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The OPERA hybrid detector was designed to search for n t appearance in the n m CNGS beam

LNGS. CERN. L = 732 km. The OPERA hybrid detector was designed to search for n t appearance in the n m CNGS beam. T flight = 2.44 ms. CNGS. Expected neutrino interactions for 22.5x10 19 pot: ~ 23600   CC + NC ~ 205  e +  e CC ~ 115   CC (m 2 = 2.5 x 10 -3 eV 2 ).

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The OPERA hybrid detector was designed to search for n t appearance in the n m CNGS beam

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  1. LNGS CERN L = 732 km The OPERA hybrid detector was designed to search for ntappearance in the nm CNGS beam Tflight = 2.44 ms CNGS Expected neutrino interactions for 22.5x1019 pot: ~ 23600  CC + NC ~ 205 e +e CC ~ 115  CC (m2 = 2.5 x 10-3 eV2) OPERA

  2. Detection principle for nt appearance in OPERA ECC brick 1 mm electronictrackers   Pb emulsion layers interface films (CS) Detection of ntCC events through characteristic topology

  3. Dipolar magnet spectrometerwith RPC and drift tubes Brick manipulator system 2 SuperModules SM1 SM2 Pb-Emulsion Target +Target Tracker VETO

  4. neutrino OPERA: sub-micrometric tracking precision of nuclear emulsion+ time trigger, kinematics and particle ID by electronic detectors Hybrid target structure 10.2 cm (CS) 7.5 cm 10 X0 12.5 cm (CS) 1 brick = 56 Pb plates / 57 emulsion films 150,000 ECC bricks (ECC=Emulsion Cloud Chamber) 111,000 m2 surface, 8.9 million films 1.25 kton of “instrumented” target

  5. Microscopic Image emulsion(44mm) 50 micron plastic base(205 mm) emulsion(44 mm) sensitivity : 32grains/100 mm Emulsion films: optical “tomography” of the vertex region Track fitting residuals 50 nm A m.i.p. track in emulsion nm beam 3D tomography:change focal plane

  6. Reading the emulsion films – “off-site” detectors High speed automatic microscopes: ~ 200 cm2 emulsion film surface/hour/facility Based on state of the art technologies: precision mechanics, high-speed CMOS, pattern recognition, image analysis Data flow:  1 GB/s/facility European Scanning System Super-UltraTrackSelector

  7. The VETO system: double layer ofglass RPC (100m2) 97% efficiency instreamer mode

  8. Target Tracker planes interleaved with brick walls > 5 p.e. for a m.i.p. (2.15 MeV) ~ 99% detection efficiency position accuracy: 10 mm angular accuracy: 23 mrad TT: 6% of target mass Walls: 0.5% of target mass

  9. Target Tracker p.e. for a m.i.p. track as a function of the distance from each end Empty dots: MC Full dots: data

  10. The magnetic spectrometers: • 1.52 T magnetic field bending particles in the horizontal plane • 24 slabs of magnetized iron interleaved with 22 RPC planes • 6 drift tube stations (HPT) for precision measurement of the angular deflection • Momentum resolution: • 20% below 50 GeV

  11. The magnetic spectrometers Momentum  charge, data (dots) vs. MC (lines) Charge misidentification: 1.2% (2.5 GeV < p < 45 GeV)

  12. RPC’s for tracking in the magnet and range measurement RPC efficiency 3500 m2bakelite RPC’s operated in streamer mode: Hadronic energy reconstruction in the spectrometer Trigger for the HPT Coarse tracking of showers (2.6 cm strip pitch)

  13. How neutrino interaction events look like in the OPERA electronic detectors 1m: event with a min the final state 20 m 0m: event without a m in the final state

  14. Neutrino interaction energy reconstruction 1m events 0m events Reconstructed energy: Dots = data Lines = MC The instrumented target is used as a calorimeter Energy resolution

  15. How a t-neutrino candidate looks like in OPERA Vertex region Vertex region (zoomed view) Electronicdetectors

  16. Topological signature through the observation of the in-flight decay of a tau lepton: ct87 mm requires micrometric tracking

  17. Info from emulsion films: topological reconstruction Interaction/decay vertex:the minimum distance point of two or more tracks The Impact Parameter has an average value of 2.3 mm (real events) • IP distribution for: • - nt events (MC) • NC+ nmCC events (MC) • NC+ nmCC events (Data)

  18. Info from emulsion films: momentum estimation through measurement of multiple Coulomb scattering Dp/p s = (22±4)%

  19. Info from emulsion films: EM shower reconstruction + energy estimation 2 EM showers give a reconstructed mass ~ 160 MeV/c2 • Shower energyis estimated bya neural-networkanalysis of the shower feaures: • # of tracks • shape • MCS of hard tracks p0 mass measuredin emulsion 35 events E = 8.1 GeV E = 0.5 GeV

  20. Info from emulsion films: discrimination of interaction/decay kinks by search for highly ionising particle tracks Fine emulsion sampling (0.5 mm tomography) to check track length and discriminate radioactivity from nuclear fragments

  21. Merging electronic detector information with emulsion information, #1: the Changeable Sheet (CS) doublets Extract brick and CS, scan CS. Confirm the event in the brick. Develop brick: ship to scanning labs. CS σx ∼ 10.0 mm

  22. On-demand brick handling Waiting for neutrinos in the target… X-ray exposure for alignment Extracted by the Brick Manipulator System Stored underground (waiting for the CS response) Films developed in surface emulsion facility Exposed to cosmic-rays for precision film alignment

  23. Emulsion film scanning: several labs share data-taking To Dubna Bern Analysis BMSDB Padova IN2P3 OPFRA Bologna DevDB Nagoya OPITA Bern BAMDB To Japan LNGS Roma To Ankara Bologna LNGS LNF LNF Bari Dubna Napoli An interconnected system of relational DB’s distributes all intermediate results and holds the analysis status of each event Currently 15 TB, expected to top 100 TB Salerno Padova LNGS Roma Bari Salerno Napoli

  24. Merging electronic detector information with emulsion information, #2: locating the neutrino interaction CSd  ~2 µm nm 2 1 1 … 53 57 48 49 50 51 52 54 55 56 2 Volume scanning (2cm3) around the disappearance point

  25. Merging electronic detector information with emulsion information, #3: event study • Estimate the total visible energy • Match event shape to vertex region and check track origin • Assess the nature of eachparticle for interesting events • Each track is followedthrough the Target Tracker, CS doublet andtarget brick sheetsuntil the endpoint isreached and checked C

  26. Merging electronic detector information with emulsion information, #3: event study The combined emulsion + electronic information is reported for the nt candidate eventAll cuts from OPERA Proposal passed The most likely interpretation in this case is: The OPERA hybrid apparatus allows detailed study for each single event!

  27. Sample event: charm candidate x-view 1ry muon 1ry vertex kink daughter muon 1.3 mm

  28. Sample event: charm candidate AB=361 mm Pl21 Pl20 nm Pl20 A B 5 Pl20 Pl20 Pl20 Pl21 2 m C C: hadroninteractionvertexAC =1640 mm Pl22 Pl21

  29. The whole machinery running 3432 eventslocated (2008+2009 runs)3162 eventsdecaysearched (‘08/’09) Pl20

  30. Conclusions • The OPERA Collaboration is successfully operating a hybrid detector to search for nt appearance in the CNGS beam • The hybrid design concept in OPERA allows detailed study of each event, exploiting the best features of its nuclear emulsions, scintillators, RPC’s and drift tubes • 1 nt candidate was found in 2010 out of a sample of 1088 fully analysed events • 3162 events searched for decays so far (41 with charm production/decay in nm interactions) from 2008/2009 runs • Data taking in progress, more results to come in the near future!

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