8/12/2000 Guy Crockford BI days 2000 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 I=10^9 to I >

10^12 (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 (2*5 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.