43rd ATF2 meeting

April 25 14:30- 16:40, Rm.725 bldg.3 at KEK.

1. Alignment of septum region for ATF2 , S.Kuroda (KEK)

file , pdf (2 pages, 48kB ), ppt(52kB)

Present alignment of three extraction line septums are compared with the ideal ones, where the coordinate origin is the center of kicker and the initial direction of beam is x . There are differences of 2mm in y positions at the third septum of BS3X and also incident angles to BS1X differ by 0.7mrad . It is difficult to measure the alignment because the septums are surrounded and covered by lead blicks. They can be re-aligned in summer 2008 during the reconfiguration of extraction line. His question was "is it possible to align as "ideal?". Since there is only one bellow between BS1X and BS2X, the 2mm alignment must be difficult.

Also he showed that orbits can be corrected by septum fine tuning with DX(position)=DPX(angle)=0 at exit of BS3X. BS3X has own power supply. BS1X and BS2X are supplied power in series with trim coils for fine adjustments.

There was a question on magnetic field of Q7 and extracted beam position at Q7. The magnetic field and beam position has never been measured.

2. Magnetic Field Simulation in The ATF Extraction Line, Sergei Seletskiy (SLAC)

file , pdf (5 pages, 244kB ), ppt (76kB)

To perform the tracking of the beam in the realistic magnetic field in the ATF extraction line, field maps of septum and A7 have been calculated; 2D map by C.Spencer and 3D map by J.Amann. The extracted beam passes through 2.2cm offset from the center of Q7. The multipole coefficients of 2D magnetic field were fitted with complex polynomials for tracking.

3. Preliminary tracking results with multipole fields, Feng Zhou (SLAC)

file , pdf (9 pages, 312kB ), ppt (172kB)

Tracking results were shown with multipole fields and also with magnet errors. Various orbit corrections were also applied with dispersion and coupling corrections. The initial tracking shows that no obvious vertical emittance growth is observed by applying the QM7-like multipoles. Magnet tilts create coupling resulting in significant vertical emittance growth. Future works are to analyze 2d and 3d septum fields, to track including septum multipole fields and to track including wakes, etc .

4.Organization of working group on "abnormal" emittance growth : discussion

We discussed on the organization of working group. European participation was presented with three study items and researchers by P.Bambade. Some of results will be shown at 4th ATF2 project meeting, LCWS2007. Hardware information ( magnet dimension, properties etc. ) should be available for the working group. There are ATF notes on emittance measurements at the extraction line since 2000, Therefore, S. Kuroda was asked for collecting these information and posting on a home page of the working group. We do not need to have regular meetings, instead we will occasionally discuss on the issues at the weekly meeting and at the project meetings.

The WG homepage is under construction.

2. KEK site meeting ( in Japanese )

QEA magnet system build up trial, R.Sugahara

file , pdf (1 page, 372kB ), ppt (412kB)

A magnet support system was built up for the beam test, especially for the first pulse calibration scheme test of QBPM in May. The system consists of IHEP-Q magnet, FFTB mover, QBPM and concrete support base, which is standard setup at ATF2. He found that dimension of FFTB mover was different from the drawing, that is the actual mover is taller by about 15mm than the drawing. This difference would require some modification. He will inspect more movers.

The next ATF2 meeting will be held on 9th May 2007, 2:30pm -, 3-gokan, 725, KEK, TV-ID#=31110 with the KEK Gatekeeper and ILC Webex.