1. 1 ATF 2 Nanobpm (Q BPM) Electronics. Mark Slater: Cambridge Yury Kolomensky, Toyoko Orimoto: UCB Stewart Boogert, Steve Malton, Alexi Liapine: UCL Mike Hildreth: Notre Dame Jeff Gronberg, Sean Walston: LLNL Josef Frisch, Justin May, Doug McCormick, Marc Ross, Steve Smith, Tonee Smith: SLAC Hitoshi Hayano, Yosuke Honda: KEK

2. 2 Requirements Primary 25 BPMs to be instrumented (50 channels) Sub 100 nanometer resolution single bunch. –Existing NanoBPM has demonstrated 20 nanometers. Large dynamic range (100 microns desired) Secondary Since absolute state-of-the-art performance not required, limit costs, simplify calibration Use technology consistent with future large scale production for ILC.

3. 3 Existing SLAC NanoBPM Electronics Dual down mix: Mix to 476MHz, then to 26MHz Filters used to reject out-of-band signals. Dual down mix allows use of wider (percentage) bandwidth filters. (20MHz at 6.5GHz is difficult). Note: existing system does not bandwidth limit amplifier noise – sacrifice approximately 3dB in noise figure. –Could fix by adding filter after each amplifier – but additional complexity.

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5. 5 SLAC NanoBPM Electronics Constructed from connectorized, “best performance” components. Front end amplifier has 1.5dB noise figure. Filtering provides excellent blocking of out- of-band signals, but may not be necessary –Cavity BPMs reject monopole mode signals due to symmetry – in principal do not need much filtering.

6. 6 SLAC / BINP NanoBPM Performance Use 3 BPMs in alignment frame Use outer 2 to predict measurements from middle BPM. Noise and stability are combination of BPM system noise and structure vibration and drift

7. 7 Resolution 20 nanometer RMS noise, center vs. end BPMs (beam motion ~15 microns p-p

8. 8 Drift of ~50 Nanometers over 1 Hour measured 50nm

9. 9 Changes for ATF 2 Nanobpms Minimize use of narrow band filters –Expensive, bulky Use PC board components Use Image Reject mixer to reduce noise Reduce power consumption – for mechanical stability want to minimize heat dissipation in tunnel

10. 10 Image Reject Mixer Standard method to reduce noise from “image” frequency that mixes to same IF.

11. 11 Electronics Block Diagram

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14. 14 Calculated Performance Noise Figure: 7.5dB –Compare with approximately 4dB estimated for existing NanoBPM electronics. Note, existing mixers increase noise by 3dB by combining 2 frequency bands. –If present system is noise limited (at 20 nanometers), corresponds to 30 nanometers resolution. –FET preamplifier would reduce system noise figure to approximately 3dB. Signal to noise and Nonlinearity: <-65dB (ratio of non-linear power to full scale power), corresponds to approximately 200 microns peak – to peak range at 40 nanometer resolution. Power dissipation: 4 Watts / BPM Calibration signal included to improve stability off center – need to experiment to evaluate performance.

15. 15 Electronics Technical Issues System is designed without input band pass filter. –Output filters, and digital processing will eliminate weak out of band signals. –Need to check BPM signals for possible strong monopole signal – if present, will need to add Band Pass filter This is a cost issue ($800/bpm), but no other significant effects. –Lack of input band pass filter exposes limiter to faster rise-time signals – need to test performance for protecting downstream components. Output IF amplifier design needs to be tested. –Existing systems use high power consumption (12 Watts / channel) class A amplifiers –Replace with low power fast (3 GHz GBP) balanced op-amp based circuit (<1 W / BPM) using feedback for linearity. Can improve input noise figure from 7.5dB to <3dB by constructing narrow band FET amplifier. –Summer student project. Can improve dynamic range by measuring signal on decaying exponential. –Requires electronics with fast recovery from overload.

16. 16 Other Issues The SLAC electronics has not operated effectively with the new KEK cavity BPMs. –Work underway to understand incompatibility. Mechanical stability may be critical. The LLNL and KEK BPM support frames are both the result of a lot of engineering. –Significant mechanical engineering effort may be required to make use of <100 nanometer resolution / stability. Calibration algorithm requires work. In principal can steer beam (or move BPMs) to find phase and amplitude corresponding to position – but this has not yet been automated. Need to integrate signals with ATF control system.