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