opera experiment, brick finding program a. chukanov joint institute for nuclear research isu, 12 th...
TRANSCRIPT
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