Public Note / ACCDT / MDETINTF ILC-NOTE-2010-053

TEN-TEV E+E- COLLISIONS WITH BEAMSTRAHLUNG COMPENSATION FOR LINEAR COLLIDER

Andrei Seryi (SLAC National Accelerator Laboratory, Menlo Park, California, USA )

Abstract: Extension of e+e- linear collider parameters into the ten-TeV energy range is usually complicated due large beamstrahlung energy spread generated during collisions of the beams. We suggest evaluating a four-beam approach for achieving the ten-TeV energy range, when the harmful beam-beam effects would be compensated by collisions of two pairs of electron and positron bunches. In contrast to four-beam collision schemes considered in the past [1,2], we suggest to optimize parameters in such a way that for the un-compensated collisions the disruption parameter Dy will be small, while the beamstrahlung energy spread dE will allowed to be very large. In this case, four-beam collision would not exhibit the beam-beam instability, allowing for an accurate compensation of the field and therefore suppression of the beamstrahlung energy spread. Moreover, for simplification of the beamline design and for simplification of decoupling the e-e- and e+e+ luminosity signals, we also consider the case when the two pairs of colliding beams have different energy, such as 1 TeV and 5 TeV per beam. This paper describes the overall concept, presents an example parameter set, discusses the scaling of the parameters, and outlines further studies needed for development of the concept.