recirculation concept - cyclotron radio frequency alternating voltage hollow metal drift tubes time...

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

0K 0 e e e e

R.S. Orr 2009 TRIUMF Summer Institute

Layers of Detector Systems around Collision Point

Generic Detector


Generic Detector

Different Particles detected by different techniques. Tracks of Ionization – Tracking Detectors Showers of Secondary particles – Calorimeters


Layers of Detector Systems around Collision Point

Computer Display of Event


ATLAS Detector



ATLAS Wedge



Wire Chamber


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


Generic Detector


Simple Drift Chamber

TRT endcap A+B

TRT endcap C

TRT barrel

SCT barrelSCT endcap

Pixels

The ATLAS Inner Detector


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


ATLAS Wedge



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


ATLAS Wedge


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


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

recirculation concept - cyclotron radio frequency alternating voltage hollow metal drift tubes time...

Documents

amplification slide

mev slide

circumference slide

constant orbital radius

different techniques

ionization drifts

primary ionization electrons

e field time