6 Design and Principles of Synchrotrons and Circular Colliders
269
There are several basic motivations for the application and development of
different beam cooling techniques:
• Collection and accumulation of rare particles, e.g. antiprotons or short lived
particles such as muons.
• Improvement of interaction rate and resolution, e.g. collision experiments with
antiprotons or with ions; increase in luminosity. For fixed target experiments:
sharply collimated and/or highly mono-energetic beams for precision experiments.
• Preservation of beam quality, mitigation and suppression of beam blow-up.
• Preparation of crystalline beams.
Several cooling techniques are operational or have been discussed:
• Radiation cooling (often referred to as radiation damping); linked to energy
loss of particles via synchrotron radiation (used in virtually all modern electron
synchrotrons).
• Stochastic cooling (works well for “hot” beams to get them “tempered).
• Electron cooling (most suitable for “tempered” beams to get them “cold”).
• Laser cooling (essentially for ions where two level transitions of electrons can be
excited).
• Ionization- and friction-cooling (mainly discussed in the context of muon
cooling).
• Resistive cooling; used to cool charged particles in a trap where the kinetic energy
of the particle is dissipated in the resistive losses of a resonant circuit.
• Coherent electron cooling, a kind of blend from stochastic cooling at very high
frequencies and electron cooling (under development at BNL theses days)
The use of the terms cooling and damping is not always well distinguished
and unambiguous in the literature. Even in the context of stochastic cooling the
authors were using the term damping in the early days. A similar observation can be
made for radiation damping and cooling. One may consider defining any action on
individual particles as “cooling” and any action on groups of particles as damping.
Examples are the feedback systems in circular machines which are commonly
referred to as dampers and which prevent emittance blow up, while a very similar
feedback system just having a much higher electronic gain can work as (stochastic)
cooler and reduce the emittance. However typically such damper systems have a
much smaller bandwidth and lower operation frequency as compared to stochastic
cooling hardware.
6.10.2 Beam Cooling Techniques
6.10.2.1 Radiation Cooling
Back in 1956, A.A. Kolomenski and A.N. Lebedev [101] pointed out that the
‘synchrotron light’ emitted by an electron moving on a curved orbit can have a
269
There are several basic motivations for the application and development of
different beam cooling techniques:
• Collection and accumulation of rare particles, e.g. antiprotons or short lived
particles such as muons.
• Improvement of interaction rate and resolution, e.g. collision experiments with
antiprotons or with ions; increase in luminosity. For fixed target experiments:
sharply collimated and/or highly mono-energetic beams for precision experiments.
• Preservation of beam quality, mitigation and suppression of beam blow-up.
• Preparation of crystalline beams.
Several cooling techniques are operational or have been discussed:
• Radiation cooling (often referred to as radiation damping); linked to energy
loss of particles via synchrotron radiation (used in virtually all modern electron
synchrotrons).
• Stochastic cooling (works well for “hot” beams to get them “tempered).
• Electron cooling (most suitable for “tempered” beams to get them “cold”).
• Laser cooling (essentially for ions where two level transitions of electrons can be
excited).
• Ionization- and friction-cooling (mainly discussed in the context of muon
cooling).
• Resistive cooling; used to cool charged particles in a trap where the kinetic energy
of the particle is dissipated in the resistive losses of a resonant circuit.
• Coherent electron cooling, a kind of blend from stochastic cooling at very high
frequencies and electron cooling (under development at BNL theses days)
The use of the terms cooling and damping is not always well distinguished
and unambiguous in the literature. Even in the context of stochastic cooling the
authors were using the term damping in the early days. A similar observation can be
made for radiation damping and cooling. One may consider defining any action on
individual particles as “cooling” and any action on groups of particles as damping.
Examples are the feedback systems in circular machines which are commonly
referred to as dampers and which prevent emittance blow up, while a very similar
feedback system just having a much higher electronic gain can work as (stochastic)
cooler and reduce the emittance. However typically such damper systems have a
much smaller bandwidth and lower operation frequency as compared to stochastic
cooling hardware.
6.10.2 Beam Cooling Techniques
6.10.2.1 Radiation Cooling
Back in 1956, A.A. Kolomenski and A.N. Lebedev [101] pointed out that the
‘synchrotron light’ emitted by an electron moving on a curved orbit can have a