99th ATF2 weekly meeting

International phone/webex meeting

Cross-checks of the large beta optics, Sha Bai (IHEP (China))

Q : Beam size can be measured from um by IPBSM at Present. Is it OK?

A : 1um is fine, also it can be measured by carbon wire scanners.

Q : How much is the horizontal beam size?

A : It is about 10um.

C Okugi ; location of wire scanner and IPBSM are different. It makes 1.5 time at the wire scanner larger than IPBSM.

Q : Where does sextupole effect appear ?

A : It would become significant at beam size with 6 times of the nominal one, which is 200nm.

Q : How much is the energy spread assumed ?

A : It is 8 x 10^-4 .

Q : What program do you use for your analysis?

A : It is MAD.

Vibration measurement on the Shintake monitor etc., Benoit BOLZON (LAPP) , Takashi Yamanaka (The University of Tokyo)

Q : Is the cooling water ON ?

A : It is OFF, but very small effect was seen.

Q : How much is the tolerance ?

A : tolerance < 10nm, which corresponds to 2% beam size error. The measured ones are 7 and 20nm at QD0 and QF1.

Q : When did you measure?

A : It was mid-night for clear transfer functions.

C : While upstream magnets have less tolerance than QD0 and QF1 for the nominal optics, how about is pushed beta optics ? The tight tolerance may extend to upstream more, say 10 m upstream.

Q : What is future measurement?

A : I will measure along the beam line.

Q : For GM -model tuning, whole set of measurement vertical and horizontally , both direction are needed ?

A : Yes, it is good especially for coupling in h and v . if time is limited, v is only fine too.