ATF 2 Nanobpm (Q BPM) Electronics.

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
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
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.

4
(No Transcript)
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
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
Resolution
20 nanometer RMS noise, center vs. end BPMs (beam
motion 15 microns p-p
8
Drift of 50 Nanometers over 1 Hour measured
50nm
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
Image Reject Mixer

• Standard method to reduce noise from image
  frequency that mixes to same IF.

11
Electronics Block Diagram
12
(No Transcript)
13
(No Transcript)
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 lt-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
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 (lt1 W / BPM) using feedback
  for linearity.
• Can improve input noise figure from 7.5dB to lt3dB
  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
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 lt100 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.