Minutes from Beamdynamics meeting

Introduction by DS with several announcements

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All financial reports are almost ready.

The first EUROTeV review took place successfully.

On the 27th Jan there will be a 1-day meeting in Hamburg concerning management issues.

The outcome of the Frascati workshop will be presented in the next Friday CLIC meeting.

There will be a workshop on Low Emittance Transport in the mid of February at CERN. A few CLIC specific issues should be discussed beforehand in a preparatory meeting, in which people from outside CERN (CEA, PSI, Upssala) could also take part.

Individual reports on the work status

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LN -> In collaboration with JR, LN has been implementing the physical aperture element by element in the lattice for PLACET. The physical aperture information is taken from a MAD file, but RT says that according to FZ this information might not be correct. Action: JR has to contact FZ to look for the correct data, which certainly exist. Tracking with aperture will allow finding the places where particles get lost. From that point on, secondary particles will be tracked. Tracking photons would also be interesting because photons create lots of background.

HB -> Continuation of synchrotron radiation studies using GEANT.

AL -> Progress in PLACET code development: modules for longitudinal motion as well as synchrotron radiation emission (in some elements) have been constructed and the modules are being integrated in PLACET. Simulation of the bunch compressor with the integrated code has been carried out and preliminary results seem reasonable.

GR -> Progress in the module for collimator wake fields: the module contains up to now the geometric kicks in different regimes (inductive, intermediate and diffractive) for the tapered parts and the resistive wall kicks for the short-range and long-range regimes (with or without ac conductivity, tapered and flat parts), but the intermediate regime (relevant for CLIC) has still to be implemented. This is not straightforward because it requires the numerical resolution of a triple integral depending on several parameters. Once the module is ready, first testing is foreseen and then integration in PLACET in collaboration with AL. Expected time scale to get to first results is a couple of weeks.

RT -> RT has been working on matching modules in Python that can read PTC output to minimize the beam size at the IP or geometric and/or chromatic terms. Problems with beam centering need to be solved before producing sensible numbers.

DS -> DS implemented routines in PLACET to simulate measurements taken from BPMs with their errors (resolution as well as scaling errors) used to re-calculate other quantities. This routine should ultimately allow the user to simulate the full dynamics of alignment.

JR -> progress on work on the nonlinear collimation system: JR has calculated the peak density at the spoiler location and estimated the lowest possible sextupole strength that does not cause luminosity reduction and still ensures the spoiler survival.