Status of the OPERA experiment

1. Status of the OPERA experiment Yoshiaki Nonoyama(Nagoya univ) On behalf of the OPERA Collaboration

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 in 1.25 kton target for 22.5x1019 pot: ~ 23600  CC + NC　 ~ 10  CC (m2 = 2.5 x 10-3 eV2)

3. -    decay “kink” - , h- , e-  oscillation   plus 3-prong decay modes ~1 mm nt identification Requirements: 1) long baseline, 2) high neutrino energy, 3) high beam intensity, 4) detect short lived ’s • No lepton except tau at 1ry vertex • Detect kink topology 3

4. 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) Changeable Sheet 0.3mm OPERA Film lead 1mm First observation of a tau neutrino in DONuT experiment

5. The OPERA detector SM1 SM1 SM2 SM2 150,000 ECC Target area Muon spectrometer

6. 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 ~9800 events will be collected until end of 2010. pot 2010 2009 2008 Days

7. Typical nmCharge CurrentnmNeutral Current 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 7

8. ECC extraction

9. Changeable Sheets (CS)  Found Track　→　Develop ECC Not found Track　→　Extract another ECC

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

11. Zoom in microscope view tanθ = 0.5 100 micron Read out 1. E 08 tracks / Film 10.0cm 12.5cm

12. CS track selection 10.0cm 12.5cm

13. Scan back location 1 Connect CS to ECC 2 Follow up track in ECC 3 Confirm the stop plate 4 Scan around stop plate ECC CS 5 mm STOP n Found CS tracks 10cm 12.5cm The Plate changer for scan back in Japan

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. Event statistics • 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 • A nt candidate event was found. • 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 17

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

19. Event topological features (Side view) 7 3 5 g2 1  g1 kink point primary vertex 2 8 (daughter) 4 ( cand) 6 1 radiation length 0.033 interaction length The invariant mass of g1 g2 is consistent with p0. The invariant mass of g1 g2 and p-(8) is consistent with r(770).

20. Pt at decay vertex Decay length mm GeV/c 20 Decay Pt Decay length red bands: values for this event with uncertainties Lead 1mm Decay Pt >300MeV/c Kink angle >20mrad Daughter momentum >2GeV/c Decay length Kink angle IP n  Decay point Primary vertex cut

21. 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 21

22. - e- h- charm in e  + e+ h+  ,e  D+ -, e- Miss identification of lepton Back ground • Charmed particle : 0.007+-0.004(syst) • Charmed particle is similar topology of nt decay • Muon ID ~95% in electronic detector. • Hadronic reinteraction : 0.011 • Searched reinteraction in 8 times of tau search length, but there was no signal in tau signal region • BG expectation for our tau candidate • 1-prong hadronic mode • 1.8% (2.36s) • all decay mode(1,3-prong h+1-prong m+1-prong e) • 4.5% (2.01s)

23. Neutrino location Status at 2010/08/30 events Track found on CS Reach ~3000 events up to end of 2010 Located (total 2251) Decay search done date

24. Summary Goal of OPERA experiment is first direct detection of nt from neutrino oscillation of nmnt channel. A t1-prong hadron decay topology has been detected. 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. It is 3 times statistics of this analysis.