Embed Size (px)
Citation preview
A TIME OF FLIGHT MODEL FOR MUON TRACKERS APPLIED TO
MUOGRAPHY
XXVI Ciclo di Dottorato in Tecnologie Innovative per Materiali, Sensori ed Imaging
UNIVERSITA’ DEGLI STUDI DI NAPOLIFEDERICO II
Ph. D. Candidate :Luigi Cimmino
27th February, 2014 - Napoli
VOLCANOS RADIOGRAPHY WITH COSMIC RAYS
muon telescopeMt. Asama (Jap.)
The muon radiography (Muography) is based on the measure of the absorption of cosmic muons in matter.
• Muons are elementary particles with high penetrating power
• A detector measures the muons direction and counts their number
• By measuring the absorption factor of muons flux, we can calculate the mean density of the rock
REQUIREMENTS FOR MUOGRAPHY• Rugged and modular structure designed for easy
installation and use in volcanic environment• Large area assembly capability• Tracking of muon trajectory• High background rejection
• Muon’s Time of Flight (TOF)• Third plane• High spatial resolution
• High angular resolution• Fast electronics
m
X1
Y1
X2
Y2
Third Plane
fake m from ‘shower’m
BACKGROUND REJECTION
Using 3 stations we are able to reject events that mimic
muons
But, using the time of flight we could reject those fake tracks without the employ of the third plane.
BACKGROUND REJECTION
fake m from ‘albedo’
m
Thanks the time of flight we can reject muons
coming from the opposite direction in respect to the
volcano
Albedo muons are those that come from the back of detector and scatter on the ground, mimicking good tracks
MUON FLUX GENERATOR
Reco Azimuth angle
distribution
Reco Tetha angle distribution
Muon flux revealead by the Detector
Muon energy spectrum and PDF (source PDG)
HOW TO MEASURE TOF?
m
tX1
tY1
tX2
tY2
• Muons cross the detector• A certain trigger logic is
satisfied• Relative time are recorder
TOP Plane (A) DOWN
Plane (B)
Toy Montecarlo Spreads generationo Physics : 700 pso TDC : 600 ps
ProblemNo information about who
triggers
TIME EXPANSION
• A local trigger is produce on the slave board and transmitted to the master when a particle hits the relative plane
• Master board receives all local triggers and if they fulfill the trigger logic, it sends to all slaves a global trigger (stop)
• We want to measure the time between every single local trigger and the stop signal
• From the production of the local trigger to the stop signal a capacitor is charged on each slave boards
Local trigger Local trigger
Enable window
Stop Stop
Char
ge
Discharge
MODEL OF TIME OF FLIGHT
• We use a trigger logic that takes into account only the X-view (2 boards)
• In the Toy Montecarlo we will consider all expansion factors having the same value E
Expected Distribution
DISTRIBUTIONS SHAPE CHECK
4 PTL
2 PTL
• Due to the variability of the trigger board in 4PTL configuration, distributions present different behaviors which are not easy to be separated
• In each distribution, the first peak is about trigger events (mean value off = 400, standard deviation = 3.4)
MODEL EXPECTATION CHECK (HORIZ. MUONS)
2 PTL4 PTL
MODEL EXPECTATION CHECK (TRANSV. MUONS)
2 PTL4 PTL
HORIZONTAL TRACKS TOF COMPARISON
2 PTL4 PTL
mean sigmaPeak 1 400.2 3.13Peak 2 417.2 5.71 Peak 1 400.2 3.1Peak 2 417.2 5.42
TOF 3.4 nsTOF 3.4 ns
mean sigmaPeak 1 400.7 3.26Peak 2 417.4 12.52 Peak 1 400.6 3.35Peak 2 417.7 12.1
TOF 3.4 nsTOF 3.36 ns
TOFexp = 1.03 m/c = 3.43 ns
TRANSVERSAL TRACKS TOF COMPARISON
2 PTL4 PTL
TOFexp = 1.41 m/c = 4.70 ns
mean sigmaPeak 1 408.6 5.46Peak 2 455.4 5.81 Peak 400.2 3.03
Tmeas C.FibraTOF 1.68 6.4 4.72 nsTOF 11.04 6.4 4.64 ns
mean sigmaPeak 1 418.2 9.25Peak 2 455.4 6.04 Peak 409.7 3.57
Tmeas C.FibraTOF 1.7 6.78 5.08 nsTOF 9.14 6.78 2.36 ns
(0.96 m)
(1.01 m)
CONCLUSIONS
• We show how to calculate the time of flight of muons when the flux is bidirectional and only relative time information are available
• A toy montecarlo has been developed to recreate a simplified muons detector
• We develop a model to analyze data distributions and calculate the time of flight of muons
• Comparing two different trigger configuration we have verified the 2 plane trigger model
