The OPERA hybrid detector was designed to search for n t appearance in the n m CNGS beam

Search for Search for -neutrino interactions -neutrino interactions in the OPERA hybrid detectorin the OPERA hybrid detector

Cristiano Bozza (University of Salerno / INFN)Cristiano Bozza (University of Salerno / INFN)for the for the OPERA CollaborationOPERA Collaboration

TIPP 2011TIPP 2011

Search for Search for -neutrino interactions in the -neutrino interactions in the OPERA hybrid detectorOPERA hybrid detector

22Cristiano Bozza for the OPERA Collaboration / TIPP 2011Cristiano Bozza for the OPERA Collaboration / TIPP 2011

The OPERA hybrid detector was designed to search for The OPERA hybrid detector was designed to search for appearance in the appearance in the CNGS beam CNGS beam

L = 732 kmCERNLNGS

Tflight = 2.44 ms

< E > 17 GeV

L 730 km

( e + e) / (CC) 0.87%

/ (CC) 2.1%

prompt negligible

Expected neutrino interactions for 22.5x1019 pot: ~ 23600 CC + NC~ 205 e + e CC~ 115 CC (m2 = 2.5 x 10-3 eV2) OPERA

CNGS



Detection principle for Detection principle for appearance in OPERA appearance in OPERA

Pb

emulsion layers

1 mm

interface films (CS)

ECC brick

electronictrackers

Detection of Detection of CC events CC events

through characteristic through characteristic topologytopology



2 SuperModules2 SuperModules

SM1 SM2Pb-Emulsion Target +Target Tracker

Dipolar magnet spectrometerwith RPC and drift tubes

Brick manipulator system

VETO



OPERA: sub-micrometric tracking precision of nuclear emulsionOPERA: sub-micrometric tracking precision of nuclear emulsion+ time trigger, kinematics and particle ID by electronic detectors + time trigger, kinematics and particle ID by electronic detectors

10.2 cm

12.5 cm7.5 cm

10 X0

neutrino

Hybrid target structureHybrid target structure

(CS)

(CS)

1 brick = 56 Pb plates / 57 emulsion films1 brick = 56 Pb plates / 57 emulsion films150,000 ECC bricks (ECC=Emulsion Cloud 150,000 ECC bricks (ECC=Emulsion Cloud Chamber)Chamber)111,000 m111,000 m22 surface, 8.9 million films surface, 8.9 million films1.25 kton of “instrumented” target 1.25 kton of “instrumented” target



Emulsion films: optical “tomography” of the vertex regionEmulsion films: optical “tomography” of the vertex region

emulsion(44mm)

emulsion(44 mm)

plastic base(205 mm)

50 micron

Microscopic Image

sensitivity : 32grains/100 mm

Track fitting Track fitting residuals residuals 50 nm50 nm

A A m.i.p.m.i.p. track in emulsion track in emulsion

beambeam

3D tomography:3D tomography:change focal planechange focal plane



Reading the emulsion films – “off-site” detectorsReading the emulsion films – “off-site” detectors

European Scanning SystemSuper-UltraTrackSelector

High speed automatic microscopes:High speed automatic microscopes: ~ 200 cm~ 200 cm22 emulsion film surface/hour/facility emulsion film surface/hour/facilityBased on state of the art technologies:Based on state of the art technologies:precision mechanics, high-speed CMOS, pattern recognition, image analysisprecision mechanics, high-speed CMOS, pattern recognition, image analysisData flow: Data flow: 1 GB/s/facility 1 GB/s/facility



The VETO system: double layer ofThe VETO system: double layer ofglass RPC (glass RPC (100m100m22))

97% efficiency in97% efficiency instreamer modestreamer mode



Target Tracker planes interleaved with brick wallsTarget Tracker planes interleaved with brick walls

> 5 p.e. for a > 5 p.e. for a m.i.p.m.i.p. (2.15 MeV) (2.15 MeV) ~ 99% detection efficiency~ 99% detection efficiencyposition accuracy: 10 mm position accuracy: 10 mm angular accuracy: 23 mradangular accuracy: 23 mradTT: 6% of target massTT: 6% of target massWalls: 0.5% of target massWalls: 0.5% of target mass



Target TrackerTarget Tracker

p.e. for a p.e. for a m.i.p. m.i.p. track as a track as a function of the function of the distance from distance from each end each end

Empty dots: MCEmpty dots: MCFull dots: dataFull dots: data



The magnetic spectrometers:The magnetic spectrometers: • 1.52 T magnetic field bending particles 1.52 T magnetic field bending particles in the horizontal planein the horizontal plane• 24 slabs of magnetized iron interleaved 24 slabs of magnetized iron interleaved with 22 RPC planeswith 22 RPC planes• 6 drift tube stations (HPT) for precision 6 drift tube stations (HPT) for precision measurement of the angular deflectionmeasurement of the angular deflection• Momentum resolution: Momentum resolution: 20% below 50 GeV20% below 50 GeV



The magnetic spectrometersThe magnetic spectrometers

Momentum Momentum charge, data (dots) vs. MC (lines) charge, data (dots) vs. MC (lines)

Charge misidentification: Charge misidentification: 1.2% (2.5 GeV < p < 45 GeV)1.2% (2.5 GeV < p < 45 GeV)



RPC’s for tracking in the magnet RPC’s for tracking in the magnet and range measurementand range measurement

RPC efficiency

3500 m3500 m22 bakelite RPC’s bakelite RPC’s operated in streamer mode:operated in streamer mode:Hadronic energy reconstruction Hadronic energy reconstruction in the spectrometerin the spectrometerTrigger for the HPTTrigger for the HPTCoarse tracking of showers Coarse tracking of showers (2.6 cm strip pitch) (2.6 cm strip pitch)



How neutrino How neutrino interaction events interaction events look like in the look like in the OPERA electronic OPERA electronic detectorsdetectors

20 m11: event with a : event with a in the final statein the final state

00: event without : event without a a in the final in the final statestate



Neutrino interaction energy reconstructionNeutrino interaction energy reconstruction

Reconstructed energy: Reconstructed energy: Dots = dataDots = dataLines = MCLines = MC

The instrumented target The instrumented target is used as a calorimeteris used as a calorimeter

11 events events 00 events events

Energy resolutionEnergy resolution



How a How a -neutrino candidate looks like in OPERA-neutrino candidate looks like in OPERA

Vertex regionVertex region

Vertex region Vertex region (zoomed view)(zoomed view)

ElectronicElectronicdetectorsdetectors



Topological signature through the observation of the in-flight Topological signature through the observation of the in-flight decay of a tau lepton: cdecay of a tau lepton: c87 87 m requires micrometric trackingm requires micrometric tracking



Info from emulsion films: topological reconstructionInfo from emulsion films: topological reconstruction

Interaction/decay vertex:Interaction/decay vertex:the minimum distance point the minimum distance point of two or more tracksof two or more tracks

The Impact Parameter has The Impact Parameter has an average value of an average value of 2.3 2.3 m (real events)m (real events)

IP distribution for: - events (MC)

-NC+ CC events (MC)

-NC+ CC events (Data)



Info from emulsion films: momentum estimation through measurement of Info from emulsion films: momentum estimation through measurement of multiple Coulomb scatteringmultiple Coulomb scattering

p/p = (22±4)%



Shower energyShower energyis estimated byis estimated bya neural-networka neural-networkanalysis of the analysis of the shower feaures:shower feaures:

• # of tracks# of tracks• shapeshape• MCS of hard MCS of hard tracks tracks

E = 0.5 GeV

E = 8.1 GeV

2 EM showers give a reconstructed mass ~ 160 MeV/c2

Info from emulsion films: EM shower reconstruction + energy estimationInfo from emulsion films: EM shower reconstruction + energy estimation

35 events

mass measuredmass measuredin emulsionin emulsion



Info from emulsion films: discrimination of interaction/decay kinks by search Info from emulsion films: discrimination of interaction/decay kinks by search for highly ionising particle tracksfor highly ionising particle tracks

Fine emulsion sampling (0.5 Fine emulsion sampling (0.5 m m tomography) to check track tomography) to check track length and discriminate length and discriminate radioactivity from nuclear radioactivity from nuclear fragmentsfragments



Merging electronic detector information with emulsion information, #1:Merging electronic detector information with emulsion information, #1:the Changeable Sheet (CS) doubletsthe Changeable Sheet (CS) doublets

Extract brick and CS, scan CS.Confirm the event in the brick.Develop brick: ship to scanning labs.

CS

σx 10.0 mm∼



On-demand brick handlingOn-demand brick handling

Waiting for neutrinos Waiting for neutrinos in the target…in the target… Extracted by the Brick Extracted by the Brick

Manipulator SystemManipulator System

X-ray exposure for X-ray exposure for alignmentalignment

Stored underground Stored underground (waiting for the CS (waiting for the CS response)response) Exposed to cosmic-rays Exposed to cosmic-rays

for precision film for precision film alignmentalignment

Films developed in Films developed in surface surface emulsion facilityemulsion facility



Emulsion film scanning: several labs share data-takingEmulsion film scanning: several labs share data-taking

To Japan

Padova

To Dubna

LNGS To Ankara

Bern

Bologna

Roma

LNF

NapoliSalerno

Bari

SalernoNapoli

OPFRA

OPITA LNGS

IN2P3

Bari

Bologna

LNGS

LNF

PadovaRoma

Nagoya

Dubna

Bern

Analysis BMSDB

BAMDB

DevDB

An interconnected system of An interconnected system of relational DB’s distributes all relational DB’s distributes all intermediate results and intermediate results and holds the analysis status of holds the analysis status of each eventeach eventCurrently 15 TB, expected to Currently 15 TB, expected to top 100 TBtop 100 TB



Merging electronic detector information with emulsion information, #2:Merging electronic detector information with emulsion information, #2:locating the neutrino interactionlocating the neutrino interaction

1257565554535251504948…21

CSd

~2 µm

Volume scanning (Volume scanning (2cm2cm33) around the disappearance point) around the disappearance point



Merging electronic detector information with emulsion information, #3: event Merging electronic detector information with emulsion information, #3: event studystudy

C

• Estimate the total visible energyEstimate the total visible energy

• Match event shape to vertex Match event shape to vertex region and check track origin region and check track origin

• Assess the nature of eachAssess the nature of eachparticle for interesting eventsparticle for interesting events

Each track is followedEach track is followedthrough the Target Tracker, through the Target Tracker, CS doublet andCS doublet andtarget brick sheetstarget brick sheetsuntil the endpoint isuntil the endpoint isreached and checkedreached and checked



Merging electronic detector information with emulsion information, #3: event Merging electronic detector information with emulsion information, #3: event studystudy

The combined emulsion + electronic The combined emulsion + electronic information is reported for the information is reported for the

candidate eventcandidate eventAll cuts from OPERA Proposal passedAll cuts from OPERA Proposal passed

The most likely interpretation in this The most likely interpretation in this case is:case is:

The OPERA hybrid apparatus allows The OPERA hybrid apparatus allows detailed study for each single event!detailed study for each single event!



Sample event: charm candidateSample event: charm candidate

kink

x-view

1ryvertex

1.3 mm

1ry muon

daughter muon



Sample event: charm candidateSample event: charm candidate

2

5

AB

AB=361 m

CC: hadroninteractionvertexAC =1640 m

Pl20

Pl20

Pl20

Pl20

Pl20

Pl21

Pl21

Pl21

Pl22



The whole machinery runningThe whole machinery running

Pl20

3432 events located (2008+2009 runs)3162 events decay searched (‘08/’09)



ConclusionsConclusions

• The OPERA Collaboration is successfully operating a hybrid detector to The OPERA Collaboration is successfully operating a hybrid detector to search for search for appearance in the CNGS beam appearance in the CNGS beam

• The hybrid design concept in OPERA allows detailed study of each The hybrid design concept in OPERA allows detailed study of each event, exploiting the best features of its nuclear emulsions, scintillators, event, exploiting the best features of its nuclear emulsions, scintillators, RPC’s and drift tubesRPC’s and drift tubes

•1 1 candidate was found in 2010 out of a sample of 1088 fully analysed candidate was found in 2010 out of a sample of 1088 fully analysed

eventsevents

• 3162 events searched for decays so far (41 with charm 3162 events searched for decays so far (41 with charm production/decay in production/decay in interactions) from 2008/2009 runs interactions) from 2008/2009 runs

• Data taking in progress, more results to come in the near future!Data taking in progress, more results to come in the near future!

The OPERA hybrid detector was designed to search for n t appearance in the n m CNGS beam

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