Status of the OPERA experiment

1. Status of the OPERA experiment Yoshiaki Nonoyama Nagoya Univ

2. OPERA: first direct detection of neutrino oscillations in appearance mode through the nmntchannel Appearance   CERNSPS 732km INFN Gran Sasso < E >17 GeV e / 0.87 % /  2.2 % prompt negligible Expected neutrino interactions for 22.5x1019 pot: ~ 23600  CC + NC　 ~ 160 e +e CC　 ~ 115  CC (m2 = 2.5 x 10-3 eV2)

3. The OPERA ECC （Emulsion Cloud Chamber ） 75.4mm 125mm 8.3kg 10X0 Sandwich structure OPERA film : 57plates 1mm thick lead : 56plates Neutrino Beam 100mm Lead plate : 1mm OPERA Film (before development) 0.3mm OPERA Film lead 1mm First observation of a tau neutrino in DONuT experiment

4. The OPERA detector SM1 SM1 SM2 SM2 Target area Muon spectrometer

5. OPERA running (CNGS) 2010: 3rd physics run since 2008 CNGS program nominal goal: 4.5x1019 potx 5 years 8219 events collected until 30 August 2010 High specific CNGS efficiency ~ 97% 2010: hoping to get as close as possible to nominal year (4.5x1019pot) 68.5 days remaining  get around 4.2E19 Foreseen (2009 letter to SPSC) two additional high-intensity runs in 2011 and 2012. 2012 Machines Stop: (would imply stopping at ~65% of the nominal goal) pot 2010 2009 2008 Days

6. Typical nmCC- and NC-like events 20 m The measured ratio of NC-like/CC-like events after muon ID and event location is ~20%, as expected from simulations 6

7. Brick extraction

8. Changeable Sheets (CS)  Found Track　→　Develop brick Not found Track　→　Extract another brick

9. 4 hour to scan full area Of one film 10cmx10cm SutsでCSすきゃん CS scanning

10. Zoom in microscope view tanθ = 0.5 100 micron Scanned information 1. E 08 tracks / Film 10.0cm 12.5cm

11. CS track selection 10.0cm 12.5cm

12. Scan back location ECC CS 5 mm STOP 1 Connect CS to brick 2 Follow up in the brick 3 Confirm the stop plate 4 Scan around stop plate n The Plate changer for scan back in Japan

13. Located neutrino interaction Emulsions give 3D vector data, with micrometric precision of the vertexing accuracy. The frames correspond to the scanning area. Yellow short lines  measured tracks. Other colored lines  interpolation or extrapolation. 1 cm 13

14. Located neutrino interaction Emulsions give 3D vector data, with micrometric precision of the vertexing accuracy. The frames correspond to the scanning area. Yellow short lines  measured tracks. Other colored lines  interpolation or extrapolation. 1 cm 14

15. Located neutrino interaction Emulsions give 3D vector data, with micrometric precision of the vertexing accuracy. The frames correspond to the scanning area. Yellow short lines  measured tracks. Other colored lines  interpolation or extrapolation. 1 cm 15

16. Located neutrino interaction Emulsions give 3D vector data, with micrometric precision of the vertexing accuracy. The frames correspond to the scanning area. Yellow short lines  measured tracks. Other colored lines  interpolation or extrapolation. 1 cm 16

17. SHORT flight decay Lead 1mm Decay point IP n  Primary vertex LONG flight decay Lead 1mm Decay point IP n  Primary vertex Tau detection in ECC SHORT flight decay : Detect large Impact parameter LONG flight decay : Detect large Impact parameter Detect tau track

18. Impact parameter mm IP distribution for: ntevents (MC) NC+CC nm events (MC), NC+CC nm events (Data) IP distribution for ntevents (MC) expanded scale 10mm < IP < 500mm

19. Event statistics Events collected by 2008-2009 run5391 Brick tagging efficiency times vertex location efficiency: ~ 60% Total found neutrino vertices: 1921 This is ~60% of the total 2008-2009 run statistics . Events for which “decay search” was completed: 1088 (187 NC) This is ~35% of the total 2008-2009 run statistics, corresponding to 1.85 x 1019 pot With the above statistics, and for Dm223 = 2.5 x10-3 eV2 and full mixing, OPERA expects: ~ 0.5 nt events 20 charm candidate events selected by the kinematical cuts, 3 of them with 1-prong kink topology. Expected: 16.0 ± 2.9 out of which 0.80 ± 0.22 with kink topology Expected BG: ~2 events 19

20. Charm candidate event (dimuon) x-view flight length: 1330 microns kink angle: 209 mrad IP of daughter: 262 microns daughter muon: 2.2 GeV/c decay Pt: 0.46 GeV/c 1ry muon 1ry vertex kink 4 mm daughter muon 1.3 mm

21. Charm candidate event (4-prong) D0 hypothesis: F.L.: 313.1 mm, f : 173.20, invariant mass: 1.7 GeV

22. ne candidate event From a subsample of ~ 800 located events we detected 6 ne candidates Additional physics subject: study nm-ne oscillations

23. Muonless event 9234119599, taken on 22 August 2009, 19:27 (UTC)(as seen by the electronic detectors)

24. From CS to vertex location a kink is detected Large area scanning Full reconstruction of vertices and gammas Scan-back in ECC CS predictions CS predictions careful visual inspection of the films behind/in front the secondary vertex: no “black” or “evaporation” tracks. Support topological hypothesis of a particle decay

25. Event reconstruction (I)

26. Event reconstruction (II) Zoom

27. Kinematical variables Satisfying all selection criteria for hadronic kink  first ntcandidate! • g1 and g2 are both assumed as attached to 2ry vertex • The uncertainty on Pt due to the alternative g2 attachment is < 50 MeV 27

28. f X(hadron shower) Signal : f =180o Azimuthal angle between the resulting hadron momentum direction and the parent track direction t-decay t- p- nt ntN t-X BG: small f Blue: MC - NC Black: MC - t kink x f p- p- cut nm nmN nmp-X rad 28

29. Event topological features (Beam view) Beam view 7 1 5 3 2 g2 g1 6 8 daughter 29

30. Event location summary for 2008 run (2010/08/30) Event location summary for 2009 run (2010/08/30)

31. Summary One muonless event showing a t1-prong hadron decay topology has been detected and studied in detail. It passes all kinematical cuts required to reduce the physics background. It is the first nt candidate event in OPERA. Up to now, we located neutrino interaction in ECC is 2251 events. Until end of 2010, We will locate 3000 event and expected tau neutrino interaction is 1.5.