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O scillation P roject with E mulsion t R acking A pparatus

O scillation P roject with E mulsion t R acking A pparatus. F. Juget Institut de Physique Université de Neuchâtel. Neutrino-CH meeting, Neuchâtel June 21-22 2004. Physics motivation The OPERA detector Physics performance Conclusion. Recent results Super-Kamiokande (NOON 2004)

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O scillation P roject with E mulsion t R acking A pparatus

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  1. Oscillation Project with Emulsion tRacking Apparatus F. Juget Institut de Physique Université de Neuchâtel Neutrino-CH meeting, Neuchâtel June 21-22 2004

  2. Physics motivation • The OPERA detector • Physics performance • Conclusion

  3. Recent results Super-Kamiokande (NOON 2004) best fit: Dm2 = 2.4 10-3 eV2 sinq23 = 1.00 1.9 10-3 eV2 < Dm2 < 3.0 10-3 eV2 sinq23 > 0.9 } at 90% CL P(nm -> nt ) = cos4(q13) sin4(q23) sin2(2q23) sin2(1.27 Dm2L/E) Motivation P(nm -> nt ) = cos4(q13) sin4(q23) sin2(2q23) sin2(1.27 Dm2L/E) Dm2 = Dm223 ≈Dm213 • Appareance search of nm <-> nt oscillations in the parameter region indicated by S-K for the atmospheric neutrino deficit. P(nm -> ne ) = sin2(q23) sin2(q13) sin2(1.27 Dm2L/E) => Search for nt appearance in the CNGS nm beam Search for nm <-> ne : put new constraints on q13 Actual result: (CHOOZ): sin2q13 < 0.1

  4. OPERA/CNGS: long base-line n project • Seach for ntappearance at the Gran Sasso laboratory 732 km from CERN • Beam optimized for ntappearance 6.7 1019 pot/year at CERN(shared mode) For Dm2 = 2.4 10-3 and maximal mixing (sin22q =1): expect 23ntCC/kton/year at Gran sasso

  5. The basic unit: The BRICK sandwich of 56 Pb sheets 1mm + 57 emulsion layers Principle: direct observation of t decay topologies in nt cc events • requires high resolution detector (mm): use photographic emulsions • Needs large target mass: alternate emulsion films with lead layer 206 336 bricksare needed→target mass:1.8 ktons

  6. Target Trackers Pb/Em. target m spectrometer n Pb/Em. brick 8 cm 8 m nt (DONUT) Basic “cell” Extract selected brick 1 mm Pb Emulsion Emulsion scanning  vertex search • Electronic detectors • select n interaction brick • decay search • m ID, charge and p • e/g ID, kinematics OPERA an hybrid detector • What the brick cannot do: • trigger for a neutrino interaction • muon identification, charge measurement =>need for an hybrid detector

  7. Spectrometer 1 May 17

  8. Last slab placing19/5 (2.5 weeks in advance)

  9. May 25: Main structure start (drilling the floor for fixing)

  10. 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

  11. ntCC interaction identified looking at the t decay => search for a kink in consecutive emulsions • t decay channels: • t -> m nm nt (17%) • t -> e ne nt (18%) • t ->h + neutrals + nt (49%) • 3h + neutrals + nt (15%)

  12. 3D reconstruction of microtracks Track linking through emulsion base Track linking through different emulsion sheets Vertex/Decay Reconstruction Basic Ideas of Volume Scanning Track processing takes further steps to reach physics goals

  13. Automatic Scanning:Nagoya and Europe R&D efforts Bari, Bern, Bologna, Lyon, Münster, Napoli, Neuchâtel, Roma, Salerno Europe prototype (Neuchâtel exemple) sq ~ 2mrad sx ~ 0.5mm Dedicated hardware Hard coded algorithms Commercial products Software algorithms Routine 10cm2/hr Near future  20cm2/hr S-UTS prototype at Nagoya

  14. Track D1 Track M Sheet 30 Sheet 29 • Manual Check • Track M was not found in sheet 29; • Track D1 was not found in sheet 30; • Track D2, pointing to interaction vertex, was found only in upstream layer of sheet 29 (electron?); Track D2 Track M Track D1 980 m Detected p interaction vertex Brick exposed to p beam at 7 GeV/c • Reconstruction • Track M having beam slopes (0.056;-0.004) and track D1 having slopes intersect in a kink topology;

  15. Movie from E. Barbuto Salerno University

  16. Event reconstruction with emulsions • High precision tracking (dx < 1mm ; dq < 1mrad) • Kink decay topology • Electron and g/p0 identification • Energy measurement • By Multiple Coulomb Scattering • DP/P < 0.2 after 5X0 up to 4 GeV Topological and kinematical analysis event by event

  17. Long decays kink • “Long” decays (t m) • kink angle qkink > 20 mrad • “Short” decays (t m) • impact parameter I.P. > 5 to 20 mm qkink Pb (1 mm) emulsion layers Pb (1 mm) I.P. Short decays plastic base Exploited t decay topologies

  18. Expected number of background events(5 years run with 1.8 kton average target mass) τe τμ τh τ3h total Charm background .31 .017 .243 .573 .44 Large angle μ scattering .174 .174 Hadronic background .139 .174 .313 Total per channel .31 .33 .42 1.50 .44 • Charm background : • Being revaluated using new CHORUS data: cross section increased by 40% • πμ id by dE/dx would reduce this background by 40% •  tested at PSI (pure beam of π or μ stop) •  x 18 ! in the μ channel without a spectrometer • Large angle μ 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 • Hadronic background : • Estimates based on Fluka standalone : 50% uncertainty • Extensive comparison of FLUKA with CHORUS data and GEANT4 • would reduce this uncertainty to ~15%

  19. Expected number of events full mixing, 5 years run @ 6.7 x1019 pot / year Channel Signal (Dm2 (eV2) ) e BR e. BR Background 1.9 10-32.4 10-3 3.0 10-3 e 3.7 6.1 9.2 19.4% 0.175 3.4% 0.31 m 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

  20. 1.9 10-3 3 10-3 Opera with foreseen beam upgrade (1.5) Opera no beam upgrade Probability of claiming a 4s discovery in 5 years Opera with beam*2 Opera with beam*3 Opera, no beam upgrade but half background Opera with beam*4 SK 90% CL

  21. 5X0 ( ~ ½ brick) 5 cm 1 mm Electron identification andEnergy measurement • Identification : Method based on shower identification and on Multiple Coulomb Scattering of the track before showering e/p ratio is measured with Cerenkov and ECC (test beam) • ECC 1.42±0.17 Cerenkov 1.46±0.11 at 2GeV • ECC 0.41±0.05 Cerenkov 0.32±0.03 at 4GeV Energy : Measured by counting the number of track segments into a cone along the electron track Multiple Coulomb Scattering before showering @ a few GeV

  22. 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 X0, eID and pID is ~ 99%. • OK for both τe and νμνe searches efficiencies for showers followed for 36 ECC (6.4 ~X0) To be tested in July @ DESY with a pure electron beam at 1-6 GeV

  23. Expected signal and background for the nm ne search Q13 signal te nmCC nmNC neCC beam 9º 9.3 4.5 1.0 5.2 18 7º 5.8 4.6 1.0 5.2 18 3º 1.2 4.7 1.0 5.2 18 e 0.31 0.032 0.34 10-4 7.0 10-4 0.082 Statistique sur le bdf…

  24. Events Preliminary nm ne Dm223 (eV2) ne beam nm nt 2.5x10-3 eV2 NC 4.50 1019 pot/yr 6.76 1019 pot/yr 0.06  7° Missing pT (GeV) sin22q13 OPERA sensitivity to q13 Only 15% increase scanning because the event location is already performed for nt search. By fitting simultaneously the Ee, missing pT and Evis distributions we got the sensitivity at 90% syst. on the ne contamination up to 10%

  25. Activities of the swiss groups • Bern and Neuchâtel 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 (Neuchâtel)

  26. Conclusions • Detector construction and installation • Installation of detector in progress • Detector (and CNGS beam !) will be ready in 2006 • Scanning strategy still to be optimised • Important Physics Program • First evidence of nm-nt 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 q13 Very low background is the key issue

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