54th ATF2 meeting

1. Hardware Check of ATF extraction line, Toshiyuki Okugi (KEK)

Okugi checked the hardware, especially the availability of steering magnets, BPMs and the SLAC-OTR at the extraction line.

There are enough number of vertical steering magnets but few of horizontal ones. The v3.7 optics has 4 horizontal steering magnets and 2 vertical ones. The horizontal steering magnets can be available by rotating vertical ones by 90^o. There are 5 power supplies for the steering magnets and 5 more power supplies which must be repaired. Therefore, all 6 power supplies will be available with repair.

At present, there are 3 kind of stripline BPMs, that is, 5 short (40mm long) stripline BPMs with wide pipe, 4 short (40mm long) stripline BPMs with narrow pipe and 5 long (120mm long) stripline BPMs with narrow pipe. So, the total number is 14, while there are 12 stripline BPMs in the v3.7 device list. Since most of them have different lengths of beam pipes compared with those in the v3.7 device list, they will be modified as listed in the presentation. Following 2 re-locations are suggested; (1) ZV6 in downstream by 80mm and (2) ML9X at upstream of QF9X.

Total length of OTR was measured to be 380mm, while it is assumed to be 300mm in the v3.7 device list.

• Q : where are readout points of BPMs ?
• A : we assume center of the electrodes.
• Q : Can the OTR be put between BS3X and ZV1X ?
• A : Since Dough may know details of the geometry of OTR, M.Woodley will ask him for this question.
• Q : Can a space is available for the carbon wire scanner ?
• A : It may depend on installation of an additional Q after IP. The carbon wire scanner needs 200mm for space .
• Q : where is the additional Q ?
• A : It is in front of bend. Shintake monitor group asked for the installation, but we have no requirement with detailed estimation yet.
• Q : What kind of Q is it ?
• A : It is a horizontal defocus Q.

2. Magnet position adjustment at the extraction line, Ryuhei Sugahara (KEK)

Concrete bases of magnet supports have been produced in JFY2006 . The bases have metal (SUS) plates with machining holes in order to place magnets precisely. The design is based on v3.5 optics. In the v3.7 optics, there are 7 changes in three type of bases and addition of 2 steering magnets as listed below;

1. ZV7X-QK1X-QD10X ( type of Q+Qk+ZV )
2. ZH5X-QF11X ( type of Q + ZH)
3. ZV8X-QK2X-QD12X ( type of Q+Qk+ZV )
4. ZV9X-QK3X-QD16X ( type of Q+Qk+ZV )
5. ZH8X-QF17X ( type of Q + ZH)
6. ZV10X-QD18X ( type of Q + ZV)
7. ZH9X-QF19X ( type of Q + ZH)
8. ZH1FF and ZV1FF between QM16FF and QM15FF

• Q : Can the above three type configurations be back to those in the v3.5 ?
• A : Some of them may be difficult. I would like to know how far to move steering magnets.
• Q : Would you give me the movements ?
• A : Yes; ( answer in the above excel file of the differences from v3.5, received after the meeting)
• Q : ZH1FF, ZV1FF seems to be too close to QM15. Can they be shifted to upstream, e.g in middle of QM16FF and QM15FF ?
• A : It is difficult since the location is at the IP phase for feedback and it is quickly changed to the final double phase. For the feedback, the optimal positions of steering magnets are center of Q, which is the reason for the close location.
• C : I will check a possibility for the close location .

3. Short-pipe C-band BPM and Re-location of IPBPM test setup,Yosuke Honda (KEK)

The short-long c-band BPM has been suggested at QD6FF for LW signals which are separated from the beam by BF5FF. Checking the geometry in drawing, it was found that the long ( standard) BPM is OK with slight modification of the adapter for 20mm diameter aperture of LW signals. One short long BPM will be installed at downstream of IP, that is QBPM24FF.

The location of IPBPM test setup has been a problem for aperture of LW signals as discussed at the 3rd project meeting. Also, nano-BPM triplet is moved to downstream for IP feedback. Since the LW signals require 20mm aperture at least, the IPBPM setup is suggested to move to upstream.

• Q : What is nBPM aperture ?
• A : It has 20mm aperture.
• C : nBPM support table needs 2m long space, while 1.5m is only available . On the ceiling shield around the location, there is a LW Laser hut. So, no access from the top.
• Q : Since we need 10nm resolution for IP feedback, is it possible to use QBPM?
• A : if we have good electronics, it can have 10nm resolution.
• C : Since the location is the IP phase location, high resolution BPM and mover are necessary.

4. Realignment of septums for extraction, Shigeru KURODA (KEK)

Since some magnets will be installed at the mew extraction line for week from 20th August, we would like to decide the septum alignment issue. Kuroda reminded this issue which has been discussed at previous meeting, April 25 2007. He updated a correction by septum fine tuning with a constraint of common power supply for BS1X and BS2X, where there is 1.2% change of current correction and 0.5mm position change. Present mis-alignment can be tuned by these corrections.

• Q : Why we move/re-align the septum ?
• A : There are two possibilities as explained; (1) re-aligh and (2) correction for error . if we chose the re-alignment, downstream-optics may be changed . If we choose the correction, the (DR?) optics may be changed. Anyway, both needs re-matching,
• Q : What happens if nothing ?
• A : There will be orbit distortion if we do nothing. So, we need re-matching. With the re-alignment, we need tuning of bending magnets at the extraction line.
• Q : Is re-alignment better, while the present mis-match is very small ?
• C : We need re-alignment twice a year in general, after the floor construction.
• C : We should decide now since we need design values .
• Q : Will you need many data in commissioning ? Can we estimate tolerance of alignment ?
• C : DR beam line, extraction line beam are always corrected by steering magnets. With data, the deck (Daihon) can be improved.

• C : There is a change of the beam dump location. It is moved to 1m downstream to the shielding wall.
• C : This change can avoid a modification of dump for signals of Shintake monitor. Also, it can make more space for the gamma detector .

5. KEK site meeting ( in Japanese )

The next ATF2 meeting will be held on 22nd August 2007, 2:30pm -, 3-gokan, 425, KEK, TV-ID#=31110 with the KEK Gatekeeper and ILC Webex.