52nd ATF2 meeting

1. Final optics and updates of the part list, Mark Woodley (SLAC)

The presentation was very comprehensive on the "final (v3.7)" optics and layout. The detailed information can be available at this web site.

A number of issues were pointed out on the parts list and the optics/simulation. Some of them are discussed here and after the meeting as follows;

1. ODR : It has been removed from the beam line and there is no plan to install it again at present.
2. Bipolar power supplies for 6 FF matching quadrupoles (QM16FF-QM11FF) ; There are two options. First is a new system with bipolar output which in integrated in the HA system. The second one is a manual switch to reverse the polarity. Both options cost significantly. So, we will continue to discuss.
3. Alexander Kalinin�fs Feedforward/Feedback devices : we received a reply from P.Burrows. That is; "There is no problem of 'coexistence' between Alexander's proposed system and 'FONT' - they are the SAME! ... we agreed to try to finalize the details of the BPM/kicker locations by the end of this year"
4. A S-band reference cavity is missing in the part list : In principle, C-band reference cavity can be used (shared). UK group expressed to bring it with the S-band BPMs.

1. cables for KEX1/KEX2 and new location for power supply
2. will there be powered trim windings on B5FF, B2FF, B1FF, BDMP?
3. have we planned for a power supply for BDMP?
4. need 2 new 20 amp bipolar power supplies for EXT skew quadrupoles (QK1X,QK4X)
5. what is actual maximum current (magnet limited) for 2.13S3.00 sextupoles (after addition of cooling circuits)?
6. need supports of three Bends (B5FF, B2FF, B1FF)

1. OTR1X �c interference with DR quadrupole QM8R.1?
2. possible reduced (20-25%) gradient for extracted beam in QM7R.1: can�ft match in EXT using only quadrupole strengths �c change DR optics to compensate?

• Q : Is there "Monalisa" system between the two nBPM-triplets ?
• A : No. The Monalisa system will be installed at IP, i.e. monitor relative displacement between QD0 and Shintake monitor.
• C : There will be the fast kicker R&D to extract multibunch beam in ILC structure. So, the fast kicker and the present double kickers may be operated alternately .

2. Detailed configuration around IP, Toshiyuki Okugi (KEK)

There is one change since the 4th project meeting. 31sy May 2007, DESY. A defocus quadrupole ( 60mm long ) is added in a space between QBPM24FF and BDMP, since the Shintake monitor group requested for the background reduction. The beam sizes were calculated at BDMP as a function of the Q-strength (K1). The Shintake group will study the performance in details.

Also, he showed two possible designs for the sweeping magnets to scan the beam at IP, which are magnetic (coil) and electric (stripline) ones. The sweeping magnets will be fabricated in next fiscal year; i.e. JFY2008.

3. Carbon wire scanner, Doug McCormick (SLAC)

The pictures of two scanners are overlaid to illustrated how this could look after joining them. The horizontal scanner measures the vertical beam size and the 45 degree's one is to measure the horizontal size. The accuracies are 1-2um and 20-30um, respectively, where the carbon wire has 4um diameter. The scanner has a step size of 100nm.

• Q : Are the carbon wire available for spare ?
• A : Yes, there must be spare wires to be confirmed.

4. Design values of beam size and parameters, S. KURODA, T.Tauchi(KEK)

There is a question on the design value of beam size. What is the right number ? The "actual" one can be estimated by MAD, ELEGANT, TURTLE, DIMAD, LUCRETIA and SAD tracking . Also, it depends on corrections as well as the beam parameter.

In discussion, it was pointed out that the geometric beam size is reasonable to represent the design value . It is 34nm as listed in page-14 of M.Woodley's presentation (ATF2v3_7.ppt ), while the tracking values are 35-37nm . Anyway, we must show the design values together with the beam parameters and the tracking scheme.

5. KEK site meeting ( in Japanese )

The next ATF2 meeting will be held on 25th July 2007, 2:30pm -, 3-gokan, 425, KEK, TV-ID#=31110 with the KEK Gatekeeper and ILC Webex.