Results of Beam Instrumentation Studies at ATF 1. Nanometer resolution Beam Position Monitors 2.
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Results of Beam Instrumentation Studies at ATF 1. Nanometer resolution Beam Position Monitors 2. High resolution readout for Ring Beam Position Monitors 3. Extraction line laser-based profile monitor (laserwire) 4. Fast feedback and feedforward 3/25/2006 KEK LCPAC Marc Ross - SLAC 1 Cavity Beam Position Monitor RD • Through use of dipole modes of monolithic (Cu) resonators, cavity BPM’s have far better resolution than striplines or buttons – Effective monopole suppression – Inherent stability – Many practical questions how to realize a large system (ATF2) • Intrinsic resolution and systematic offsets much less than 1 um – Excellent resolution allows online calibration process without interrupting nominal operation KEK, Tohoku, SLAC, LBNL, LLNL, Cornell, Cambridge, UCL, RHUL, Notre Dame Goal: Prove viability of cavity BPMs for ILC – Resolution, systematic errors, calibration process • 2 sets of triplets installed at ATF – Triplet: residual determines resolution & allows study of systematic errors – ‘full blown’ mover calibration, including angles • Excellent ~20 nm resolution from 2004 – (world record) • Carbon fiber metrology tube (LLNL) mounted in Jan 06 – Monitor thermal space frame internal motion Two sets of triplets (z ~ 6m): SLAC/US/UK triplet KEK triplet 3/25/2006 KEK LCPAC Plan to test each individually then connect (2006) Marc–Ross - SLAC Present results 4 from both! Generic Cavity BPM Design: TM11-mode Selective Coupler signal • Dipole frequency: 11.424 GHz • Dipole mode: TM11 • Coupling to waveguide: magnetic • Beam x-offset couple to y port • Sensitivity: 1.6mV/nC/m (1.6109V/C/mm) signal Z. Li 3/25/2006 • Couple to dipole (TM11) only • Does not couple to TM01 –Low Q with narrow cavity gap –May need to damp TM01 –OR, use stainless steel to lower Q 5 KEK LCPAC Marc Ross - SLAC FFTB IP Cband cavity BPM triplet – this is the way to test BPM performance … T. Shintake - 1998 Calibration - SLAC +/- 20 um range of motion • Move one BPM at a time with movers • Extract BPM phase, scale, offset as well as beam motion by linear regression of BPM reading against mover + all other BPM readings. 3/25/2006 KEK LCPAC Marc Ross - SLAC 7 250 pulse sequence residual Move BPM in 1 um Steps SLAC – upstream triplet – 17 nm resolution 3/25/2006 KEK LCPAC Marc Ross - SLAC 8 System – – – Development of Cavity BPM - KEK Three Cavity BPMs developed in KEK Mover system with an active stabilization using an optical interferometer Analog down conversion and phase detection electronics Performance – – Resolution of the BPM: 17nm Active mover stabilizes the system better than the resolution Downstream triplet – KEK QuickTi meý Dz T IFFÅiLZWÅj êLí£ÉvÉçÉOÉâÉÄ Ç™Ç±ÇÃÉsÉNÉ`ÉÉÇ ¾å ©ÇÈǞǽDžÇÕïKó vÇÇ• ÅB Recent results: High resolution readout - Ring Beam Position Monitors • Goal: Upgrade ATF ring BPM electronics for improved resolution (100nm), stability (1um), calibration (1e-4) – Should allow beam tuning for 1pm-rad vertical emittance – Multi-pass system • Use existing storage ring technology – fast digital receivers – Notch filter @ 50 Hz – SLS, Fermilab, APS, SPEAR • Total replacement cost dominated by receiver electronics cost ~400K – Primary effort in designing and testing front end and infrastructure KEK, SLAC, Fermilab 7 ‘y’ BPMs: 3 upgraded & 4 original Stored Beam – 10 minute time scale; ATF lifetime ~ few minutes EchoTeck Fast ‘jitter’ – slow changes removed Vs time for 10 minutes (stored beam) Each point 20 ms accumulation (86500 turns) 500 nm rms Legacy – single turn system Fast ‘jitter’ – slow changes removed vs time for 10 minutes (stored beam) Each point single turn measurement 11.6 um rms 3/25/2006 KEK LCPAC Marc Ross - SLAC 13 Ring Electronics: Status • Receiver produced (20 units) – Cal system in design • Initial commissioning Feb 2006 • Second test in June – Fermilab will join the group, and bring a full crate system for testing – This is Fermilab’s first direct contribution to ATF • Partial system remains in use at ATF (8 BPMs) 3/25/2006 KEK LCPAC Marc Ross - SLAC 14 ATF Laser-wire •Goal: •At ATF, we will aim to measure micron-scale electron spot-sizes with green (532 nm) light. • Aim at intra-train (fast) scan for 150 ns bunch spacing. • The final spot-size measurable at ILC will have implications for the length and layout of the BDS diagnostics section. pulsed laser-wire location • The ATF/ATF2 results will be crucial to determine the technical boundaries. BESSY, DESY, Oxford, Royal Holloway, UCL, CCLRC, KEK, Kyoto, SLAC ATF-LW Vacuum Chamber Built at Oxford DO + Workshop Vacuum Tested At DL ATF Laser-wire Vacuum chamber built in Oxford and Installed in ATF extraction Line in December 2006. Laser light transported to IP, but no collisions yet seen; probably a detector issue. New run planned For April 06. Designing diagnostics insertion at Oxford LW Practical Considerations f1 geometry is challenging • Limitations from power • Limitations from angle • Surface optical quality • Alignment tolerance f1 Lens design is challenging • Limitations from power • Limitations from ghost images • Alignment tolerance • Lens currently under construction Canidate f/1 Lens Designs Aspheric doublet Vacuum window ZEMAX course held at JAI in January 2006. Expertise and possibilities are expanding Spheric triplet N. Delerue et al. Laserwire Plans Up to Apr 07 • Data run in Spring 2006 • More runs 06/07; lots of systematics to understand (eg beam jitter, BPM integration …) • Integrate solid wire scanner into vac. vessel design • Iteration on lens design. • Provide statement to GDE on technical feasibility of reliable micronscale LW Beyond Apr 07 (subject to new funding) • • • • • Play a major role in ATF2 LW system. Develop fast scanning Multiple IP’s, laser system, light transport. Investigate running with UV light. Collaborate on “Shintake” type systems. 3/25/2006 KEK LCPAC Marc Ross - SLAC ATF2 20 Feedback On Nanosecond Timescales (3) ATF extraction line beam direction Adjustable-gap kicker BPM ML11X Superfast amplifier BPM ML12X BPM ML13X Superfast BPM processor Aim: Feedbac k TOTAL latency < 20 ns Oxford, DESY, CCLRC, KEK, Tokyo Metropolitan, SLAC FONT3: latency budget • Time of flight kicker – BPM: • Signal return time BPM – kicker: • Irreducible latency: • BPM processor: • Amplifier + FB: • Electronics latency: • Total latency budget: 4ns 6ns 10ns 5ns 5ns 10ns 20ns • Will allow 56/20 = 2.8 periods during an ATF multi-bunch train FONT3: BPM processor tests (single-bunch, December 2004 beam tests) FONT3: Results (June 3 2005): Delay-loop feedback w. latency 23 ns 56ns bunchtrain 200um FB on 23ns FB + delay loop on KEK LCPAC Marc Ross - SLAC 24 FONT1,2,3: Summary 67 ns 54 ns 23 ns Even fast enough for CLIC intra-train FB! May also be used at ILC FONT4: Prototype Digital Feedback System for ILC IP • ATF/(ATF2): 1.3 GeV beam, 3 bunches with spacing c. 150ns • FONT4 (2005-6): • modified FONT3 BPM front-end signal processor • digital FB system • modified FONT2 solid-state amplifier: 300ns long o/p pulse • FEATHER adjustable-gap kicker • • • Aiming for first demonstration of FB w. ILC-like bunches: total latency 140ns (electronics + signal propagation) stabilisation of 3rd bunch at um level • First component tests at ATF December 2005/April 2006 KEK LCPAC Marc Ross - SLAC 26 FONT4: Digital FB Processor Module (Dabiri Khah) JTAG connector Serial connector JTAG circuit Flash/ EEPROM RAM UART circuit DAC AOUT2 DAC AOUT1 ADC Differential To single AIN4 ADC Differential To single AIN3 ADC Differential To single AIN2 ADC Differential To single AIN1 FPGA USB connector USB circuit Clock circuit IN Power Jack & switch 3/25/2006 Clk IN 5v 3.3v 2.5v ? v Latency goal 100ns KEK LCPAC Marc Ross - SLAC 27 FONT plans for ATF/ATF2 1. FONT4 prototype ILC digital FB system Dec 05: modified analogue BPM processor tests Apr 06: test of digital FB board Jun 06: closed-loop FB system test with 3-bunch train 2. Ring -> extraction-line feed-forward Dec 05: jitter correlations + transfer matrix studies 2006: design + tests of feed-forward system ILC ring extraction 3. FONT5 prototype ILC digital FB system 2007: algorithm development + tests w. 20-bunch train KEK LCPAC Marc Ross - SLAC 28 Instrumentation Studies at ATF – 2006 • 20 nm resolution cavity BPM demonstrated – Link 2 systems (2006) • 500 nm resolution ring BPM system demonstrated – Offsets & drifts (2006) – pm-radian emittance (2006) • 1 um laserwire scans (2006) • Fast feedback demonstrated (23ns) – ILC parameters (2006) 3/25/2006 KEK LCPAC Marc Ross - SLAC 29