1. Ron Johnson Beam Position Monitorsron_johnson@slac.stanford.edu October 29-31, 2007 1 Beam Position Monitors FAC Review October 29-31, 2007 Stripline BPM Performance and AFE Modifications Cavity BPM Electronics BPM Digitizer Comparison

2. Ron Johnson Beam Position Monitorsron_johnson@slac.stanford.edu October 29-31, 2007 2 Stripline BPM Performance and AFE Modification

3. Ron Johnson Beam Position Monitorsron_johnson@slac.stanford.edu October 29-31, 2007 3 BPM Performance Take data synchronized pulse-by-pulse Use linear prediction of each BPM from adjacent BPMS Example: Compare bunch charge pulse- pulse 300 pulses 17 BPMs Average rms/mean 0.0007 May include pulse-pulse variation in losses

4. Ron Johnson Beam Position Monitorsron_johnson@slac.stanford.edu October 29-31, 2007 4 Performance Predict BPM position reading from linear fit to adjacent BPMs (model-independent) 300 machine pulses Effective beam charge 0.35 nC  x = 2.5 microns  y = 1.7 microns

5. Ron Johnson Beam Position Monitorsron_johnson@slac.stanford.edu October 29-31, 2007 5 BPM Performance Q~ 200 pC Resolution requirement is 10 microns for the small aperture BPMs Meets resolution requirements

6. Ron Johnson Beam Position Monitorsron_johnson@slac.stanford.edu October 29-31, 2007 6 AFE Modifications CAL – Additional switch to improve isolation CAL – Add on/off control to oscillator CAL – Replace BP filter with packaged unit Chan – Replace 2 nd attenuator with 0-31 dB unit Chan – Put anti-alias BP filter on the PCB Revise limiter Revise layout and connectors

7. Ron Johnson Beam Position Monitorsron_johnson@slac.stanford.edu October 29-31, 2007 7 Status Plan to build 53 modules for BSY/LTU/Dump. Includes 3 spares for the injector. And 3 modules for sector 24/25 (at the request of the commissioning team). Installation in January. Most parts for AFE, PAD, and Clock Board on order (certainly long lead items). Bulk of modules ready for installation in March/April.

8. Ron Johnson Beam Position Monitorsron_johnson@slac.stanford.edu October 29-31, 2007 8 Cavity BPM Electronics

9. Ron Johnson Beam Position Monitorsron_johnson@slac.stanford.edu October 29-31, 2007 9 LTU and Undulator BPM System Specification ParameterSpecification Limit Condition Resolution < 1  m 0.2 – 1.0 nC +/- 1 mm range Offset Stability < +/- 1  m 1 hour +/- 1 mm range 20.0 +/- 0.56 Celsius Offset Stability < +/- 3  m 24 hours +/- 1 mm range 20.0 +/- 0.56 Celsius Gain Error< +/- 10 %+/- 1 mm range 20.0 +/- 0.56 Celsius Dynamic Range, Position+/- 1 mm10 mm diameter vacuum chamber Dynamic Range, Intensity> 14 dBPC Gun 0.2 – 1.0 nC

10. Ron Johnson Beam Position Monitorsron_johnson@slac.stanford.edu October 29-31, 2007 10 Cavity BPM Electronics

11. Ron Johnson Beam Position Monitorsron_johnson@slac.stanford.edu October 29-31, 2007 11 VME ADC Module

12. Ron Johnson Beam Position Monitorsron_johnson@slac.stanford.edu October 29-31, 2007 12 BPM Digitizer Comparison Steve Smith August 8, 2007

13. Ron Johnson Beam Position Monitorsron_johnson@slac.stanford.edu October 29-31, 2007 13 Analysis CW input from RF generator Through 140 MHz bandpass filter to reduce generator harmonics Digitize Plot spectrum Find apparent frequency from data Fit sine curve to data Look at residuals to fit Compare phase noise

14. Ron Johnson Beam Position Monitorsron_johnson@slac.stanford.edu October 29-31, 2007 14 VME Digitizer @ -1 dB FS Fit good to 6.5 ADC counts rms ENOB = 11.5 Harmonics <-80dBc

15. Ron Johnson Beam Position Monitorsron_johnson@slac.stanford.edu October 29-31, 2007 15 VME digitizer PAD @ -1 dB FS Fit good to 16 ADC counts rms ENOB = 10.2 Harmonics <-72dBc

16. Ron Johnson Beam Position Monitorsron_johnson@slac.stanford.edu October 29-31, 2007 16 Compare Noise floor Harmonic distortion Other lines in spectrum Input range

17. Ron Johnson Beam Position Monitorsron_johnson@slac.stanford.edu October 29-31, 2007 17 Digitizer Comparison VME 5 dB better on noise floor VME 8 dB better on worst harmonic ParameterVMEPADComments Amplitude-12-12dB FullSscale Rms fit error6.54.2167.1ADC counts ENOB11.512.110.211.3Bits (ref Full Scale) Worst harmonic -80-85-72-68dBc Phase noise (full spectrum) 0.0130.0310.531.9degrees (includes harmonics) (PAD dominated by 2 nd harmonic) Phase noise (<20 MHz) 0.0080.014 0.021degrees

18. Ron Johnson Beam Position Monitorsron_johnson@slac.stanford.edu October 29-31, 2007 18 Comparison Simplification Reduces the number of accelerator ethernet ports, private ethernet ports, and DIGI ports. Communication with the ADC is over the VME backplane. PAD would require enclosure and PS not yet designed. Simplifies clock distribution (10 vs 18 dBm input) Performance Reduces broadband noise and harmonics. FPGA has more computing power than the Coldfire. Comparable data transfer rates ( measured 28 Mbytes/s for VME ADC). Software Both would need modification of the IOC software. VME ADC needs a driver.

19. Ron Johnson Beam Position Monitorsron_johnson@slac.stanford.edu October 29-31, 2007 19 Status Two VME ADC modules produced and tested. Production of 40 additional modules to start in November. Cable plant is designed and in CAPTAR. Clock and LO distribution is being designed (Andrew Young). Power supplies and power distribution is being designed (Steve Smith). Hardware and software will be ready by April.

20. Ron Johnson Beam Position Monitorsron_johnson@slac.stanford.edu October 29-31, 2007 20 AFE Modification (Additional Slides)

21. Ron Johnson Beam Position Monitorsron_johnson@slac.stanford.edu October 29-31, 2007 21 AFE Modifications

22. Ron Johnson Beam Position Monitorsron_johnson@slac.stanford.edu October 29-31, 2007 22 Calibration Calibrate through BPM Via stripline-stripline coupling Performance not yet verified

23. Ron Johnson Beam Position Monitorsron_johnson@slac.stanford.edu October 29-31, 2007 23 CAL Modifications

24. Ron Johnson Beam Position Monitorsron_johnson@slac.stanford.edu October 29-31, 2007 24 RF BPM Analysis Steve Smith September 5, 2007 Updated Oct. 26

25. Ron Johnson Beam Position Monitorsron_johnson@slac.stanford.edu October 29-31, 2007 25 Procedure Calibrate with 2 mm scans: LCLSscan_Horiz_Cal_200pc_2000um_VertOffset3mm_1_HighGain-2007-232-0820- 131859.x.sdds LCLSscan_Vert_Cal_200pc_2000um_VertOffset3mm_1_HighGain-2007-232-0820- 131157.y.sdds Check against other calibration scans Analyze LCLSscan_Vert_Cal_200pc_200um_VertOffset3mm_2_HighGain-2007-232-0820- 161336.y.sdds Take 1 st 50 pulses to fix BPM-to-BPM alignment Predict X2 = linear combination of (X1, Y1, X3) Y2 = linear combination of (X1, Y1, Y3) For remaining events Compare (X2, Y2) to predictions from (X1, Y1, X3, Y3) All data taken at 200 pC charge

26. Ron Johnson Beam Position Monitorsron_johnson@slac.stanford.edu October 29-31, 2007 26 Calibration

27. Ron Johnson Beam Position Monitorsron_johnson@slac.stanford.edu October 29-31, 2007 27 Check Calibration Scales Analyze two more independent sets of calibration data Confirms scale Note apparent mover inconsistency for last step of X scan

28. Ron Johnson Beam Position Monitorsron_johnson@slac.stanford.edu October 29-31, 2007 28 Data Set In middle of run beam (mover?) changes Position jumps ~200 microns Apparent beam angle changes Study only first 150 pulses

29. Ron Johnson Beam Position Monitorsron_johnson@slac.stanford.edu October 29-31, 2007 29 X  x = 360 nm

30. Ron Johnson Beam Position Monitorsron_johnson@slac.stanford.edu October 29-31, 2007 30 Y  Y = 270 nm

31. Ron Johnson Beam Position Monitorsron_johnson@slac.stanford.edu October 29-31, 2007 31 Resolution Conclusion Both X & y resolution are below 500 nm Movers are a pain Beam jitter is troublesome Requires large scans to get a calibration Should move BPMs independently Then beam jitter doesn’t affect calibration

32. Ron Johnson Beam Position Monitorsron_johnson@slac.stanford.edu October 29-31, 2007 32 Stability Tests (Sept. 6)

33. Ron Johnson Beam Position Monitorsron_johnson@slac.stanford.edu October 29-31, 2007 33 Check Short Term Stability Data: LCLSsynchlog_200pc_Horiz_00um_Vert_3000um_1_HighGain-2007-232-0820- 132521.sdds 1000 points at 6 Hz Digitizer trigger glitch points removed Y steering during first 30 points, ignore them Alignment fit to next 50 points Drift, resolution taken from remaining ~900 pulses Resolution:  x = 440 nm  Y = 380 nm Drift ~ 200nm in X, less than 100 nm in Y in 2.5 minutes

34. Ron Johnson Beam Position Monitorsron_johnson@slac.stanford.edu October 29-31, 2007 34 3 Hour Cruise LCLSslowlog_1HourStab_4-2007-234- 0822- 161515.sdds 30 pulses every minute 5345 pulses total ~ 3 hours Many multi-mm jumps pulses 350 and 700 Clock seems unlocked from 390 to 490 Ignore first 700 pulses Use next 150 pulses (5min) of data for alignment Estimate resolution and drift from remaining pulses Resolution:  X = 1.6 microns  Y = 1.9 microns Drift: Look at fit residual plots (Vertical axes are in mm) ~5 microns in X ~3 microns in Y Over 2.5 hours Biggest motions coincide with beam motion (miscalibration)

35. Ron Johnson Beam Position Monitorsron_johnson@slac.stanford.edu October 29-31, 2007 35 Stability Conclusions Stability results are almost good enough Probably need better calibration Maybe mechanical stability Calibration is from 2 days prior to stability run ???