1. The OPERA long baseline neutrino experiment : status and first results.
Magali Besnier
Laboratoire d’Annecy-le-Vieux de Physique des Particules
On behalf of the OPERA collaboration
LLWI february 21st 2008

2. OPERA Oscillation Project with Emulsion tRacking Apparatus
Search for tau neutrino appearance at Gran Sasso laboratory
in a pure muon neutrino beam produced at CERN (732 km)
First direct observation of nm nt oscillation
Possibility of nm ne oscillation search for q13 measurement
International Collaboration (Europe + Asia)
IIHE (ULB-VUB), Brussels
Sofia
IHEP Beijing, Shandong
IRB Zagreb
LAPP Annecy, IPNL Lyon,
IRES Strasbourg
Berlin Humboldt, Hagen, Hamburg, Münster, Rostock
Technion Haifa
Bari, Bologna, LNF Frascati, L’Aquila, LNGS, Napoli,
Padova, Roma La Sapienza, Salerno
Aichi, Kobe, Nagoya, Toho, Utsunomiya
INR Moscow, ITEP Moscow, JINR Dubna, Obninsk
Bern, Neuchâtel, Zurich
METU Ankara
37 INSTITUTS, ~160 PHYSICISTS

3. vacuum tests successful
CNGS beam (CERN Neutrino to Gran Sasso)
vacuum
p.o.t. /year
700 m m m m
To Gran Sasso
400GeV
Ø at GS=2km 3.2° angle
Decay tube
vacuum tests successful
target
Muon chambers
Horn
Hadron stop
Civil engineering completed (June ’03)
Hadron stopper and decay tube installed (June ’04)
Target section completed in 2006 (first CNGS beam in August 2006)

4. t nt CNGS beam (CERN Neutrino to Gran Sasso)
P(nm->nt)*s(nt CC) Dm223 = eV²
nm Flux at Gran Sasso (given by Fluka)
nm flux
CNGS beam (CERN Neutrino to Gran Sasso)
p.o.t. /year
Number of expected events at Gran Sasso (0-100 GeV):
(before reconstruction and detection efficiencies)
N nm CC= 3000/yr/kton
N ne CC= 20 /yr/kton
N nt CC= 14 /yr/kton
.Detection of  CC interaction and direct observation of decay topology
.High background rejection
t-  m- nt nm (17.4%)
t-  e- nt ne (17.8%)
t-  h- nt n(po) (49.5%)
t-  p+ p- p- nt n(po) (14.5%) nt t
t decay kink
~ 0.6 mm
 appearance signature

5. OPERA Performances for nm  nt oscillation
full mixing, 5 years 4.5x1019 pot / year
channel
Reconstruction efficiency %
Back-ground
11.06
10.4
14.9
0.75
Total
Number of expected signal and background events
4-s evidence
3-s evidence
OPERA Discovery probability vs. Dm2
Most important background : charm particle production
Discovery probability (%)
Best value of Dm223 = eV²
3s range : eV²
T.Schwetz, hep-ph/
4s Discovery probablility > 90% for Dm223> eV²
3s range

6. 1.35 kton lead target ~4000 nmCC/yr
OPERA detector at LNGS (Notional Laboratory of Gran Sasso, Italy, 120 kms from Rome)
rock thickness 1400m (3800 m.w.e.)
cosmic muon flux: 1/m2/h
m spectrometer: Dipolar magnet + RPC chambers
Target Trackers
Pb/Em. target
Precision tracker: Drift tubes n
B=1.6 T
2 super modules
1 super module = 29 walls Target Tracker muon spectrometer (22 RPC planes + 6 drift tube planes)
bricks
1.35 kton lead target ~4000 nmCC/yr
52*51 bricks/wall
p/p < 20% for E<50GeV
OPERA (CNGS1)
ICARUS (CNGS2)
Hall C
Hall B
BOREXINO
brick
(56 Pb/Em. “cells”)
8 cm (10X0)
scintillator strips
brick wall
module
LNGS-INFN

7. OPERA bricks : main target detector component
Emulsion Cloud Chamber (ECC) : 1 ECC brick = 56 sheets Pb + 57 photographic emulsions Pb
Emulsion layers n t
1 mm
300µm emulsion films and
1mm thin lead foils by
Fuji Film (Japan)
JLGoslar (Germany)
This technology allows a few micron spatial resolution, and a 3D reconstruction of particle tracks, necessary for t detection
12.5 cm
8 cm
8.6 kg
10 cm
12.5cm
10.2cm
2 emulsion layers (45 m thick) poured on a 210 m plastic base
The most precise tracker
Résolution (microtracks) spatial : 0.06 µm Angular : ~ 2 mrad
Vertex position resolution : ~1µm in transverse plane
2mm
6mm
MC ntt3h
- Measurement of hadrons momenta by MCS
- dE/dx pion/muon separation at low energy
- Electron identification and energy measurements for electrons and photons
Reconstructed electronic shower
14 mm

8. BAM (Brick Assembling Machine)
Target preparation
BAM (Brick Assembling Machine)
Automatic lead/emulsion piling in a dark room (~700 bricks/day)
5 articulated robots
2003 : start building detector
June 2008 : end of filling target
Begining 2007
now
Insertion and extraction of bricks following intelligent procedures.
The BMS(Brick Manipulator System)
one robot on each side of the detector
now

9. LNGS Hall C Detector today : electronics fully instrumented and tested
Brick filling on the way : Bricks already inserted
LNGS Hall C

10. OPERA event analysis procedure
max
p.h. 
Brick finding :
31 tracking scintillator planes (TT)/super modules
Trigger(>99%) Brick finding (7090%)
selection of the interaction brick provided by time correlation of electronic detectors
Emulsion Development of candidate bricks at Gran Sasso (surface facilities)
20-30 bricks extracted / day
Emulsion shipment
Example of a vertex in emulsion
Emulsion Scanning with automated microscopes :
10 laboratories in Europe and Japan

11. emulsion digitisation
Scanning :
emulsion digitisation
Reconstruction of micro-tracks (45µm)
10 scanning laboratories in Europe and Japan
16 tomographic images = 45µm
300µm
Field of vue
2D images processing
3D reconstruction of particle tracks
2 emulsion sides (45 mm)
1 plastic base (200 mm)
speed : 20cm²/hour/emulsion side
Résolution (grains) spatial : 0.06 µm Angular : ~ 2 mrad
1 emulsion sheet (2 sides) : h scanning - ~5GB

12. n interaction in magnet (Fe)
First OPERA results with CERN neutrino beam
Positive electronic tests during first beam run (August 06 : integrated pot)
n interaction in magnet (Fe)
cosmics
Beam events
More than 300 registred events correlated in time with beam : interactions inside the rock and inside the detector (TT and spectrometers)
First events from the CNGS neutrino beam detected in the OPERA experiment R. Acquafredda et al 2006 New J. Phys

13. Muon track inside emulsions
First OPERA results with target bricks from cosmic run
< 1 event per day inside the acceptance ! ~20 ‘good’ muons per month
Muon track inside emulsions
April 17th- May 15th 2007 :
30 bricks extracted
28 muons found in emulsions
45 µm
Cosmic muons in OPERA detector (ray bandle)
210 µm
Mean prediction accuracy (ED-brick):
Δx = 11 mm (along the tray)
Δy = 14 mm (vertical direction)
Δθx = 6.0 mrad
Δθy = 3.3 mrad
These first data have confirmed the good accuracy of the ED predictions and validated the analysis chain

14. Problems in ventilation control units of the proton target
First OPERA results with target bricks from CNGS run (SM1 filled at 80%)
Nominal intensity : pot /yr (1yr=200 days)
CNGS integrated intensity from September 24th to October 20th :
pot
20/10/07
12/10/07
Comissioning
Physics
Problems in ventilation control units of the proton target
9/10/07
pot
59 : CNGS very stable at pot/day
326 expected events in bricks
38 events registered during the 2007 CNGS run :
29 CC
9 NC
Expected 75% CC and 25%NC proportions
5/10/07
pot

15. nµCC 18 m m- nµ Em=7.8 GeV n 12/29 located in bricks so far 1 cm
First OPERA neutrino event located in brick (October 2nd 2007)
nµCC
Hadronic shower
muon nµ m-
Hadronic shower
Em=7.8 GeV n
12/29 located in bricks so far
18 m
Bologna scanning laboratory
1 cm

16. 3/9 located in bricks so far
nµ NC
Hadronic shower nµ n
Hadronic shower
3/9 located in bricks so far
18 m
Nagoya scanning laboratory
2 cm

17. Conclusion
OPERA is the first experiment for nt appearance in a nm beam
Hybrid detector with passive lead target and active electronic detectors
Electronic parts fully commissioned
0.9 kton (99000 Bricks) already inserted in the detector
First results
CNGS beam run in August 2006 : electronic detectors gave good results
Cosmic run : brick candidate extraction ; scanning and analysis have validated the full analysis chain
Neutrino events have been observed in OPERA bricks during the CNGS beam run of Location and reconstruction of neutrino vertex in emulsions was an important learning phase. Analysis is on the way.
Future
Next CNGS beam run with full target completed expected by june ~20 neutrino interactions / day  1st t event expected

19. CNGS CERN:
Proton extractions from SPS with 3 cycles of 6s each : 2 extractions of 10.5 ms, separated by 50 ms.
time
~1extraction
Beam event selection : TOPERA – (TSPS + TOF) < Tgate
~2.4ms
Nominal intensity : pot /yr, with pot/extraction (FE)

20. Control of the neutrino beam direction:
With the horizontal profile of the CNGS muons in the 2 muon detectors
1st muon chamber
2nd muon chamber p
m, nm
>1km
67m
- First muon detector : ≤ 2.5 x 107 muons / cm2 / 1013 pot
- Second muon detector :  ≤ 4 x 105 muons / cm2 / 1013 pot

21. CERN-LNGS time correlation
All events within a window of ms since the beginning of the extraction
Extraction 1
Should start at 0 and last up to µs.
 New calibrations will be done with a new GPS system receiver and a Cs clock of 1ns accuracy. ns
Extraction 2 ns

22. Target chamber Solution :
Replace damaged electronics
Find another place for ventilation control units
These doses were computed by the Fluka group and known since many years !!
They were not just taken into account when the ventilation was installed
Radiation protection measurements confirm the calculations

23. 1.7 m 6.9m Target Tracker Reconstructed cosmic track LNGS
64 strips/module
●Trigger:  > 99%
● Brick finding :   7080%
● Initiate muon tagging
Plastic scintillator strips
(AMCRYS-H, 6.7m x 2.6cm x 1cm)
readout by Kuraray WLS fibres +
Hamamatsu PMT’s (64 channels)
Tracker wall
2 x 256 strips
Reconstructed cosmic track
LNGS

24. Muon spectrometer Inner Tracker: 11 planes of RPC’s B= 1.55 T
base
slabs
coil
8.2 m
M ~ 950t
Drift tubes
12 Fe slabs
(5cm thick)
RPC’s
2 cm gaps
Inner Tracker: 11 planes of RPC’s
21 bakelite RPC’s (2.9x1.1m2) / plane
Precision tracker: 6 planes of drift tubes
diameter 38mm, length 8m
4 staggered layers / plane,
each layer consisting of 168 tubes
efficiency: 99%
space resolution: 300µm
 identification:  > 95% (TT)
p/p < 20% , p < 50 GeV/c
misidentified  charge prob.  0.1  0.3%

25. PEANUT : OPERA test-beam at FERMILAB
goal : to observe neutrino interactions in OPERA bricks
Detector placed in the front of the MINOS near detector:
-4 walls of 3*4 OPERA bricks exposed to NUMI beam (nm ) in « low energy » configuration (<E>=10GeV, Epeak=3GeV )
-DONUT SFT (scintillators) between each wall
Brick piling in dark room
5 nm events/brick /day expected bricks exposed ~20days
Exposure time: October 18th > Mars 1st 2006 total 160 Bricks made, exposed and developped
developper
SFT-emulsions alignment
Neutrino reconstruction in emulsions
~500µm spatial resolution
~5mrad angular resolution
Salerno scanning lab analysis

26.   e oscillation search
2.5x10-3 eV2
m232 = 2.5 x 10-3 eV2
23 = 45°
nominal CNGS beam
5 years
Combined fit of Ee, Evis, (pt)miss
sin2(213)< 13 < 7.1º
90% C.L. limits on sin2(213) and 13 :