Contribution Oral presentation
Polarisation and beam energy measurement at linear e+e- colllider
The International Linear Collider (ILC) is a future e⁺e⁻ collider at the energy frontier. Its physics goals are clearly focused on precision measurements at the electroweak scale and beyond. Beam polarisation and beam energy are two important parameters, which need to be measured and monitored to unprecedented possible precision. In this talk we will present the concepts of polarisation and energy measurement according to the baseline design of the Technical Design Report of the ILC. Two Compton polarimeters per beam line will determine the beam polarisation. The anticipated precision of this measurement of ∆P/P = 2.5 × 10⁻³ puts highest demands on detector alignment and linearity. We will comment on recent detector developments as well as detector calibration, which allows for meeting this challenging design goal. The beam energy will be measured before and after the interaction point to a targeted precision of ∆E/E = O(10⁻⁴). We will discuss both planned independent concepts in this talk: A noninvasive energy spectrometer based on beam position monitors is planned to be operated before the interaction region. Behind the interaction region, a synchrotron radiation imaging detector will allow not only for measuring the beam energy, but also gives access to the beam energy spread of the beam after collision.