Agenda:

1) 2mrad extraction with diagnostics -- Y.Nosochkov et al
2) Geant simulations of 2mrad extraction -- T.Maruyama
3) New ILC parameters and head-on with RF kicker -- L.Keller
4) Status of ILC-FF9 with E-spectrometer -- A.Seryi, M.Woodley
5) SC quad engineering design, allowable power deposition -- B.Parker at al
6) Antisolenoids for SiD -- B.Parker, A.Seryi (deferred to the next meeting)
7) Status of feedback simulations in ILC BDS -- Linda Hendrickson
 

Summary:

Yuri presented an updated version of the 2mrad extraction line, based on February 20 version, which now includes location for downstream beam diagnostics, which is parallel to the beam at the IP and where the beam is focused. In comparison with the previous version, where a triplet was used in the beginning of the line, now a single split quadrupole with sextupole is used. The unused QEXF2 and QEXF3 can be removed or replaced by collimator of SR photons coming from the beam. Evaluation of new ILC parameters has been started for this optics. So far the nominal cases (0.5 and 1 TeV CM, assuming same magnets) do not show any losses, while there are big losses on QD0 and QEXF1 for high luminosity parameter case. Further evaluation and optimization is necessary. 

Takashi have shown that Geant simulation confirm absence of beam losses or beamstrahlung photon loads in the case with nominal parameters. Synchrotron radiation from the beam start touching the beamline at QEXF2 location. Since this magnet is OFF in the latest optics, it can be removed and replaced with a collimator for beam SR, to protect downstream magnets.  Brett made a comment that for proper design of SR masks one need to take into account the divergence angle of SR photons at a particular location.

Lew presented considerations of new ILC parameters for the head-on scheme with rf-kicker. Losses on the 2cm kicker gap are about 5kW is the nominal beam has 200nm vertical offset. With high luminosity parameters, these losses are about 3kW with zero beam offset and they reach 0.5MW for the beams with 120nm vertical offset. The losses on the protection collimator (located 86m from IP) also increase to more than a MW in this case.

Mark presented the latest BDS design with energy spectrometer incorporated after the energy collimator.

Brett described the latest engineering design of SC QD0, and parameters which are essential for heat removal calculations. With the tapered shape, the side of QD0 which is most close to the IP has tighter requirements for the power losses in this area.  The calculated heat transfer capacity at that end is approximately 4 W. In order to increase this value to 10 - 20 W, the flow area for He II in the insertion end must be increased. The design will be further optimized.

Discussion of the antisolenoid layout for SiD was deferred to the next meeting.

Linda presented ongoing work on feedback simulations, in the linac and beam delivery. In particular, Linda is using normal and so called "rogue" wakes, which have one high order mode poorly damped (this is the same mode that was unexpectedly observed in TTF measurements). The bunch offset variation along the train is much larger in this case, and does not appear to decay along the train. The train straightener can reduce this jitter, and the bunch-to-bunch feedback at the end of the linac can reduce this jitter even further. The BDS feedback simulations are focused on correcting the orbits at sextupoles, and need to be optimized further.

Andrei Seryi, 03/08/05