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zero suppression with APV-DAQ

2012/02/07 SVDPXD meetingSeoul National Univ, Changwoo Joo

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Introduction• We are developing APVDAQ in J-PARC• With our DAQ, event rate is

o eight APVDAQ => up to ~20Hzo 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

o Apv25=>VME : ~200 uso VME=>PC : ~dozens ms

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Zero Suppression (ZS)• Build up FPGA firmware level data suppression

• Put ZS block between data pipe line and FIFO

ZS block FIFO

(Memory) To PCapv25data

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ZS block - inside

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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)o 1. Save data from apv25 chipo 2. Find hit channelo 3. Send hit channel data to FIFO (memory)

• How to find hit?o 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 TestGet [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

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Test experiment in RCNP OSAKA

• SSD sensor~290um thick~78um strip pitch~6x6cm2 effective area

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Result – hit pattern PMT triggerUp 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.

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Result – hit pattern MPPC triggerUp 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.

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Result – analysis parameter

Scin 21kHz

Un

Scin 1.5MHz

Un

Scin 190kHz 1.5-ZS

Scin 1.1MHz 2-ZS

Scin 1.2MHz 2.5-ZS

MPPC 2.1MHz

Un

MPPC 1.7MHz 2.5-ZS

80828486889092949698

100

Efficiency (%)

TriggerBeam rate

Data

• I’d like show the comparison between unsup-pressed 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)

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Result – efficiency

Scin 21kHz

Un

Scin 1.5MHz

Un

Scin 190kHz 1.5-ZS

Scin 1.1MHz 2-ZS

Scin 1.2MHz 2.5-ZS

MPPC 2.1MHz

Un

MPPC 1.7MHz 2.5-ZS

80828486889092949698

100

Efficiency (%)

TriggerBeam rate

Data

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Trigger Beam rate

Data format

Thres-hold

Sensor efficiencyCoincidentefficiencyA B C D

Scin 21kHz Un 99.96(%)

99.94(%)

99.94(%)

99.86(%)

99.82(%)

Scin 1.5MHz Un 100.00 99.94 99.52 99.94 99.40

Scin 190kHz ZS 1.5(Ts) 100.00 99.96 99.90 99.96 99.82

Scin 1.1MHz ZS 2 100.00 99.88 99.52 100.00 99.40

Scin 1.2MHz ZS 2.5 99.90 99.87 99.80 99.90 99.77

Mppc 2.1MHz Un 89.45 89.09 88.66 88.43 88.11

Mppc 1.7MHz ZS 2.5 86.81 86.37 85.44 85.12 84.80

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Result – Signal Noise Ratio (SNR)

TriggerBeam rate

Data

Scin 21kHz

Un

Scin 1.5MHz

Un

Scin 190kHz 1.5-ZS

Scin 1.1MHz 2-ZS

Scin 1.2MHz 2.5-ZS

MPPC 2.1MHz

Un

MPPC 1.7MHz 2.5-ZS

30313233343536373839

SNR

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Trigger BeamRate

Datafor-mat

Thres-hold

SNR for each sensorTotalSNRA B C D

Pmt 21kHz Un 42.62 34.02 37.24 36.59 37.57

Pmt 1.5MHz Un 38.08 30.27 32.77 32.51 33.22

Pmt 190kHz ZS 1.5 41.87 33.24 36.52 35.66 36.78

Pmt 1.1MHz ZS 2 38.73 30.59 33.39 32.82 33.88

Pmt 1.2MHz ZS 2.5 42.25 33.35 36.99 36.80 37.37

Mppc 2.1MHz Un 43.34 35.33 38.95 36.02 38.29

Mppc 1.7MHz ZS 2.5 42.59 34.53 38.54 35.19 37.64

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Result – Time resolution

TriggerBeam rate

Data

Scin 21kHz

Un

Scin 1.5MHz

Un

Scin 190kHz 1.5-ZS

Scin 1.1MHz 2-ZS

Scin 1.2MHz 2.5-ZS

MPPC 2.1MHz

Un

MPPC 1.7MHz 2.5-ZS

00.5

11.5

22.5

33.5

44.5

5

Time resuolution (ns)

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Trigger Beam rate

Data for-mat

Thres-hold

Time resolution of sensorsTotal

signalA B C D

Pmt 21kHz Un 2.61(ns) 2.76(ns) 2.64(ns)

2.62(ns)

2.74(ns)

Pmt 1.5MHz Un 2.96 3.23 2.77 2.61 3.14

Pmt 190kHz ZS 1.5 2.70 2.95 2.59 2.62 2.78

Pmt 1.1MHz ZS 2 3.08 3.03 2.60 2.49 2.99

Pmt 1.2MHz ZS 2.5 2.64 2.81 2.50 2.52 2.75

Mppc 2.1MHz Un 5.74 4.88 5.21 3.58 3.64

Mppc 1.7MHz ZS 2.5 4.17 4.35 4.15 3.93 4.33

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Result – Time resolution condi-tion

• Time resolution analysis conditiono Cut out unreasonable fitting parametero Cluster width is less than threeo Cut out Bad timing signal

• We had bad beam and triggero Fake trigger due to signal reflection.o We got several cycles of beam.o Eventually we got off timing beam.

• We lost 20~30% of event in analysis

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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 => Rhit data size• We want to check average and stability of data

size

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Result – Average of data size

TriggerBeam rate

Data

Scin 21kHz

Un

Scin 1.5MHz

Un

Scin 190kHz 1.5-ZS

Scin 1.1MHz 2-ZS

Scin 1.2MHz 2.5-ZS

MPPC 2.1MHz

Un

MPPC 1.7MHz 2.5-ZS

012345678

Data size (% of original data size)ZS data size Rhit data size100

%100%

100%

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Trigger Beamrate

Data format

Thres-hold ZS data size Rhit data size

Pmt 21kHz Un 100(%) 0.36(%)

Pmt 1.5MHz Un 100 0.31

Pmt 190kHz ZS 1.5 6.50 0.31

Pmt 1.1MHz ZS 2 3.17 0.32

Pmt 1.2MHz ZS 2.5 2.25 0.29

Mppc 2.1MHz Un 100 0.41

Mppc 1.7MHz ZS 2.5 2.19 0.32

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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)

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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.

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Back up

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Signal analysis

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

nsec

adc ch

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Algoritm – ZS block ebit correction

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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

Calibra-tion Run01 Run02 Run03

Cal Run01 Run02 Run03Cal Cal

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• Introduction• Data suppression

- FPGA code- Algorithm

• Test experiment- set up and beam- result- calibration

• Conclusion

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Our Goal

We are developing APVDAQ for higher event rate.

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Event rate of APVDAQ

Four APVDAQ => up to 70HzOne APVDAQ => up to

340Hz

Expected trigger rate is ~30kHz in Su-perB

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

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Algoritm – ZS block step 3

• Send marked channel data to FIFO

• Example1 | 16 | 358 | 7462 | 16 | 412 | 2283 | 16 | 403 | 7134 | 16 | 390 | 7235 | 16 | 368 | 7326 | 16 | 356 | 232

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Introduction – data• There is bottle neck of data from VME to PC• Data transfer time

o Apv25=>VME : ~200 uso 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