Oscillation Project with Emulsion tRacking Apparatus F. Juget Institut de Physique Universit© de Neuch¢tel Neutrino-CH meeting, Neuch¢tel June 21-22 2004

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Oscillation Project with Emulsion tRacking Apparatus F. Juget Institut de Physique Universit de Neuchtel Neutrino-CH meeting, Neuchtel June 21-22 2004 Slide 2 Physics motivation The OPERA detector Physics performance Conclusion Slide 3 Motivation Appareance search of oscillations in the parameter region indicated by S-K for the atmospheric neutrino deficit. P( ) = cos 4 ( ) sin 4 ( 23 ) sin 2 (2 23 ) sin 2 (1.27 m 2 L/E) P( e ) = sin 2 ( ) sin 2 ( 13 ) sin 2 (1.27 m 2 L/E) m 2 = m 2 23 m 2 13 Search for e : put new constraints on Actual result: (CHOOZ): sin 2 13 < 0.1 => Search for appearance in the CNGS beam Recent results Super-Kamiokande (NOON 2004) best fit: m 2 = 2.4 10 -3 eV 2 sin 23 = 1.00 1.9 10 -3 eV 2 < m 2 < 3.0 10 -3 eV 2 sin 23 > 0.9 } at 90% CL P( ) = cos 4 ( ) sin 4 ( 23 ) sin 2 (2 23 ) sin 2 (1.27 m 2 L/E) Slide 4 OPERA/CNGS: long base-line project Seach for appearance at the Gran Sasso laboratory 732 km from CERN Beam optimized for appearance For m 2 = 2.4 10 -3 and maximal mixing (sin 2 2 expect 23 CC/kton/year at Gran sasso 6.7 10 19 pot/year at CERN (shared mode) Slide 5 Principle: direct observation of decay topologies in cc events The basic unit: The BRICK sandwich of 56 Pb sheets 1mm + 57 emulsion layers 206 336 bricks are needed target mass: 1.8 ktons requires high resolution detector ( m): use photographic emulsions Needs large target mass: alternate emulsion films with lead layer Slide 6 8 m Target Trackers Pb/Em. target Electronic detectors select interaction brick Emulsion scanning vertex search Extract selected brick Pb/Em. brick 8 cm Pb 1 mm Basic cell Emulsion decay search spectrometer e/ ID, kinematics ID, charge and p (DONUT) OPERA an hybrid detector What the brick cannot do: trigger for a neutrino interaction muon identification, charge measurement => need for an hybrid detector Slide 7 Slide 8 Slide 9 Spectrometer 1 May 17 Slide 10 Last slab placing 19/5 (2.5 weeks in advance) Slide 11 May 25: Main structure start (drilling the floor for fixing) Slide 12 Detector installation schedule Brick walls and Target Tracker walls for SM1 Aug. 04 Jun 05 Brick walls and Target Tracker walls for SM2 Jul. 05 Mar 06 Installation of Brick Manipulator System (BMS) Beginning 2005 Start filling walls with bricks July 2005 Ready to take data for 2006 Slide 13 CC interaction identified looking at the decay => search for a kink in consecutive emulsions decay channels: (17%) e e (18%) h + neutrals + (49%) 3h + neutrals + (15%) Slide 14 Basic Ideas of Volume Scanning 3D reconstruction of microtracks Track linking through emulsion base Track linking through different emulsion sheets Vertex/Decay Reconstruction Track processing takes further steps to reach physics goals Slide 15 Automatic Scanning:Nagoya and Europe R&D efforts Bari, Bern, Bologna, Lyon, Mnster, Napoli, Neuchtel, Roma, Salerno Routine 10cm 2 /hr Near future 20cm 2 /hr S-UTS prototype at Nagoya Dedicated hardware Hard coded algorithms Europe prototype (Neuchtel exemple) Commercial products Software algorithms ~ 2mrad x ~ 0.5 m Slide 16 Track M Track D 1 Manual Check Track M was not found in sheet 29; Track D 1 was not found in sheet 30; Track D 2, pointing to interaction vertex, was found only in upstream layer of sheet 29 (electron?); Sheet 30 Sheet 29 Track M Track D 1 Track D 2 980 m Reconstruction Track M having beam slopes (0.056;- 0.004) and track D 1 having slopes intersect in a kink topology; Brick exposed to beam at 7 GeV/c Detected interaction vertex Slide 17 Movie from E. Barbuto Salerno University Slide 18 Event reconstruction with emulsions Topological and kinematical analysis event by event High precision tracking ( x < 1 m ; < 1mrad) Kink decay topology Electron and / 0 identification Energy measurement By Multiple Coulomb Scattering P/P < 0.2 after 5X 0 up to 4 GeV Slide 19 Long decays ( ) kink angle kink > 20 mrad kink kink Long decays Pb (1 mm) Short decays ( ) impact parameter I.P. > 5 to 20 m plastic base I.P. Short decays emulsion layers Pb (1 mm) Exploited decay topologies Slide 20 Expected number of background events (5 years run with kton average target mass) 1.50.42.33.31 Total per channel.313.174.139 Hadronic background.174 Large angle scattering.573.243.017.31 Charm background total hhee 1. Charm background : Being revaluated using new CHORUS data: cross section increased by 40% id by dE/dx would reduce this background by 40% tested at PSI (pure beam of or stop) x 18 ! in the channel without a spectrometer 2.Large angle scattering : Upper limit from test @ CERN Calculations including nuclear form factors give a factor 5 less will be measured this autumn in X5 beam with Si detectors 3.Hadronic background : Estimates based on Fluka standalone : 50% uncertainty Extensive comparison of FLUKA with CHORUS data and GEANT4 would reduce this uncertainty to ~15% 3h3h.44 Slide 21 Expected number of events Channel Signal ( m 2 (eV 2 ) ) BR BR Background 1.9 10 -3 2.4 10 -3 3.0 10 -3 e 3.7 6.1 9.2 19.4% 0.175 3.4% 0.31 3.1 4.8 7.6 16% 0.175 2.8% 0.33 h 3.2 5.1 7.8 5.8% 0.50 2.9% 0.42 3h 1.4 2.2 3.5 8.3% 0.15 1.25% 0.44 Total 11.4 18.2 28.1 49.5% ~1 10.35% 1.5 full mixing, 5 years run @ 6.7 x10 19 pot / year Slide 22 Probability of claiming a 4 discovery in 5 years SK 90% CL Opera, no beam upgrade but half background Opera with beam*2 Opera with beam*3 Opera with beam*4 Opera no beam upgrade Opera with foreseen beam upgrade (1.5) 1.9 10 -3 3 10 -3 Slide 23 Electron identification and Energy measurement Identification : Method based on shower identification and on Multiple Coulomb Scattering of the track before showering e/ ratio is measured with Cerenkov and ECC (test beam) ECC 1.420.17 Cerenkov 1.460.11 at 2GeV ECC 0.410.05 Cerenkov 0.320.03 at 4GeV 5X 0 ( ~ brick) 1 mm 5 cm Energy : Measured by counting the number of track segments into a cone along the electron track Multiple Coulomb Scattering before showering @ a few GeV Slide 24 Electron identification efficiency e.m. and hadronic shower simulated in OPERA brick. No background simulation. Analysis based on neural network. Note that in the range 2 15 GeV and for particle crossing at least 2.5 X 0, eID and pID is ~ 99%. OK for both e and e searches efficiencies for showers followed for 36 ECC (6.4 ~X 0 ) To be tested in July @ DESY with a pure electron beam at 1-6 GeV Slide 25 Expected signal and background for the e search 185.21.04.71.233 0.0827.0 10 -4 0.34 10 -4 0.0320.31 e CC beam NC CC ee signal 13 185.21.04.65.877 185.21.04.59.399 Statistique sur le bdf Slide 26 OPERA sensitivity to 13 Only 15% increase scanning because the event location is already performed for search. Preliminary 2.5x10 -3 eV 2 0.06 7 sin 2 2 13 m 2 23 (eV 2 ) 4.50 10 19 pot/yr 6.76 10 19 pot/yr syst. on the e contamination up to 10% By fitting simultaneously the E e, missing p T and E vis distributions we got the sensitivity at 90% NC e e beam Events Missing p T (GeV) Slide 27 Activities of the swiss groups Bern and Neuchtel are involved in OPERA Electronics Frontend Chip for the target tracker (Bern) Test and calibration of PMT for the Target Tracker (Bern) Scanning 1 microsope in each lab is already working A third one will be installed this year in Bern Development of an automatic emulsion changer (Bern) Simulation Geant4 simulation (Neuchtel) Slide 28 Conclusions Important Physics Program First evidence of - appearance in few years data taking In a five years run: 18 signal (SK best fit) and 1.5 background events Studies to improve efficiency and to reduce the background Significant measurement of 13 Detector construction and installation Installation of detector in progress Detector (and CNGS beam !) will be ready in 2006 Scanning strategy still to be optimised Very low background is the key issue