Status of the OPERA experiment Yoshiaki Nonoyama Nagoya Univ

732km OPERA: first direct detection of neutrino oscillations in appearance mode through the     channel  Appearance 17 GeV e /  0.87 %  /  2.2 %  prompt negligible  CERN SPS INFN Gran Sasso Expected neutrino interactions for 22.5x10 19 pot: ~  CC + NC ~ 160 e + e CC ~ 115  CC (  m 2 = 2.5 x eV 2 )

The OPERA ECC （ Emulsion Cloud Chamber ） 125mm 100mm 75.4mm 8.3kg 10X 0 Neutrino Beam OPERA Film (before development) 1mm lead 0.3mm OPERA Film Lead plate : 1mm Sandwich structure OPERA film : 57plates 1mm thick lead : 56plates First observation of a tau neutrino in DONuT experiment

Target area Muon spectrometer SM1SM2SM1SM2 The OPERA detector

OPERA running (CNGS) YearBeam days Protons on target SPS Eff. Events in the bricks x % x % x10 19 (30 August) 80%2828 (30 August) 8219 events collected until 30 August 2010 High specific CNGS efficiency ~ 97% 2010: hoping to get as close as possible to nominal year (4.5x10 19 pot) 68.5 days remaining  get around 4.2 E 19 Foreseen (2009 letter to SPSC) two additional high-intensity runs in 2011 and Machines Stop: (would imply stopping at ~65% of the nominal goal) Days 2010: 3 rd physics run since 2008 CNGS program nominal goal: 4.5x10 19 pot x 5 years pot

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

Brick extraction

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

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

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

10.0cm 12.5cm CS track selection

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

1 cm 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. Located neutrino interaction 13

1 cm 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. Located neutrino interaction 14

1 cm 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. Located neutrino interaction 15

1 cm 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. Located neutrino interaction 16

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

Impact parameter IP distribution for   events (MC) IP distribution for:   events (MC) NC+CC  events (MC), NC+CC  events (Data) expanded scale mm 10  m < IP < 500  m

19 Event statistics Events collected by run 5391 Brick tagging efficiency times vertex location efficiency:~ 60% Total found neutrino vertices: 1921 This is ~60% of the total run statistics. Events for which “decay search” was completed: 1088 (187 NC) This is ~35% of the total run statistics, corresponding to 1.85 x pot With the above statistics, and for  m 2 23 = 2.5 x10 -3 eV 2 and full mixing, OPERA expects: ~ 0.5  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

Charm candidate event (dimuon) 4 mm 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 kink x-view 1ry vertex 1.3 mm 1ry muon daughter muon

D 0 hypothesis: F.L.: mm,  : , invariant mass: 1.7 GeV Charm candidate event (4-prong)

e candidate event From a subsample of ~ 800 located events we detected  e candidates Additional physics subject: study  - e oscillations

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

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

Event reconstruction (I)

Zoom Event reconstruction (II)

27 Kinematical variables VARIABLEAVERAGESelection criteria kink (mrad)41 ± 2>20 decay length (  m) 1335 ± 35within 2 lead plates P daughter (GeV/c) >2 Pt (MeV/c) >300 (  attached) missing Pt (MeV/c) <1000  (deg) 173 ± 2>90 Satisfying all selection criteria for hadronic kink  first  candidate !  1 and  2 are both assumed as attached to 2 ry vertex The uncertainty on Pt due to the alternative  attachment is < 50 MeV

Azimuthal angle between the resulting hadron momentum direction and the parent track direction Signal :  =180 o  -decay --    - X (hadron shower)  N  - X --   kink  N   - X --  x BG: small   28 Blue: MC - NC Black: MC -  rad cut

29 Event topological features (Beam view)   8 daughter Beam view

Event location summary for 2008 run (2010/08/30) 0mu1muAll Events predicted by the electronic detector Found in CS Located in ECC Located in dead material Decay search performed mu1muAll Events predicted by the electronic detector Found in CS Located in ECC Located in dead material Decay search performed Event location summary for 2009 run (2010/08/30)

Summary One muonless event showing a   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  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.