57th ATF2 meeting

1. Experimental proposal to study emittance growth in the existing ATF EXT, Andrei Seryi (SLAC) , Mark Woodley (SLAC) , Feng Zhou (SLAC)

The detailed layout of present extraction point is shown in page-11.

C (Naito) : There is one H-corrector (ZH101R in page.12) in front of QM7 for the fast kicker study in coming run, whose bending strength is 0.3mrad. So, one V-corrector should be installed. You can see the presentation of "Plan of beam extraction by using strip-line kicker with pulse bump orbit", the 4th TB/SGC meetings at http://atf.kek.jp/collab/ap/meetings/TB-SGC/TB-SGC-meeting.php .

C : The coupling correction is very difficult, where good measurement of beam matrix is necessary. However, it is good experiment of measure emittance growth as a function of local bump.

C : Since there is no good BPMs, it is difficult to measure directly the local bump.

C : There is a BPM20 which is special, i.e. it has smaller aperture and smaller buttons of electrodes. So, the resolution would be 1-2mm . It has never used for orbit position measurement.

Q : How is BPM21?

A : It suffers from the kicker noise. So, it is difficult to use it.

Q : How is MB1X?

A : It is the same as BPM20.

C : We may use ML1X at just downstream from DR to observe the dumps, since MB2X is also difficult to see orbits. Or, we must rely on the settings.

Q : Can one V-corrector set near QM7 ?

A : There is no problem for enough space, answered by Naito.

C : SLAC group can install it in this December run.

Q : Is it well calibrated ?

A : It has data of magnetic field.

C : We have a plan of modification for stripline kicker test.

Q : What is the schedule?

A : We will test in this Nov.-Dec. run.

Q : In this proposal, two shifts are assumed to be requested. Is it enough?

A : First, we will observe a free oscillation. Then, we will close the bump for emittance measurement. Number of measurements will be 10-20.

Q : Are European colleagues interested in the participation ?

A : Sure, we are very happy with this proposal.

Q : Is the injection OK for the 5mm bump is very large, seeing in page-12?

Q : Does the bump end in the BT line ? How large is the dump?

A : There will be two pulsed correctors of ZH102R and ZH100R, whose power supplies will arrive by end of this December.

note by K.Kubo, "Can orbit depend on intensity due to wakefield in ATF DR ?"
"(CONCLUSION) It is not likely wakefield can cause mm level orbit change in the damping ring. So, it is not likely wakefield is the source of the abnormal emittance increase in the extraction line."

2. Magnet installation at the new extraction line (inside DR), Ryuhei Sugahara (KEK)

4 magnets of QD16X, 17X, 18X AND 19X were installed except for QD16X at the new extraction line inside the DR-shield, whose concrete support base are type-1, -2A, -2B and -2B, respectively. Wrong position of bolt-holes were found in the type-1 base so that QD16X could not be installed. The bases were glued with polymer concrete on the floor. They were aligned within 2mm in both directions.

Q : What is difference between 2A and 2B ?

A : Sizes are the same, but configuration of magnets is different, i.e. V-corrector and Q, H-corrector and Q for 2A and 2B, respectively.

Q : Are all the type-1 bases wrong ?

A : Yes, they must be corrected.

Q : Can the top plates be re-drilled on the bases for matching the present lattice design?

A : It is possible in principle. However, two holes ( present and new) are very close so that the actual process must be very difficult.

Q : How much is diameter of holes ?

A : It is 12mm diameter.

Q : How did you aligned them ? Where are the reference points, particularly in height ?

A : The height was aligned with respect to magnets at DR for they are close to the extraction line.

Q : Are they mount on movers ?

A : They are not mount on movers.

3. KEK site meeting ( in Japanese )

BSM signal line at the beam dump, T.Suehara, pdf (1 page, 8kB)

The next ATF2 meeting will be held on 12th September 2007, 2:30pm -, 3-gokan, 425, KEK, TV-ID#=31110 with the KEK Gatekeeper and ILC Webex.