OPERA

OPERAOPERAMaximiliano Sioli (Bologna University and Maximiliano Sioli (Bologna University and

INFN)INFN)for the OPERA Collaborationfor the OPERA Collaboration

NOW 2006, Conca Specchiulla, Sep 9-16, 2006NOW 2006, Conca Specchiulla, Sep 9-16, 2006

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Maximiliano Sioli, NOW 2006Maximiliano Sioli, NOW 2006 22

The OPERA The OPERA Collaboration Collaboration

(37 groups, (37 groups, ~160 physicists~160 physicists))BelgiumIIHE (ULB-VUB) BrusselsBulgariaSofiaChinaIHEP Beijing, ShandongCroatiaIRB ZagrebFranceLAPP Annecy, IPNL Lyon, IRES StrasbourgGermanyHamburg, Münster, RostockIsraelTechnion HaifaItalyBari, Bologna, LNF Frascati, L’Aquila, LNGS, Naples, Padova, Rome La Sapienza, SalernoJapanAichi, Kobe, Nagoya, Toho, UtsunomiyaRussiaINR Moscow, ITEP Moscow, JINR Dubna, ObninskSwitzerlandBern, Neuchâtel, ZurichTurkeyMETU Ankara


OutlineOutline

Physics goal of OPERAPhysics goal of OPERAThe OPERA detectorThe OPERA detectorPhysics performances:Physics performances:

oscillation channeloscillation channel ee oscillation channel oscillation channel

Low intensity runLow intensity runConclusionsConclusions


Physics motivationPhysics motivation

provide an unambiguous evidence for μ→ oscillation in the region of atmospheric neutrinos by looking for ντ appearance in a pure νμ beam

CNGS beam (1999)CNGS1 (2000)

Atmospheric neutrino anomalyinterpretable as μ→ oscillation

CHOOZ: no μ→e oscillation


The CNGS beam: The CNGS beam: overviewoverview

dEEEEPEMNN CCDA )()()()(

Beam main featuresBeam main features

LL 732 km732 km

<E<E>> 17 GeV17 GeV

L/ <EL/ <E>> 43 km/GeV43 km/GeV

((ee++ee)/)/ 0.87%0.87%

/ / 2.1%2.1%

promptprompt negligiblenegligible

“Off peak”Limiting for↔ ↔ eesearches

Event rate for OPERA (at 4.5x1019 pot/year, 200 days/year):~6200 (CC+NC)/year, ~25 CC/year @ 2.4x10-3 eV2

Radial distributionat LNGS


dEEEmEPEMNN CCDA )()(),()( 2

OPERAOPERA ≡ ≡ OOscillation scillation PProject roject with with EEmulsion tmulsion tRRacking acking AApparatuspparatus

Primary goal of OPERA:direct observation of leptons produced in

CC interactions

decay “kink”

~ 0.6 mm

Detector resolution must be O(1 mm)

Target massmust be O(1 kton)for m2 =O(10-3 eV2)

ECC concept adopted


TheThe EEmulsion mulsion CCloud loud CChamber techniquehamber technique

Pb

1 mm ECCECC ≡ sequence of emulsion- ≡ sequence of emulsion-lead layers:lead layers:

LeadLead: target mass: target mass

EmulsionEmulsion: tracking device: tracking device

It allows high spatial resolution capability and the possibility to have large masses in a modular wayIn OPERA, the basic ECC unit is the “BRICK”

Sequence of 56 lead sheets + 56 emulsion

layers (10X0 for p measurements and eID)

12.9 cm

10.3 cm

8.3 kg7.8 cm


supermodule

8 m

Target

Extract selected brick

1 mm

ECC cell

Emulsion

Pb

Pb/Em. brick

8 cm

Spectrometer

Vertex Location

Target Tracker: trigger and localize the interaction

Spectrometer: measure ID, charge and momentum

ECC: measure kink, pID,momentum (via MCS),dE/dX, e/ separation,

general event kinematics“changeable

sheets”


The Gran Sasso Laboratory(Central Italy, 900 m a.s.l.)

CNGS

External Lab

Underground Lab:1400 m of rock shielding: Cosmic Ray flux reduced by a factor 106 wrt surface; very reduced enviromental radioactivity.


OPERA general structureOPERA general structureHybrid detector (electronic + emulsions) with a modular structure:2 supermodules = 2*(31 walls + 1 spectrometer)

↳ 31 walls = 31*(56*64 bricks + 1 scintillator tracker plane)Total mass = 1766 tons, # of bricks = 206336

SM1 SM2

Target sections Magnetic spectrometers


dipolar magnets (1.55 T)dipolar magnets (1.55 T)SpectrometersSpectrometers RPC+XPC (RPC+XPC (ID + ID + shower energy)shower energy)

drift tubes (muon drift tubes (muon momentum)momentum)

Iron slabs8.

2 m

B= 1.55 T

coil

12

coil

Fe(5 cm)

RPC

12 Fe slabsper magnet side

Total Fe weight ~ 1.2 kton

22 gaps filled with RPC

12

coil

Precision Trackers(drift tubes)

1-charge ≅ (0.1-0.3)%p/p ≃ (20-25)%ID ≳ 95% (with TT)

eventrecordedin the firstmagnet


Target section: TT + Target section: TT + WallsWalls

TT ≡ plastic scintillators Trigger neutrino interactions Find the brick to be extracted Muon tracking and ID

XY planes (7000m2 in total) readout by WLS fibers 1000 PMT Hamamatsu

(64channels)

Suspension from the top

Tensioning from the bottom

Hei

ght

~ 6

.7

m


OPERA in OPERA in picturespictures

BMS ready tofill the target

Details of the first spectrometer

BAM at LNGS:~1000 bricks/dayat regime


Automatic emulsion scanning

S-UTS in Japan (Nagoya)

Dedicated hardwareHard coded algorithms

European station

Commercial productsSoftware algorithms

Based on the tomographic acquisition of emulsion layersThe experiment size requires a scanning speed of ~20 cm2/h.(tens of interaction/day → thousend of cm2/day)

- Ultra High Speed CCD Camera for S-UTS (3k frames/sec)- 15m/brick for 15 predictions- 1h35m/brick for 100 predictions

- Running at ~20 cm2/h- High efficiency (>90%) and high purity

- resolution ~2 mrad


Search for Search for ↔↔ oscillations:oscillations:

expected number of expected number of eventsevents

Full mixing, 5 years run, 4.5ˣ1019 pot/year, 1.8 kton fiducial mass

decay decay channelchannel

signalsignal((mm22 = 2.4x10 = 2.4x10-3-3

eVeV22))

signalsignal((mm22 = 3.0x10 = 3.0x10-3-3

eVeV22))backgroundbackground

ττee 4.34.3 6.76.7 0.230.23ττμμ 3.63.6 5.65.6 0.230.23ττhh 3.83.8 5.95.9 0.320.32

ττ33hh 1.11.1 1.71.7 0.220.22TotalTotal 12.812.8 19.919.9 1.01.0


discovery discovery potentialpotential

Probability to observe, in 5 years,a signal far away 4 from the bg

90% CL exclusion plot (i.e. in absence of a signal) in 5 years of

data taking

Uncertainties on background (33%) and on efficiencies (15%) are accounted for

m2 (eV2) sin22

m2 (

eV2 )

Prob

abilit

y


e oscillation channel

Due to its good eID capability, OPERA is well suited for Due to its good eID capability, OPERA is well suited for e searches

Main backgrounds are: e beam contamination (larger contribution) 0 identified as electrons produced in

NC or CC with the muon not

identified e from oscillations1313 signalsignal ee CCCC NCNC eeCC CC

beambeam99ºº 9.39.3 4.54.5 1.01.0 5.25.2 181888ºº 7.47.4 4.54.5 1.01.0 5.25.2 181877ºº 5.85.8 4.64.6 1.01.0 5.25.2 181855ºº 3.03.0 4.64.6 1.01.0 5.25.2 1818

EfficiencyEfficiency 0.310.31 0.0320.032 0.34x100.34x10-4-4 7.0x107.0x10-4-4 0.0820.0825 years data taking, nominal CNGS, m2

23=2.5x10-3 eV2, sin2223=1


2.5x10-3 eV2

7.1o6.4o

0

0,02

0,04

0,06

0,08

0,1

0,12

0,14

0,16

0,134 0,112 0,095 0,078 0,067 0,062 0,056 0,05

4,5 6,75 9 13,5 19 20,3 27 33,8

e sensitivity SS/B enhanced with simultaneous fit of /B enhanced with simultaneous fit of

EEvisiblevisible, E, Eelectronelectron and missing p and missing ptt Sensitivity fully dominated by statisticsSensitivity fully dominated by statistics

pot (x10x101919))

sinsin22 22

1313


50 ms10.5 s 10.5 s

1st extraction

2nd extraction

1.7x1013 pot/extraction

Low intensity run (18Low intensity run (1830 Aug 30 Aug 2006)2006)

Unix time

TOTAL:7.6 E17 potEXT1: 3.81 E17 potEXT2: 3.79 E17 pot

MD daysFri 1

8 A

ug. 2

006

13:4

0

Wed

30

Aug

. 200

6 05

:00


Δt first extraction (ns)

50 ms

Ext1 Ext2

Zoom on the spill peaks

Δt closest extraction (ns)

10 µs

Event selection by electronic detectorsusing GPS timing information

N. of in-spill events in the whole run ~320


CC event originated upstream of the detector (rocks)

Beam eventsBeam eventsCC event originated

in the first magnet

First TTCS connections successfully tested!


Zoom on beam eventscoming 3.5° from below

Angular distribution of recorded Angular distribution of recorded eventsevents

y >0y <0

y

z

Angle with respect to the

horizontal direction (deg)

DATA

MC (only cosmics)Very preliminary!Very preliminary!


SummarySummary The main aim of the OPERA experiment is to The main aim of the OPERA experiment is to

unambiguously confirm/disproof the unambiguously confirm/disproof the atmospheric oscillation channelatmospheric oscillation channel

The low intensity CNGS run operated smoothly The low intensity CNGS run operated smoothly with good quality and stabilitywith good quality and stability

The electronic detectors of OPERA took data The electronic detectors of OPERA took data almost continuously and with the expected almost continuously and with the expected tracking performancestracking performances

More than 300 in-spill events have been recorded More than 300 in-spill events have been recorded with a clear time distributionwith a clear time distribution

The detector is ready for the next phase: The detector is ready for the next phase: observing neutrino interactions inside ECC bricksobserving neutrino interactions inside ECC bricks


SparesSpares


“Long” decays kink angle kink > 20 mrad

“Short” decays impact parameter I.P. > 5 to 20 m

kinkkink

Long decays

Pb(1 mm)

plastic base

I.P.

Short decays

emulsion layers

Pb(1 mm)

decay decay topologiestopologies

eh (n0)3h (n0)

e

- e- e

- -

- h- (n0)

17.8%

17.4%

49.5%- 3h- (n0) 14.5%


Angular and position Angular and position resolutionsresolutions For ≃ 0.013 rad

2.1 mrad 2.1 mrad

0.4 m 0.4 m


Ag grain after development

dx

= 0.06mCompton Electron

Fog

M.I.P. Track

100m

m.i.p. Track

intrinsic tracking accuracy

Grain Density: ~30grains / 100m for m.i.p. Grain Size: 0.2 m (original crystal)

0.8 m (after development) x = 0.2m/12 = 0.06m However, DAQ effects spoils the resolution (CCD pixel size, stage movements); routinely we have x = 0.3m

Tracking resolution with Tracking resolution with emulsionsemulsions


Fuji emulsions, Fuji emulsions, from production to from production to scanningscanning Production at FUJI

Refreshing

Transportation from JAPAN to LNGS

Brick assembly

Refreshing in the Tono Mine in Japan: started

Refreshing conditions:• Humidity : > 95%• Temperature : 30 ºC• Time : ~ 3 days

Mass production started April 2003 (~150,000 m2)

First batch to LNGS by June ’04

Emulsion storage barrack ready in Hall B

ExperimentCosmic Ray exposure Scanning

Documents

OPERA