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zero suppression with APVDAQ . 2012/02/07 SVDPXD meeting Seoul National Univ , Changwoo Joo. Introduction. We are developing APVDAQ in J-PARC With our DAQ, event rate is eight APVDAQ => up to ~20Hz Four APVDAQ => up to ~60Hz We’d like to increase event rate of APVDAQ.

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zero suppression with apvdaq

zero suppression with APVDAQ

2012/02/07 SVDPXD meeting

Seoul National Univ, ChangwooJoo

introduction
Introduction
  • We are developing APVDAQ in J-PARC
  • With our DAQ, event rate is
    • eight APVDAQ => up to ~20Hz
    • Four APVDAQ => up to ~60Hz
  • We’d like to increase event rate of APVDAQ.
  • There is bottle neck of data from VME to PC
  • Data transfer time
    • Apv25=>VME : ~200 us
    • VME=>PC : ~dozens ms
zero suppression zs
Zero Suppression (ZS)
  • Build up FPGA firmware level data suppression
  • Put ZS block between data pipe line and FIFO

ZS

block

apv25

data

FIFO

(Memory)

To PC

zs block algorithm
ZS block - algorithm
  • Because of sensor configuration, ZS block can handle 3 apv25 chips 6 sampling mode. => We can adjust it.
  • ZS process (it takes ~86us)
    • 1. Save data from apv25 chip
    • 2. Find hit channel
    • 3. Send hit channel data to FIFO (memory)
  • How to find hit?
    • ZS block generates T value for each channel

T = ADC height of 2nd sample – pedestal of 2nd sample

+ (3nd sample) + (4th sample) + (5th sample)

And then compares T with threshold to find hit channel

  • ZS block needs calibration run for pedestal and threshold.
  • Standard deviation of T in calibration run is unit of threshold. (Ts)
zs fpga test
ZS FPGA Test

Get [ZS data] and [unZS data] of same event

with 2 sigma threshold, forced trigger.

ZS by FPGA

ZS by PC

Compare

No error for ~20000 events

test experiment in rcnp osaka
Test experiment in RCNP OSAKA
  • SSD sensor
  • ~290um thick
  • ~78um strip pitch
  • ~6x6cm2effective area
result hit pattern pmt trigger
Result – hit pattern PMT trigger

Up stream (SSDA, B)

Down stream (SSDC, D)

Strip pitch is ~78um, total 768 strips. ~6cm x 6cm window.

No big difference between unsuppressed, ZS data.

result hit pattern mppc trigger
Result – hit pattern MPPC trigger

Up stream (SSDA, B)

Down stream (SSDC, D)

Strip pitch is ~78um, total 768 strips. ~6cm x 6cm window.

No big difference between unsuppressed, ZS data.

result analysis parameter
Result – analysis parameter
  • I’d like show the comparison between unsuppressed data and ZS data.
  • Result shows 7 runs. 3 unsuppressed and 4 ZS data.
  • Each run has ~5000 events.
  • Scin : scintillator + PMT trigger
  • MPPC : multi pixel photon counter trigger
  • Beam rate counted by PMT1
  • Un : unsuppressed data
  • ZS : suppressed data
  • number : threshold (standard dev of T distribution)

Trigger

Beam rate

Data

result efficiency
Result – efficiency

Trigger

Beam rate

Data

result time resolution
Result – Time resolution

Trigger

Beam rate

Data

result time resolution condition
Result – Time resolution condition
  • Time resolution analysis condition
    • Cut out unreasonable fitting parameter
    • Cluster width is less than three
    • Cut out Bad timing signal
  • We had bad beam and trigger
    • Fake trigger due to signal reflection.
    • We got several cycles of beam.
    • Eventually we got off timing beam.
  • We lost 20~30% of event in analysis
result data size
Result – Data size
  • Because ZS block sends data of hit channel only,

data size is dynamic . => ZS data size

  • In analysis, we pick up real hit channel from ZS data => Rhitdata size
  • We want to check average and stabilityof data size
result average of data size
Result – Average of data size

100%

100%

100%

Trigger

Beam rate

Data

calibration off beam on beam
Calibration – off beam on beam
  • We had mistake running calibration with beam.
  • It explains 3% eff drop of MPPC, 1.7MHz, ZS run
  • Still we can believe analysis result because we used low threshold and T value.

(We use off beam calibration result for analysis)

conclusion
Conclusion
  • We try to increase event rate of APVDAQ with data suppression by FPGA firmware development.
  • We confirmed ZS with noise run.
  • We had test experiment with proton beam.
  • Analysis result of suppressed data is similar with unsuppressed data one.
  • Suppression rate is 2~6% of original data size.

=> We can suppress more. (Rhit size ~0.4%)

  • We had beam, trigger, calibration problem

=> But ZS itself works well.

signal analysis
Signal analysis

adcch

Y = p0(X - p1)exp( -(X-p1)/p2 )

nsec

calibration off beam on beam1
Calibration – off beam on beam
  • We had mistake running on beam calibration.
  • It explains 3% eff drop of MPPC, 1.7MHz, ZS run
  • Still we can believe analysis result because we used low threshold and T value.

Beam off

Beam on

Calibration

Run01

Run02

Run03

Cal

Run01

Cal

Run02

Cal

Run03

slide27

Introduction

  • Data suppression

- FPGA code

- Algorithm

  • Test experiment

- set up and beam

- result

- calibration

  • Conclusion
our goal
Our Goal

We are developing APVDAQ

for higher event rate.

event rate of apvdaq
Event rate of APVDAQ

Four APVDAQ => up to 70Hz

One APVDAQ => up to 340Hz

Expected trigger rate is ~30kHz in SuperB

DAQ event rate is ~300Hz in J-PARC(K1.8)

algoritm zs block step 3
Algoritm – ZS block step 3
  • Send marked channel data to FIFO
  • Example

1 | 16 | 358 | 746

2 | 16 | 412 | 228

3 | 16 | 403 | 713

4 | 16 | 390 | 723

5 | 16 | 368 | 732

6 | 16 | 356 | 232

introduction data
Introduction – data
  • There is bottle neck of data from VME to PC
  • Data transfer time
    • Apv25=>VME : ~200 us
    • VME=>PC : ~dozens ms
  • But we don’t need data of whole 128 channels
  • We need

pedestal, adc height

sample #, channel #, chip #

of hit channel

  • Usually one event has 1~3 hit channels/sensor
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