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IP Feedback. Feedback On Nanosecond Timescales (FONT): Philip Burrows Neven Blaskovic, Douglas Bett, Glenn Christian, Michael Davis, Young Im Kim, Colin Perry John Adams Institute Oxford University. Outline. Reminder of CLIC IPFB prototype Remarks on L* ATF2 IP FB concept
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IP Feedback Feedback On Nanosecond Timescales (FONT): Philip Burrows Neven Blaskovic, Douglas Bett, Glenn Christian, Michael Davis, Young Im Kim, Colin Perry John Adams Institute Oxford University
Outline • Reminder of CLIC IPFB prototype • Remarks on L* • ATF2 IP FB concept • Results of recent beam runs
IP beam feedback concept • Last line of defence against relative beam misalignment • Measure vertical position of outgoing beam and hence beam-beam kick angle • Use fast amplifier and kicker to correct vertical position of beam incoming to IR FONT – Feedback On Nanosecond Timescales
Comments on L* • Current geometry: • time of flight IP BPM kicker IP ~ 24 ns • Demonstrated FONT3 electronics latency = 13ns • Estimated IPFB latency = 37ns
CLIC IP FB performance Single random seed of GM C Resta Lopez
CLIC IP FB performance For noisy sites: factor 2 - 3 improvement
Comments on L* • Current CDR geometry: • time of flight IP BPM kicker IP ~ 24 ns • Demonstrated FONT3 electronics latency = 13ns • Estimated IPFB latency = 37ns • In principle, change of L* need not affect IPFB position and latency, but needs to be engineered carefully, considering other beamline components
FONT5 installation at ATF2 ATF2 extraction line 12
ATF2 IP FB loop scheme IP kicker IPBPMs e- Eventual goal is to stabilise the small ATF2 beam (design 37nm) at the nanometer level FONT amplifier IPBPM electronics FONT digital FB
Nanometer beam FB at ATF2 IP • Much harder than IPFB at ILC or CLIC! • Only 1 beam must measure beam position directly • nm-level stabilisation requires nm-level position meas. • Cavity BPMs (rather than striplines) • Cavities intrinsically slow, signal processing complicated • Cavities required to resolve 2 bunches within << 300ns • Low-Q cavities and low-latency signal processing • New BPMs+electronics (KNU), new IP chamber (LAL)
Layout with new IP kicker Designed by Oxford Fabrication arranged by KEK
Preparatory tests June 2013 Existing IPBPMs IP kicker IPBPMs e- FONT amplifier IPBPM electronics Honda low-latency electronics FONT digital FB
Preparatory test IPFB loop Analogue Front-end BPM processor FPGA-based digital processor Kicker drive amplifier Beam Strip-line kicker Cavity BPM
IP Feedback Results FB Off Correlation: 81% FB Off Jitter: 170 ± 10 nm FB On Jitter: 93 ± 4 nm
IP Feedback Results FB Off Correlation: 81% FB On Correlation: -16% FB Off Jitter: 170 ± 10 nm FB On Jitter: 93 ± 4 nm
Incoming Beam Position Scan 10 μm pos. scan Bunch 1 Bunch 2
IP BPM resolution • Beam size during measurements ~ 100 nm • Model beam jitter ~ 20% of beam size, i.e. 20nm • Assuming results are resolution limited … • Resolution = 93 nm / sqrt(2) ~ 65 nm • (no direct resolution measurement possible)
New IP chamber installed summer 2013 • Commissioning • Started November: • alignment, • BPM signals
11cm Low-Q IP-BPM design Designed frequency X-port: 5.712 GHz Y-port: 6.426 GHz Full size : 11cmx11cm(to install IP-Chamber) Light weight: 1 kg (Singlecavity) 2 kg (Double cavity) 100mm 100mm Sensor cavity Wave guide Antenna 11cm Low-Q IP-BPM drawings of HFSS
In May tests resumed w. Honda electronics FF quad current scan to set vertical beam waist at IPB
In May tests resumed w. Honda electronics Centre beam in BPM using mover optimise resolution
In May tests resumed w. Honda electronics Centre beam in BPM using mover optimise resolution
Summary • ATF2 IPFB prototype is progressing • Beam stabilised (June 2013) to ~ 100nm level • Beam jitters measured (June 2014) ~ 60nm (best) • Beam studies continue until June 20th • Attempting to disentangle jitter/resolution • Looking at boosting signal levels resolution • Hope to close FB loop with improved resolution