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TDR for data processing

TDR for data processing. 22nd February 1999 Ian Lazarus Nuclear Physics Group CLRC, Daresbury Lab. TDR for data processing Introduction. Delayed coincidence setup problems : Dead time time of flight from target to focal plane high rate of gammas (singles/doubles)

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TDR for data processing

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  1. TDR for data processing 22nd February 1999 Ian Lazarus Nuclear Physics Group CLRC, Daresbury Lab Ian Lazarus NPG, CLRC

  2. TDR for data processingIntroduction • Delayed coincidence setup problems: • Dead time • time of flight from target to focal plane • high rate of gammas (singles/doubles) • Correlation between detectors Ian Lazarus NPG, CLRC

  3. TDR for data processingAn example: Jurosphere and RITU Picture taken from University of Liverpool NS web pages, http://ns.ph.liv.ac.uk/posters/ptg/poster1.html Ian Lazarus NPG, CLRC

  4. TDR for data processing Why TDR? Rate at target for VEGA running singles. for 15k rate on Ge centre contacts is: 4 x 4 x 15k = 240k i.e. ave. one g every 4ms. Recoil-gamma coincidence rate: CDT dead time is T.O.F ( 1-5ms) (rejected) or peak+convert+read (12ms) (accepted). CDT loses data significantly in both cases. Ian Lazarus NPG, CLRC

  5. TDR for data processingWhat is TDR? • TDR is Total Data Readout • No hardware trigger • Uses a global timestamp • Reads virtually all data. • Limited only by shaping/conversion time Ian Lazarus NPG, CLRC

  6. TDR for data processingGREAT electronics PIN diodes Si strip Seg clover Target Ge array Ge strip NIM and CAMAC shape amps and CFDs 356 energy signals 32 TACs 388 gates Metronome VXI time stamping ADCs (13 x 32 channels in, 13 links out) Data Acquisition system Ian Lazarus NPG, CLRC

  7. TDR for data processingWhat do we need? Time stamp everything @ 100MHz (10ns) New VXI ADC (32 channels, 32 gates, 5us 14bit pk sensing ADC per channel, data link.) New “Metronome” for synchronisation Correlate later in software using temporal and spatial association Ian Lazarus NPG, CLRC

  8. TDR for data processingHow does it work? Simple example: Accept gammas detected at the target only if: 1) There is a recoil at the focal plane with timestamp Tg+3000ns (+/-200ns) or 2) There are 4 other gammas with timestamps within +/- 50ns of Tg Ian Lazarus NPG, CLRC

  9. TDR for data processingTDR data rates. Target position rate: 15kHz per channel: TDR: sensitive to only channel dead time = 5ms pk det + 5ms convert =10ms (15%) Pileup loss (2ms shaping) is 19.5%. So TDR doesn’t cause any g data loss. Focal plane rates are lower. FP Channels will be free for rare events and a,b emissions from implanted recoils. Ian Lazarus NPG, CLRC

  10. TDR for data processingTotal Data Readout Summary. TDR solves recoil-g problems of dead time from high rate gamma singles and T.O.F. TDR allows us to collect and correlate all available data, limited only by pileup. TDR is now feasible because of increased processing power for reconstruction on-line. Ian Lazarus NPG, CLRC

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