Beam Position Monitors Facility Advisory Committee October 12
Beam Position Monitors Facility Advisory Committee October 12, 2006 Action Items from previous review Requirements / Specifications System overview Status Schedule October 12, 2006 LCLS Facility Advisory Committee 1 S. Smith ssmith@slac. stanford. edu
Action Items from Previous FAC Decide on a Digitizer Echotek glitches, lockups, lack of progress Plan B Plan A: Select 4 channel PAD digitizer. Fix schedule Still schedule trouble Plan barely finishes on time No schedule contingency October 12, 2006 LCLS Facility Advisory Committee 2 S. Smith ssmith@slac. stanford. edu
PRD 1. 1 -314 Full document: October 12, 2006 LCLS Facility Advisory Committee 3 S. Smith ssmith@slac. stanford. edu
Beam Position Monitor System Analog Frontend Version Three October 12, 2006 LCLS Facility Advisory Committee 4 S. Smith ssmith@slac. stanford. edu
Beam Test 100 machine pulses Effective beam charge 0. 35 n. C sy = 2. 5 microns October 12, 2006 LCLS Facility Advisory Committee 5 S. Smith ssmith@slac. stanford. edu
Resolution vs. Charge 5 mm @ 200 p. C Measured with beam in machine Tightest machine requirement: 5 micron resolution @ 200 p. C Achieve 4 micron resolution @ 200 p. C Resolution scales like 1/Q for the three measured bunch charges, as expected October 12, 2006 LCLS Facility Advisory Committee 30 6 400 S. Smith ssmith@slac. stanford. edu
Linearity Measured IP 3 of BPM signal path found IP 3 within a few d. B of calculation Bench test of apparent position vs. amplitude looks good Test consists of 15 k. Hz AM of 140 MHz signal Results impeccable. But beam test shows big amplitude position modulation Discovered prototype not built to schematic Gain distribution wrong Fixed Took further steps: Raise amp idle current 90 m. A 140 m. A Reduce bandwidth of first filter, raise that of second filter Narrowband filter before 2 nd gain stage October 12, 2006 LCLS Facility Advisory Committee 7 S. Smith ssmith@slac. stanford. edu
Status Prototype meets resolution requirement Stability not well established Long weekend test looks great But doesn’t apply controlled temperature cycles Attempt to resurrect CPE environmental chambers not successful Thermal cycle tests yet to be performed Proceeding with first article production October 12, 2006 LCLS Facility Advisory Committee 8 S. Smith ssmith@slac. stanford. edu
Calibration Calibrate through BPM Via stripline-stripline coupling Not prototyped October 12, 2006 LCLS Facility Advisory Committee 9 S. Smith ssmith@slac. stanford. edu
Schedule What should be done: (E. M. 9/20/2006) PCB layout – end of September - 29 ? PCB fabrication – one week – October 9 ? PCB assembling – one board here – October 13 Chassis layout – September 28 Panels punching and painting - early October buy the rest of the components – connectors, resistors, capacitors, etc. buy 23 chassis Write detailed test procedure October 12, 2006 LCLS Facility Advisory Committee 10 S. Smith ssmith@slac. stanford. edu
Software & Interface VME IOC EPICS PVs SLC - Aware EVR Archive FIFO Timing X, Y, TMIT Calib. Waveform->U, V, S Dedicated Ethernet PAD IOC AFE CTL Timing + Cal Data ADC Acq. diagnostic EPICS PVs AFE October 12, 2006 LCLS Facility Advisory Committee 11 S. Smith ssmith@slac. stanford. edu
BPM Controls Description User Interface Layer (EPICS, SLC-aware) VME IOC Converts raw waveforms into X, Y, TMIT and feeds them (timestamped) to SLC. Conversion parameters are Pvs Controls calibration PAD IOC Sends raw data upstream (dedicated ethernet) Diagnostic EPICS PVs October 12, 2006 LCLS Facility Advisory Committee 12 S. Smith ssmith@slac. stanford. edu
Software Functionality (Day 1) From SLC-aware IOC averaged BPM readings buffered acquisition EPICS raw waveforms conversion params. (raw position -> x, y) attenuator settings diagnostics October 12, 2006 LCLS Facility Advisory Committee 13 S. Smith ssmith@slac. stanford. edu
Functionality (Near Future) Calibration [some features may be present at day one; untested]. More sophisticated history buffers [other than SLC 'buffered acq'] Filtering of beam codes in EPICS Adjusting to beam charge in 'real-time' October 12, 2006 LCLS Facility Advisory Committee 14 S. Smith ssmith@slac. stanford. edu
Conclusions Good performance demonstrated Schedule critical October 12, 2006 LCLS Facility Advisory Committee 15 S. Smith ssmith@slac. stanford. edu
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