Beam Physics Meeting

Wednesday 11 Jun 2008, 16:00 → 18:00 Europe/Zurich

1/1-025 (CERN)

Vacuum specification

Participants: * K. Elsener, I. Ahmed, E. Adli, D. Schulte, F. Antoniou, B. Jeanneret, G. Rumolo, Y. Papaphillipou, R. Tomas, O. Mete, H. Burkhard, M***, B. Dalena DS: * purpose of meeting: finalize CLIC vacuum specification. Needed: - vacuum level - beam pipe - surface YP: * damping ring - a realistic lattice design is not yet ready, but we assume r=20mm (8mm for wigglers) - <0.1 nTorr limit wrt. fast-ion instability - Resistive wall: ~ 1 ms rise time (~ 1000 turns) -> prob. not a problem? - SEM should be kept ~< 1 (groves, coating ...) BJ: * transfer line - <0.1 nTorr wrt. fast-line instability - r = 100 mm RT: * Beam Delivery System - prelim. simulations shows ~1 nTorr wrt. fast-ion (shorter length than above), but we stick with 0.1 nTorr DS: * Main linac - not enough info yet to give a vacuum specification (?) HBu: * halo/background requirements - ~10 nTorr is probably OK; for sure 1 nTOrr - anything less than 0.1 nTorr: will be dominated by thermal photons anyway -> so, should be OK if other specs are fufilled (except Main Linac TBD) Discussion: * Resistive wall wake: limits the aperture, except for BDS * Study of effects of wake fields: Beam pipe alignment tolerance main linac: 20 um (tight) * radius BDS: 9 mm (stainless steel) ... but model too simple? * Giovanni: 6 mm (Cu) -> some disrepancy... factor 2? * For the BDS: different aperture would be given for different parts of the BDS EA, 11-jun-2008