Abstract 

Collimators in the CLIC BDS could cause luminosity reduction through the action of single-bunch wake fields. In fact, the effect of wake fields can result in jitter amplification and/or emittance growth. According to the chosen ranges of parameters, differences in the transverse kicks felt by the bunch particles due to both the geometric and resistive wall components of the wake fields for different regimes are discussed (inductive or diffractive for the geometric  wake fields, short- or long-range, intermediate regimes for both). A module for collimator wake field calculation based on these kicks has been constructed and implemented in the tracking code PLACET to study the direct effect of collimator wake fields on luminosity performances. First tracking results are shown.

Hans presented Eric Adli who will join the CLIC team working on TBL issues soon.

Giovanni introduced geometric and resistive-wall wakefields from collimators and compared the analytical formula for a geometric wake to simulations by GdfidL. A module calculating both types of wakes has been implemented in the PLACET code whereof some examples were shown.