This is a note by K. Kubo on the apparent differences between results of the main linac DFS simulations by Kirti Ranjan and by K. Kubo.
http://ilcagenda.linearcollider.org/materialDisplay.py?materialId=1&confId=753
http://ilcagenda.linearcollider.org/getFile.py/access?contribId=18&sessionId=10&resId=0&materialId=slides&confId=2364
BPM offset sensitivity:
As pointed out by P. Lebrun in the meeting, and also suggested by several people before, the difference may come from difference of the weight factor (relative weight of orbit difference and orbit itself) in DFS. It will not be difficult to confirm this.
Cavity tilt sensitivity:
As pointed out by P. Lebrun in the meeting, the effects of cavity tilt is dominant at low energy part, at the beginning of the linac. In my simulations, injection energy, not only the cavity voltage, is changed. Kirti did not change the injection energy, only cavity voltage was changed and “Linac is divided into 18 segments (w/ 50% overlap) & 1st DF segment starts from 8th BPM”. It is possible the apparent difference of the sensitivity to the cavity tilt came from this difference in the procedures of DFS. It will not be difficult to confirm this (but need much more work than for previous problem).
2008.03.25
Kiyoshi Kubo
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