New PS Trajectory Measurement System

1. New PS Trajectory Measurement System Uli Raich BE/BI OP Shutdown Lectures 2009 (many transparencies stolen from J. Belleman BI-PI) U. Raich CERN BE/BI

2. Change of Title Definitions: • Trajectory: Position at each BPM for a single bunch and a single turn • Orbit: mean position of the bunch over several turns If trajectories are measured over the whole acceleration cycle then orbits can easily be calculated U. Raich CERN BE/BI

3. Trajectory System in the PS U. Raich CERN BE/BI

4. Radiation Levels • 40 kGy/y at 1.3 m • 1 kGy/y on the floor • 40 Gy/y in the gap • Cable length from PU to pre-amplifier: 5m • Doubly shielded cable U. Raich CERN BE/BI

5. Analogue Electronics U. Raich CERN BE/BI

6. Analogue Electronics The Hybrid Test Signal Remote Control Amplifier Amplifier Amplifier U. Raich CERN BE/BI

7. CODD System • Uses 2 channels per PU to measure • Δx, Δy, Σ for 2 subsequent turns • This measurement can be done every 5 ms • The integration gates are generated by dedicated external electronics • Integration is done on the analogue signal • The user reserves a measurement slot (timing is defined before performing the measurement • 3 DSCs are used: • Data readout • Synchronization • Gain control U. Raich CERN BE/BI

8. CODD Electronics • CODD system architecture • 3 DSCs: • Acquisition • PU control (e.g. gain) • Synchronization • Control room application: • timing • reservation of resources • coherence of usage of the 3 DSCs • Incoherent system state due to • abnormal application termination • remaining software problems • wrong use U. Raich CERN BE/BI

9. The new trajectory system • Frontend electronics remains unchanged • Data from the BPMs are digitized with 125 MHz ADCs • Integration is done numerically in an FPGA • Synchronization is accomplished with a numeric PLL in the FPGA • Baseline correction again achieved in the FPGA • Data are sampled for each bunch and all turns during the full acceleration cycle. • No prior (timing) reservation • Data are recovered after the measurement. Up to 200.000 data points can be transferred • You can look at e.g. 2000 trajectories or 200.000 positions of a single BPM U. Raich CERN BE/BI

10. Datarates • Sampling rate: 125 MHz • 250 Mbytes (for 2 s cycle) * 3 channels * harmonic number (up to 21) = 1.6 Gbytes per PU • Too much! Must restrict dataflow • Numerically integrate the Σ and Δ signals and store only the integrated values Problems: • Must create integration gates which change during acceleration and during harmonic number changes • The data structure changes when changing harmonic number • Integrated values are stored in circular buffer U. Raich CERN BE/BI

11. Calculating the position Red: The sum signal Green: The difference signal Procedure: Produce integration gates and Baseline signals Baseline correct both signals Integrate sum and difference signals and store results in memory Take external timing events into account e.g. harmonic number change, γ-transition etc. CERN OP shutdown lecture

12. Baseline restoration Low pass filter the signal to get an estimate of the base line Add this to the original signal CERN OP shutdown lectures 2009

13. Beams in the PS U. Raich CERN BE/BI

14. Revolution Frequency vs B-Field U. Raich CERN BE/BI

15. System Architecture • 14 PU processing engines • Treating 3 Pus each • 3 cPCI controllers • cPCI controllers connected to system controller through Gbit Ethernet U. Raich CERN BE/BI

16. System Architecture ADCs: LTC2255, 14 bit, 125MS/s FPGA: Xilinx Virtex-4 Memory: 256MB/PU Data is streamed into a circular buffer. Persistence: A few seconds U. Raich CERN BE/BI

17. The System Architecture U. Raich CERN BE/BI

18. Current State • The system is fully installed and cabled for the horizontal plane • The old trajectory system, measuring 2 turns only, runs in parallel • All necessary readout software is available • The application programs still needs to be implemented but results can be obtained directly from the front-end program • It is intended to use the new system in operation after the yearly shutdown • The system was tested with all types of beam available end of 2008 • The PLL is stable also during harmonic number changes • Measurements between new and old system are comparable • New system allows observation of • Injection oscillations over many turns • Transition crossing • Injection and ejection bumps • Several thousands of turns for each bunch at each PU • 200000 turns on a single BPM U. Raich CERN BE/BI

19. Synchronization The system uses 3 common accelerator timings: • Start of cycle • Harmonic number change • End of Cycle And 3 specific timings: • Start of Calibration • End of Calibration • Injection These signals control a state machine in the FPGA whose transitions are defined in tables for each cycle. U. Raich CERN BE/BI

20. Synchronisation Accelerator timing Controls state machine and signal path U. Raich CERN BE/BI

21. The state machine A dedicated editor is used to create a state table per user line The state table is loaded prior to the cycle U. Raich CERN BE/BI

22. Typical Cycle SCY: Load appropriate phase table and initialize Frev to Fcal. CALSTRT: Acquire calibration data. CALSTP: Stop acquiring calibration data. C168: Initialize Frev to Finj. Phase-align all NCOs. INJ: Switch LO from MSB to LO1. Start acquiring beam data. HCH: Switch LO1 frequency. Acquisition continues. ELFT: Stop acquisition. Data can now be retrieved. U. Raich CERN BE/BI

23. Harmonic Number Changes U. Raich CERN BE/BI

24. Gate signal during bunch splitting Gate is initially centered on the first bunch During bunch splitting is covers the 3 emerging bunchlets External timing signal prompts it to readjust and cover a single “new” bunch U. Raich CERN BE/BI

25. Comparison new and old system EASTC at C181 (Single-bunch 37e10ppb) U. Raich CERN BE/BI

26. The Injection Bump U. Raich CERN BE/BI

27. Injection Oscillations + Tune FFT spectrum of the first 400 turns First 1600 turns seen by PU 87 U. Raich CERN BE/BI

28. Transition Crossing (SFTPRO PU 33) 128k revolutions 20k 4k U. Raich CERN BE/BI

29. Multi-turn Ejection tests Intensities measured with PU 15 (uses Σ signal only) The ejection pump seen with PU 15 (beam positions at ejection) U. Raich CERN BE/BI

30. Orbit measurement Orbit during an EASTC PU 43 full acceleration cycle U. Raich CERN BE/BI

31. Injection Oscillations on EASTB PU 87 U. Raich CERN BE/BI

32. Software FESA class is available • Trajectories bunch by bunch • Orbit (average over all bunches integrated over 1 ms) • Mean radial position • Orbit per bunch • Mean radial position per bunch U. Raich CERN BE/BI

33. Spin-off, multi-turn transformer Still baseline problems when high intensity and all buckets filled Baseline is not well defined U. Raich CERN BE/BI

34. Conclusions The hardware has been tested with all available cycles during 2008 but only for the horizontal plane MD measurements for multi-turn extraction The PLL algorithm used to synchronize the integration gate with the bunch signal is stable even during harmonic number changes All bunch positions can be acquired during a full accelerating cycle FESA class is ready and has been tested YASP application has been adapted to include ABS based on the new system but is untested A specific application is being developed System must now be tested in normal operation Old CODD will run in parallel to the new system during this year Spin-offs are being developed U. Raich CERN BE/BI