The 2mrad crossing angle scheme for the international linear collider

http://cern.ch/AccelConf/e08/papers/mopp005.pdfInternational audienceThe present baseline configuration of the ILC has a 14 mrad crossing angle between the beams at the interaction point. This allows easier extraction of the beams after col- lisions, but imposes on the other hand more constraints on the control of the beams prior to colliding them. More- over, some limitations to physics capabilities arise, in par- ticular because of the degraded very forward electromag- netic detector hermeticity and because calibration proce- dures for (gaseous) tracking detectors become more com- plex. To mitigate these problems, alternative configurations with very small crossing angles are studied. A new version of the 2 mrad layout was designed last year, based on sim- pler concepts and assumptions. The emphasis of this new scheme was to satisfy specifications with as few and feasi- ble magnets as possible, in order to reduce costs