Minutes from Beamdynamics meeting

Lionel informed that he has taken a look at the intra-beam scattering in the damping ring according to Franks idea. This he can also discuss with Maxim who has studied how this affects emittance.

Giovanni has finished the module for collimator wakefields. The only thing that still remains is to integrate it into Placet. This he will sort out together with Andrea. He has also worked on geometric ? together with Warner.

Piotr explained that he has implemented PTC in MADX. Any MADX parameter should be possible to match w. PTC. According to Rogelio matching of a function of parameters is for the moment not possible w. MADX. This should be investigated.

Andrea has created a tool to convert from XSIF to Placet format. This tool now works well. He will now have a look at how to match the beam from the BC into the linac.

Peder has just finished preparing a plot for the next ILC newsline. Daniel proposed that he should now try to make a list of the dynamic effects that have an influence on emittance tuning. This includes for example, beam jitter and phase jitter.

Rogelio reported that he is writing a note on how to use the Python class for optimisation of σ_x and σ_y at the IP. He is also working on the FFS for LHC and commented that some if this work might be useful for CLIC.

Daniel has been running some ILC simulations with Placet in order to compare the code to other tracking codes. Differences of 10% have been found even for the betatron motion. He has also done some modification in Placet to make it possible see a graphical overview of the beamline. He also implemented a function AddElement that can be used to add elements after the beamline has been set.

Javier is studying the new shorter non-linear collimation lattice that is of roughly the same length as the linear one. The luminosity is slightly lower than for the longer lattice. But it might be possible to optimise further if a better spoiler material can be found. He has also run some BDSIM and GEANT4 simulations lately and have found some problems that was reported to Ilya Agapov and are now fixed. Daniel proposed that Javier should study how the phase space is limited by collimators. In this way one can quickly see whether a halo will survive or not.

Warner said that he found a bug in his electron cloud tracking code when he was running some simulations. The bug caused an error in the space-charge calculations. He will redo the simulations done before the bug was found. He has also spent some time thinking about how to speed up the code, which has given good improvement. For the moment Daniel thinks that it is more important to get results than to continue speeding up the code.

Maxim presented the work he has done on FFS knobs for luminosity tuning. He has sofar looked into how to use sextupole movements to adjust first and second order matrix elements. Five sextupoles have been used so far. Vertical offsets of as little as 200nm gave luminosity losses of 20%. The vertical dispersion was not changed though which is a bit strange. Daniel proposed that Maxim should study how to change quantities like offset, angle, coupling and waist instead of matrix elements, which might be interesting to continue with later. Daniel also wondered what effect an error in quad strength would have and if this could be corrected by the FFS knobs. Rogelio mentioned that it can maybe be done by K-modulation and Daniel said that a DFS-like method might also be possible.

Next meeting will take place in one or three weeks.