Determination of the Luminosity-Weighted Polarisation Average

While the polarimeters measure the instantenous beam polarisation far away from the electron-position interaction point (IP), the physics measurements at the ILC rely on a precise knowledge of the luminosity-weighted average polarisation for a given dataset at the IP. The latter can in addition be calibrated from the electron-positron collision data itself by making use of well-known Standard Model processes as reference. By means of simulation studies of the accelerator, the polarimeters and the collision measurements, the strategy for calibrating the polarimeters and for extracting the information relevant for physics analysis.

Master thesis or part of a PhD thesis

Polarimeter Alignment and Calibration of the Analysing Power

Compton polarimetry relies on the measurement of the spacial distribution of about 1000 Compton scattered electrons per particle bunch in a (multi-channel) Cherenkov detector. Testbeam measurements showed that position resolution within a single detector channel can be achieved by employing segmented photodetectors. The impact of such an improvement on the actual polarisation determination needs to be evaluated by means of simulations and the existing testbeam data of two detector prototypes.

Master thesis or part of an PhD thesis

The ultimate Polarimeter Detector

Two different technologies for the polarimeter detectors have been prototyped in the past years and testbeam data has been taken with both of the individually. In order to decide which technology is best suited for the upstream or downstream polarimeter, a combined testbeam with both detectors needs to be performed. Based on the past experience and the analysis this campaign needs to be prepared, performed and the data analysed to draw final conclusions if the ``self-calibrating'' aspect of the Quartz-detector holds up.

PhD thesis

A Pixel Polarimeter

When instead of a Cherenkov detector a pixel detector would be used, the transverse polarisation component could be measured in addition to the longitudinal one, and the measurement precision could possibly be improved significantly. A conceptional study to quantify the expected improvement on the longitudinal polarisation measurement ouwl be ideally suited as a Master thesis.

Master thesis