Minutes from Beamdynamics meeting

Helmut mentioned that he is planning to replace the SR routines in MAD. At some point also in Placet.

Giovanni said that he, together with Andrea, has simulated the wakefields in the collimators using Placet. No non-linear effects are taken into account for the moment. Non-linear effects are already taken into account in HEADTAIL, so it should be straightforward to include in Placet as well. Will the time-consumption be a problem? Probably not, but there is a lot of cos/sin evaluations.

Warner informed that he has found the reason for the factor between his code and other for the steady-state. Now the difference is smaller than a factor 2. He has also started running simulations with saw-tooth (grooved) surfaces. Mesh for a sawtooth surface. During these simulations some new problems showed up (eg. too much SEY) that have to be sorted out. Warner also showed some results obtained by Wang for sawtooth surfaces.

Javier is currently trying to calculate the coherent tune-shift for LHC caused by the impedance of all collimators of the non-linear and linear collimation system respectively.

Lionel has integrated HDGEN into the head Placet branch. "make hdgen" has to be used to compile this version of placet due to external software needed. He has run simulations using BDSIM for comparison and could conclude that for 5000 particles a run took 3 hours with BDSIM and less than a minute with Placet.

Daniel explained that he had been asked to run simulations of the crab-crossing cavities. They are now included in the BDS. He has implemented the wakefield modes that he got from Roger Jones. Due to wakes a bunch jitter of 1σ at the entrance to the BDS leads to a 5σ jitter at the IP. For ILC there will at least be an IP feedback. What can be done for CLIC?