Storage Rings for Charged Particles Kai Hock Cockcroft Institute and University of Liverpool Birmingham University, 24 February 2009.

Storage Rings for Charged Particles

Kai HockCockcroft Institute and University of Liverpool

Birmingham University, 24 February 2009

Birmingham, 24 Feb 09: Storage Rings 2

Outline

• Major uses of the charged particle storage rings

• Basic principles and designs

• Beam dynamics and stability

• Relevance to the atom storage ring

• Ideas for research and development


Major uses of the charged particle storage rings

• Synchrotron light source– Stores electrons– Produces high quality radiation for scientific experiments

• Damping rings– Stores electrons or positrons– Produces very narrow beams for particle physics experiments

• Others– Storing muons to produce neutrinos– Cooling protons for particle physics experiments– Cooling ions for nuclear physics experiments, etc.


The Diamond Synchrotron, Oxfordshire


The ATF Damping Ring, Japan


Basic Principles and Design

• Charged particles are guided in a vacuum pipe around a ring using dipole magnetic fields.

• They are strongly focused into bunches using quadrupole magnetic fields and rf cavity electric field – the key to stable circulation.

• Fine tuning to the focusing is made using sextupole magnets.• Energy is lost by radiation when particles are bent by

magnetic fields, or by collision with residual gas.• Energy is replenished in the rf cavity by electric fields in the

same direction as the particle orbit.• Diagnostic instruments are available to measure beam

position, beam profile and radiation profile.


Damping Ring for the Linear Collider

injection extraction

e+

8 RF cavities

10 RF cavities

wiggler

wiggler

wiggler

IP

wiggler

accelerateparticles

alternating magneticfields to cool electrons


Enabling Technologies

Beam position monitorQuadrupole magnet

WigglerDipole magnet Superconducting rf cavity

Sextupole magnet


Basic Principles of Operation

15

23

4

6 12345


Injection/Extraction

trajectory of stored beam

trajectory of incoming beam

preceding bunch

following bunch

emptyRF bucket

injection kicker


Injection and extraction kickers

Technical subsystems


Bending and focusing magnets

Dipole field for bending Quadrupole field for focusing


Radiation damping stabilises the particle

particle trajectory

closed orbit

emitted photon

bending magnet


Wiggler increases the radiation rate


rf cavity replenishes the lost energy


Interaction with beam pipe produces wake fields


Scattering from residual gases cause instability


Feedback systems stabilises the particles

single bunchshown atdifferent times

pick-up

amplifier

kicker

y

py


Atom Ring by Georgia TechElectron ring in Oxfordshire

Relevance to Atom Ring


Comparison of main features

• Similarities with the charged particle ring– Magnetic field can be used to guide the particles– Scattering from gas molecules shortens lifetime of particles– Same beam dynamics theory can be applied– Particles can be organised into bunches

• Differences in the atom ring– Energy is orders of magnitude smaller– No synchrotron radiation– Gravity effect is significant


Atom Interferometry for Inertial Guidance

The ICE Cube, Institut d’Optique, France


Some ideas for research and development

• Related activities around the world – Molecule storage rings, Netherlands: molecular experiments– ICE cube, France: inertial sensing project for space underway– Sagnac interferometer, Strathclyde: inertial sensing with atom ring– Atom chip interferometry, Imperial: precise control developed

• Ideas from accelerator physics– Strong focusing in all three dimensions for long term stability– Beam stability studies and feedback control systems– Energy source: The equivalence of an rf cavity?– Component ideas? Injectors, extractors, kickers, rings, focusing magnets– Presence of Intrabeam scattering, beam beam interactions?– Designing lines and lattices for atom transport and manipulation


Linear Collider and the Atom Chip

The International Linear Collider

Atom Chip Interferometry at Imperial College


Storage Rings for Charged Particles Kai Hock Cockcroft Institute and University of Liverpool Birmingham University, 24 February 2009.

Documents

atom ring slide

storage rings8

storage rings5

storage rings4

storage rings22

storage rings12

storage rings24

atom storage ring ideas