Summary:

Takashi Maruyamai:  Results of photon reflection from the face of QF1 in small horizontal crossing angle scheme

• The assumptions were: halo population of 1e-3, NLC BDS optics upstream of IP, FD with L* =4.2 m downstream of IP, pole tip radius of QF1 is 7mm, the VX radius and luminosity monitor radius are from NLC parameters.
• There is a direct view from QF1 to the vertex. However, in the assumptions mentioned above, the number of reflected photons reaching the vertex and converted to background is about 17/bunch, which is about 10% of the total VX hits from other sources.
• Other potentially more important background sources are photo-neutron production and disrupted beam loss due to the fringe field of QF1, that need to be studied further, as well as the possibility to have downstream diagnostics in this case.  

Yuri Nosochkov: Options of the final quadruplet

• •Yuri Nosochkov presented several options of the final quadruplet (in similar way as UK colleagues have done) or final triplet or penta-plet for head-on final focus optics.
• The optics considered allow to squeeze the disrupted beam considerably, making almost round beam (would this allow horizontal, rather than vertical, extraction?).
• This optics can now be used to design final focus for the head-on IR.
• In the considered options the vertical beta-function was allowed to be higher than in the FD case. Further work will include tests of SR effects in this optics and also designing another options which would limit the vertical beta-function.

Andrei Seryi: Final Focus optics for a Crossing Angle IR

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• Andrei Seryi presented a version of optics for crossing angle IR, based on NLC optics, where betatron collimation were modified to allow survivable spoilers (in contrast to consumable in NLC case). The IP bandwidth of this optics is good, the FD bandwidth may need further optimization. Collimation performance studies can be started with this optics.

Tom Markiewicz, 11/05/04