Tdr for data processing
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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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Tdr for data processing

TDR for data processing

22nd February 1999

Ian Lazarus

Nuclear Physics Group

CLRC, Daresbury Lab

Ian Lazarus NPG, CLRC


Tdr for data processing introduction

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


Tdr for data processing an example jurosphere and ritu

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


Tdr for data processing why tdr

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


Tdr for data processing what is tdr

TDR for data processingWhat is TDR?

  • TDR isTotal Data Readout

  • No hardware trigger

  • Uses a global timestamp

  • Reads virtually all data.

  • Limited only by shaping/conversion time

Ian Lazarus NPG, CLRC


Tdr for data processing great electronics

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


Tdr for data processing what do we need

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


Tdr for data processing how does it work

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


Tdr for data processing tdr data rates

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


Tdr for data processing total data readout summary

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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