Minutes of 45th FFIR/BDSIM meeting on 1/15/2003

The meeting was held in a room of 425 at KEK, 10:00-11:00, 1/15/2003. We discussed on implementation of synchrotron radiation in SAD and fast feedback system (FEATHER), collimation system.

(1) Collimation system(T.Ohgaki, KEK)

(transparencies, 1 page, pdf ,7KB ) Ohgaki updated the package of synchrotron radiations in SAD as Yokoya-san suggested. Angular divergence of the radiation is incorporated, while the previous version assumes the same direction as electrons. He also updated to save emission points (including a component number in the beam line) with Stokes parameters of photons as well as particle species of radiator. He is checking this package.

(2) Fast feedback system(N.Delerue, KEK)

(transparencies, 6 pages, pdf ,852KB ) Nicolas named the fast feedback system "FEATHER" of Feedback AT High Energy Requirements, which sounds lighter than FONT (Feedback On Nanosecond Timescales) of the English system. He tested the delayed model with new amplifiers with low noise figure which have been recently available. Since the delay loop works fine, the delayed model design was validated. At ATF, a kicker (magnet) requires O(1kV) input pulse to steer the displaced beam adequately into the right position. However, usual amplifier can not deliver such high voltage pulse at about 1 GHz. Therefore, the input must be filtered at lower frequency. He demonstrated that the filtered signals properly propagated in both simple and delayed models. Toward the improved model, non linear response has been obtained by a linear input-circuit, where there are two gains separated by a diode and the second gain can be adjusted manually at present. In next week, spare kicker and BPM will be installed at the ATF-extraction line ( which was already installed on 17 January ). First beam tests could be done soon ( which was also scheduled to be in 29 and 31 January).

The next meeting will be on 29 January (Wed.), 2003,10:00 - 12:00 am at 3 gokan, 425 .