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nt channel
CERN　SPS
732km 
Appearance
INFN Gran Sasso
< E > 　 GeV
e /  　 　　　　 %
 /  %
 prompt negligible
エネルギー
Expected neutrino interactions in 1.25 kton target for 22.5x1019 pot:
~  CC + NC　
~ 10  CC (m2 = 2.5 x 10-3 eV2)

3. nt identification -     No lepton except tau at 1ry vertex
decay “kink”   
~1 mm
oscillation
, h-
, e-
plus 3-prong decay modes
Requirements:
1) long baseline, 2) high neutrino energy, 3) high beam intensity, 4) detect short lived ’s
Kink
t-　→　e-
17.8 ％
t- 　→　μ-
17.4 ％
t- 　→　h-
(t- 　→　r-)
49.5 ％
(25 ％)
Trident
t- 　→　h- h- h+
15.2 ％
No lepton except tau at 1ry vertex
Detect kink topology 3 3

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

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

6. 8219 events collected until 30 August 2010
OPERA running (CNGS)
Year
Beam days
Protons on target
Events in the bricks
2008
123
1.78x1019
1698
2009
155
3.52x1019
3693
2010
187
2.67x1019
(30 August)
2828
2010:
3rd physics run since 2008
CNGS program nominal goal:
4.5x1019 pot x 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 Current nmNeutral Current like events
The measured ratio of NC-like/CC-like events after muon ID and event location is ~20%, as expected from simulations
20 m 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. Read out 100 micron tanθ = 0.5 10.0cm 12.5cm 1. E 08 tracks / Film
Zoom in microscope view
10.0cm
12.5cm

12. CS track selection
10.0cm
12.5cm

13. n 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
STOP
5 mm 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 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 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 16

17. A nt candidate event was found.
Event statistics
Total found neutrino vertices:
(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 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
Expected NC/CC=0,31 -> 0,20 due to vertex location and muID bias/ BF x VTXloca=0,6 -> CC=0,64 NC=0,4
BF: NC=0,70 and CC = 0,80/ VTXloca: CC=0,80 NC=0,57
Scaling Proposal we expect 0,83 evts. Now we get 0,53. The discrepancy comes from a lower vtxloca for NC events: 0,64 -> 0,4 17 17

18. nt candidate event , 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
track #
tan x
tan y
p [GeV/c] 1
0.176
0.363 2
-0.650
0.000 3
0.108
0.113
4（parent）
-0.027
0.022 5
0.157
0.267 6
0.334
-0.584
7(from neutral track)
0.438
0.419
8（daughter）
-0.007
-0.014
The invariant mass of g1 g2 is consistent with p0.
The invariant mass of g1 g2 and p-(8) is consistent
with r(770).
12
(8)12
120 ± 20 ± 35 MeV
MeV

20. Decay Pt
Decay length 20
Pt at decay vertex
cut
GeV/c mm
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

21. p- cut f =180o t-decay x t- Azimuthal angle between
Signal :
f =180o
t-decay t- nt p-
X (hadron shower)
ntN t-X nm
kink
nmN nmp-X f x
BG:
small f
Azimuthal angle between
the resulting hadron momentum
direction and the parent track direction 21
Blue: MC - NC
Black: MC - t
rad
cut

22. 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  - e- h-

,e
-, e- + e+ h+ D+
Miss identification of lepton
charm in e
for the 1-prong hadronic channel ±0.004 (syst) background events are expected for the analyzed statistics
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 It is the first nt candidate event in OPERA.
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.