SoLid Recent results from the SM1 run Antonin Vacheret for the - PowerPoint PPT Presentation

SoLid Recent results from the SM1 run Antonin Vacheret for the SoLid collaboration AAP 2015 Arlington, Virginia, USA

Outline • The SoLid experiment & technology • New results from the first SoLid module • summary and outlook 2

The SoLi ∂ experiment BR2 hall reactor core 5.5 m SoLid detector modules personal communication. By courtesy of SCK•CEN • Search for new oscillation • Precise position and energy measurement to demonstrate oscillation • 235 U flux measurement • improve reactor flux prediction distance Energy • demonstrate reactor monitoring with a new generation of compact detectors 3

SoLi ∂ collaboration • 4 countries, 10 institutes, ~ 50 people and growing… 4

Sensitivity to a new massive neutral state 10 1 Phase I arXiv:1303.3011 RAA Gallium L C % SoLid detectors 5 9 5.5 m ■ ● BR2 core 3.6 m 10 0 8x sub-modules PVT cubes + WLS fibres Δ m 2 [ eV 2 ] up to 2 tonnes fiducial • 40% IBD efficiency 3 σ CL 10 - 1 • S:B ~ 3 95 % CL • Phase I, 1yr - 2t @ 14 % Background is 1/E 2 and flat • 2% relative energy scale uncertainty SoLi ∂ PRELIMINARY 1 calendar year corresponds 150 days of reactor - on • 10 - 2 shape only measurement 10 - 2 10 - 1 10 0 sin 2 2 θ 5

Sensitivity to a new massive neutral state 10 1 Phase II arXiv:1303.3011 RAA Gallium 95 % CL SoLid detectors 5.5 m ■ ● BR2 core 1 m 3.6 m 10 0 CHANDLER module WLS PVT cubes + PMTs Δ m 2 [ eV 2 ] 1 tonne fiducial • 40% IBD efficiency 3 σ CL 10 - 1 • S:B ~ 3 95 % CL Phase I, 1yr - 2t @ 14 % • Background is 1/E 2 and flat Phase II, 3yr - 2t @ 14 % + 1t @ 6 % • 2% relative energy scale uncertainty SoLi ∂ PRELIMINARY 1 calendar year corresponds 150 days of reactor - on • 10 - 2 shape only measurement 10 - 2 10 - 1 10 0 sin 2 2 θ 6

The neutrino source : BR2 Personal communication. By courtesy of SCK•CEN • Careful assessment of reactor backgrounds reveals low energy gamma-rays and very low neutron rate Rn < 10 -5 Hz (2-20 MeV) Rgam = 0.4 Hz/cm 2 • Pth = 72 MW at R1 port 5.0 m from core • Compact source • Highly enriched Uranium No shielding • pure 235 U antineutrino flux Pb shield 5 cm • High Power (40-80) MW • duty cycle : 150 days / year 7 personal communication. By courtesy of SCK•CEN

SoLid detector module SM1 45 cm 80 cm 80 cm Δ t ~ 1-200 us • 16 x 16 x 9 PVT cubes • Robust neutron ID • 9 detector planes • High segmentation • 288 read out channels • localisation of IBD • 288 kg fiducial mass • positron only energy reconstruction 8

SM1 module DAQ & trigger Y fibre MPPC 4x “GLIB” modules X && Y Deimos FMC 16 ch cards CERN Deimos GLIB 16 ch temp DAC HV, sensors Cal pulse SC MBED X fibre MPPC CORTEX IP bus Clock distribution board Custom SC PC DAQ PC Saffron • 65 MS rate (16 ns sample) C++ software Disk server Data processing 10 TB • Threshold at 0.6 MeV Raw data conversion calibration, • ~15 Hz/channel and DQ plots reconstruction • 50 ns coincidence window 9

Test run at BR2 10

SM1 run at BR2 • SM1 run Dec 2014 - March • Calibration with sources 2015 • 60 Co, AmBe in April 2015 • 3-4 days reactor ON • • ~ 1 month reactor OFF 252 Cf in situ August 2015 period in March SoLid preliminary Data 11

6 LiF:ZnS neutron identification • Identification based on neutron pulse shape SoLid preliminary • proportional to integral • Data confirms robustness Neutron PID value n SoLid preliminary of 6 LiF:ZnS neutron tag 4 10 40 AmBe data 30 3 10 • neutron ID to be 20 2 10 implemented in trigger 10 0 decision 10 EM 10 − 1 200 300 400 500 600 700 800 900 1000 Amplitude ADC 12

SM1 Neutron PID a.u. Entries 7179103 Entries 7179103 6 Background 10 Mean Mean 0.1104 0.1104 Reactor Pth = 60 MW RMS RMS 0.9891 0.9891 60 5 Co source 10 AmBe source SoLid preliminary 4 10 3 10 2 10 10 1 20 10 0 10 20 30 40 50 − − neutron PID • Can distinguish a neutron in millions of signals 13

Muons @ SoLid Entries SoLid preliminary 6 10 R μ ~ 70 Hz 5 10 4 10 3 10 0 20 40 60 80 100 120 Data ∆ T in between muons in ms Data • tracking of muons: • precise in-situ calibration and monitoring with dEdx • simplify source calibration • Handle on correlated backgrounds Data Reactor side 14

In situ calibration with muons SoLid • in-situ energy calibration using dEdx preliminary • channels intercalibration • cube response equalisation • Light yield measured : 25 PA/cube • MPPC gain measured with dark count rate • no need for LED system Data RMS = 1.5% SoLid preliminary Data 15

Calibration stability Data • First look at stability over time • Very good stability of energy scale observed (few %) • Temperature is well controlled at BR2 : ± 0.5 C variations 16

Muon correlated events μ 14000 Entries μ μ EM SoLid preliminary 12000 A - T/ ∆ τ f( T) = e ∆ τ 10000 = 2.28 0.01(stat) 0.11(syst) s τ ± ± µ e - 8000 6000 n 4000 2000 2 4 6 8 10 12 Data T since last muon in s ∆ µ Entries 250 μ n SoLid preliminary • Michel electrons activity Data 200 Best Fit observed A - T/ ∆ τ f( T) = e + C ∆ τ 150 = 113.26 12.54(stat) s τ ± µ • Muon - neutron-like events 100 correlations observed 50 • Use for muon veto cut 100 200 300 400 500 600 700 800 900 1000 Data T since last muon in s ∆ µ 17

Detector capture time : AmBe prompt to neutron capture time difference (AmBe source) normalized counts 1 SoLid preliminary G4 simulation Measured data − 1 10 2 − 10 fitting results (G4): a + a exp(- t/ ) + a exp(- t/ ) ∆ τ ∆ τ fitting results (Data): 0 1 1 2 2 = 10.82 0.01 s τ ± µ = 11.30 0.28 s τ ± µ 1 1 3 − 10 = 91.36 0.02 s τ ± µ = 90.39 0.31 s τ ± µ 2 2 2 = 1.09 2 χ = 27.98 χ norm norm 3 10 × 0 100 200 300 400 500 t (ns) ∆ • AmBe source run used to study fast neutron signature and time coincidence 18

Neutron capture time summary Neutron capture time on LiF:ZnS(Ag) 93.20 0.50 s ± µ IBD Monte-Carlo 90.39 0.31 s ± µ Am/Be data 91.36 0.02 s ± µ Am/Be Monte-Carlo 89.59 3.17 s ± µ Fast neutrons Monte-Carlo Spallation neutron data 113.26 12.54 s ± µ SoLid preliminary 40 60 80 100 120 140 ( s) τ µ 19

IBD analysis • First data processing completed Δ R • data reduction, filtering, n calibration and reconstruction • SM1 MC response tuning SoLid preliminary ongoing • Study of background events and selection cuts started • Expect S:Bacc ~2:1 using cube segmentation • aim for result early next year 20

IBD candidate event display prompt delayed SM1 data Reactor wall behind 21

Summary • The SoLid experiment will make a very sensitive search for antineutrino disappearance using a new generation of compact detector • The SM1 run has been succesfull • Excellent neutron ID • Precise calibration with muons • cube PVT response equalisation at 1.5% level ! • simplify calibration procedure • Low background at BR2 has been confirmed • segmentation is already effective in reducing accidental background • focus now on correlated signals and antineutrinos ! • more results in the new year 22

Outlook • R&D phase now completed • cost-performance optimisation ongoing • Light yield increase per fibre end • mechanical design • Electronics • target lower cost-per-channel • development of a neutron trigger and new triggering scheme • increase low energy sensitivity • enable full use of event topology • Construction phase to start early next year • Phase I planned to start in second half of 2016 23

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AmBe neutrons energy and capture time • neutrons with short coincidence time are captured before reaching thermal energy 25

Proton target determination • Precision measurement rely on precise target mass determination • dN p < 1% achieved ! 26

Flux determination • Reactor group lead by Subatech and SCK•CEN experts • MCNP geometry from BR2 • evolution validated in MURE • Acceptance correction in tracking MC 235 U flux : • HEU core gives pure • key ingredient for precise flux determination 27