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EMMA: update on BPM system

EMMA: update on BPM system. Ian Kirkman and Graham Cox July 29 th 2010. EMMA commissioning shifts so far. June 21 st , 22 nd , 23 rd and July 12 th , 13 th , 14 th , 15 th

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EMMA: update on BPM system

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  1. EMMA: update on BPM system Ian Kirkman and Graham Cox July 29th 2010

  2. EMMA commissioning shifts so far • June 21st, 22nd, 23rd and July 12th, 13th, 14th, 15th • “Analogue” BPM measurements taken on all dates using long cables fed from the front ends to the MCR and into an oscilloscope: • Each cable provides e.g. L&R or U&D • Some testing of reading the BPMs through the EPICS system was carried out on July 15th Slide 1

  3. Different BPM assemblies • Types of pickups: Injection/Extraction Lines: UD/LR, circular/circular D=34mm; Ring: (1) UD/LR, circular/circular D=48mm; (2a) and (2b) UD/LR, circular/taped, two modifications; - UD/LR, taped/volume; - UU/DD, rectangular (77x26 mm) (near Septum & Kicker) [Alex Kalinin] • Each assembly has been modelled separately using CST, with some bench testing for confirmation • Results from modelling produce a “mapping”, relating the individual button signals to the actual x-y position of the bunch Slide 2

  4. Contributions to errors • Random: - Button noise (thermal): 43 µm at 16 pC – ultimate resolution [AK] - analogue: - cable noise - human error reading from an oscilloscope screen - EPICS: - cable noise between front ends and rack room - ADC - clock timing jitter • Systematic: - physical/mechanical button offsets – can’t be modelled, must be laser surveyed or otherwise deduced (±250 µm) [INCOMPLETE] Slide 3

  5. Estimation of uncertainty based on repeated measurements Slide 4

  6. Example of x’ uncertainty Slide 5

  7. BPMs through EPICS: tests on 15-07-10 Slide 6

  8. EPICS hardware available • All required 21-Slot VME Crates + MVME 5500 processors (x7) • 3 x Prototype VME interface cards • 1 x Hand built production VME interface card • Sufficient ADC and clock mezzanine cards to fully populate 4 VME interface cards • 1 VME crate currently installed in the EMMA Rack room containing the 4 VME cards fully populated with clock and ADC mezzanine cards for development and testing of the EPICS data acquisition. • Master reset timing signal derived from ALICE laser via delay generator feeding EMMA septum & kicker magnets Slide 7

  9. EPICS software • vxWorks device driver tested with EMMA beam (13-15th July 2010) • Basic EPICS input/output (raw pickup data) tested with EMMA beam (13-15th July 2010) • ADC clock delay and attenuation tested (13-15th July 2010) • Basic clock delay scanning and signal optimisation tested – MS Excel (13-15th July 2010) • BPM pickup and position calculation from EPICS data tested – MS Excel (13-15th July) • BPM pickup and position calculation within EPICS implemented - to be tested with EMMA beam (29th July) • Full signal optimisation within EPICS to be implemented and tested (TBC) • BPM database created - cell, number, type, fitting coefficients, offsets • Program will be produced to graphically display x-y position for several BPMs in real time Slide 8

  10. Plans for July 29th This evening (July 29th): Start with analogue procedure: - measure again the x,x’ at septum exit (or quad D entrance) with ring BPMs 1 and 2 (quads off), as so far - “parasitic” examination of IL BPMs 1 and 2 can proceed in parallel Ramp down and re-wire analogue cables to study betratron oscillations further down the ring In parallel to this analogue work, use EPICS system to read ring BPMs 1 and 2, and compare with the earlier measurements Slide 9

  11. Continuing work • Production VME cards being sent for testing by Wareworks They will set the clock delay (13.8 ns) between the 2 time multiplexed button signals (Alex will tweak these timings with bench tests when he returns) In situ testing/commissioning of production VME cards with EMMA beam Multiple turn EPICS data acquisition and data processing to be tested when EMMA ring complete EPICS automated signal optimisation (clock delay and attenuation) Development of GUI software for visualisation of data from EMMA BPM system Archiving of EPICS BPM data for future analysis Slide 10

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