ILC Asia WG4 : Minutes of 56th meeting
February 22 10:00- noon
Rm.425 bldg.3 at KEK.

Update of the ATF2 optics (optimal v.3.1) by M.Woodley, and discussion on the Layout

(presentation, pdf (825KB, 10 pages)

M.Woodley, who is visiting for the ATF experiment, presented update of the optimal 3, i.e. version 3.1 at this moment. Improvements from v.3.0 are (1) filp sign of the 2nd kicker for both to bend the same way (-I compensation ?), (2) replace the EXT bending with two BH1Xs for final trajectory parallel to DR north straight with a 6.7m separation . (3) add small quadrupole between BH1Xs for dispersion correction and (4) add match (after 2nd kicker) to skew correction section, all of which aim minimization of dispersion. Also, he pointed out following issues to be discussed and studied;

It was also pointed out that the GDE-RDB (R&D Board) may ask the fast kicker study at the ATF2. While this upgrade was included in the ATF proposal, the GDE initiative may accelerate it. So, we should take account of it in the optical/layout design from the beginning.

No. of movers and sextupole component in Bends by S.Kuroda

(presentation, pdf (97KB, 1 page)

First, Kuroda specified the number of movers which is absolutely necessary for space limitation to install steering magnets and chromaticity tuning knob for the sextupole magnets. The total number is 21, where 16 for Qs and 5 for SXs. NO mover is necessary for octupoles, while the tail-holding octupoles may need them which are not included in the present optics.

Second, he presented beam size (&sigmay) growth with sexupole components on the three Bends (B5, B2, B1) in the ATF2-FF by SAD simulations. The normalized components (B2/B0) were presented at K2=1 and r=10mm, where r is radial distance from the beam line at the Bends and there is a difference between SAD and MAD conventions to be noted. B2 has the most severe SX component limit; &sigmay=39nm at K2=1. He will summarize the tolerances at next meeting, 1 March 2006.

Report of the LET meeting at CERN by K.Kubo

(presentation, pdf (96KB, 8 pages)

Kubo reported the LET meeting, CERN, focused on the BDS related talks and future plans. There were two talks: (1) Beam-beam tuning" with beamstrahlung energy loss, by P.Eliasson and D. Schulte and (2) "ILC BDS Alignment, Tuning and Feedback Studies", where alignment and tuning strategy were proposed, by G.Whilte . The meeting concluded to define action items, especially calling for new-commers to verify the results by simulations. He suggested Kuroda and Okugi to be involved in this action for the ATF2 should be a prototype of ILC BDS and the ATF2 optics people should understand beam dynamics in the ILC BDS. We all agree on his suggestion.

Woodley asked if the computer firm, which G.Whilte uses for the simulations, is available for these people. Kubo will communicate with him on this question. The LET group will have its own regular meetings (next meeting on 24 Feb.) .

Cable length of the movers, discussion

We discussed on the cable length since we were requested by A.Seryi (SLAC) who will dismount the FFTB movers in this April. Our conclusion is that the cables should have the longest lengths since the layout wont be finalized before April 13. So, We would like to cut the cables, i.e. optimize the lengths, at KEK.

Organization of BDS/MDI working group in Japan by T.Sanuki

(presentation, pdf in Japanese (213KB, 13 pages)

Presentation and discussion were executed in Japanese since this issue was re-organization of Japanese group. After intensive discussions, we reached following agreements; (1) this weekly meeting becomes the ATF2 meeting, (2) the ILC-Asia WG4 meeting may be non-regular to discuss on non-ATF2 issues such as permanent and SC FD magnet, RF kicker and gamma-gamma collider R&D, Sanuki will organize this meeting. (3) We will collaborate even more with H.Yamamoto, who is a GDE-AG-BDS member and the MDI panel chairman, for the ILC-RDR.

The next meeting will be 1st March 2006.