Summary of technical decisions taken at ATF2 meeting at KEK:
Andrei reported about several meetings which took place at KEK during this weekend:
Meeting on ATF2 organization, international collaboration and schedule, May 28.
Discussion of ATF2 tolerances on magnet strength, field quality & position errors, May 29.
Third Mini-Workshop on Nano Project at ATF, KEK, May 30-31.
On May 28, the ATF2 organization, international collaboration and schedule were discussed. More detailed on this meeting will be discussed at Thursday ILC meeting (June 2). In brief, the discussion went very well. On the technical side, there was very strong support of the optimal optics layout (the one which goes straight) in comparison with the baseline (which includes "snake" or "s-bend" to avoid crab-cavity test area). It was agreed to concentrate on the optimal optics design, which would also include an extended diagnostics section.
Discussion of ATF2 design, tolerances on magnet strength, multipole components and position errors took place on May 29. Results of recent simulations by James Jones were discussed. Summary (by A.Seryi and T.Tauch) can be found here.
Some summary of the ATF2 organizational discussion can be found in the talk of Junji Urakawa posted here
http://acfahep.kek.jp/subg/ir/nanoBPM/nano.project/third/third.htm
Also, more details will be given at Thursday's meeting on June 2.
Feasibility of SC magnets for ILC IR, scaling models:
Brett discussed the factors which affect feasibility of large aperture SC magnets and suggested scaling models which can be used in design of the SC magnets, in particular, for the 2mrad IR. Scaling of achievable gradient and external dimensions versus the aperture were given. Factors such as current density, critical field, and influence of the detector solenoid field were taking into account.
Several examples were discussed. In particular, the scaled gradient for the TESLA TDR quad with 27mm inner coil radius is close to 250T/m TDR value. For the quad with 45mm inner coil radius, the achievable gradient reduces to 163T/m. However, if it would be placed in 1.3T background field of the detector (SiD at 4m), the gradient would decrease to 161/m, and in 3.7T background field (TESLA detector at 4m) it decrease to 147T/m.
It is also important to distinguish between inner coil radius and inner beampipe radius, which could be smaller by 3-4mm. In particular, for a quad with 45mm clear aperture for the beam, in 1.3T background field, the achievable gradient would be 152T/m.
The external dimensions of such magnets are affected by the size of coil, size of the yoke which should resist the force and contain the coil, and size of cryostat. In particular, the quad with 45mm aperture radius for the beam would have external radius of about 21cm.
Andrei Seryi, 05/31/05
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