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Measurement of the neutrino velocity with the OPERA detector in the CNGS beam

Measurement of the neutrino velocity with the OPERA detector in the CNGS beam. Gabriele Sirri Istituto Nazionale di Fisica Nucleare BOLOGNA, ITALY on behalf of the OPERA COLLABORATION. Time and Matter , Venice , 04 March 2013 . Contents. OPERA Experiment and CNGS Neutrino Beam

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Measurement of the neutrino velocity with the OPERA detector in the CNGS beam

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  1. Measurement of the neutrino velocity with the OPERA detector in the CNGS beam Gabriele SirriIstituto Nazionale di Fisica NucleareBOLOGNA, ITALY on behalf of the OPERA COLLABORATION Time and Matter, Venice, 04 March 2013

  2. Contents • OPERA Experiment and CNGS Neutrino Beam • Neutrino TOF measurements • Geodesy • Data analysis • Statistical analysis (2009-2011 data) • 2011 bunched-beam analysis • 2012 bunched-beam analysis • Conclusions G.Sirri - INFN BOLOGNA

  3. OPERA Experiment CNGS Neutrino Beam G.Sirri - INFN BOLOGNA

  4. OPERA Collaboration Bari BolognaLNF FrascatiL’Aquila LNGS Napoli PadovaRoma Salerno LAPP Annecy IPHC Strasbourg LHEP Bern IHE Brussels Hamburg IRB Zagreb INR Moscow NPI MoscowITEP MoscowSINP NSU Moscow JINR Dubna International collaborationof ∼ 150 physicistsfrom 28 institutions and 11 countries AichiToho KobeNagoya Utsunomiya METU Ankara Technion Haifa Jinjiu http://operaweb.lngs.infn.it/ G.Sirri - INFN BOLOGNA

  5. OPERA: OscillationProject with EmulsiontRackingApparatus Physics goaldetection of oscillationin directappearancemode in channel Signatureidentification of leptonfrom CC interaction Basic principle long baseline beam beamenergy to maximizeapperance and CC interactionsat the atmospheric neutrino scale eV Requirements - high target mass (kt) - high spatialresolution ( 1 μm) - low background rate G.Sirri - INFN BOLOGNA Status of the OPERA experiment

  6. CNGS CERN Neutrino to Gran Sasso beam CERN 730 Km LNGS In addition: the experimentiswellsuited to determine the neutrino velocitywith high accuracythrouhg the measurementsof the Time Of Flight and the distancebetween the source of CNGS neutrino beamat CERN and the OPERA detector at LNGS G.Sirri - INFN BOLOGNA

  7. CNGS target magnetic horns decay tunnel hadron absorber muon detector pit 1 muon detector pit 2 G.Sirri - INFN BOLOGNA

  8. 800m 100m 1000m 26m 67m vacuum Scheme for production of neutrinos (graphite) SPS LNGS p + C (interactions)p+, K+ (decay in flight)m+ + nm Two extractions separated by 50 ms, each pulse length: 10.5 ms Proton intensity: 2 x1013protons on target (p.o.t)/extraction Expected performance: 4.5x1019 p.o.t./year ~ pure muon neutrino beam (<E> = 17 GeV) travelling through the Earth’s crust →LNGS G.Sirri - INFN BOLOGNA

  9. 730 km 3.50 G.Sirri - INFN BOLOGNA

  10. CNGS Beam Performance production threshold (3.5 GeV) high energy beam “off peak" w.r.t. maximum oscillation prob. (1.5 GeV) nominalintensity in 5 years expectedidentified by OPERA: 7.6 signal 0.8 background [New Journal of Physics 14(2012)033017] ... and ~20000 in-target events G.Sirri - INFN BOLOGNA

  11. The LNGS underground physics laboratory 1400 m rock coverage Cosmic µ reduction = 10-6 (1 µ/m2/h) Underground area: 18 000 m2 External facilities Easy access 800 scientists from 25 countries 1400 m CNGS • Research lines • Neutrino physics (mass, oscillations, • stellar physics) • Dark matter • Nuclear reactions of astrophysics interest • Gravitational waves • Geophysics • Biology OPERA G.Sirri - INFN BOLOGNA

  12. The OPERA detector wall Pb/emulsion SM1 SM2 brick wall scintillator strips ν brick (56 Pb/Em.) 8 cm 10 X (10X0) 0 Target Tracker + brick walls 150000 bricks (2x31) muon spectrometer (1.25 kt) (RPC + drift tubes) 8.3kg G.Sirri - INFN BOLOGNA

  13. The Electronic Detectors The spectrometers Target Tracker plasticscintillator strips(26.4 mm), σ~8 mm Drift tubes Dipole magnet + (precision tracker) RPC (inner tracker) y Inner tracker coil x (RPC in magnet, σ ~ 13 mm) 12 Fe slabs trigger to PT in total 8.2 m Fe RPC 62 walls (496 modules) 7.5x7.5 m2Hamamatsu multianode PMTs (64 channels) B= 1.55 T (5 cm) slabs Precision Tracker base Tube: vertical, ∅=38 mm, length=8m σ<0.5 mm G.Sirri - INFN BOLOGNA

  14. «internal» and «external» events G.Sirri - INFN BOLOGNA

  15. just few slides about neutrinooscillations… G.Sirri - INFN BOLOGNA

  16. detectiontechnique Event-by-eventdirectobservation of the τleptondecay TopologyDecay mode B.R. 10X0 EmulsionCloudChamber • Micrometricresolutionachievedto detect the • τdecaykink • Target segmented in small unitscalled «bricks». • Brick: 57 layers of nuclearemulsioninterleaved • with 56 layers of lead1 mm thick. • Initialtotal target mass ~ 1.25 kt(about 150000 bricks) G.Sirri - INFN BOLOGNA Status of the OPERA experiment

  17. The automatic emulsion scanning 1. S-UTS automatic microscopes generation (Japan)2. European Scanning System. 15-16 frames/45 microns Developed grains frame 2-3 µm G.Sirri - INFN BOLOGNA

  18. Data Analysis Progress Event location in emulsion bricks CNGS data taking In targetev. extracted scanned located integrated intensity of 18.2x p.o.t. Bunched beam run periods 2011 22/10 to 6/11 2012 10/05 to 24/05 Preliminary Preliminary G.Sirri - INFN BOLOGNA Status of the OPERA experiment

  19. Oscillation Results: First candidate Phys. Lett. B 691(2010)138 G.Sirri - INFN BOLOGNA

  20. Oscillation Results: Second candidate 2° tau candidate NEUTRINO 2012 G.Sirri - INFN BOLOGNA

  21. Neutrino TOF measurements G.Sirri - INFN BOLOGNA

  22. Past experimental results FNALexperiment (Phys. Rev. Lett. 43 (1979) 1361) high energy (En > 30 GeV) short baseline experiment. Tested deviations down to |v-c|/c ≤ 4×10-5 (comparison of muon-neutrino and muon velocities) at 95% C.L. SN1987A (see e.g. Phys. Lett. B 201 (1988) 353) electron (anti) neutrinos, 10 MeV range, 168’000 light years baseline. |v-c|/c ≤ 2×10-9 at 95% C.L. Performed with observation of neutrino and light arrival time. MINOS (Phys. Rev. D 76 072005 2007) muon neutrinos, 730 km baseline, Eν peaking at ~3 GeVwith a tail extending above 100 GeV. (v-c)/c = (5.1 ± 2.9) ×10-5 at 68% C.L. (significance 1.8 s). G.Sirri - INFN BOLOGNA

  23. Principle of the neutrino velocity measurement GPS Satellite Precise Time link ~ 2 nsec by GPS Common View Mode Operation + All Possible corrections PolaRx2e +Cs atomic Clock PolaRx2e +Cs atomic Clock CERN LNGS BCT OPERA 731278.0 ± 0.2 m Precise Distance Measurement by GPS + Optical Geodesy measurement BCT • tagging of neutrino interaction time • tagging of neutrino production time C Predicted Neutrino Event Time Profile Observed Proton Time Profile = Neutrino Production Time Profile Observed NeutrinoEvent time Profile • long baseline needed for high accuracy 18/26 G.Sirri - INFN BOLOGNA Nakamura M. (Nagoya Univ.)

  24. CERN-LNGS Synchronization new already existingsystem (not enough accurate) already existingsystem (not enough accurate) system Time-transfer Time-transfer equipment equipment PolaRx2e, calibrated by METAS (Swiss metrology institute) G.Sirri - INFN BOLOGNA

  25. GPS Common View Mode Standard GPS operation: resolves x, y, z, t with ≥ 4 satellite observations Common-view mode (same satellite for two sites, for each comparison): x, y, z known from former dedicated measurements determine time differences of local clocks (both sites) w.r.t. the satellite, by offline data exchange 730 km << 20000 km (satellite altitude)  similar paths in ionosphere (and make use of more than one frequency !) G.Sirri - INFN BOLOGNA

  26. Result: TOF time-link correction (event by event) G.Sirri - INFN BOLOGNA

  27. Relative calibration of CERN-to-LNGS GPS time link [http://operaweb.lngs.infn.it/Opera/publicnotes/note134.pdf] Independent twin-system calibration by the Physikalisch-TechnischeBundesanstalt High accuracy/stability portable time-transfer setup @ CERN and LNGS GTR50 GPS receiver, thermalised, external Cs frequency source, embedded Time Interval Counter Correction to the time-link: tCERN - tLNGS= (2.3 ± 0.9) ns Blue: Code basedcommon-view (P3 ionosphrefree linear combination), fixedpositions, TR positionestimated by PPP Red: Precise Point Positioning (PPP) G.Sirri - INFN BOLOGNA

  28. LNGS Timing GPS Antenna GPS Antenna ExternalLab PolaRx2e ESATGPS2 HERTZ PPS ESAT PPmS 8 km OPERA Event Time StampingTriggers from Target Tracker : time-stamped by an FPGA (100MHz) DAQ cycle : 0.6 s ; Reset and Clock provided by OPERA Master Clock (hall C) FPGA increments two counters: M: coarse counter incremented by DAQ RESET . N : fine counter which increments every 10 ns When a trigger is issued  the FPGA assigns to it the reading of the two counters. DAQ Time-Stamps delayed by the time to transfer the GPS information to the FPGA (red path). CTRI 121 … 122…123… OPERAMasterClock CTRI Log O/E MC PPmS TMC Underground FPGA 10 MHz DAQ RESET every 600 PPmS 20 MHz T10 FPGA 100 MHz 121 … 122…123… M*0.6 s N*10 ns DAQTimeStamp Ts TRIGGER ROC TEVENT <59.6 > ± 3.8 ns Master Clock oscillator:10 MHz VECTRON OC-050 (stability 10-12/s) PMT Scint. Strip 30-90 cmWLS G.Sirri - INFN BOLOGNA

  29. Time delay from the external Lab to the OPERA Master Clock GPS Antenna tA + tB ESATGPS2 TimedelaytAbetween2 referencepoints: HERTZreferenceof the GPS2 ESAT UTC time. MC PPmSgeneratedby the OPERA Master Clock, synchronouswith the ESAT PPmS RX TX LASER TX LNGS ExternalLab ESAT PPmS HERTZ MC PPmS PatchPanel tA tB Fiber 23 8 km The “two-way” technique measure : tA – tB and tA + tB PatchPanel Splitter LNGS Underground LVD ICARUS BOREXINO Scope Scope 5 m Fiber TX RX OPERA MasterClock 5.9 ns tA – tB To FEBs G.Sirri - INFN BOLOGNA

  30. Tagging Neutrino INTERACTION Time @LNGS Typical neutrino event time distributions w.r.t kicker magnet trigger pulse cosmics D. Autiero - CERN - 23 September 2011 OPERA data: narrow peaks of the order of the spill width (10.5 µs) Negligible cosmic-ray background: O(10-4) Offline selection procedure kept unchanged since first events in 2006 G.Sirri - INFN BOLOGNA

  31. CERN Timing Shapereflectsthe PS extraction PrevessinCentr. Cont. Room High PrecisionGPS XLi Polarx2e CTRI in Prevessincompares GPS Clock Reference Signal CTRI General Machine Timing (GMT) Typical waveform (2011) HCA442 CTRI CTRI in HCA442 tagsthe referenceand the kickersignal and produces a replica of kicker to trigger the WFD Wave Form Digitizer (WFD) Kickersignal ts1 BCT time BeamCurrentTransformer : a toroidal transformercoaxial to the beam signal current protons ν π,K BCT Target Decay Tunnel SPS 743.40 m G.Sirri - INFN BOLOGNA

  32. Tagging Neutrino Production Time = Proton Timing SPS Proton timing by Beam Current Transformer Fast BCT 400344 (~ 400 MHz) CNGS • Proton pulse digitization: • Acquires DP110 1GS/s waveform digitizer (WFD) • WFD triggered by a replica of the kicker signal • Waveforms UTC-stamped and stored in CNGS database for offline analysis 2010 calibration with Cs clock G.Sirri - INFN BOLOGNA

  33. BCT Calibration Dedicated beam experiment: BCT plus two pick-ups (~1 ns) using the LHC beam (12 bunches, 50 ns spacing) WFD ns WFD BPK1 BPK2 BCT CNGS SPS : derived by measurement and survey LHC ZOOM result: signal comparison Amplitude [a.u.] after ΔtBCTcompensation LHC beam time [ns] time [ns] G.Sirri - INFN BOLOGNA

  34. TimeCorrections (ns) CERN LNGS GPSReceivers 2.3 OPERA M.C. 41068.6 CTRI CTRI 8.3 km fiber Controller Board FPGA ts2 24.5 4262.9 CTRI 10085.0 WFD Kickersignal 30 TTstrip 59.6 ts1 580 BCT time p ν π,K OPERA BCT Target Decay Tunnel SPS BASELINE = 731278.0 ± 0.2 m other time corrections * C G.Sirri - INFN BOLOGNA

  35. SystematicUncertainty (ns) The overallsystematicuncertaintywascomputednumericallyby takingintoaccount the individualcontribution andtheircorrespondingprobabilitydistribution(gaussianifnotwritten). CERN LNGS GPSReceivers 1.7 OPERA M.C. 3.7 CTRI CTRI 8.3 km fiber Controller Board FPGA 1.0 1.0 CTRI 2.0 TTstrip WFD 1.0 PMT Kickersignal 3.0 2.3 BCT 5.0 time p ν π,K OPERA BCT Target Decay Tunnel SPS Baseline: 0.67 (20 cm) 0.67 Overallsystematicuncertainty( -8.0 , + 8.3 ) ns Mesondecaypoint: 0.2 (exponential, 1 side) 0.2 Interactionpoint of externalevents: 2.0 (flat, 1 side) 2.0 G.Sirri - INFN BOLOGNA

  36. Summary of time corrections (2011) 5.5 ns (CERN) 5.5 ns (OPERA) G.Sirri - INFN BOLOGNA

  37. Cross-Checksduring 2011 winter shutdown G.Sirri - INFN BOLOGNA

  38. Dedicatedcampaign Dec11-Feb12 LNGS Test of the delay of 8.3 km long optical fiber and of the DAQ internal delays ESAT2000 Frequencydistribution OPERA M.C. 8.3 kmfiber CTRI Controller Board FPGA + ~74 ns TTstrip - ~15 ns • Two identified issues: • Faulty connection of the optical fiber to the Master Clock artificially increasing the neutrino anticipation by ~74 ns. • Internal Master Clock frequency off by Δf/f = 1.24x10-7 (124 ns/s) artificially decreasing the neutrino anticipation by ~15 ns (DAQ time bin 10 ns → 9.99999877 ns). • Time when "anomalous" conditions occurred during data taking and stability of these conditions subjected to "a special investigation" 4 ν OPERA G.Sirri - INFN BOLOGNA

  39. How stablewere the «anomalous» conditions ? Coincidences using horizontal cosmic muons(Joint OPERA-LVD analysis) [Eur. Phys. J. Plus (2012) 127: 71] "anomalous" period isflat ± 3.7 ns 74 ns «Teramo» µ ~ 160 m OPERA-LVD time delay the fiber problem started in 2008 and lasted until end of 2011 when it has been well connected to the OPERA Master Clock (considered data period: 2009-2011). New systematic uncertainties : ± 3.7 ns. the oscillator is running at a frequency higher than the nominal since 2008. (0.113 ±0.020) ppm Time drift confirmation Time diff. in DAQ cycle (ns) DAQ cycle (0.6 s) G.Sirri - INFN BOLOGNA

  40. Details and updatedresults in : 2012 February 23, Press Release The OPERA collaboration has identified two issues … 2012 March 12, Report from the OPERA Collaboration to the scientific committees http://operaweb.lngs.infn.it/Opera/ptb/pubref/pubref/OPERAReport0312toSC.pdf 2012 March 28, Mini-Workshop - "LNGS results on the neutrino velocity topic" http://agenda.infn.it/materialDisplay.py?materialId=slides&confId=4896 G.Sirri - INFN BOLOGNA

  41. Geodesy G.Sirri - INFN BOLOGNA

  42. Geodesyat LNGS Dedicated measurements at LNGS: July-Sept. 2010 (Rome Sapienza Geodesy group) 2 new GPS benchmarks on each side of the 10 km highway tunnel GPS measurements ported underground to OPERA GPS GPS G.Sirri - INFN BOLOGNA

  43. Combination with CERN Geodesy [http://operaweb.lngs.infn.it/Opera/publicnotes/note132.pdf] • CERN – LNGS measurements (different periods) combined in the ETRF2000 European Global system, accounting for earth dynamics (collaboration with CERN survey group) • Cross-check: simultaneous CERN-LNGS measurement of GPS benchmarks, June 2011 LNGS benchmarks In ETRF2000 Resultingdistance (BCT – OPERA reference frame) (731278.0 ± 0.2) m G.Sirri - INFN BOLOGNA

  44. Data analysis Statistical analysis (2009-2011 data) G.Sirri - INFN BOLOGNA

  45. Analysis Method •  For each neutrino event in OPERA  proton waveform of the corresponding extraction •Sum up and normalize: PDF W(t) separate likelihood for each extraction Maximised versus δt: δt= TOFc- TOFν Positive (negative) δt  neutrinos arrive earlier (later) than light statistical error evaluated from log likelihood curves •  ~1020 pot •  7235 internal events •  7988 external events G.Sirri - INFN BOLOGNA

  46. New results [JHEP10(2012)093] extraction 1 extraction 2 •  no seasonal effect•  no day/night effect•  no energy dependence •  no beam intensity effect •  no difference between internal and external events. Total systematicuncertaintiescomputednumerically by takinginto account the individualcontributions and theircorrespondingp.d.f. G.Sirri - INFN BOLOGNA

  47. Data analysis 2011 bunched-beam analysis G.Sirri - INFN BOLOGNA

  48. Test with short-bunch wide-spacingprotonbeam October 22 to November 6 (2011) 2009-2011 •  TOFν for each detected neutrino•  4x1016pot •  6 internal events•  14 external events •  events evenly distributed in thefour bunches of the extraction •  mode not compatible with OPERA oscillation program. •  statistical method for TOFν extraction •  ~1020 pot •  7235 internal events •  7988 external events G.Sirri - INFN BOLOGNA

  49. Test with short-bunch wide-spacingprotonbeam Results with the Target Tracker data In agreement with the previous value (6.5±7.4 ns) Excludes possible biases affecting the statistical analysis based on the proton waveforms Indicates the absence of significant biases due to: •  cumulative response of beam line to long proton pulses •  pulse duration effects in the BCT response. 20 events δt=1.9±3.7 ns (same syst. errors) Results with the RPC data 16 events [JHEP10(2012)093] G.Sirri - INFN BOLOGNA

  50. Data analysis 2012 bunched-beam analysis G.Sirri - INFN BOLOGNA

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