OPERA Experiment,Brick Finding Program

A. Chukanov

Joint Institute for Nuclear Research

ISU, 12th February, 2007

Outline

• OPERA experiment

• Status of the OPERA detector

• Brick Finding program description

• Conclusion

OPERA:OPERA: OOscillation scillation PProjectrojectwithwith EEmulsionmulsion ttRRackingacking AApparatuspparatus

732

km

• Long baseline experiment • Direct search for oscillations by looking at the appearance of in a pure

beam to explain atmospheric neutrinos anomaly and results of K2K and MINOS.

• Search for the sub-dominant e oscillations for 13 measurement

OPERA Dete

ctor

Detection of the appearance signal

Two conflicting requirements: Large mass low Xsection High granularity

signal selection background rejection

Target:1800 tons, 5 years running

• 30 000 neutrino interactions• ~150 interactions• ~15 identified• < 1 event of background

Toplogy selection:

Kink signature

The challenge is to identify interactions from interactions

-

Decay “kink”

-

~1 mm

oscillation

-

Target(31 TT modules + 31 Brick walls / SM)

Magnetic Spectrometers

SM1 SM2

Modular structure: 2 super-modules

Total target mass: 1.8 kt

The OPERA detectorThe OPERA detector

Target Tracker

7 m

7 m

6.9m

1.7m

Plastic scintillator strips (AMCRYS-H, 6.7m x 2.6cm x 1cm)readout by Kuraray WLS fibres +Hamamatsu PMT’s (64 channels)

Target Tracker tasksTarget Tracker tasks

● ● Trigger: Trigger: > 99% > 99%● ● Brick finding : Brick finding : 70 7080%80%● ● Initiate muon taggingInitiate muon tagging

31 walls

Muon spectrometer

identification: identification: > 95% (TT) > 95% (TT)

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

misidentified misidentified charge prob. charge prob. << 0.3% 0.3% B

= 1

.55

T

base

slabs

coil

8.2 m

M ~ 950t

Drift tubes

12 Fe slabs(5cm thick)

RPC’s

● ● muon identification (TT)muon identification (TT)● ● range measurementrange measurement

11 + 11 planes of RPC’s11 + 11 planes of RPC’s21 bakelite RPC’s (2.9x1.1m21 bakelite RPC’s (2.9x1.1m22) / plane) / plane

Inner TrackerInner Tracker

Precision TrackerPrecision Tracker

6 planes of drift tubes6 planes of drift tubesspace resolution: space resolution: 300300µmµm

● ● momentum measurementmomentum measurement

Lead – Emulsion target

8.3kg

brick (target unit) 56 Pb plates + 57 emulsions

2 emulsion layers (44 m thick)poured on a

200 m plastic base

12.5cm

10.2cm

10 X0’s

● Micro-metric space resolution (Emulsion) + target mass (Lead)● Compact and modular structure

Total target mass : 1766 t(206336 bricks, 12 M emulsions and Pb plates)

Brick Manipulator System

Ventouse Vehicle

Brick

Carousel mechanism

Robot for brick insertion (target filling) and removal (during run)

Automatic scanning of nuclear emulsionsAutomatic scanning of nuclear emulsions

High speed CCD Camera (3 kHz)

Piezo-controlled objective lens

Constant speed stage

Synchronization of objective lens and stage

~ 30 bricks will be daily extracted from target and analyzed using high-speed automatic systems

S-UTS (Japan)

Customized commercial optics and mechanics + asynchronous DAQ software

Hard-coded algorithms

scanning speed ~ 20 cm2 / h

European Scanning System

Two testing runs

August 2006

testing CNGS beam

testing Changeable Sheet

October 2006

register events in real bricks

water leak in a reflector cooling system

There are 28 beam correlated events have been registered

during october run

Brick Finder Program

Brick Finding Program requirements – high efficiency

No new bricks will be inserted

(to save the effective mass of target)

~30 Bricks per day (5 years of data taking)

Cleaning Event

Cellular Automation

Reconstruction muon track directionHough Method

Kalman Filter

Tracing Method

Reconstruction Hadron Jet direction

Reweighting hits method

Define wall with interaction

Neural Network

Find Brick

Define most probable brick

Results (CC events) “1 of 3” Full detector

Wall reconstruction efficiency:

1 wall 0.94 0.85

Brick finding efficiency

1 brick 0.71 0.702 bricks0.87 0.853 bricks0.91 0.92