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Study of Neutrino Oscillations in the OPERA Experiment

Study of Neutrino Oscillations in the OPERA Experiment. Umut KOSE INFN-PADOVA. OUTLINE. The OPERA experiment status of data taking progress in event analysis      analysis     e analysis (preliminary result) Conclusions.  .  .

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Study of Neutrino Oscillations in the OPERA Experiment

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  1. Study of Neutrino Oscillations in the OPERA Experiment Umut KOSE INFN-PADOVA U.KOSE, LLWI 2013, Alberta, Canada

  2. OUTLINE • The OPERA experiment • status of data taking • progress in event analysis •    analysis •   e analysis (preliminary result) • Conclusions U.KOSE, LLWI 2013, Alberta, Canada

  3.   Oscillation Project with Emulsion-tRackingApparatus Aiming at thefirst direct detection of neutrino oscillations inappearance mode where the  is identified by the charged lepton created in its Charged Current (CC) interaction. -   The challenge is to distinguish interactions from interactions. Decay ,e- - ,h-  oscillation - ,3h- ~1 mm • Conventional  beam optimized for  appearance  high energy beam, intensity, long baseline • Detector O(kton): Large target mass and submicron resolution • Event by event separation of CC interactions from dominant CC interactions by direct observation of -lepton decay. U.KOSE, LLWI 2013, Alberta, Canada

  4. CNGS neutrino beam OPERA sensitive region Ø at GS=2km 3.2° angle LNGS * Interaction rate at LNGS Covers the region indicated by Super-K, K2K & MINOS For 22.5x1019 POT　→　Expected Events7.6 Signal, 0.7 Background Ref: New Journal of Physics 14(2012)033017 U.KOSE, LLWI 2013, Alberta, Canada

  5. OPERA detector* *JINST 4 P04018, 2009. SM1 SM2 Muon Spectrometer RPC+ Drift Tubes (HPT) Brick walls+Target Tracker(TT) Target area ~150000 ECC bricks  1.25kton Muon Spectrometer Muon ID, momentum and charge measurement Each brick wall is followed by a plane of plastic scintillator strips in X/Y direction. TT used for localization of interaction brick. ECC brick= 56 lead plates + 57 films ~8kg (10X0) U.KOSE, LLWI 2013, Alberta, Canada

  6. Typical  CC-like and  NC-like events With m ・m CC ・CC, t→m(17.4%)  20 m Without m ・ NC ・CC, t→e(17.8%) ・CC, t→h, 3h(64.8%)  ・e CC U.KOSE, LLWI 2013, Alberta, Canada

  7. Neutrino interaction location in ECC Step 2-4: CS-ECC connection, ScanBack, Volume data taking Step 1: CS scanning Step 5-6: validation of neutrino interaction vertex and decay search for short lived particles U.KOSE, LLWI 2013, Alberta, Canada

  8. CNGS physics runs U.KOSE, LLWI 2013, Alberta, Canada

  9. Impact Parameter (IP) measurement: U.KOSE, LLWI 2013, Alberta, Canada

  10. First candidate 2008-2009 decay search, released in 2010 (Phys. Lett. B (2010) 138) --  • 12 • 120 ± 20 ± 35 MeV Prompt nt~ 10-7/CC Decay of charmed particles produced inne interactions~ 10-6/CC Double charm production~ 10-6/CC Decay of charmed particles produced innm interactions ~ 10-5/CC Hadronic interactions ~ 10-5/CC • 12 • 640 +125-80 +100-90 MeV U.KOSE, LLWI 2013, Alberta, Canada

  11. 2000 m Second  candidate I U.KOSE, LLWI 2013, Alberta, Canada

  12. Event kinematics Second  candidate II All track were identified as hadron. Event satisfies the specified criteria for - h+ h- h-  U.KOSE, LLWI 2013, Alberta, Canada

  13.   control sample Charm’s life time is similar with tau.  Tau detection efficiency validation sample Expected events: 51  7.5 Observed events: 49 Charmed hadron – muon angle in the plane transverse to  direction U.KOSE, LLWI 2013, Alberta, Canada

  14.   eoscillations search I (Preliminary results) • Systematic search for electron neutrinos applied • to 505 located events without muon in the final state (runs 2008 – 2009) • For each located event: • Extrapolate primary tracks to CS • Search for cluster of shower on CS • if shower hints found on CS, open an additional volume. • As a result 19 e event observed, compatible with background-only hypothesis expectation of 19.82.8(syst). • Applying cut on reconstructed energy in order to increase signal to background ratio, we observe 4 events with an expectation of 4.6 events. Gives an upper limit sin2(213) < 0.44 at 90% C.L. E = 15.6 GeV Preliminary U.KOSE, LLWI 2013, Alberta, Canada

  15.   eoscillations search II Search at large m2 We have used the conventional approach of translating the   eoscillation probability as We observe 6 events below 30GeV cut on reconstructed energy with an expectation of 9.41.3 events. This result yields an upper limit of 7.2 10-3 on sin2(2new) at 90% C.L. Preliminary U.KOSE, LLWI 2013, Alberta, Canada

  16. Conclusions • OPERA experiment: Direct detection of    oscillations in APPEARANCE MODE, successfully taking data since 2008, by December 2012, 17.97 1019 pot (80% of the nominal value • 22.5 1019 pot) collected. •    analysis • Two tau candidate events have been found: • Tau 1prong • Tau3prongs • Analysis is going on some more interesting events under investigation (cross-check). • A first results from   e oscillations • 19 events (4 events with Erec<20GeV) observed with an estimation of 19.82.8 (4.6 with Erec<20GeV) events. • At large m2 region, we observed 6 events with an estimation of 9.4 1.3 events gives an upper limit of 7.2 10-3 at 90% C.L. on sin2(2new) U.KOSE, LLWI 2013, Alberta, Canada

  17. Thank you for your attention Image taken using OPERA emulsion film with pinhole hand made camera by D. Diferdinando U.KOSE, LLWI 2013, Alberta, Canada

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