ILC Beam Switchyard: Issues and Plans Based on ongoing discussions with Deepa Angal-Kalinin, Grahame Blair, Brett Parker, Tom Mattison, Andrei Seryi, PT, and others September 13, 2005 ILC BDS Meeting

What is the “BSY”? Skew correction and emittance diagnostic section BCD: “Diagnostics Section”, G. Blair, M. Woodley Fast extraction system and tuneup dump line BCD: “Tuneup Extraction Line, MPS, Energy Diagnostics”, T. Mattison, M. Woodley, D. Angal-Kalinin Big Bend system (for 2 mrad IR) BCD: “Beam Switchyard”, M. Woodley IR transport lines September 13, 2005 ILC BDS Meeting

Issues (1) skew correction system coupling correction philosophy Paul Emma’s NLC design (writeup/refs) coupling correction philosophy projected vertical emittance optimization (writeup/refs) emittance diagnostic section σy at laserwires too small (modify optics) detection of laserwire signals in chicane … synchrotron radiation? need integrated skew correction and emittance tuning performance simulations (a la LET) September 13, 2005 ILC BDS Meeting

Issues (2a): fast extraction detection of “runaway” beam very near to fast extraction system is required number of errant bunches allowed to reach collimation system spoilers: off-energy and betatron oscillations (writeup/refs) energy spread measurement not required here < 1% ISR emittance growth @ 1 TeV cm (reasonable?) ignore critical energy of ISR photons (?) another iteration of the design is needed timing: detection of betatron oscillations in diagnostic section and energy offsets in chicane, propagation, processing kicker strength Brett’s initial design and TESLA kickers not very different (in-vacuum electrodes vs yoked magnets) assume (somewhat optimistic) 10 μrad/m (with septa?) kicker rise time 100 nsec in TDR; 150 nsec in Brett’s initial design for 150 nsec bunch spacing, wait until after 2nd bunch passes before triggering kickers faster kickers means weaker kickers … optimum? kicker flattop duration abort signal propagation back to DR 80 μsec in TDR; 150 μsec for 0.9c propagation to upstream end of 1 TeV cm linac September 13, 2005 ILC BDS Meeting

September 13, 2005 ILC BDS Meeting BSY Diagnostic Chicane Issues & Questions (M. Woodley, August 25, 2005) ======================================================================= - functional requirements 1) detection of off-energy bunches and abort triggering 2) location of detectors for BSY diagnostic section laserwires 3) measurement of energy and energy spread - issues 1) distance from energy BPM to FEXL kickers (how many bunches get through?) 2) ISR emittance growth 3) total chicane length 4) magnet technology (H-bends? C-bends?) 5) energy offset resolution 6) resolution of dispersion/betatron motion discrimination 7) minimum beam size for laserwire ~ 3 um 8) need vacuum window and line-of-sight to laserwire photon detectors (one near center of chicane for upstream emittance laserwires, one after central chicane bends for energy spread laserwire) 9) minimum clearance for laserwire detectors ~ 1 inch - beam parameters 1) normalized emittance emitxn = 10e-6 m 2) energy spread (dP/P) = 0.06 % @ 250 GeV, 0.03 % @ 500 GeV (PT) ... undulator? 3) minimum dispersion determines chromatic spot size ... etax = 20 mm gives 12 um @ 250 GeV, 6 um @ 500 GeV 4) for energy spread resolution, need geometric spot size (at most) equal to chromatic spot size ... betax = 5 m gives 10.1 um @ 250 Gev, 7.1 um @ 500 GeV 5) sigmax = 15.7 um @ 500 GeV, 9.3 um @ 500 GeV - questions/comments 1) ISR emittance growth limits: 1% @ 500 GeV? 0.1 % ? 1% @ 250 GeV? 2) kickers in 2nd leg of chicane? (issue 1) ... if so, must have QD (or no quad at all) at exit of chicane which makes optics tricky given 5 m betax at center of chicane and chicane length needed to preserve emittance 3) quadrupoles in chicane? 4) "bad beam" threshold: +- 2% dP/P, 25 sigmax @ 250 GeV, 43 sigmax @ 500 GeV 5) threshold for incoming betatron oscillations? September 13, 2005 ILC BDS Meeting

from Brett … September 13, 2005 ILC BDS Meeting

Issues (2b): dump line energy acceptance of dump line (±20%) beam size on dump window needs to be increased (modify optics) rastering system (add to design) energy/energy spread diagnostics (add) designs for special magnets (“coil pocket” quads, septum quads, Panofsky quads) another iteration of the design is needed need performance and tuning simulations (a la LET) September 13, 2005 ILC BDS Meeting

Issues (3) choice of combined-function FODO lattice compare with TESLA DBA, TME (writeup/refs) need performance and tuning simulations (a la LET) September 13, 2005 ILC BDS Meeting

Other Issues deflection cavities for diagnostics? deflection cavities for fast extraction? acceptance of post-linac systems linac aperture is 7 cm BSY aperture is 1.2 cm September 13, 2005 ILC BDS Meeting

My Plans (such as they are … ) try to nail down the functional requirements allowable emittance growth required bandwidth response time (how many bunches get through?) instrumentation resolution magnet specifications redesign emittance diagnostic section optics larger vertical beam size redesign diagnostic chicane smaller dispersion, larger betas, shorter system redesign fast extraction system 10 μrad/m kickers downstream of chicane maybe a (more conservative) TDR-like system, too? redesign dump line bigger spot on dump window add rastering system do system performance simulations September 13, 2005 ILC BDS Meeting