2.3 Circe^{[ohl circe paper]}

Circe is a parametrisation of guinea-pig output written by T. Ohl in 1997. It provides a faster way to generate beamstrahlung beam data, and the function it uses as a parametrisation of the spectrum is often used as a fitting function for linear collider luminosity spectra (cf. Ref [1Monig reconstruct paper].)

The fitting function used is of the form:

(equ. 1.)

where f(x) represents the luminosity spectrum ∂L/∂√S,

x is the √S/√S_nominal, the ratio of center of mass energy to beam energy,

and a₀ ...a₃ are the four fitting parameters—one of which is usually be found by normalisation of the spectrum.