENO, Daya Bay)
• 4σ excess in [4,6] MeV window in Daya Bay data
• no effect on θ13 measurement
• Is it a real feature of the spectrum or something else ?
• Measurement with HEU and different technology
Daya Bay
D-Chooz
RENO
Eν ≃ Ee+ + mn - mp
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New Reactor experiments
10
Prospect - ORNLNeutrino-4 - SM3DANSS - KNPP
POSEIDON - PIK
STEREO - ILL
SoLid - BR2
Korean projectCARR project
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SoLi∂
Friday, 6 February 15
SoLid Collaboration• 3 countries, 9 institutes, ~40 people
12
UK Belgium France
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SCK•CEN BR2 reactor
• Tank in Pool MTR research reactor
• Licensed to run at power up to 100 MW
• variable operating power (45-80 MW)
• 6 cycles per year*
• Beam ports not in use
• Primary circuit pipes away from experimental site
• ~10 mwe overburden on level 3
Level 10m67on axis with reactor
Confinement building
* will increase from 2016
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Aluminum pressure Vessel
Beryllium matrixand assemblies
1.0 m
BR2 Twisted core
BR2
ILL
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BR2 background measurementsBackground rates at level 3
• Neutrons
• Large system to measure atm neutrons
• Rn ~ 1Hz En < 15 MeV
• Reactor ON : portable neutron counter :
• Rn < 10-5 Hz (2-20 MeV)
• Reactor ON gamma-rays
• HPGe detector w and w/o shielding
• Rgam ~ 0.4 Hz/cm2 (> 500 KeV) Pb 5cm
BR2Entries 12291Mean 773.1RMS 776.7
Energy [keV]1000 2000 3000 4000 5000 6000 7000 8000 9000 10000
-210
-110
1
10
BR2Entries 12291Mean 773.1RMS 776.7
No shieldingPb shield 5 cm
BR2 HPGe detectorBR2 portable neutron detector Oxford Large
neutron detector
41Ar
60Co
208Tl24Na
40K
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Crosscheck with Floor 1
• Ge energy efficiency checked with nitrogen decay gammas
• 1st floor just behind concrete wall
• 1 hour exposure time
• Rgam ~ 140 Hz/cm2 (> 500 KeV)
• rate x350 and hard spectrum
Energy (keV)1000 2000 3000 4000 5000 6000 7000 8000 9000 10000
Entri
es10
210
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Reactor core calculations
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SoLid experiment set up
• Baseline L = 5.5-11 m
• reconfigurable to reduce detector systematics
• 2.88 tonnes total fiducial mass
• Limit passive shielding
• Data taking in early 2016
BR2 coreSoLid
Detectors
Neutron shielding
lead wall
5.5m
• Good energy resolution Eres~ 17% @ 1 MeV
• Use high position resolution (<5cm)
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Expected sensitivity• Event rate 416 νe/day/ton
• 2.88ton detector mass
• Energy resolution : 0.17 at 1 MeV
• 300 days running (140 days/year)
• Positron threshold (600 keV)
• S:B of 6:1 assumed
• Systematics
• Spectrum norm.: 1.8%
• Spectrum shape: 0.7-4%
• Thermal power: 3%
• Detection efficiency 2%
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SoLi∂ technology
Friday, 6 February 15
SoLid concept
• Neutron / gamma-ray discrimination from pulse
• distinctive response for prompt and delayed signal
• neutron used to trigger event read out
• Voxelisation of target volume
• neutron captured in neighboring cube increasing localisation of IBD event
s)µTime (0 5 10 15 20 25
Hei
ght (
ADC
)
02000400060008000
10000120001400016000180002000022000
s)µTime (0 5 10 15 20 25
Hei
ght (
ADC
)
0
200
400
600
800
1000
1200
Δt ~ 1-200 us
⌫̄e + p ! e+ + n
1 m 1 m
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Optimisation of Voxel size
• Require good containment for e+ energy
• 85% are contained within one cube of 5 cm
• neutrons caught in proximity of positron
• reduce volume for event selection
• background reduction
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Energy response
• Tested light yield for 5cm cube with 3mm2 MPPC read out using cosmics setup
• Large light yield measured on real dimension PVT cubes with BCF-91A fibre and MPPC read out
• 40-50PE @ 1 MeV (x2 MPPC)
• dE/E ~ 17%
• Optical model tuned on data
• Very good uniformity within cube (>95%)
• High IBD reconstruction efficiency
• Flat in energy both for e+ and neutron
S1
S2MPPC
fibre bundleEJ-200picoscope
muon
MC
DATAMC
Correction of MPPC linearity response not included !
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Enabling imaging of interactions
• Locate precisely neutrino interaction
• New way to reject ALL class of backgrounds
• Mitigate unknown backgrounds
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Fast n
νe
= 1 Hit + neutron capture
Fast n
= N x 3D Hits + neutron capture
Homogenous volume :
Volume divided in voxels :
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Additional discrimination
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n99.90% rejection
Reconstructed Visible Energy [NPE]0 20 40 60 80 100 120 140 160 180 200
Entri
es
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210
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96.86% rejection γ
MC
MC
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Expected IBD efficiency
• IBD selection :
• Look for a neutron trigger
• apply time cut 300 ns < Δt < 100,000 ns
• Select MPPC pair E > ~600 keV around trigger
• apply position cut (2 cubes max around trigger)
cut Efficiency
n trigger 0.71
coincidence 0.58
Energy cut (20PE/600keV) 0.48
spatial cut 0.47
multiplicity cut 0.41
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SoLi∂ detectors
Friday, 6 February 15
SoLid Technology development
80 cm
20 cm
• NEMENIX 8kg 64 voxels, 32 chan.
• SoLid Module 1 (SM1) 288kg
9 Detector planes2304 voxels, 288 chan.
20x
5x
• SoLid modules 1.440 tonnes 11520 voxels, 1920 chan.
need 2x
2013
2014-2015
2016
Proof of concept of composite scintillator technique TRL 2-31. demonstrate neutron PID2. Measure bkgs3. measure PVT-n concidence
Large scale system TRL 3-51. demonstrate scalability and test production schedule 2. demonstrate segmentation capability3. do some physics ?
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Current set up
SM1288kg
NEMENIX 8kg
PbHDPE
muon veto
muon veto
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Oxford 2013 prototype
• 8 Kg, 64 cubes, 32 read out channels
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NEMENIX PID
• 2013 : good dynamic range of signal but deadtime
• 2014 : new PVT cubes and upgraded DAQ with no deadtime but threshold slightly higher and dynamic range reduced for cosmics
• PID technique demonstrated
1
10
210
310
410
510
Peak amplitude [PE]0 100 200 300 400 500 600 700 800
Inte
grat
ed c
harg
e
0
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60310×
neutrons
EM signal : γ,e±
cosmic muons
2013 campaign
2014 campaign
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Reactor studies
• can monitor neutron and PVT events
• Accidentals from gamma-rays low as expected
• dominated by environmental background at R1 alcove
• Correlated signal measured
• more data on tape to be analysed
s]µ t(ZnS - PVT) [Δ-2000 -1500 -1000 -500 0 500 1000 1500 2000
Zns
- PVT
coi
ncid
ence
s
0
20
40
60
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120
140
160
180
200reactor off
reactor on
2014 campaign2014
campaign
Pth = 60 MW~7 days
exposurecharge threshold
readjusted
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2014 Large scale module (x20)• 0.3 Tonnes, 9 planes, 2304 cubes, 288 channels, Fast digitiser electronics
• 8 months from construction to commissioning !
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cube filling
Commissioning at Gent November 2014Detector Plane assembly
Detectorframes design
frame machining @ Oxford
Sensor PCB production
Oxford
FE electronics Oxford
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Construction and target mass
• All material composing planes weighed to better than 1%34
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Plane testingOctober 2014
• First characterisation of plane response
• using final electronics !
• ON-OFF response
• using Cs and Co sources
• First measurement of attenuation length
• Indication of Latt ~15%/m
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SM1 installation at BR2Detector wrapping Loading at Gent
alignment in front of R1position known to ~2mm
Detector in position 27th November 2014
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SM1 outlook
• As of today SM1 currently under commissioning
• commissioning trigger
• BR2 running until end of February
• Rate measurement at 5.5m : Aim to reach <5% statistical accuracy
• measure IBD efficiency and reconstruct energy spectrum
10 100distance from reactor [m]
0.7
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• The SoLid experiment can achieve unprecedented sensitivity to short baseline oscillations
• It is designed for high sensitivity
• if sterile neutrinos are the explanation it will be ground-breaking discovery !
• BR2 reactor well suited for a low risk and precise experiment
• Main phase of experiment planed for 2016
• Concept has been validated with first prototype
• Large scale module under commissioning at closest distance
• Technology has real potential for antineutrino detection which opens the path to various applications
Summary
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The End
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New reactor experimentsTech Reactor P [MW] L (m) M (tonnes)
Nucifer (Fr) LS+Gd OSIRIS 70 7 0.8
POSEIDON LS+Gd PIK 100 5-8 ~3
STEREO (Fr) LS+Gd ILL 57 8.8-11.2 1.75
Neutrino-4 (Ru) LS+Gd SM3 100 6-12 1.5
PROSPECT (US) LS + Gd/6Li ORNL HFIR 85 7-18 1 & 10
SoLid (UK/B/Fr) PVT + 6LiF:ZnSSCK•CEN
BR245-80 5.5-11 1.44/2.88
DANSS (Ru) PS + Gd KNPP 3000 9.7-12.2 0.9
Hanaro (KO) PS + Gd/6LiHanaro/
Younggwang30-2800 6-? ~1
Friday, 6 February 15