ILC Asia WG4 : Minutes of 22nd meeting http://lcdev.kek.jp/ILC-AsiaWG/WG4notes/ April 6 10:00 Rm.425 bldg.3 at KEK.
Honda will report the angular jitter (as well as divergence) effect on the resolution at the next meeting.
Kuroda introduced Pivi's talk on the bunch compression system consisting of a chicane sandwiched between two RF cavities of S and C-band. The energy spread is inversely proportional to the bunch length in his design. However, Yokoya pointed out that a non Gaussian tail in the compressed beam must create significant background for the Shintake monitor. So, aperture must be wide enough for the "1%" energy spread.
After discussions, we finally agreed that the baseline design has no bunch compression because of the background issue and limited space as well as saving the budget.
So, at today's meeting, we agreed that we make a baseline design with no interference with the KEKB crab cavity area and an optional(ideal) design of the straight beam line adding a Mark's 10m long coupling correction section. Apparently, the baseline design can not have additional space for the coupling correction. Both beam lines must keep off the piping system (blue area in the figure) and the RF gun area both with 3m open space for concrete shield. No bunch compression system is considered in both designs.
Kuroda will make these designs consulting with the optical design group by the next meeting. Also he ask Araki-san for drawing the layout in the assembly hall.
Kubo will ask Mark for simulation of the coupling correction under the present condition at the ATF extraction line. Mark' talk can be found on this home page ( ILC-BDS at SLAC) .
When the beam line increases in length close to the assembly hall wall, the beam dump must be thicker than the present one of 3m thick concrete. Kuroda (Terunuma) will ask radiation safety group for the necessary thickness, where the beam dump must be 3m apart from the wall. Also, Tauchi (Urakawa) will estimate additional cost for the extension by the next meeting.