3/25/2006 KEK LCPAC Marc Ross - SLAC 1 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

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

3/25/2006 KEK LCPAC Marc Ross - SLAC 4 Two sets of triplets (z ~ 6m): SLAC/US/UK triplet KEK triplet Plan to test each individually – then connect (2006) Present results from both!

3/25/2006 KEK LCPAC Marc Ross - SLAC 5 Generic Cavity BPM Design: TM 11 -mode Selective Coupler Dipole frequency: GHz Dipole mode: TM 11 Coupling to waveguide: magnetic Beam x-offset couple to y port Sensitivity: 1.6mV/nC/  m (1.6  10 9 V/C/mm) Couple to dipole (TM 11 ) only Does not couple to TM 01 –Low Q with narrow cavity gap –May need to damp TM 01 –OR, use stainless steel to lower Q signal Z. Li

FFTB IP C- band cavity BPM triplet – this is the way to test BPM performance … T. Shintake

3/25/2006 KEK LCPAC Marc Ross - SLAC 7 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. Calibration - SLAC 250 pulse sequence +/- 20 um range of motion

3/25/2006 KEK LCPAC Marc Ross - SLAC 8 Move BPM in 1 um Steps SLAC – upstream triplet – 17 nm resolution residual

Development of Cavity BPM - KEK System –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 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 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

Fast ‘jitter’ – slow changes removed Vs time for 10 minutes (stored beam) Each point 20 ms accumulation (86500 turns) 500 nm rms EchoTeck

3/25/2006 KEK LCPAC Marc Ross - SLAC 13 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 14 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)

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. The ATF/ATF2 results will be crucial to determine the technical boundaries. pulsed laser-wire location 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 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 N. Delerue et al. Spheric triplet ZEMAX course held at JAI in January Expertise and possibilities are expanding Vacuum window

3/25/2006 KEK LCPAC Marc Ross - SLAC 20 Laserwire Plans 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 micron- scale LW Up to Apr 07 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. ATF2

Feedback On Nanosecond Timescales (3) Adjustable-gap kicker BPM ML11X Feedbac k Superfast BPM processor Superfast amplifier BPM ML12X BPM ML13X Aim: TOTAL latency < 20 ns Oxford, DESY, CCLRC, KEK, Tokyo Metropolitan, SLAC ATF extraction line beam direction

FONT3: latency budget Time of flight kicker – BPM: 4ns Signal return time BPM – kicker: 6ns Irreducible latency: 10ns BPM processor: 5ns Amplifier + FB: 5ns Electronics latency: 10ns Total latency budget: 20ns Will allow 56/20 = 2.8 periods during an ATF multi-bunch train

FONT3: BPM processor tests (single-bunch, December 2004 beam tests)

KEK LCPAC Marc Ross - SLAC 24 FONT3: Results (June ) : Delay-loop feedback w. latency 23 ns 56ns bunchtrain FB on FB + delay loop on 23ns 200um

FONT1,2,3: Summary 67 ns 54 ns 23 ns Even fast enough for CLIC intra-train FB! May also be used at ILC

KEK LCPAC Marc Ross - SLAC 26 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 3 rd bunch at um level First component tests at ATF December 2005/April 2006 FONT4: Prototype Digital Feedback System for ILC IP

3/25/2006 KEK LCPAC Marc Ross - SLAC 27 FPGA DAC ADC Differential To single AIN4AIN3AIN2AIN1 AOUT1AOUT2 RAM Clock circuit JTAG circuit USB circuit UART circuit IN Power Jack & switch 5v2.5v? v3.3v JTAG connector Serial connector USB connector Flash/ EEPROM Clk IN Differential To single Differential To single Differential To single FONT4: Digital FB Processor Module (Dabiri Khah) Latency goal 100ns

KEK LCPAC Marc Ross - SLAC 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 3. FONT5 prototype ILC digital FB system 2007: algorithm development + tests w. 20-bunch train FONT plans for ATF/ATF2 ILC ring extraction

3/25/2006 KEK LCPAC Marc Ross - SLAC 29 Instrumentation Studies at ATF – 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)