Minutes of 9th FFIR meeting on 5/10/2000

The meeting was held in a room of 3-425 at KEK, 13:30-15:00, 5/10/2000. We discussed on (1) structure analysis on support tube and a plan for prototyping the support tube, (2) super-conducting QC1&2, (3) magnetic field calculation of conventional QC1 for the dump line, (4) status of tail re-population and so on.

(1) structure analysis on support tube and a plan for prototyping the support tube: (transparencies, 9 pages of pdf, 1.4MB) or tiff, 1.4MB He investigated a connection part of the support tube by ANSYS. Two segments are tightly jointed by 16 M16-bolts with a torque of 2037 kg/bolt. One segment of 2m long weights 5.4 tons, where the weight of QC1 is uniformly distributed. Connected faces are tapered for no free space but with possible slide. He very concerned the slide. The segment was supported only at one side and the other free side was bent downward by its self-weight. Amount of this displacement was calculated to be 0.18mm which should be compared with 0.025mm without any slide, where the bolts were extended by 30 micro-m and the segment was slid by 10 micron-m. To decrease the displacement, thicker bolts shall be used. The present analysis had 4 hours CPU ( 100MHz clock ).

He also presented a plan for construction and test of the prototype-support tube. Until this July, he is going to analyze the structure and to review oscillators and sensors for final selections to be ordered. For two months (August and September), the prototype ( ~ 1/10 ) will be constructed. The test will be in this October. The result will be available at the end of this year. The most preferable place might be B4 at Fuji-experimental hall. We will negotiate the place with other users.

(2) Super-conducting QC1&2: ( transparencies 9 pages of pdf, 358kB or tiff, 358kB ). Tsuchiya presented a design of super-conducting QC1 (S-QC1). The S-QC1 has 196T/m and asymmetric coils due to a space for exit beam with synchrotron radiations in one-horizontal direction assuming 7 mrad crossing. The inner aperture is r=30mm. The magnetic center is horizontally shifted (~7mm) due to the asymmetry. It has correction coils for H- and V-steerings. The present design has less whole for exit beam so a lot of synchrotron lights will hit the correction coil. Although large multiple components due to the asymmetric coils shall be reduced to 1/100, this reduction seems to be not so difficult. He also presented a design of S-QC2. Since the S-QC2 has smaller magnetic field (70 T/m), the shape can be symmetric even with horizontal slits.

(3) Dump line: Miyamoto briefly reported calculations of fringing field of the conventional QC1 for a design of dump line. Finally, mesh sizes were optimized for smooth field lines. He will indeed complete the calculations within this week.

(4) Tail re-population: Sanuki explained the present status. Consulting with Kubo-san, he could succeed to run examples on SAD routine on his linux-PC. Detailed examination of outputs will be conducted with Kubo's help after the meeting. His first task is to add gas-scattering process in the SAD to estimate a probability of developing tails after the pre-linac collimation. The final goal is to estimate these machine-related backgrounds caused by tail's particles in the JLC detector and an optimization of collimation system.

The next meeting will be on 24 May, 2000 13:30 - 15:30 at 3 gokan, 425.