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Kaname HAMADA (Nagoya University) on behalf of the OPERA collaboration

Status of the OPERA experiment. O scillation P roject with E mulsion t R acking A pparatus. Kaname HAMADA (Nagoya University) on behalf of the OPERA collaboration. NEW TRENDS IN HIGH-ENERGY PHYSICS (CRIMEA 2011). 1. The goal of OPERA :.

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Kaname HAMADA (Nagoya University) on behalf of the OPERA collaboration

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  1. Status of the OPERA experiment Oscillation Project with Emulsion tRacking Apparatus Kaname HAMADA (Nagoya University) on behalf of the OPERA collaboration NEW TRENDS IN HIGH-ENERGY PHYSICS (CRIMEA 2011) 1

  2. The goal of OPERA : Establish detection of neutrino oscillations in appearance mode through the  channel. Following the Super- Kamiokande observaion of oscillations with atmospheric neutrinos and the confirmation obtained with solar neutrinos and accelerator beams. Important, missing tile in the oscillation picture. The PMNS 3-flavor oscillation formalism predicts: P() ~ sin2223cos413sin2(m223L/4E) Full mixing and m223 ~ 2.4 x 10-3 eV2 The light blue band indicates the OPERA allowed region (90% CL) for the above parameter values for 22.5 x 1019 pot 2

  3. Difference between  CC and  CC interaction   CC interaction   decay “kink”   CC interaction -, h- ,e-    oscillation ~1 mm plus 3-prong decay modes In order to detect , the nuclear emulsion is used in a hybrid apparatus. Emulsion record charged particles as 3D tracks, and it has sub-micron resolution. 3

  4. Belgium ULB Brussels Italy Bari Bologna LNF Frascati L’Aquila, LNGS Naples Padova Rome Salerno Russia INR RAS Moscow LPI RAS Moscow ITEP Moscow SINP MSU Moscow JINR Dubna Croatia IRB Zagreb France LAPP Annecy IPNL Lyon IPHC Strasbourg Switzerland Bern ETH Zurich Japan Aichi Toho Kobe Nagoya Utsunomiya Germany Hamburg Turkey METU Ankara Israel Technion Haifa The OPERA Collaboration160 physicists, 30 institutions, 11 countries Korea Jinju http://operaweb.lngs.infn.it/ 4

  5. LNGS L = 732 km CERN Tflight = 2.44 ms Expected interactions for 22.5x1019 pot(nominal pot in 5 years for 1.25kton target): ~23600  CC + NC ~160 e +e CC ~115  CC (m2 = 2.5 x 10-3 eV2) ~8 CC identified (BG<1) < E >( GeV ) 17 (e + e) /  0.87 %* /  2.1 %* prompt Negligible* CNGS beam CERN SPS  732km 1,400m underground LNGS conventional  beam * Interaction rate at LNGS 5

  6. 7.5cm 12.5cm 8.3kg 10X0 Neutrino Beam (vertical for films) 10cm 50 micron OPERA target – ECC brick – Emulsion Cloud Chamber (ECC) OPERA emulsion film 10cm Lead plate : 1mm 12.5cm Microscopic image Stack of 57 OPERA emulsion films, 56 lead plates (10X0) Recorded as silver grains along the line where a charged particle passed through horizontal track Resolution : 0.3 m 6

  7. OPERA detector 150,000 ECC side view ~1.25kton ECC + Target Tracker ECC + Target Tracker Muon spectrometer Muon spectrometer  ~20 m zoom in OPERA emulsion film 7

  8. Scintillator Strips Target Tracker and brick trays Module: 64 6-m scintillator strips Signal transmitted by WLS fibers Read at both ends by 64-PMT • 5 p.e. for a m.i.p. • ~ 99% detection efficiency  trigger • Position accuracy: ~ 8 mm brick location • Probability map of event location in bricks Brick trays: only 0.5% of target mass 8

  9. Magnetic Spectrometers: muon ID and momentum • Dipole magnet • 1.52 T magnetic field bending particles in the horizontal plane • 24 slabs of magnetized iron interleaved with 24 RPC planes • 6 drift tube stations for precision measurement of the angular deflection • Momentum resolution: • 20% below 30 GeV Muon ID essential to reject Charmed particles background in nm CC interactions 9

  10. top view Typical nmCC-likeand NC-like events   charged current like 20 m side view  top view  Neutral current like side view  10 10

  11. ECC brick extraction ECC brick tagging by electronic detector 11

  12.  charged current interaction in ECC Short flight decay decay in same Pb plate  lifetime is short (c = 87m) Decay point Impact Parameter distribution n IP  Primary vertex ntevents (MC) NC+CC nm events (MC) NC+CC nm events (Data) (Mean 104.3 m) 1mm Pb Events with IP>10mm are visually inspected: possible decay topologies Long flight decay decay in further downstream Pb plate Decay point IP n   decay topology Primary vertex 1mm Pb 12

  13. Emulsion data taking – automatic scanning system – ECC brick Scan & analysis  JP : EU = 50:50 European Scanning System (ESS) Japanese Scanning System (S-UTS) Scanning speed/system: 20cm2/h *Customized commercial Optics and mechanics *Asynchronous DAQ software Scanning speed/system: 75cm2/h *High speed CCD camera (3 kHz) *Piezo-controlled objective lens *FPGA Hard-coded algorithms 5 systems in Japan 33 systems in Europe 13

  14. Vertex plate Interactions location in ECC brick Follow back in brick tracks found in CS until they disappear: vertex plate TT hit ECC CS Large area ~100 cm2 Point scan ~100x100 mm2 neutrino emulsion emulsion TT hit Lead emulsion Lead emulsion Lead emulsion Lead emulsion Lead emulsion Lead emulsion Lead emulsion 14 14

  15. Track reconstruction in ECC brick Scan about 10 films around vertex plate, and reconstruct tracks over several films. 1 cm n 15

  16. Reject passing-through tracks and tracks connected in few films. 1 cm n 16

  17. Search tracks making vertex by neutrino interaction. 1 cm n 17

  18. ECC feature Particle ID Particle ID is possible in ECC by dE/dx. (hadron or muon or electron) Momentum measurement Measurement of the position or angular displacement caused by the multiple Coulomb scattering Soft muon data sample Muon momenta measured by MCS as a function ofthe momenta obtained from the electronic detectors. The relativedifference between the two measurements with respect to the electronic detector measurement. Compatible ! 18

  19. CNGS beam Summary of the 4 physics runs As of 20 Aug. 2011 pot 2011 Total: 12.65x10 19 pot Goal of the experiment: 22.5x1019 pot 2010 2009 2008 Days 19

  20. Global performance Interactions located in the ECC bricks Decay Search completed 20

  21. 1st  candidate event 21

  22. Event topological features (Side view) ・ 1-prong hadronic mode topology ・ IP = 55 ± 4 [m] (long flight decay) 7 3 5 g2 1  beam g1 kink point primary vertex 2 8 (daughter) 6 4 (candidate) 1 radiation length 0.033 interaction length The viewer of scintillation Target Tracker top view  beam interaction ECC -> pink color side view 22

  23. attachment to the vertices Pointing resolution (1s) for a given gamma: function of scattering and distance g2 kink point primary vertex g1 * probability to find an IP larger than the observed one Invariant mass reconstruction The invariant mass of g1 g2 is consistent with p0. The invariant mass of g1 g2 and p-(daughter) is consistent with r(770).   with a B.R. of 25% ) 23

  24. Kinematical variables g1 and g2 are both assumed as attached to 2ry vertex The uncertainty on PT due to the alternative g2 attachment is < 50 MeV Satisfying all selection criteria for hadronic kink  1st ntcandidate! 24

  25. Finding efficiency of the charged charmed particles - Charged charmed particles have lifetimes similar to that of the  lepton and share analogous decay topologies. - The finding efficiecy of the decay vertices is therefore also similar for both types of particles. - Comparing the observed charm event sample in size, decay topologies and kinematics with expectations from simulations is thus a straightforward way to verify that prompt-decay selection criteria and their corresponding efficiencies and backgrounds are well understood. 25

  26. Charmed particle analysis with the 2008-2009 sample 26

  27. Background sources for  interaction • Interactions of hadrons produced in  interactions • - Decay of charmed particles produced in  interactions 27

  28. Hadron re-interaction background signal Decay  n daughter  CC interaction signal, BG separation 1mm Pb • Kinematical cut • “daughter” momentum (p) > 2 GeV/c • “daughter” transverse momentum • (PT) > 0.6 GeV/c • ( If gamma attached: PT > 0.3 GeV/c ) BG re-interaction n h “daughter”  NC interaction 1mm Pb 28

  29. Pion interaction studies Hadronic tracks in neutrino interactions with Kink topology far from primary vertex Hadronic interactions in test beam brick signal region signal region 14 m, equivalent to 2300 NC events No events found in the signal region. 29

  30. Charmed particles background Charmed particles have similar decay topologies to the  signal BG  CC interaction e CC interaction - e- h-  + e+ h+ ,e  D+ -, e- primary lepton not identified • Charm production in CC events represents a background source to all tau decay channels • This background can be suppressed by identifying the primary lepton 30

  31. Summary of the backgrounds 31

  32. Signal events One candidate event observed in the hadronic decay mode, with a BG of 0.05 +-0.01 events. (0.49 +-0.12 expected signal events) For standard oscillation parameter values this corresponds to 95% probability that the event is not due to a BG fluctuation. Considering all decay modes: expected 1.65 +-0.41 events, BG = 0.16 +-0.03 events. Probability of BG fluctuation: 15% 32

  33. An example of e candidate events • - 14 events in the analyzed sample • - Developing dedicated analysis to increase the detection efficiency • Estimation of BG in progress: prompt e beam component and  conversion contamination • -  -e oscillation analysis in progress 33

  34. Summary • The goal of OPERA: Establish detection of neutrino oscillations in appearance modethrough the  channel, the  signature being the identification of the  lepton produced in its charged current interaction. • In order to detect the appearance of  though the identification of the  lepton produced in their CC interactions, a massive hybrid detector is used where the required m spatial resolution is provided by emulsion films. • - We observed 1st candidate event in last year. • - After the observation of a 1st candidate event, OPERA is progressing with the analysis of new data. • - Our goal is to collect by the end of 2012 a total statistics (2008-2012) as close as possible to the goal of the experiment, namely 22.5x1019 p.o.t. • In the analysed sample, expected signal = 1.65 +-0.41 events, BG = 0.16 +-0.03 events. •  - e oscillation analysis in progress. 34

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