Novel Method of Compensation of the Effects of Detector Solenoid on the Vertical Beam Orbit in a Linear Collider

Abstract

This paper presents a method for compensating the vertical orbit change through the Interaction Region (IR) that arises when the beam enters the Linear Collider detector solenoid at a crossing angle. Such compensation is required because any deviation of the vertical orbit causes degradation of the beam size due to synchrotron radiation, and also because the nonzero total vertical angle causes rotation of the polarization vector of the bunch. Compensation may be necessary to preserve the luminosity or to guarantee knowledge of the polarization at the Interaction Point (IP). The most effective compensation is done locally with a special dipole coil arrangement incorporated into the detector (Detector Integrated Dipole). The compensation is effective for both e{sup +}e{sup -} and e{sup -}e{sup -} beams, and the technique is compatible with beam size compensation either by the standard method, using skew quadrupoles, or by a more effective method using weak antisolenoids.