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Status of TTF HOM Project Aug 9, 2005

Status of TTF HOM Project Aug 9, 2005. Project Scope: Instrument both couplers for all SC cavities in the TTF2. (80 channels). System expected to operate as BPM system Expect <~few micron resolution (train average) Expect <~30 micron resolution (bunch to bunch)

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Status of TTF HOM Project Aug 9, 2005

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  1. Status of TTF HOM ProjectAug 9, 2005 • Project Scope: Instrument both couplers for all SC cavities in the TTF2. (80 channels). • System expected to operate as BPM system • Expect <~few micron resolution (train average) • Expect <~30 micron resolution (bunch to bunch) • Expect readout rate ~1 Hz for all BPMs (5Hz May be possible) • Want full integration into TTF2 control system.

  2. Hardware Status – Downmix Chassis • First Prototype board completed / stuffed Aug 5. • Preliminary tests of Gain, Noise, linearity “look good”, should have numbers in a few days. • Board designed for machine assembly • Parts ordered • In principal, just ship parts to vendor for assembly • In practice, probably more involved that that, but no serious problems expected • Chasses now simplified due to lower board power consumption (~5 W / board). • 5 Chasses + spare, to be assembled at SLAC • No problems anticipated

  3. Other Hardware • VME crate / digitizers: All commercial parts, but need to decide on control hardware. • LO source: Synthesizer, amplifier, Fan-out: Straightforward. • Calibration reference: Must produce ~1700 MHz tone, locked to harmonic of beam with ~1 picosecond stability • Not designed yet (ideas only) – technically challenging. • Needs to use TTF triggers, timing signals to produce clean reference

  4. Timing • The software / hardware must allow the HOM signals measurements to be correlated with specific conventional BPM measurement pulses. • HOM system probably will not run at full 5Hz beam rate, so need method to identify which pulses are measured

  5. Software • This probably represents >3/4 of the entire project effort!!! • Software architecture determines which VME hardware to purchase • Architecture will depend on which group does which part of the work (software can have a steep learning curve). • Need to make decisions soon!

  6. Software Components • Data Download: 10, 8 channel, 100Ms/s (12 or 14 bit) VME digitizers. • For 1 millisecond, get 8M samples / pulse, Can produce up to 80MByte/second data rate. • Can run slower, but then this is limits bpm update rate • Data Digital Downconversion, filtering to produce I,Q data for each bunch. Matrix multiply (small) to produce X,Y for each cavity. • Very approximately 1 Gflop maximum processing required. ~1Gbyte memory. • DOOCS Server: 1000 pulses, with X,Y, X’, Y’ for 40 cavities, at 5Hz beam rate. • Total possible rate 800KWords / second. • Calibration Software: Same concept as existing HOM system but much more complex. • Must move correctors, read conventional and HOM BPMs throughout machine. • Use MIA, and model dependant analysis to determine cavity BPM calibration coefficients, download to DOOCS server. • Does not need real time, but calculations can be complex. Probably have 1 computer as front-end, separate computer for calibration.

  7. Front End • Data Download,Digital Down Conversion, DOOCS server. 2 Reasonable Options • Standard DOOCS, VME crate controller (Force SPARC-56 CPU) • Easy integration with TTF2 • Easy Support, (need new driver for digitizers) • Low performance (250 specfp2k) • SIS VME-PCI bridge • Existing drivers for LINUX pc from SIS • 80MB/sec transfer demonstrated by SIS • ~1600 specfp2k for PC. • VME-2e • Unique hardware – difficult support

  8. Calibration Computer • LINUX PC with Matlab probably the most reasonable solution. • Interface with front end computer through DOOCS. • Are large data transfers (1GB) in DOOCS OK? • If we use a PC (PCI-VME bridge) for front end, can probably use same computer for calibration.

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