Minutes of nanoBPM meeting on 25 December, 2003

"X-band Cavity BPM", T.Naito

(transparencies, 4 pages, pdf, 1.3MB )

Naito reported that a X-band cavity BPM was fabricated at the KEK Mechanical Engineering Center. It has a reference cavity to determine the direction of beam-displacement. After a frequency test of the cavity, it will be installed at the ATF injection linac end which is about 5m upstream of the beam dump. Major reason of installation at the linac is the shorter bunch length (10psec) than that of the DR. Beam size can be focussed to 50μm there. The beam test will be conducted in next ATF experimental run, i.e. after 19 January 2004.

"Optical Anchor", Y. Higashi

(transparencies, 1 page, pdf, 218KB )

Higashi estimated a bending of the reference bar by vacuum pressure at pipes for laser beams which are connected at both ends of the bar. Diameter of the pipe is 10mm and the vacuum pressure is 1kgf each. We had to choose Aluminum for material of the reference bar since the most preferable CFRP is very expensive. Assuming that the cantilever length is 230(200)mm, the maximum bending was estimated to be 28(18.4)nm.

"Status of prototype mover", Y.Honda

(transparencies, xx page, pdf, KB )

The prototype mover was just completed. It took 2 months for slow machining of wire cut (0.5mm/minute). @Very preliminary inspection shows good performances especially in the hinge structures.

Update of reference system, schedule etc.

(transparencies, location, 2 pages, pdf, 1.5MB , update of the reference system, 8 pages, pdf, 288KB)

First, we discussed on location of our KEK system. The location is the most downstream of the extraction line. Usual space for the installation is between two quadrupoles whose distance is 2m. Since there are BPM, wire scanner, steering magnet, actual space would be less than 1.5m. The present length of the KEK system is 1.5m ( of the reference bar). The total length can be shortened by cutting 200mm of the granite girder. Hereby, the cantilever length becomes to 130mm, and the bending would be reduced as (130/230)3=0.18.

We also updated the schedule of installation of the KEK system as well as the LLNL/SLAC system, fabrication of the KEK cavities, and improvements of the ATF beam (3-train extraction, μm feedforward system, suppression of 50Hz fluctuation etc.). Ground motion covering low frequency region of less than 0.1Hz will be measured at the ATF extraction line in next year by R.Sugahara in cooperation with J-POWER company. The most updated schedule is posted on the NanoBPM home page.

Next meeting will be held in 22 January,2004, at 1:30pm-.