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OPERA

n m →n t. OPERA. Maximiliano Sioli (Bologna University and INFN) for the OPERA Collaboration NOW 2006, Conca Specchiulla, Sep 9-16, 2006. The OPERA Collaboration (37 groups, ~160 physicists ). Belgium IIHE (ULB-VUB) Brussels Bulgaria Sofia China IHEP Beijing, Shandong Croatia IRB Zagreb

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OPERA

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  1. nm→nt OPERA Maximiliano Sioli (Bologna University and INFN) for the OPERA Collaboration NOW 2006, Conca Specchiulla, Sep 9-16, 2006

  2. The OPERA Collaboration (37 groups, ~160 physicists) BelgiumIIHE (ULB-VUB) Brussels BulgariaSofia ChinaIHEP Beijing, Shandong CroatiaIRB Zagreb FranceLAPP Annecy, IPNL Lyon, IRES Strasbourg GermanyHamburg, Münster, Rostock IsraelTechnion Haifa ItalyBari, Bologna, LNF Frascati, L’Aquila, LNGS, Naples, Padova, Rome La Sapienza, Salerno JapanAichi, Kobe, Nagoya, Toho, Utsunomiya RussiaINR Moscow, ITEP Moscow, JINR Dubna, Obninsk SwitzerlandBern, Neuchâtel, Zurich TurkeyMETU Ankara Maximiliano Sioli, NOW 2006

  3. Outline • Physics goal of OPERA • The OPERA detector • Physics performances: • nm nt oscillation channel • nm  ne oscillation channel • Low intensity run • Conclusions Maximiliano Sioli, NOW 2006

  4. Physics motivation Atmospheric neutrino anomaly interpretable as nμ→nt oscillation CHOOZ: no nμ→ne oscillation provide an unambiguous evidence for nμ→nt oscillation in the region of atmospheric neutrinos by looking for ντ appearance in a pure νμ beam CNGS beam (1999) CNGS1 (2000) Maximiliano Sioli, NOW 2006

  5. The CNGS beam: overview “Off peak” Limitingfor nm ↔ ne searches Radial distribution at LNGS Event rate for OPERA (at 4.5x1019 pot/year, 200 days/year): ~6200nm (CC+NC)/year, ~25ntCC/year @ 2.4x10-3 eV2 Maximiliano Sioli, NOW 2006

  6. tdecay “kink” t ~ 0.6 mm nt OPERA≡ Oscillation Project with Emulsion tRacking Apparatus Primary goal of OPERA:direct observation of t leptons produced in ntCC interactions Detector resolution must be O(1 mm) Target mass must be O(1 kton) for Dm2 =O(10-3 eV2) ECC concept adopted Maximiliano Sioli, NOW 2006

  7. TheEmulsion Cloud Chamber technique ECC ≡ sequence of emulsion-lead layers: Lead: target mass Emulsion: tracking device 1 mm t n Pb 10.3 cm It allows high spatial resolution capability and the possibility to have large masses in a modular way In OPERA, the basic ECC unit is the “BRICK” 12.9 cm 8.3 kg 7.8 cm Sequence of 56 lead sheets + 56 emulsion layers (10X0 for p measurements and eID) Maximiliano Sioli, NOW 2006

  8. 8 cm 8 m ECC cell Pb 1 mm Emulsion Target Tracker: trigger and localize the n interaction Spectrometer: measure m ID, charge and momentum ECC: measure kink, pID, momentum (via MCS), dE/dX, e/g separation, general event kinematics Spectrometer Target “changeable sheets” supermodule Vertex Location Pb/Em. brick Extract selected brick Maximiliano Sioli, NOW 2006

  9. The Gran Sasso Laboratory (Central Italy, 900 m a.s.l.) CNGS  External Lab Underground Lab: 1400 m of rock shielding: Cosmic Ray flux reduced by a factor 106 wrt surface; very reduced enviromental radioactivity. Maximiliano Sioli, NOW 2006

  10. OPERA general structure Hybrid detector (electronic + emulsions) with a modular structure: 2 supermodules = 2*(31 walls + 1 spectrometer) ↳ 31 walls = 31*(56*64 bricks + 1 scintillator tracker plane) Total mass = 1766 tons, # of bricks = 206336 SM2 SM1 n Target sections Magnetic spectrometers Maximiliano Sioli, NOW 2006

  11. 8.2 m dipolar magnets (1.55 T)m SpectrometersRPC+XPC (mID + shower energy)drift tubes (muon momentum) coil coil 1-e charge ≅ (0.1-0.3)% Dp/p ≃ (20-25)% mID ≳ 95% (with TT) 12 Fe slabs per magnet side 12 12 B= 1.55 T RPC Fe (5 cm) event recorded in the first magnet 22 gaps filled with RPC Iron slabs coil Precision Trackers (drift tubes) Total Fe weight ~ 1.2 kton Maximiliano Sioli, NOW 2006

  12. Target section: TT + Walls • TT ≡ plastic scintillators • Trigger neutrino interactions • Find the brick to be extracted • Muon tracking and ID Suspension from the top • XY planes (7000m2 in total) readout by WLS fibers • 1000 PMT Hamamatsu (64channels) Height ~ 6.7 m Tensioning from the bottom Maximiliano Sioli, NOW 2006

  13. BAM at LNGS: ~1000 bricks/day at regime OPERA in pictures Details of the first spectrometer BMS ready to fill the target Maximiliano Sioli, NOW 2006

  14. Automatic emulsion scanning Based on the tomographic acquisition of emulsion layers The experiment size requires a scanning speed of ~20 cm2/h. (tens of n interaction/day → thousend of cm2/day) Dedicated hardware Hard coded algorithms Commercial products Software algorithms European station S-UTS in Japan (Nagoya) • - Running at ~20 cm2/h- High efficiency (>90%) and high purity - resolution ~2 mrad - Ultra High Speed CCD Camera for S-UTS (3k frames/sec) - 15m/brick for 15predictions - 1h35m/brick for 100 predictions Maximiliano Sioli, NOW 2006

  15. Search for nm ↔ nt oscillations:expected number of events Full mixing, 5 years run, 4.5ˣ1019 pot/year, 1.8 kton fiducial mass Maximiliano Sioli, NOW 2006

  16. nm  nt discovery potential Probability to observe, in 5 years, a signal far away 4s from the bg 90% CL exclusion plot (i.e. in absence of a signal) in 5 years of data taking Dm2 (eV2) Probability sin22qmt Dm2 (eV2) Uncertainties on background (33%) and on efficiencies (15%) are accounted for Maximiliano Sioli, NOW 2006

  17. nm  ne oscillation channel • Due to its good eID capability, OPERA is well suited for nmnesearches • Main backgrounds are: • ne beam contamination (larger contribution) • p0 identified as electrons produced in nmNC or nmCC with the muon not identified • te from nmnt oscillations 5 years data taking, nominal CNGS, Dm223=2.5x10-3 eV2, sin22q23=1 Maximiliano Sioli, NOW 2006

  18. nm  ne sensitivity • S/B enhanced with simultaneous fit of Evisible, Eelectron and missing pt • Sensitivity fully dominated by statistics 6.4o 7.1o sin22q13 2.5x10-3 eV2 pot (x1019) Maximiliano Sioli, NOW 2006

  19. 10.5 ms 10.5 ms 50 ms Low intensity run (1830 Aug 2006) 1.7x1013 pot/extraction TOTAL: 7.6 E17 pot EXT1: 3.81 E17 pot EXT2: 3.79 E17 pot 1st extraction Wed 30 Aug. 2006 05:00 Fri 18 Aug. 2006 13:40 MD days 2nd extraction Unix time Maximiliano Sioli, NOW 2006

  20. Event selection by electronic detectors using GPS timing information Ext2 Ext1 50 ms Zoom on the spill peaks 10 µs Δt first extraction (ns) N. of in-spill events in the whole run ~320 Δt closest extraction (ns) Maximiliano Sioli, NOW 2006

  21. First TTCS connections successfully tested! Beam events CC event originated upstream of the detector (rocks) CC event originated in the first magnet Maximiliano Sioli, NOW 2006

  22. Angular distribution of recorded events y Very preliminary! qy >0 z qy <0 MC (only cosmics) Zoom on beam events coming 3.5° from below DATA Angle with respect to the horizontal direction (deg) Maximiliano Sioli, NOW 2006

  23. Summary • The main aim of the OPERA experiment is to unambiguously confirm/disproof the nm ntatmospheric oscillation channel • The low intensity CNGS run operated smoothly with good quality and stability • The electronic detectors of OPERA took data almost continuously and with the expected tracking performances • More than 300 in-spill events have been recorded with a clear time distribution • The detector is ready for the next phase: observing neutrino interactions inside ECC bricks Maximiliano Sioli, NOW 2006

  24. Spares Maximiliano Sioli, NOW 2006

  25. emulsion layers I.P. Short decays plastic base t- e-ne nt 17.8% t decay topologies t- m-nm nt 17.4% t- h-nt (np0) 49.5% t- 3h-nt (np0) 14.5% “Long” decays kink angle qkink > 20 mrad “Short” decays • impact parameter I.P. > 5 to 20 mm Long decays kink qkink Pb (1 mm) Pb (1 mm) tm te th (np0) t3h (np0) tm te Maximiliano Sioli, NOW 2006

  26. Angular and position resolutions For q≃ 0.013 rad q 2.1 mrad 2.1 mrad 0.4 m 0.4 m Maximiliano Sioli, NOW 2006

  27. Tracking resolution with emulsions 100mm Ag grain after development M.I.P. Track dx m.i.p. Track intrinsic tracking accuracy Fog s = 0.06mm Compton Electron • Grain Density: ~30grains / 100mm for m.i.p. • Grain Size: 0.2 m (original crystal) 0.8 m (after development) sx = 0.2m/12 = 0.06m • However, DAQ effects spoils the resolution (CCD pixel size, stage movements); routinely we have sx = 0.3m Maximiliano Sioli, NOW 2006

  28. Fuji emulsions, from production to scanning Production at FUJI Mass production started April 2003 (~150,000 m2) • Refreshing in the Tono Mine in Japan: started • Refreshing conditions: • Humidity: > 95% • Temperature : 30 ºC • Time: ~ 3 days Refreshing Transportation from JAPAN to LNGS First batch to LNGS by June ’04 Brick assembly Emulsion storage barrack ready in Hall B Cosmic Ray exposure Scanning Experiment Maximiliano Sioli, NOW 2006

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