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ILC Beam Switchyard Update

ILC Beam Switchyard Update. M. Woodley, September 6, 2005. BSY Diagnostic Chicane Issues & Questions (M. Woodley, August 25, 2005) ======================================================================= - functional requirements 1) detection of off-energy bunches and abort triggering

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ILC Beam Switchyard Update

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  1. ILC Beam Switchyard Update M. Woodley, September 6, 2005

  2. 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) 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?

  3. vacuum chamber Ф=15 mm laserwire photons go through here Brett’s BMP magnet has a wide (±28 mm) clear horizontal aperture … put in a small (but reasonable) vacuum chamber for the beam and use the reamining clear aperture to pass laserwire photons

  4. total length = 111.1 m laserwire detector (σδ) energy BPM, laserwire (σδ) ΔE/E = ±20% trajectories window  clearance=12.5 mm vacuum chamber Ф=15 mm  window laserwire detector (ε) Brett Parker’s BMP dipoles (20)

  5. length of chicane, required beam waist at central laserwire, and maximum beta at the waist means kilometer-size beta at beginning and end of chicane … still looking for matching solution for non-extracted beam • matching problems might push me away from having kickers in the chicane, so kickers would then start just downstream of the chicane … delay time is ~50 ns (assuming a cable signal velocity of 0.8c) • I need to know a “reasonable” kick angle per unit length, given the required temporal properties of the kicker/pulser combination (TDR: 5.3 μrad/m (scaled to 500 GeV beam); BP: 40 μrad/m)

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