112th ATF2 weekly meeting

International phone/webex meeting

Progress report of tilt monitor, Daisuke Okamoto (Tohoku University)

Okamoto reported status of tilt monitor to be tested by beam, whose proposal has been approved by the ATF Technical Board (TB).

The tilt monitor can uniquely measure tilt angle of beam passing through a rectangle cavity with resolution of 35nrad. The output amplitude is proportional to the tilt angle. There is one change in the design, which is from two signal outputs to single one and other one for frequency tuner, since the proposal presentation ( 8th TB/SGC meeting). The tuner can finely adjust the frequency from 2.85 to 2.885 GHz by inserting a rod with 20mm diameter, while a typical machining error of 10um causes only ±0.002GHz change.

The engineering design is nearly finalized by Takatomi-san(KEK engineer) . It will be ordered within a week and will be completed in October. First, basic parameters such as frequencies and Q-values will be measured in so called "cold test". We would like to install it at the test section, i.e. upstream of QM16, in November. Performances will be experimentally checked by correlation with beam jitters measured by BPMs and signal response as a function of mechanical tilt angle controlled by the piezo-mover.

Also, I like to study the performances, especially beam stabilization with the tile monitor, by using flight simulator. At present, the software installation was successfully completed.

I will stay at KEK for October through December, 2009.

Q : When will be the machine time you like to have?

A : It is December.

Q : Which BPMs will be used for the jitter measurement ?

A : They ate QBPMs since the tile monitor will be installed at upstream of QM16 .

Q : Is there any residual sensitivity to position due to the mechanical imperfection?

A : There should be no sensitivity from vertical one at least.

Q : Is symmetry of monopole filed affected by adding the tuner at one side?

A : Yes, it becomes slightly asymmetric.

Q : Does the asymmetry generate a horizontal offset ?

A : Yes, but no vetical one.

Q : Who will be at KEK as the flight simulator experts in October for collaboration with Okamoto-san?

A : Glen and Yves will come to KEK from mid-October.

KEK site meeting

Optical tracking for phase change
- Calculated change of path length which corresponds to phase does not match the measurement.

C: If you use a kinematic mirror, mirror rotation in one axis affects the other axis rotation

C: It will be better to check the position displacement before the phase change

Alignment around the Final Focus will be started from September 15. Alignment for the IPBSM detector and so on will be in the week of September 22.