Minutes from Beamdynamics meeting

Daniel pointed out that the EPAC papers should be submitted to Hans before 16 May. The papers should also be sent to the groupleader and the ones related to EUROTeV should be sent there as well.

Javier is working on his LHC EPAC paper. No CLIC work for the moment. He has also recently studied the collimation efficiency.

--> Should study collimation efficiency for horizontal and vertical plane separately.

Warner showed results from his ECLOUD simulations. Using a fine grid the charge density is a factor 100 off compared to previously predicted for steady state. This factor can for the moment not be explained. Previous simulations agreed for several different codes.

--> Warner has to find the reason for this discrepancy.

Lionel has studied multipole errors in the CLIC linac. Phase and deformation factor studied for different δ. The deformation of the core is stronger than the deformation of the tail.

--> This has to be understood.

Maxim explained that he has studied how well a vertical waist shift can be compensated with a realistic waist knob consisting of 5 BDS sextupoles (that are moved horizontally).

--> Should study the use of quadrupoles and also try to create coupling knobs.

Giovanni and Andrea have been investigating the effect of hor. and vert. collimator misalignments in the BDS. Luminosity studied with GUINEAPIG. For hor. misalignments of less than 10μm the effects are small. Horizontal misalignments of the order of 50μm have a similar effect on luminosity as vertical misalignments of the order of 10μm, both giving luminosity loss of 20% in worst cases.

Helmut said that the GEANT4 SR procedure, together with examples and samplejobs have been committed. He is currently working on the documentation and has agreed with Albert Hoffmann that he will have a look at the draft of it.

Peder explained he has just come back from two weeks in Japan, one of which was spent at Sokendai for the first International Accelerator School for Linear Colliders. The school was tough but rewarding.

Rogelio is currently writing a CLIC-note about his PTC optimisation of the BDS. He is also preparing a talk for the 9 June.

Daniel finally mentioned he is studying multibunch effects on the main linac tuning. He also mentioned that there will be an ILC video meeting next week as a first step of preparing for the Vancouver meeting in July.