Minutes from Beamdynamics meeting

Daniel informed about the Vancouver meeting. One of the objectives of the meeting is to estimate the cost of ILC. This cost estimate will not be public.

Javier showed results from his recent work on collimation efficiency, starting by reminding everyone about the definition of efficiency in this context for linear collimation systems. He has tried to apply the same definition to the non-linear CS. The cleaning inefficiency is high for the the non-linear CS, but this simulation is not 100% correct and a new simulation has already been started.

--> This study should also be carried out for monochromatic beams to see if the high inefficiency is caused by energy spread.

Javier also presented loss maps. These show that collimation mainly occur in vertical spoilers.

Warner presented his latest results on electron cloud effects. He has calculated the position of the flux maxima for different bunch charges ranging from 2*10^10 - 1.6*10^11. He also explained that he had a corrected a bug reducing the factor differing his steady state results from results obtained with other codes from 100 to 10.

Peder informed that he is running simulations and preparing slides for the Vancouver meeting. The results concern DFS and emittance tuning bumps for straight and curved ILC linacs. These simulations also include effects of the BPM scale errors.

--> Peder should start writing a quick routine for estimating the performance of linear main linac tuning bumps.

Maxim reported about his work on determination of BDS quadrupole strength sensitivity. He has calculated the maximum strength change tolerable to stay below 2% luminosity loss. In a few cases this tolerance is a lot tighter than 10^-4.

--> Should study stability over a few pulses.

Apparently realistic luminosity loss levels (<2%) will giv every tight tolerances on quadrupole strength stability.

Philipe (summer student working with Rogelio) explained how he has improved the speed of Rogelios MAPCLASS program with 39%. This was done using a python module called PEXPECT to reduce the number of calls to MAD. He has also used MAPCLASS to try to improve FFS luminosity. This gave a 28% improvement compared to nominal luminosity.

Rogelio said that his article on BDS optimisation has been accepted. Andrei Seryi was in the committee and he was impressed by how much faster the sextupoles can be optimised with this method compared to older methods. Instead of days it now takes 10 minutes.

There will be a new meeting next week.