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

2. Maximiliano Sioli, NOW 2006 2 The OPERA Collaboration (37 groups, ~160 physicists) Belgium IIHE (ULB-VUB) Brussels Bulgaria Sofia China IHEP Beijing, Shandong Croatia IRB Zagreb France LAPP Annecy, IPNL Lyon, IRES Strasbourg Germany Hamburg, Münster, Rostock Israel Technion Haifa Italy Bari, Bologna, LNF Frascati, L’Aquila, LNGS, Naples, Padova, Rome La Sapienza, Salerno Japan Aichi, Kobe, Nagoya, Toho, Utsunomiya Russia INR Moscow, ITEP Moscow, JINR Dubna, Obninsk Switzerland Bern, Neuchâtel, Zurich Turkey METU Ankara

3. Maximiliano Sioli, NOW 2006 3 Outline Physics goal of OPERA The OPERA detector Physics performances:    oscillation channel    oscillation channel   e oscillation channel   e oscillation channel Low intensity run Conclusions

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

5. Maximiliano Sioli, NOW 2006 5 The CNGS beam: overview Beam main features L 732 km 17 GeV L/ L/ 43 km/GeV ( e + e )/  0.87%  /   / 2.1%  prompt  promptnegligible “Off peak” Limiting for  ↔ e  ↔ e searches Event rate for OPERA (at 4.5x10 19 pot/year, 200 days/year): ~6200  (CC+NC)/year, ~25  CC/year @ 2.4x10 -3 eV 2 Radial distribution at LNGS

6. Maximiliano Sioli, NOW 2006 6 OPERA ≡ Oscillation Project with Emulsion tRacking Apparatus Primary goal of OPERA: direct observation of  leptons produced in  CC interactions  decay “kink” ~ 0.6 mm   Detector resolution must be O(1 mm) Target mass must be O(1 kton) for  m 2 =O(10 -3 eV 2 ) ECC concept adopted

7. Maximiliano Sioli, NOW 2006 7 The Emulsion Cloud Chamber technique Pb  1 mm ECC ≡ sequence of emulsion-lead layers: Lead: target mass Emulsion: tracking device 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” Sequence of 56 lead sheets + 56 emulsion layers (10X 0 for p measurements and eID) 12.9 cm 10.3 cm 8.3 kg 7.8 cm

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

9. 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 10 6 wrt surface; very reduced enviromental radioactivity.

10. 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 SM1 SM2 Target sections Magnetic spectrometers

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

12. 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  XY planes (7000m 2 in total) readout by WLS fibers  1000 PMT Hamamatsu (64channels) Suspension from the top Tensioning from the bottom Height ~ 6.7 m

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

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

15. Maximiliano Sioli, NOW 2006 15 Search for  ↔   oscillations: expected number of events Full mixing, 5 years run, 4.5ˣ10 19 pot/year, 1.8 kton fiducial mass  decay channel signal (  m 2 = 2.4x10 -3 eV 2 ) signal (  m 2 = 3.0x10 -3 eV 2 ) background τeτeτeτe4.36.70.23 τμτμτμτμ3.65.60.23 τhτhτhτh3.85.90.32 τ3hτ3hτ3hτ3h1.11.70.22 Total12.819.91.0

16. Maximiliano Sioli, NOW 2006 16    discovery potential    discovery potential Probability to observe, in 5 years, a signal far away 4  from the bg 90% CL exclusion plot (i.e. in absence of a signal) in 5 years of data taking Uncertainties on background (33%) and on efficiencies (15%) are accounted for  m 2 (eV 2 ) sin 2 2    m 2 (eV 2 ) Probability

17. Maximiliano Sioli, NOW 2006 17   e oscillation channel  Due to its good eID capability, OPERA is well suited for  Due to its good eID capability, OPERA is well suited for   e searches   Main backgrounds are:   e beam contamination (larger contribution)    0 identified as electrons produced in  NC or  CC with the muon not identified    e from    oscillations  13 signal eeee  CC  CC  NC  NC e CC beam e CC beam 9º9º9º9º9.34.51.05.218 8º8º8º8º7.44.51.05.218 7º7º7º7º5.84.61.05.218 5º5º5º5º3.04.61.05.218 Efficiency0.310.032 0.34x10 -4 7.0x10 -4 0.082 5 years data taking, nominal CNGS,  m 2 23 =2.5x10 -3 eV 2, sin 2 2  23 =1

18. Maximiliano Sioli, NOW 2006 18 2.5x10 -3 eV 2 7.1 o 6.4 o   e sensitivity S/B enhanced with simultaneous fit of E visible, E electron and missing p t S/B enhanced with simultaneous fit of E visible, E electron and missing p t Sensitivity fully dominated by statistics Sensitivity fully dominated by statistics x10 19 ) pot (x10 19 ) sin 2 2  13

19. Maximiliano Sioli, NOW 2006 19 50 ms 10.5  s 1 st extraction 2 nd extraction 1.7x10 13 pot/extraction Low intensity run (18  30 Aug 2006) Unix time TOTAL: 7.6 E17 pot EXT1: 3.81 E17 pot EXT2: 3.79 E17 pot MD days Fri 18 Aug. 2006 13:40 Wed 30 Aug. 2006 05:00

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

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

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

23. Maximiliano Sioli, NOW 2006 23 Summary The main aim of the OPERA experiment is to unambiguously confirm/disproof the atmospheric oscillation channel The main aim of the OPERA experiment is to unambiguously confirm/disproof the    atmospheric oscillation channel The low intensity CNGS run operated smoothly with good quality and stability 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 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 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 The detector is ready for the next phase: observing neutrino interactions inside ECC bricks

24. Maximiliano Sioli, NOW 2006 24 Spares

25. Maximiliano Sioli, NOW 2006 25 “Long” decays kink angle  kink > 20 mrad “Short” decays impact parameter I.P. > 5 to 20  m kink  kink Long decays Pb (1 mm) plastic base I.P. Short decays emulsion layers Pb (1 mm)  decay topologies   e  h (n  0 )  3h (n  0 )   e -- e - e   --  -    -- h -  (n  0 ) 17.8% 17.4% 49.5% -- 3h -  (n  0 ) 14.5%

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

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

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