An interaction region with head-on collisions is considered an alternative to the baseline configuration
of the International Linear Collider which includes two interaction regions with finite crossing-angles
(2 and 20 mrad). Although more challenging from the point of view of the beam extraction, the head-on
scheme is favoured by the experiments because it allows an easier optimisation of the detector configuration,
particularly in the forward region. The optics of the head-on extraction is revisited, as compared to the
TESLA TDR, by separating the e+ and e- beams horizontally, first by electrostatic separators operated at
their LEP nominal field and then using a defocusing quadrupole of the final focus beam line. In this way the
septum magnet is protected from the beamstrahlung power. The influence of parasitic collisions is shown
to lead to a region of stable collision parameters. |
