TDR for data processing

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TDR for data processing

• 22nd February 1999
• Ian Lazarus
• Nuclear Physics Group
• CLRC, Daresbury Lab

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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

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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
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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 peakconvertread (12ms)
(accepted). CDT loses data significantly in both
cases.
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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

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TDR for data processingGREAT electronics
Target Ge array
PIN diodes
Si strip
Ge strip
Seg clover
NIM and CAMAC shape amps and CFDs
356 energy signals
388 gates
32 TACs
VXI time stamping ADCs (13 x 32 channels in, 13
links out)
Metronome
Data Acquisition system
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TDR for data processingWhat do we need?
Time stamp everything _at_ 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
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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 Tg3000ns
(/-200ns) or 2) There are 4 other gammas with
timestamps within /- 50ns of Tg
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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 doesnt 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.
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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.