Minutes from Beamdynamics meeting

Time: 16:00 30 Mar 2005
Place: 6/2-002
Participants: T. Asaka, H. Burkhardt, R. Corsini, P. Eliasson, J. Resta Lopez, F. Ruggiero, D. Schulte, F. Tecker, C. Welsch, F. Zimmermann

Daniel started the meeting by reporting about simulations that Ronen has carried out to compare the predicted and measured beam energy along the CTF3 linac. The energy was obtained by measuring the response in the bpms to a kick of the beam. Towards the end of the linac there are large discrepancies between the simulated and measured values. This might be caused by problems with the dipole correctors. Some of the correctors might be of another kind than the others.

Frank T then informed that he has investigated how the initial energy is used for tracking in MAD. He thought that the ERESET option might have an effect on the code comparison that Javier and Takao are doing.

Frank Z explained showed results of studies of the damping ring effects. Overall things look promising, but the space charge tune shift might be a problem. Helmut asked about TMCI and Frank will have a look at it.

Helmut said he has looked more into MAD-X and SR. He would like to see what it works like for CLIC-simulations. Frank Z pointed out that he might get problems because of the thin/thick lens approximations used in MAD-X/MAD8. Daniel still wants to see first if SAD, MAD8 and Placet are enough for the simulations needed.

Takao showed a comparison of phase space plots for Placet, SAD and MAD. The simulations were performed for 40000 particles with and without SR. He also showed histograms of the x- and y-coordinates for the three codes. The results from the different codes now agree well. The previous problems were caused by some octupoles in SAD.

Javier showed plots that he and Takao had obtained by studying the phase space ellipse for different energies (-0.3%, nominal, +0.3%). The agreement is ok but not even for the nominal energy perfect. Francesco mentioned that off-energy particle calculations are known to be treated in a not very good way in MAD.

Daniel proposed that Javier should create a movie showing the movement of the phase space ellipse along the line.

Daniel finally explained that he has studied how much the beam can be offset before one gets a 10% loss. He did this with and without wake-fields included.

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Last updated: 02 Jun 2005