First, N. Yamamoto investigated the new optics with L*=4.5+0.1m, where the sextupoles have not been adjusted. (transparencies, 1 page, pdf ,xxxkB ) He showed a growth of vertical beam size (sigma_y) as a function of horizontal emittance. The sigma_y increases rapidly, while the sigma_y of L*=4.5m (original Pantaleo and Frank optics) remains the same value. At the nominal emittance, the sigma_y becomes larger in 2-order of magnitude than the nominal value. The new optics was found to be very sensitive to L*. For an example, Panta's optics has 300m length at L*=2m and 500m length at L*=4.3m for Ebeam=500GeV. He will try to adjust the sextupoles for L*=4.6m.
Next, K.Kubo showed an extraction line up to 200m from the IP, where a beam dump must be located. The second IP is located at 75m from the IP. (transparencies, 2 pages, pdf ,17.9kB ) Adding a horizontal bending magnet, the extracted beam line can be separated by 6m from the incoming beam. The 6m-separation seems to be enough for a space of the beam dump. Most of background from upstream of the second IP may be stopped by masks at the 2nd IP, where the extracted (disrupted) beam shall be focussed. In general, what are other issues for designing a dump line to the dump? T. Tauchi will summarize these issues for cases of TESLA and NLC until next FFIR meeting. A design of dump line is also necessary for a cost estimation which is investigating by a costing group at KEK.
The next meeting will be on 17 January (Thu.), 2002 13:30 - 15:00 at 3 gokan, 425.