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The OPERA long The OPERA long baseline neutrino baseline neutrino

experiment : status and experiment : status and first results.first results.Magali Besnier

LLWI 08 - february 21st 2008

Laboratoire d’Annecy-le-Vieux de Physique des Particules

On behalf of the OPERA collaboration

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Search for tauneutrino appearance at Gran Sasso laboratory

in a pure muon neutrino beam produced at CERN (732 km)

First direct observation of First direct observation of oscillationoscillation

37 INSTITUTS, ~160 PHYSICISTS

OPERAOscillation Project with Emulsion tRacking Apparatus

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

Possibility of Possibility of eeoscillation search for oscillation search for 1313 measurement measurement

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targettarget

Civil engineering completed (June ’03)

Hadron stopper and decay tube installed (June ’04)

Target section completed in 2006 (first CNGS beam in August 2006)

CNGS beam (CERN Neutrino to Gran Sasso)

vacuum 4.5 1019 p.o.t. /year

700 m 100 m 1000m 67 m

400GeV

Ø at GS=2km 3.2° angle

To Gran Sasso

HornHorn

Decay tube Decay tube vacuum tests successfulvacuum tests successful

Hadron stopHadron stop

Muon Muon chamberschambers

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P(CC) m2

23 = 2.5 10-3

eV²

Flux at Gran Sasso (given by Fluka)

flux

CNGS beam (CERN Neutrino to Gran Sasso) 4.5 1019 p.o.t. /year

Number of expected events at Gran Sasso (0-100 GeV):

(before reconstruction and detection efficiencies)

N CCyr/kton

N eCCyr/kton

N CCyr/kton

.Detection of CC interaction and direct observation of decay topology

.High background rejection

(17.4%) e- (17.8%) h- n (49.5%) n() (14.5%)

decay kink

~ 0.6

mm

appearance signature

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OPERA Performances for oscillationoscillation

full mixing, 5 years run @ 4.5x1019 pot / year

Most important background : charm particle production

Best value ofm223

= 2.5 10-3 eV²3 range : 1.9 - 3.2 10-3 eV²

T.Schwetz, hep-ph/0606060

4 Discovery probablility > 90% for m223>2.5 10-3 eV²

4- evidence

3- evidence

OPERA Discovery probability vs. m2

Number of expected signal and background events

0

20

40

60

80

100

Dis

co

very

pro

bab

ilit

y (%

)

0 .05 0.1 0.15 0.2 0.25 0.3 0.35 m eV 2 3 210

channel Reconstruction efficiency %

Back-ground

11.06 10.4 14.9 0.75Total

33 range range

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rock thickness 1400m (3800 m.w.e.)cosmic muon flux: 1/m2/h

OPERA (CNGS1)

ICARUS (CNGS2)

Hall C

Hall B

BOREXINO

LNGS-INFN

OPERA detector at LNGS (Notional Laboratory of Gran Sasso, Italy, 120 kms from Rome)

spectrometer: Dipolar magnet + RPC chambers

Target Trackers

Pb/Em. target

Precision tracker: Drift tubesB=1.6 T

2 super modules

1 super module = 29 walls + 31 Target Tracker + 1 muon spectrometer (22 RPC planes + 6 drift tube planes)

154 750 bricks

1.35 kton lead target ~4000 CC/yr

52*51 bricks/wall

p/p < 20% for E<50GeV

scintillator strips

brick wall

module

brick(56 Pb/Em. “cells”)

8 cm (10X0)

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OPERA bricks : main target detector componentEmulsion Cloud Chamber (ECC) : 1 ECC brick = 56 sheets Pb + 57

photographic emulsions

Pb

Emulsion layers

1 mm 300µm emulsion films and1mm thin lead foils

byFuji Film (Japan)JLGoslar (Germany)

This technology allows a few micron spatial resolution, and a

3D reconstruction of particle tracks, necessary for

detection

12.5 cm

8 cm

8.6 kg

10 cm 12.5cm10.2cm

2 emulsion layers (45 m thick) poured on a 210 m plastic base

The most precise trackerThe most precise tracker

Résolution (microtracks) spatial : 0.06 µm Angular : ~ 2 mrad

Vertex position resolution : ~1µm in transverse plane

2mm

6mm

MC 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

14 mm

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BAM (Brick Assembling Machine)

Automatic lead/emulsion

piling in a dark room

(~700 bricks/day)

5 articulated robots5 articulated robots

Insertion and extraction of bricks following intelligent

procedures.

The BMS(Brick Manipulator System)

one robot on each side of the

detector

Target preparation

Begining 2007 now

now

2003 : start building detector

June 2008 : end of filling target

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Detector today : electronics fully instrumented and testedBrick filling on the way : 99000 Bricks already inserted

LNGS Hall C

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20-30 bricks extracted / day

selection of the interaction brick provided by time

correlation of electronic detectors

Emulsion Development

of candidate bricks at Gran Sasso (surface

facilities)

Example of a vertex in emulsion

Emulsion Scanning with automated microscopes :

10 laboratories in Europe and Japan

Emulsion shipment

OPERA event analysis procedure

0 max

p.h.

Brick finding :

31 tracking scintillator planes (TT)/super modules

Trigger(>99%) + Brick finding (7090%)

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Reconstruction of micro-tracks (45µm)

2D images 2D images processingprocessing 3D reconstruction of 3D reconstruction of

particle tracksparticle tracks

speed : 20cm²/hour/emulsion side

Résolution (grains) spatial : 0.06 µm Angular : ~ 2 mrad

1 emulsion sheet (2 sides) : 12h scanning - ~5GB

10 scanning laboratories in Europe and Japan

2 emulsion sides (45

m)

1 plastic base (200 m)

16 tomographi16 tomographic c images images = 45µ= 45µmm300

µm

300µ

m

300µm300µm

Field ofField of vue vue

Scanning :

emulsion digitisation

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First OPERA results with CERN neutrino beam

cosmicsBeam events

Positive electronic tests during first beam run (August 06 : 0.084 1019

integrated pot) interaction in magnet (Fe)

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. 8 303

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Muon track inside emulsions

First OPERA results with target bricks from cosmic run

April 17th- May 15th 2007 :

30 bricks extracted

28 muons found in emulsions

Cosmic muons in OPERA detector (ray bandle)

< 1 event per day inside the acceptance ! ~20 ‘good’ muons per month

These first data have confirmed the good accuracy of the ED predictions and validated the analysis

chain

Mean prediction accuracy (ED-brick):• Δx = 11 mm (along the tray)• Δy = 14 mm (vertical direction)• Δθx = 6.0 mrad• Δθy = 3.3 mrad

45 µm 210 µm

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First OPERA results with target bricks from CNGS run (SM1 filled at 80%)CNGS integrated intensity from September 24th to October 20th :

6.72 1017 pot

5/10/07

9/10/07Comissioning Physics

3.91 1017 pot

8.24 1017 pot20/10/07

Problems in ventilation control units of the proton

target

12/10/07

59 : CNGS very stable

at 1.58 1017 pot/day 326 expected events in bricks

38 events registered during the 2007 CNGS run :

29 CC

9 NC

Expected 75% CC and 25%NC proportions

Nominal intensity : 4.5 1019 pot /yr (1yr=200 days)

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µCCHadronic shower muon µ

-

nHadronic

showerE=7.8 GeV

12/29 located in bricks so far

First OPERA neutrino event located in brick (October 2nd 2007)

18 mBologna scanning laboratory

1 cm

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µ

nHadronic shower

µ

µ NC

Hadronic shower

3/9 located in bricks so far

18 mNagoya scanning laboratory

2 cm

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ConclusionConclusion•OPERA is the first experiment for appearance in a 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 2007. 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 2008 ~20 neutrino interactions / day 1st event expected

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Beam event selection : TOPERA – (TSPS + TOF) < Tgate ~1extraction

~2.4ms

Proton extractions from SPS with 3 cycles of 6s each : 2 extractions

of 10.5 s, separated by 50 ms.

time

CNGS beam @ CERN:

Nominal intensity : 4.5 1019 pot /yr, with 2.4 1013 pot/extraction (FE)

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With the horizontal profile of the CNGS muons in the 2 muon detectors

- First muon detector : ≤ 2.5 x 107 muons / cm2 / 1013 pot- Second muon detector :  ≤ 4 x 105 muons / cm2 / 1013 pot

p 67m

1st muon chamber

2nd muon chamber

>1km

Control of the neutrino beam direction:

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ns

ns

All events within a window of +- 20 s since the beginning of the extraction

Extraction 1

Extraction 2

Should start at 0 and last up to 10500 µs.

New calibrations will be done with a new GPS system receiver and a Cs clock of 1ns accuracy.

CERN-LNGS time correlation

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These doses were computed by the Fluka group and known since many years !!They were not just taken into account when the ventilation was installedRadiation protection measurements confirm the calculations

Target chamberSolution :Solution :

Replace damaged electronics

Find another place for ventilation control units

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6.9m1.7 m

64 strips/module

Target Tracker

●●Trigger: > 99%● Brick finding : 7080%● 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)

LNGSLNGS

Tracker wall

2 x 256 strips

Reconstructed cosmic track

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Muon spectrometer

B=

1.5

5 T

base

slabs

coil

8.2 m

M ~ 950t

Drift tubes

12 Fe slabs(5cm thick)

RPC’s

2 cm gaps

identification: > 95% (TT)

p/p < 20% , p < 50 GeV/c

misidentified charge prob. 0.1 0.3%

21 bakelite RPC’s (2.9x1.1m2) / plane

Precision tracker: 6 planes of drift tubes

diameter 38mm, length 8m4 staggered layers / plane,

each layer consisting of 168 tubes

efficiency: 99%space resolution: 300µm

Inner Tracker: 11 planes of RPC’s

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PEANUT : OPERA test-beam at FERMILAB

Detector placed in the front of the MINOS near detector:

-4 walls of 3*4 OPERA bricks exposed to NUMI beam ( ) in « low energy » configuration (<E>=10GeV, Epeak=3GeV )

-DONUT SFT (scintillators) between each wall

goal : to observe neutrino interactions in OPERA bricks

5 events/brick /day expected bricks exposed ~20days

Exposure time: October 18th 2005 -> Mars 1st 2006

total 160 Bricks made, exposed and developped

Brick piling in dark room

developper

Salerno scanning lab analysis

Neutrino reconstruction in emulsions

SFT-emulsions alignment~500µm spatial resolution

~5mrad angular resolution

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e oscillation search

mm232322 = 2.5 x 10-3 eV2 23 23 = 45°= 45°

nominal CNGS beam 5 years

90% C.L. limits on sin2(213) and 13 :

Combined fit of ECombined fit of Eee, E, Evisvis, (pt), (pt)missmiss

sinsin22(2(21313)<0.06 )<0.06 13 13 < 7.1º< 7.1º

2.5x10-3 eV2

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