1. Status and results from the OPERA experiment Tsutomu FUKUDA ( Nagoya University ) On behalf of the OPERA Collaboration NNN10, 14 Dec 2010, Toyama International Conference Center in Toyama, JAPAN

2. Oscillation Project with Emulsion-tRacking Apparatus First direct detection of neutrino oscillations in appearance mode through the    channel.   oscillation  -- decay “kink”  ~1 mm --,h -,e -  Requirements : high neutrino energy & intensity & long base line & large target mass & detect short lived  ’s

3. 2 important experimental results for OPERA design Neutrino oscillation (disappearance) Result from SK in 1998 Direct observation of  events Result of DONuT in 2001 OPERA start !!  Flight Length ： 280um  DONuT  event 1mm Iron

4. Belgium IIHE-ULB Brussels Croatia IRB Zagreb France LAPP Annecy IPNL Lyon IPHC Strasbourg Germany Hamburg Münster Rostock Italy Bari Bologna LNF Frascati L’Aquila LNGS Naples Padova Rome Salerno Japan Aichi Toho Kobe Nagoya Utsunomiya Israel Technion Haifa Korea Jinju Russia INR RAS Moscow NPI RAS Moscow ITEP Moscow SINP MSU Moscow JINR Dubna Switzerland Bern ETH Zurich Turkey METU Ankara 180 physicists, 33 institutions in 12 countries Tunisia CNSTN Tunis The OPERA Collaboration

5. Our philosophy following the Super- Kamiokande discovery of oscillations with atmospheric neutrinos and the confirmation obtained with solar neutrinos and accelerator beams. Important, missing tile in the oscillation picture. Full mixing and ∆m 2 23 ~ 2.4 x 10 -3 eV 2 The light blue band indicates the OPERA allowed region (90% CL) for the above parameter values for 22.5 x 10 19 pot OPERA give a clear and strong evidence for the existence of neutrino oscillation. OPERA is also searching for first direct observation of Lepton Flavor Violation.

6. CNGS beam line CERN LNGS 732km conventional beam ( GeV ) 17 ( e + e ) /  0.87 %*  /  2.1 %*  prompt Negligible* Expected interactions for 22.5x10 19 pot (nominal pot in 5 years for 1.25kton target): ~23600  CC + NC ~160 e + e CC ~115  CC (  m 2 = 2.5 x 10 -3 eV 2 ) ~10  CC identified (BG<1) * Interaction rate at LNGS

7. The OPERA target – ECC brick – 50 micron Microscopic Image Recorded as silver grains along the line where a charged particle passed through Resolution of 0.3 micron OPERA emulsion film Lead plate : 1mm 57 OPERA films and 56 lead plates piled up. 125mm 100mm 75.4mm 8.3kg 10X 0 Neutrino Beam Emulsion Cloud Chamber (ECC)

8. The OPERA detector OPERA emulsion film Emulsion + Target Tracker Muon spectrometer Emulsion + Target Tracker Muon spectrometer

9. Typical  CC-like and NC-like events 20 m  CC-like event  NC-like event

10. Emulsion Scanning for CS CS Scan & analysis  NAGOYA : LNGS = 50:50 ECC brick CS Changeable Sheets (CS), two OPERA films fixed downstream of the ECC bricks, are used as interfaces between the electronic trackers and the ECC bricks. When a neutrino interaction is detected by the electronic detectors, the most probable brick is extracted and the CS are developed and analyzed. If one or more predicted tracks are found, the brick films are developed. If not, the brick is returned back to the detector with new CS and the next brick is extracted. By using CS, emulsion analysis speed become about 10 times faster.

11. Emulsion Scanning for ECC brick ECC brick Scan & analysis  JP : EU = 50:50 To Japan Padova Bern Bologna Roma LNF Napoli Salerno Bari LNGS After tracks are found on CS, ECC brick films are developed and sent to scanning labs along with the CS information.

12. Neutrino event location 5 mm CS ECC brick CS  ~100cm 2 large area scan ECC  ~100  100  m 2 point scan How to locate 1. Connect track CS to ECC brick. 2. Follow up track in ECC brick. (Scan Back method) 3. Confirm the stop plate. 4. Scan around stop plate. The Plate changer system for Scan Back in Japan. Films of ECC brick are glued on a sheet for changing plates easily. STOP

13. 1 cm Scan about 10 plates around stop plate by follow up from down stream. Located neutrino interaction in ECC brick

14. 1 cm Reject passing trough track and only few plates connect track. Located neutrino interaction in ECC brick

15. 1 cm Search tracks making vertex by neutrino interaction. Located neutrino interaction in ECC brick

16. 2010 2009 2008 Days POT YearDays beam POTEventsRun 20060.076×10 19 no bricksCommissioning 20070.082×10 19 38Commissioning 20081231.78×10 19 1698First physics run 20091553.52×10 19 3693Physics run 20101874.04×10 19 4248Physics run 9639 events collected (within 1  in agreement with expectations from pot) → 2.1 nominal years in 3 years. POT of 2010: 90% of nominal year Progress of CNGS runs

17. Location Status Event location is going well. 2779 events are already located. Based on the 2008 run efficiencies, about 5650 events to be located in ( 2008 + 2009 + 2010 run ). Interaction in the target Events with at least 1 brick extracted Events with a positive CS result Interactions located in the bricks Decay Search completed

18. Decay topology search IP distribution for   events (MC) IP distribution for:   events (MC) NC+CC  events (MC), NC+CC  events (Data) A Charm event (dimuon event) Kink angle = 209mrad Flight Length = 1330micron Decay P t ~ 460MeV/c 1ry  Charm ++ In 901 sub-sample events, 20 charm events were found. (expected : 16.0±2.9)

19. The analysis of a sub-sample of the data taken in the 2008-2009 runs was completed. Number of events completed: 1088 (187 NC) This is ~20% of the total 2008-2010 run statistics, corresponding to 1.85 x 10 19 pot With the above statistics, and for  m 2 23 = 2.5 x10 -3 eV 2 and full mixing, OPERA expects: ~ 0.5  events Event statistics for Decay search

20. The first  candidate event was found This result is opened at June/2010. Event number 9234119599, taken on 22 August 2009, 19:27 (UTC)

21. 2 11 3 22 7 5 1 6 8 (daughter) 4 (  cand) track # tan  x tan  y p  [GeV/c] 1 0.176 0.3630.78 +0.13 -0.10 2-0.650 0.0000.32 +0.31 -0.11 3 0.108 0.1131.97 +0.33 -0.25 4 （ parent ） -0.027 0.022 5 0.157 0.2671.30 +0.22 -0.16 6 0.334-0.5840.36 +0.18 -0.09 7(from neutral track) 0.438 0.4190.49 +0.29 --0.13 8 （ daughter ） -0.007-0.01412 +6 -3 1 radiation length 0.033 interaction length primary vertex kink point Event topological features (Side view) beam top view side view Event ECC  pink color The viewer of scintillation Target Tracker

22. primary vertex kink point   Pointing resolution (1  ) for a given gamma: function of scattering and distance γattachment to the vertices Distance from 2ry vertex (mm) IP to 1ry vertex (  m) IP to 2ry vertex (  m) Prob. of attach. to 1ry vtx* Prob. of attach. to 2ry vtx* Attachment hypothesis 1 st  2.245.0 7.5 <10 -3 0.322ry vertex 2 nd  12.685.6 22 0.100.822ry vertex (favored) * probability to find an IP larger than the observed one The invariant mass of  1  2 is consistent with  0. The invariant mass of  1  2 and   (8) is consistent with     120 ± 20 ± 35 MeV640 +125 -80 +100 -90 MeV

23. Kinematical variables The event passes all the kinematical cuts required. The uncertainty on Pt due to the alternative  attachment is < 50 MeV. VARIABLEMeasured Selection criteria Kink (mrad) 41 ± 2>20 Decay length (  m) 1335 ± 35 Within 2 plates P daughter (GeV/c) 12 +6 -3 >2 Pt daughter (MeV/c) 470 +230 -120 >300 (  attached) Missing Pt (MeV/c) 570 +320 -170 <1000 ϕ (deg) 173 ± 2>90 (Animation)

24. Missing Pt at primary vertex cut Pt at decay vertex cut GeV/c Blue: MC NC Black: MC -  GeV/c Missing Pt at primary vertex cut Features of the decay topology… red bands: values for the “interesting” event with uncertainties mm Decay length GeV/c cut Daughter momentum 1335 ± 35  m 12 +6 -3 GeV rad Accepted kinks > 20 mrad Kink angle 41 ± 2 mrad..and kinematical cuts to be passed Reject NC events with larger missing Pt (neutrino) Reject hadron interactions 470 +230 -120 MeV 570 +320 -170 MeV

25. Background sources Prompt  ~ 10 -7 /CC Decay of charmed particles produced in e interactions ~ 10 -6 /CC Double charm production ~ 10 -6 /CC Decay of charmed particles produced in  interactions ~ 10 -5 /CC Hadronic reinteractions  ~ 10 -5 /CC Main Background

26. Hadronic reinteraction background cross check ① (4GeV  test-beam data) multi- prong 1-prong 18 times track length of tau search The number of estimated hadronic reinteraction BG is 0.011±0.006 by using FLUKA simulation code. cross check ② (scan-forth data) signal region no event in the signal region 90% CL upper limit of 1.54 x 10 -3 kinks/NC event The number of events outside the signal region is confirmed by MC (within the ~30% statistical accuracy of the measurement) 8 times track length of tau search

27. Charmed particles have similar decay topologies to the  charm production in CC events represents a background source to all tau decay channels this background can be suppressed by identifying the primary lepton  ~ 95% muon ID for the 1-prong hadronic channel 0.007±0.004 (syst) background events are expected for the analyzed statistics ,e ,e - +e+h++e+h+ D+D+ primary lepton not identified Charm background

28. We observe 1 event in the 1-prong hadron  decay channel, with a background expectation (estimating a ~ 50% error for each component) of: 0.011 events (reinteraction) 0.007 events (charm) 0.018 ± 0.007 (syst) events 1-prong hadron all decay modes: 1-prong hadron, 3-prongs + 1-prong μ + 1-prong e : 0.045 ± 0.020 (syst) events total BG By considering the 1-prong hadron channel only, the probability to observe 1 event due to a background fluctuation is 1.8%, for a statistical significance of 2.36  on the measurement of a first   candidate event in OPERA. If one considers all  decay modes which were included in the search, the probability to observe 1 event for a background fluctuation is 4.5%. This corresponds to a significance of 2.01 . Statistical significance

29. The OPERA experiment is aimed at the first direct detection of neutrino oscillations in appearance mode through the study of the     channel. In 2008 – 2010, data has been taken corresponding to 2.1 nominal years. In 2010, beam intensity has reached 90% nominal. One muon-less event showing a   1-prong hadron decay topology has been detected and studied in a subsample of 20% of the accumulated data. It passes all kinematical cuts required to reduce the physics background. It is the first  candidate event in OPERA. The expected number of events in the analysed subsample is 0.54 ± 0.13 (syst.) The statistical significance of 2.01  on the measurement of a first  candidate event in OPERA when considering all tau decays is relevant. Conclusions

30. In 2011, 6 extra weeks of beam in dedicated mode have been attributed corresponding to 1.2 nominal years. If 2012 (or 2013) is like 2011: Data on ~ 19.7×10 19 POT or ~ 87% of Proposal beam intensity collected Analysis of 2008/2009 events will be closed in Feb/2011 and new results on oscillations will be released in spring 2011. Outlook

31. Thank you for your attention ! Tsutomu FUKUDA ( Nagoya University ) NNN10, 14 Dec 2010, Toyama International Conference Center in Toyama, JAPAN