Agenda:
1) Update on 20mrad extraction line design -- Y.Nosochkov
2) Discussion of protection collimator losses -- L.Keller
3) Magnetic field insensitive MET seismometer for IR -- A.Seryi
4) Gamma-gamma with nominal ILC parameters -- A.Seryi
Summary:
Yuri presented an updated version of the 20mrad extraction line design based on DFDF configuration. The energy spectrometer chicane is moved closer to IP, to facilitate post IP diagnostics. Distribution of disrupted beam losses are calculated for nominal and high luminosity cases for 500GeV CM and 1TeV CM. The losses are very small and manageable in all cases except the 1TeV CM high luminosity case, where losses on SC quads reach 500W/m (in comparison with 0-1.8W/m on SC quads for other cases). In terms of further developments of the optics -- the protection collimators need to be included, to avoid distributed losses in the magnets.
Lew reviewed design of the protection collimators used in the SLAC linac. They consist of ~40cm block of copper with water cooling and capable of handling up to 20kW of beam losses. Protection collimators for ILC BDS are based on similar design. (The ILC PCs are 21cm long (15 r.l.) -- need to reevaluate if 15r.l. is sufficient or if longer PCs need to be used). Similar PCs need to be included into the extraction line optics.
Andrei presented results of tests in magnetic field of the MET (Molecular Electronic Transfer) seismometers that resulted from the SBIR program and were made available to SLAC by the PMD/eentec. The results are good: sensors have good sensitivity in the range of 0.1-100Hz and do not show any sensitivity to magnetic field. They can be used as a prototype sensors for the ILC IR, to monitor stability of final quads.
Andrei also presented discussion of the gamma-gamma option with nominal ILC emittances (10*0.04e-6m). In this case, the realistically achievable horizontal beta-function is 3mm, and the effective beta-functions (which takes into account beam size dilution due to aberrations) are 5.1mm*0.33mm. Correspondingly, the luminosity is about 2.7E34, not including reduction due to conversion coefficient.
Andrei Seryi, 04/12/05