Zero suppression with apvdaq
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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 inside

ZS block - inside


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 signal noise ratio snr

Result – Signal Noise Ratio (SNR)

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.


Back up

Back up


Signal analysis

Signal analysis

adcch

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

nsec


Algoritm zs block ebit correction

Algoritm – ZS block ebit correction


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


Zero suppression with apvdaq

  • 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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