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Status of the OPERA experiment

Status of the OPERA experiment. Yoshiaki Nonoyama(Nagoya univ) On behalf of the OPERA Collaboration. OPERA : first direct detection of neutrino oscillations in appearance mode through the n m  n t channel. Appearance.  .   CERN SPS. 73 2 km. INFN Gran Sasso. < E  > 17 GeV

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Status of the OPERA experiment

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  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 identified (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 Branching of t • nt makes tau particle and tau decays • with kink topology. • nt identification is detected kink and • no lepton except tau at 1ry vertex. 3

  4. The OPERA ECC （Emulsion Cloud Chamber ） 75.4mm 125mm 8.3kg 10X0 Sandwich structure OPERA emulsion film : 57plates 1mm thick lead : 56plates Neutrino Beam 100mm Lead plate : 1mm t nt 1 mm Pb Emulsion layers OPERA Film (before development) Changeable Sheet Life time(ct) of t is ~87mm

  5. The OPERA detector SM1 SM1 SM2 SM2 Total ECC 150,000 Total mass 1.25 kton Target area Muon spectrometer

  6. Beam performance 2010: 3rd physics run since 2008 CNGS program nominal goal: 4.5x1019 potx 5 years pot 8219 events collected in target until 30 August 2010 ~9800 events will be collected until end of 2010. 2010 2009 2008 Days

  7. nmCharge Current target Muon spectrometer 20 m Neutral Current 7

  8. ECC extraction Zoom in electronic detectors view

  9. Judgment of n interaction by CS (Changeable Sheets) • Judgment of n interacted in ECC by found track from n interaction. • Doublet of low BG emulsion films. • Attached downstream of ECC.  ECC Developed CS CS Found track → Develop ECC Not found track → Extract another ECC

  10. High speed read out microscope 4 hour to scan full area Of one film 10cmx10cm SutsでCSすきゃん CS scanning

  11. Location of neutrino interaction in ECC ECC CS 5 mm STOP How to locate ?? 1. Connect track CS to ECC. 2. Follow up track in ECC. 3. Confirm the stop plate. 4. Scan around stop plate. n The Plate changer in Japan Put emulsion like the seat. for changing plates easily.

  12. Located neutrino interaction in ECC Scan about 10 plates around stop plate by follow up from down stream. 1 cm n 12

  13. Located neutrino interaction in ECC Reject passing trough track and few plates connect track. 1 cm n 13

  14. Located neutrino interaction in ECC Search tracks making vertex by neutrino interaction . 1 cm n 14

  15. nt search result at June • Total found neutrino vertices: 1921 • (This is ~60% of the total 2008-2009 run statistics.) • Events for which “nt 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. 15

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

  17. 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).

  18. Pt at decay vertex Lead 1mm Decay length Decay length Kink angle IP n  Decay point Primary vertex mm GeV/c 18 Decay Pt Decay length red bands: values for this event with uncertainties Decay Pt >300MeV/c Kink angle >20mrad Daughter momentum >2GeV/c cut

  19. Azimuthal angle between the resulting hadron momentum direction and the parent(t) track direction NC  ntN → t-X nmN → nmp-X X(hadron shower) x f Signal : f° BG : small f f t- p- p- p- nt nm Data Blue: MC – NC Black: MC - t cut rad 19

  20. - e- h- charm in e  + e+ h+  ,e  D+ -, e- Miss identification of lepton Back ground (in analyzed statistics) • 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)

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

  22. 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.

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