1. MTM Bologna, 17/6/ 2005 We know that in Nature there are three kinds of neutrinos and in particular atmospheric neutrinos show a deficit of  This effect, found first by the SuperKamiokande and confirmed by many other experiments (for example by MACRO and K2K), has been deeply studied. So, the disappearance of muon neutrinos seems doubtless stated. Moreover, the experimental data agree very well    oscillations. with the hypothesis of    oscillations. However, the experiments performed until now do not allow to observe the particle that should be produced in the oscillation:  the     In order to be sure that the oscillation    is the right explanation of the data,  we need the direct observation of the  INTRODUCTION

2. The OPERA experiment MTM Bologna, 17/6/ 2005  …….. to “see” the 

3. Physics motivations    decay ~ 0.6 mm  appearance signature:  appearance signature: detection of  CC interactions and direct observation of  decay topology Provide unambiguous evidence for    oscillations    oscillations in the parameter region indicated by atmospheric neutrino data by searching for  appearance  appearance in the CNGS  beam in the CNGS  beam MTM Bologna, 17/6/ 2005

4. The CNGS Beam 17 GeV  prompt  promptnegligible Expected  CC interactions/year: 25 Expected  CC interactions/year: ~25 (  m 2 = 2.4x10 -3 eV 2, maximal mixing) Beam to LNGS in May 2006 L = 732 km MTM Bologna, 17/6/ 2005

5. The Oscillation Project with Emulsion tRacking Apparatus In order to detect the decays of the  particles produced in CC interactions of  ‘s from  oscillations a high-resolution tracking detector is required Nuclear emulsions Nuclear emulsions 3D particle reconstruction 3D particle reconstruction Sub-micron spatial resolution Sub-micron spatial resolution High granularity (~300hits/mm) High granularity (~300hits/mm) Modular detector basic unit (BRICK): sequence of lead/emulsions MTM Bologna, 17/6/ 2005

6. Detector structure 2 super-modules muon spectrometer + target walls 52x64 bricks 20m 10m 10m hybrid set-up: visual + electronic detection techniques MTM Bologna, 17/6/ 2005 TOTAL > 220000 bricks

7. Automatic microscopes for emulsion scanning European Scanning System running in : Bari, Bern, Bologna, Lyon, Napoli, Neuchâtel, Roma, Salerno S-UTS (Nagoya) High speed CCD Camera (3 kHz) Piezo-controlled objective lens Constant speed stage Synchronization of objective lens and stage Scanning speed ~ 20 cm 2 /h/side Single side track finding efficiency ~ 95% Sheet-to-sheet alignment (8 GeV/c) ~ 0.5  m Angular resolution ~ 2 mrad MTM Bologna, 17/6/ 2005

8. Automatic emulsion scanning 16 tomographic images 2D Image processing 3D reconstruction of particle tracks Field of view Track segments found in 8 consecutive plates Connected tracks with >= 2 segments Passing-through tracks rejection Vertex reconstruction MTM Bologna, 17/6/ 2005

9. Conclusions  A complex modular detector, using visual and electronic detection techniques, has been designed techniques, has been designed The detector construction and installation at LNGS are  The detector construction and installation at LNGS are well underway well underway  Impressive progress in emulsion scanning automation has been achieved after challenging R&D after challenging R&D The OPERA experiment will start running in May 2006 The OPERA experiment will start running in May 2006 to unambiguously confirm    oscillations to unambiguously confirm    oscillations MTM Bologna, 17/6/ 2005

10. fine

11.    oscillation search    oscillation search  m 2  m 2 = 1.9 x 10 -3 eV 2  m 2  m 2 = 2.4 x 10 -3 eV 2  m 2  m 2 = 3.0 x 10 -3 eV 2 8.012.8 19.91.0  decay channels Background Signal ALL Main background sources: charm production and decays hadron re-interactions in lead large-angle muon scattering in lead MTM Bologna, 17/6/ 2005

12. LNGS – Gran Sasso National Laboratory OPERA (CNGS1) ICARUS Hall C Hall B BOREXINO rock thickness 1400m (3800 m.w.e.) cosmic muon flux:  1/m 2 /h MTM Bologna, 17/6/ 2005

13.   e oscillation search   e oscillation search  m 23 2  m 23 2 = 2.5 x 10 -3 eV 2  23 = 45° nominal CNGS beam5 years 90% C.L. limits on sin 2 (2  13 ) and  13 : Combined fit of E e, E vis, (pt) miss sin 2 (2  13 )<0.06  13 < 7.1º hep-ph/0210043 2.5x10 -3 eV 2

14. Belgium IIHE (ULB-VUB) Brussels Bulgaria Sofia China IHEP Beijing, Shandong Croatia IRB Zagreb France LAPP Annecy, IPNL Lyon, LAL Orsay, IRES Strasbourg Germany Berlin Humboldt, Hagen, 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 Turkey METU Ankara The OPERA Collaboration

15. WIN05, Delphi, June 6-11, 2005  m 2  m 2 = 1.9 x 10 -3 eV 2  m 2  m 2 = 2.4 x 10 -3 eV 2  m 2  m 2 = 3.0 x 10 -3 eV 2 6.6 (10.0)10.5 (15.8)16.4 (24.6)0.7 (1.1) 8.0 (12.1)12.8 (19.2)19.9 (29.9)1.0 (1.5) Signal Background Old analysis New analysis full mixing, 5 years run @ 4.5x10 19 pot / year (…) CNGS beam intensity increase (x 1.5) Comments on background - possible improvements Comments on background - possible improvements: ●  /  separation at low energy by dE/dx in emulsion (charm background reduction) ● extensive comparison of FLUKA with GEANT4/CHORUS data (reduction of the uncertainty on hadron re-interaction calculations, based on FLUKA, 50% systematic error assumed) ● experimental measurement of large-angle muon scattering

16. Experiment strategy  Target Spectrometer On-line analysis of electronic data Brick identification and removal To the Scanning Stations - Laboratories Emulsion analysis interaction vertex  decay kink particle identification and kinematics

17. WIN05, Delphi, June 6-11, 2005 Lead – Emulsion Target Emulsion films (Fuji) mass production started in April ‘03 production rate ~8,000m 2 /month (206,336 brick  ~150,000m 2 ) Lead plates (Pb + 2.5% Sb) requirements: low radioactivity level, emulsion compatibility, constant and uniform thickness 6.7m Wall prototype 2 emulsion layers (44  m thick) glued onto a 200  m plastic base 52 x 64 bricks 12.5cm 10.2cm Pb 1 mm   8.3kg 10 X0’s BRICK: 57 emulsion foils + 56 interleaved Pb plates Total target mass : 1766 t

18. WIN05, Delphi, June 6-11, 2005 Detection of  decays  New channel recently taken into account in the analysis:   3h Main background sources: kink angle kink > 20 mrad impact parameter I.P. > 5 ÷ 20  m short decays:    µ    e long decays:    µ    e    h kink  kink I.P. charm production and decays hadron re-interactions in lead large-angle muon scattering in lead

19. WIN05, Delphi, June 6-11, 2005  detection efficiency Recent improvements Recent improvements:    3h now included in the analysis + updated brick finding algorithm * weighted sum on DIS and QE events DIS longQE long DIS short Overall* 2.72.31.3 3.4 2.42.50.7 2.8 3.5-2.9 Total 8.0 8.31.3 9.1 %   e  h

20. WIN05, Delphi, June 6-11, 2005 BRLong dec.LocationKink+ kinematics Id  + ECC connection Others 0.1740.390.73 0.800.96 Step-by-step efficiencies,   µ

21. WIN05, Delphi, June 6-11, 2005 OPERA OPERA + background reduction -50% probability to observe a number of events  4  background fluctuation (5 years)    oscillations :    oscillations : OPERA sensitivity OPERA + background reduction (under study, -30%)

22. AHEP 2003, Oct. 14-18, Valencia - Spain Particle separation by dE/dx Grain density in emulsion is proportional to dE/dx By measuring grain density as a function of the distance from the stopping point, particle identification can be performed. pions protons Test exposure (KEK) : 1.2 GeV/c pions and protons, 29 plates IONISATION MCS expected value: pions expected value: protonsCalibration