S. Smith LCLS Facility Advisory October 12, Beam Position Monitors Facility Advisory Committee October 12, 2006 Action Items from previous review Requirements / Specifications System overview Status Schedule

S. Smith LCLS Facility Advisory October 12, 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

S. Smith LCLS Facility Advisory October 12, Full document: PRD

S. Smith LCLS Facility Advisory October 12, Beam Position Monitor System Analog Frontend Version Three

S. Smith LCLS Facility Advisory October 12, Beam Test 100 machine pulses Effective beam charge 0.35 nC  y = 2.5 microns

S. Smith LCLS Facility Advisory October 12,  200pC Resolution vs. Charge Measured with beam in machine Tightest machine requirement: 5 micron 200 pC Achieve 4 micron 200 pC Resolution scales like 1/Q for the three measured bunch charges, as expected

S. Smith LCLS Facility Advisory October 12, Linearity Measured IP3 of BPM signal path found IP3 within a few dB of calculation Bench test of apparent position vs. amplitude looks good Test consists of 15 kHz 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 mA  140 mA Reduce bandwidth of first filter, raise that of second filter Narrowband filter before 2 nd gain stage

S. Smith LCLS Facility Advisory October 12, 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

S. Smith LCLS Facility Advisory October 12, Calibration Calibrate through BPM Via stripline-stripline coupling Not prototyped

S. Smith LCLS Facility Advisory October 12, 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

S. Smith LCLS Facility Advisory October 12, Software & Interface VME IOC EVR SLC - Aware Waveform->U,V,S X,Y,TMIT Archive FIFO Timing EPICS PVs Calib. Timing + Cal Data Dedicated Ethernet PAD IOC AFE AFE CTL diagnostic EPICS PVs ADC Acq.

S. Smith LCLS Facility Advisory October 12, 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

S. Smith LCLS Facility Advisory October 12, 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

S. Smith LCLS Facility Advisory October 12, 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'

S. Smith LCLS Facility Advisory October 12, Conclusions Good performance demonstrated Schedule critical