Intrabeam scattering: Difference between revisions

Revision as of 20:11, 30 August 2006

Revision as of 20:21, 30 August 2006

Line 1:

'''Intrabeam scattering''' ([[IBS]]) is an effect in [[accelerator physics]] where collisions between particles couple the [[beam emittance]] in all three dimensions. This generally causes the beam size to grow. In proton accelerators, intrabeam scattering causes the beam to grow slowly over a period of several hours. This limits the [[luminosity]] lifetime. In circular lepton accelerators, intrabeam scattering is counteracted by [[radiation damping]], resulting in a new equilibrium beam emittance with a relaxation time on the order of milliseconds. Intrabeam scattering creates an inverse relationship between the smallness of the beam and the number of particles it contains, therefore limiting [[luminosity]].

The two principle methods for calculating the effects of intrabeam scattering were done by [[Anton Piwinski]] in 1974 and J.[[James Bjorken]] and S.[[Sekazi Mtingwa]] in 1983. The Bjorken-Mtingwa formulation is regarded as being the most general solution. Both of these methods are computationally intensive. Several approximations of these methods have been done that are easier to evaluate, but less general. These approximations are summarized in ''Intrabeam scattering formulas for high energy beams'' by K. Kubo ''et al''.

Intrabeam scattering rates have a <math>1/\gamma^{4}</math> dependence. This means that its effects diminish with increasing beam energy. Other ways of mitigating IBS effects are the use of [[Wiggler (synchrotron)|wigglers]], and reducing beam intensity. Transverse intrabeam scattering rates are sensitive to dispersion.