Recirculation Concept - Cyclotron
Radio frequency alternating voltage
Hollow metal drift tubes
time t =0
time t =½ RF period
D-shaped RF cavities
• Orbit radius increases with momentum• Orbital Frequency independent of momentum• Particle motion and RF in phase
Lawrence:4” – 80 keV11” - 1.2 MeV
B mve
pe
f rev v2
v2eBmv
eB2m
Constant revolution frequency
p
eB
momentum
radius magneticfield
Equilibrium Orbit
MagneticForce
CentrifugalForce=
Synchrotron Ring Schematic
Focusing magnets
Vacuumtube
Accelerating Voltage
Bending magnets
• During acceleration, momentum increases
• Increase magnetic field during acceleration.
• Constant orbital radius
Colliding Beam Synchrotron
B mve
pe
f rev v2
v2eBmv
eB2m
Constant revolution frequency
Equilibrium Orbit
p
eB
momentum
radius magneticfield
CERN Seen from the Air
• Tunnels of CERN accelerator complex superimposed on a map of Geneva.
• Accelerator is 50 m underground
• 25 km in circumference
Alors, c’est fini!Et maintenant?
Interaction of Charged Particles with Matter• All particle detectors ultimately use
interaction of electric charge with matter– Track Chambers– Calorimeters– Even Neutral particle detectors
• Ionization• Multiple Scattering• Cerenkov• Transition Radiation• Electron’s small mass - radiation
0n
How we did it in the past – Bubble Chamber
Magnet
You could actually see what was going on
1960scomputer
Bubble Chamber – ionization trails in superheated liquid hydrogen
Electron knocked out of atom
Spirals in magnetic field
• •
e e
ee
0K 0 e e e e
R.S. Orr 2009 TRIUMF Summer Institute
Layers of Detector Systems around Collision Point
Generic Detector
R.S. Orr 2009 TRIUMF Summer Institute
Generic Detector
Different Particles detected by different techniques. Tracks of Ionization – Tracking Detectors Showers of Secondary particles – Calorimeters
R.S. Orr 2009 TRIUMF Summer Institute
Generic Detector
Different Particles detected by different techniques. Tracks of Ionization – Tracking Detectors Showers of Secondary particles – Calorimeters
R.S. Orr 2009 TRIUMF Summer Institute
Layers of Detector Systems around Collision Point
Computer Display of Event
R.S. Orr 2009 TRIUMF Summer Institute
ATLAS Detector
Different Particles detected by different techniques. Tracks of Ionization – Tracking Detectors Showers of Secondary particles – Calorimeters
R.S. Orr 2009 TRIUMF Summer Institute
ATLAS Wedge
Different Particles detected by different techniques. Tracks of Ionization – Tracking Detectors Showers of Secondary particles – Calorimeters
R.S. Orr 2009 TRIUMF Summer Institute
Wire Chamber
R.S. Orr 2009 TRIUMF Summer Institute
3 stages in signal generation
1) Ionization by track passing through cell
2) Ionization drifts in E field
time
3) In high E field region near wire, primary ionization electrons gain enough energy to start ionizing the gas
- Avalanche- More charges- Charge amplification- Noise free amplifier
7~10 microvolt signal if no amplification
R.S. Orr 2009 TRIUMF Summer Institute
Generic Detector
R.S. Orr 2009 TRIUMF Summer Institute
Generic Detector
R.S. Orr 2009 TRIUMF Summer Institute
Simple Drift Chamber
TRT endcap A+B
TRT endcap C
TRT barrel
SCT barrelSCT endcap
Pixels
The ATLAS Inner Detector
R.S. Orr 2009 TRIUMF Summer Institute
ATLAS Tracker
Inner Detector (ID)The Inner Detector (ID) comprises four sub-systems:
•Pixels (0.8 108 channels)
•Silicon Tracker (SCT)(6 106 channels)
•Transition Radiation Tracker (TRT)
(4 105 channels
R.S. Orr 2009 TRIUMF Summer Institute
ATLAS Wedge
Different Particles detected by different techniques. Tracks of Ionization – Tracking Detectors Showers of Secondary particles – Calorimeters
R.S. Orr 2009 TRIUMF Summer Institute
PN Junction
SCT barrel
Pixel Layer-2 – half shell
Pixel Layer2, once clamped, outside
Pixel Layer2, once clamped, inside
“Ready for installation” date is 1st April 2007
R.S. Orr 2009 TRIUMF Summer Institute
ATLAS Wedge
Different Particles detected by different techniques. Tracks of Ionization – Tracking Detectors Showers of Secondary particles – Calorimeters
Liquid Argon/Metal
Charged Particle
Kinetic Energy of ParticleConverted to Ionization
Of Liquid Argon
Electrical SignalProportional to
Incoming Energy
Why Is It Called a Calorimeter?
Readout Electronics
R.S. Orr 2009 TRIUMF Summer Institute
Comparison of Hadronic & Electromagnetic Showers
LAr and Tile CalorimetersTile barrel Tile extended barrel
LAr forward calorimeter (FCAL)
LAr hadronic end-cap (HEC)
LAr EM end-cap (EMEC)
LAr EM barrel
LAr Forward Calorimeters
• FCAL C assembly into tube – Fall 2003
Oct 2002
Hadronic Endcap
HEC – FCAL Assembly
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