New application software for SPS wire scanner controls

1
New application software for SPS wire scanner
controls

• G.Crockford SL/OP

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Motivation

• Need to eradicate OS9 and TG3 systems in favour
  of LynxOS on PowerPC and TG8 (SL/CO supported
  hardware).
• Improved emittance measurement facilities
  required for LHC machine developments.
• Old application and server software written in
  1992. Decide to replace this with more efficient
  software, better able to meet user requirements
  and ease software maintenance.

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User Requirements

• Need 2 pairs of wire scanner in both non
  dispersive region and high dispersion section.
• Intensity range of bunches from I109 to I gt
  1012 (need for optical filters).
• Multi-bunch FAST WS allowing measurements
• Averaged over the whole batch.
• On different slices of the batch.
• On selected single bunches (given sufficient
  spacing).
• SLOW measurement for general use.
• IN and OUT scan performed in the same cycle.

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The Hardware for fast/slow measurements

• Two hardware requirements for fast acquisition.
• Fast signal response from photo multiplier.
• Beam synchronous timing to allow acquisition
  gating.
• 2 photo multipliers installed in LSS4.
• 1 connected to a local amplifier in the tunnel,
  and a 50 ohm impedance line to the surface giving
  fast signal response, but with the disadvantage
  of a noisier signal.
• 1 connected directly to a 1 kilo ohm line to the
  surface providing a slow measurement integrated
  over 3 SPS turns.
• Provides less noisy measurement, integrated over
  the whole beam, which works for all types of beam.

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BSG for fast acquisition

• Beam synchronous gate has 7 programmable fast
  acquisition modes. Currently set as follows.
• Fixed Target, 2 batches, 10 acquisitions (25 CPS
  extractions).
• Lead Ions, 4 batches, 4 acquisitions.
• 4 LHC beam options.
• 3 batches, 3 acquisitions.
• 1 batch, 3 acquisitions (3 slices of same batch).
• 1 bunch, 1 acquisition (effectively same as
  slow).
• 1 batch, 1 acquisition.
• 1 user option, single gate, adjustable with
  respect to the revolution frequency and
  adjustable gate size.
• Effective resolution of the fast acquisition is
  of the order of 200ns.

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The Software

• Chose to integrate wire scanner into TZ
  measurement application.
• 1 standard application for many BI systems
  (already used for SEM, Fast SEM, OTR, TLPOS).
• Measurement selection presented in a standard
  way.
• Takes advantage of the TZ database
  infrastructure.
• Application completely data-driven. New equipment
  can be added, parameters modified for different
  super cycles without touching the software.
• Separate application provided by BI oriented for
  equipment specialists.

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New software features

• Predefined optical filter control. Filter
  selection dependant on which HW selected and
  acquisition mode (fast or slow).
• Both Potentiometer and Ruler data returned with
  each scan (in practice the optical ruler is
  limited to slow wire velocity and therefore very
  low intensity beams).
• Chi squared fitting routine to calculate fit beam
  size and position.
• Visualization of several profiles from a single
  scan in the case of fast measurements.
• Jitter on wire start time measurement improved by
  a factor 10. Now less than 1ms jitter. Improved
  normalized emittance calculation.
• Scanner address (family,member), filters,
  configuration parameters and twiss parameters all
  stored in TZ database.

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Measurement parameters

• Acquisition mode (fast or slow).
• For fast measurement, BSG file option (1-7).
• If user option 7 selected.
• Gate delay (micro seconds).
• Gate size (micro seconds).
• Acquisition time for IN scan.
• Delay between IN and OUT scan.
• HT of photo multiplier (volts).
• Fitting routine (rms or chi squared).
• Fit threshold.
• Momentum spread (DP/P).

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Hardware plans for 2001

• BA2 wire scanners to be moved to BA5.
• Rotational scanner at 21955 moves to 51995.
• Linear scanner at 21956 moves to 52116.
• BA4 installation.
• High dispersion region scanner at 41420.
• Non dispersive region scanner at 41677.
• Linear scanner at 41807 moves to 42193.
• Calculation of the delay between start of wire
  movement and beam crossing (wire fly time).
• Modification of photo multiplier electronics.
• Single PM in the tunnel, slow/fast mode switching
  at surface.

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Acknowledgments

• J.Koopman Hardware installation.
• G.Ferioli Hardware installation.
• H.Hiller Server and BI application.
• J.J.Gras Consultations.