Minutes from Beamdynamics meeting

Daniel started by mentioning that a test program for the structures has been discussed. No major breaktroughs.

Warner showed his results of simulations of SEY for grooved surfaces. His results are similar to the ones of Wang, but in general higher (almost by a factor 2). He has also prepared a EUROTeV paper on impedance studies. Warner also mentioned that he is currently working on a 3D version of his code.

Rogelio has been trying to reduce the length of the FFS by scaling while keeping β* constant. An improvement of 25% has been achieved so far. Emittance is not improved by more than 5%. Luminosity seems to be very difficult to improve.

--> Rogelio has to study the effect on diagnostics.

Giovanni showed a draft of his talk about "LC e-cloud activities at CERN".

--> Warner's work, in particular on grooved surfaces, will also be included in the talk. And also Giovanni's work on HEADTAIL during the end of last year.

Maxim is currently working on beam-based alignment of the BDS. A test beam energy difference of 1% will not be enough for the DFS algorithm. Another way of determining the dispersion could be to change the quadstrength/energy matching. NB! This might at the same time lead to an offset of the quadrupole magnetic centre.

--> Maxim should have a look at the work of Glen White to understand how his algorithms work.

Andrea explained how he recenty has been working on an octave interface for Placet. This octave interface will be able to open up from inside the Tcl interface and would allow the use of Octave's mathematical tools.

Peder has calculated the emittance growth due to different misalignments as a function of DFS weight when both DFS and tuning bumps are used for alignment. For this study he has been using his new Placet routine for quick optimisation of linear tuning bumps. Results agree quite well with Daniel's results from last year which were calculated with the old beam parameters. For cavity realignment errors the emittance growth is clearly lower because final emittance has been used as a tuning signal instead of local measurements.

--> Should make sure that cavity movements needed for the tuning are not too large.

Erik Adli presented himself and the work he is going to do on TBL quadrupole instabilities. He has started by studying the required theory and has been trying to use Placet.

Lionel said that he will include vacuum settings for the Placet simulations. He also mentioned that the HDGEN package has now been merged into the main thread of Placet.

A discussion about the documentation of Placet was then held. The Placet documentation has to be updated. A lot of new functionalities have been added during the last year which have to be described. Besides, there was never much written about the TBL specific commands. Maybe a Placet tutorial would be a good idea. It was decided that small Placet tutorial will be arranged from time to time. Next weeks meeting will be devoted to a Placet tutorial. Rogelio will present a minimal BDS tracking example using Placet.

Daniel finally reminded people to submit ICAP material. According to Giovanni the deadline has been moved until the end of October.