Study of Accidental Activity at the Front Barrel of the KOTO - - PowerPoint PPT Presentation

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Study of Accidental Activity at the Front Barrel of the KOTO - - PowerPoint PPT Presentation

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Study of Accidental Activity at the Front Barrel of the KOTO Detector Ryota Shiraishi Yamanaka Group Kuno-Yamanaka Group Year-End Presentation 2019 Ryota Shiraishi 2019.12.23 Kuno-Yamanaka Group Year-End Presentation 2019 Introduction

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Ryota Shiraishi 2019.12.23 Kuno-Yamanaka Group Year-End Presentation 2019

Study of Accidental Activity at the Front Barrel of the KOTO Detector

Ryota Shiraishi Yamanaka Group Kuno-Yamanaka Group Year-End Presentation 2019

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SLIDE 2

Ryota Shiraishi 2019.12.23 Kuno-Yamanaka Group Year-End Presentation 2019

Introduction

2

The KOTO experiment

Purpose : To observe the decay . Signal : 2 photons + “nothing”

KL → π0ν¯ ν

➥ detected at the CsI calorimeter ➥ other veto detectors make sure of no extra hits

γ γ π0 ν¯ ν

KL

CsI

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SLIDE 3

Ryota Shiraishi 2019.12.23 Kuno-Yamanaka Group Year-End Presentation 2019

Accidental Signal Loss

3

Accidental hits on veto detectors coincident with the decay could cause signal loss. Major sources…

  • Other KL decay
  • Neutron from the J-PARC primary beam line

π0

decay signal @CsI

π0

Accidental hit @veto detector

Discarded (Acceptance loss) Accidental hits need to be reduced.

Veto Window

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SLIDE 4

Ryota Shiraishi 2019.12.23 Kuno-Yamanaka Group Year-End Presentation 2019

Purpose of This Study

4

  • To understand accidental activities at the Front

Barrel of the KOTO detector.

  • To calculate accidental hit rates by using data

taken in 2019.

  • To check consistency of accidental hit rates

between physics-triggered data and TMON- triggerd data.

Physics trigger…trigger to collect data TMON trigger…trigger to reproduce accidental hits

KL → π0ν¯ ν

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Ryota Shiraishi 2019.12.23 Kuno-Yamanaka Group Year-End Presentation 2019

Front Barrel

5

View from the downstream side

  • Sandwich of lead & plastic

scintillators

  • 2.75m long
  • Sampled by125MHz FADC
  • 16 modules
  • 32 readout channels

(inner/outer layers are read separately)

Front Barrel

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Ryota Shiraishi 2019.12.23 Kuno-Yamanaka Group Year-End Presentation 2019

TMON Trigger

6

TMON trigger is…

A random trigger generated from the signals of the Target

  • Monitor. The rate is proportional to the beam intensity.

We use this trigger to reproduce accidental activities and

  • verlay the waveforms on generated waveforms in simulation.

Proton Beam

Au Target 50° 16° KOTO Beam Line Plastic Scintillators

TMON Trigger

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Ryota Shiraishi 2019.12.23 Kuno-Yamanaka Group Year-End Presentation 2019

Energy Distribution

7

TMON data Energy is distributed up to ~600 MeV. Now, set the energy threshold to 2 MeV. Consider only events with FBAREne > 2 MeV. ➤

FBARModID 5 10 15 20 25 30 FBAREne [MeV] 100 200 300 400 500 600 1 10

2

10

3

10

4

10

FBAREne:FBARModID {ExtTrigType==2}

FBARModID FBAREne [MeV]

h Entries 30082 Mean 2.337 RMS 4.122

5 10 15 20 25 30

2

10

3

10

4

10

h Entries 30082 Mean 2.337 RMS 4.122

FBAREne {FBARModID==0 && ExtTrigType==2 && FBAREne<50}

# of events

FBAREne {FBARModID==0 && ExtTrigType==2}

600

FBAREne:FBARModID {ExtTrigType==2}

104 103 102 2

FBAREne [MeV]

30

Higher counts in inner channels Lower counts in outer channels

➞

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SLIDE 8

10 10 20 30 40 50 60 70

Rate [Hz]

FBAR Rate ch0 (E>2.000000MeV)

100 200 300 400 500 600

3

10 ×

FBAR Rate ch0 (E>2.000000MeV)

FBARPTime [clock]

10 − 10 20 30 40 50 60 70

ratio (phys / tmon)

0.5 1 1.5

− : Physics − : TMON

FBARPTime [clock] Rate [Hz] Ratio (phys./tmon) FBAR Rate ch0 (E > 2 MeV)

600

×103

Ryota Shiraishi 2019.12.23 Kuno-Yamanaka Group Year-End Presentation 2019

Comparison between Phys. & TMON data

8

Rate[Hz] per bin(= 1clock=8ns)

Rate = #events / (∆T×#triggered) (∆T = 1clock = 8ns)

Earlier timing region

  • > consistent

Later timing region

  • > subtle discrepancy exists
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SLIDE 9

Ryota Shiraishi 2019.12.23 Kuno-Yamanaka Group Year-End Presentation 2019

Rates in 10 - 20 clock timing

9

Ratio = Phys./TMON = 1 ~ 1.1

Energy Threshold : 2MeV Rate = #events/(∆T×#triggered) ∆T = ∆T1

10 10 20 30 40 50 60 70

Rate [Hz]

FBAR Rate ch0 (E>2.000000MeV)

100 200 300 400 500 600

3

10 ×

FBAR Rate ch0 (E>2.000000MeV)

FBARPTime [clock]

10 − 10 20 30 40 50 60 70

ratio (phys / tmon)

0.5 1 1.5

∆T1 FBAR Rate ch0 (E>2 MeV)

FBARPTime [clock] Rate [Hz] Ratio (phys./tmon)

− : Physics − : TMON

➞ Good agreement

5 10 15 20 25 30

Rate [Hz]

50 100 150 200 250 300

3

10 ×

(FBARPTime>10.000000 && FBARPTime<20.000000) FBAR Rate E>2.000000MeV

FBARModID

5 10 15 20 25 30

ratio (phys / tmon)

0.9 1 1.1 1.2

E > 2MeV, 10 < FBARPTime < 20

FBARModID Rate [Hz] Ratio (phys./tmon) Outer Channels Inner Channels 300 ×103

⟶ Primary beam line side

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SLIDE 10

Ryota Shiraishi 2019.12.23 Kuno-Yamanaka Group Year-End Presentation 2019

How we will reduce accidental hits

10

Accidental activities by neutrons coming from the J-PARC primary beam line

KOTO detector

To reduce the neutron flux, we installed a 33cm-thick iron wall.

Iron Wall

KOTO Detector

neutron

Primary Beam Line Iron Wall

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SLIDE 11

Ryota Shiraishi 2019.12.23 Kuno-Yamanaka Group Year-End Presentation 2019

Summary / To do

11

  • Confirmed consistency of accidental counting

rates in physics/TMON data.

  • To reduce neutrons from the primary beam

line, we installed an iron wall and will check the reduction effect.

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Ryota Shiraishi 2019.12.23 Kuno-Yamanaka Group Year-End Presentation 2019

Backup

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Ryota Shiraishi 2019.12.23 Kuno-Yamanaka Group Year-End Presentation 2019

Detector

13

View from the downstream side

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Ryota Shiraishi 2019.12.23 Kuno-Yamanaka Group Year-End Presentation 2019

Waveforms at the Front Barrel

14

Waveform Examples

Physics-triggerd event Energy : 13.8 [MeV] Time : 17.7 [clock=8ns] TMON-triggerd event Energy : 3.1 [MeV] Time : 47.3 [clock=8ns]

Consider an energy threshold and timing distributions.

Iteration$ 10 20 30 40 50 60 70 FBAR.Data 500 600 700 800 900

FBAR.Data:Iteration$ {FBAR.ModID==0 && Entry$==256}

FBAR.Data:Iteration$ {FBAR.ModID==0 && Entry$==256} Time [clock=8ns] ADC counts 20

Iteration$ 10 20 30 40 50 60 70 FBAR.Data 485 490 495 500 505 510 515 520

FBAR.Data:Iteration$ {FBAR.ModID==0 && Entry$==706}

FBAR.Data:Iteration$ {FBAR.ModID==0 && Entry$==706} Time [clock=8ns] ADC counts 40

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Ryota Shiraishi 2019.12.23 Kuno-Yamanaka Group Year-End Presentation 2019

Time Distribution

15

Take the moving average -> make waveforms smoother Calculate a parabolic curve using three samples around the peak. The parabola time closer to the nominal time (~31 clocks) for the Front Barrel is selected. Tend to have a structure like a broad hill.

➤

htemp Entries 8044 Mean 28.49 RMS 16.34 FBARPTime 10 20 30 40 50 60 50 100 150 200 250 300 350 htemp Entries 8044 Mean 28.49 RMS 16.34

FBARPTime {FBARModID==0 && FBAREne>2 && FBARPTime>-10 && ExtTrigType==2}

FBARPTime [clock]

# of events

TMON

FABRPTime {FBARModID==0 && FBAREne>2 && FBARPTime>-10 && (ScaledTrigBit&0x1)==0x1} 30

htemp Entries 78920 Mean 28.95 RMS 15.4 FBARPTime 10 20 30 40 50 60 500 1000 1500 2000 2500 3000 3500 htemp Entries 78920 Mean 28.95 RMS 15.4

FBARPTime {FBARModID==0 && FBAREne>2 && FBARPTime>-10 && (ScaledTrigBit&0x1)==0x1}

FBARPTime [clock]

# of events

Physics

FABRPTime {FBARModID==0 && FBAREne>2 && FBARPTime>-10 && ExtTrigType==2} 30

Concentrated around the nominal time Dominated by accidental hits Parabola time Parabola curve

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Ryota Shiraishi 2019.12.23 Kuno-Yamanaka Group Year-End Presentation 2019

Moving Average

16

Calculation Code

Take the average of five consecutive samples. Make waveforms smoother and mitigate local fluctuations.

/sw/koto/e14ana/release/v4.01.10/AnalysisLibrary/UserProjects/ E14ProdLibrary/E14ProdDstConv/src/E14CrateData125MHz.cc

10 20 30 40 50 60 460 480 500 520 540 560 580 600

wfm2

Entries 64 Mean x 31.5 Mean y 503.8 Std Dev x 18.47 Std Dev y 16.24

wfm2

Entries 64 Mean x 31.5 Mean y 503.8 Std Dev x 18.47 Std Dev y 16.24

FBARWfm[0]:Iteration$ {Entry$==153}

10 20 30 40 50 60 460 480 500 520 540 560 580 600

wfm

Entries 60 Mean x 31.5 Mean y 503 Std Dev x 17.32 Std Dev y 15.12

wfm

Entries 60 Mean x 31.5 Mean y 503 Std Dev x 17.32 Std Dev y 15.12

wfm

Averaged Wfm Time [clock] Time [clock] ADC ADC

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Ryota Shiraishi 2019.12.23 Kuno-Yamanaka Group Year-End Presentation 2019

Parabola Interpolation Method

17

ptime

Moving Average Calculation of ptime

Peak Search

Nominal Time Condition

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Ryota Shiraishi 2019.12.23 Kuno-Yamanaka Group Year-End Presentation 2019

Rates in 10 - 20 clock timing

18

Ratio = Phys./TMON = 1 ~ 1.1

Energy Threshold FBAREne > 2MeV

10 10 20 30 40 50 60 70

Rate [Hz]

FBAR Rate ch0 (E>2.000000MeV)

100 200 300 400 500 600

3

10 ×

FBAR Rate ch0 (E>2.000000MeV)

FBARPTime [clock]

10 − 10 20 30 40 50 60 70

ratio (phys / tmon)

0.5 1 1.5

∆T1

FBAR Rate ch0 (E>2 MeV)

FBARPTime [clock] Rate [Hz] Ratio (phys./tmon)

− : Physics − : TMON

Rate = #events/(∆T×#triggered) ∆T = ∆T1

➞ Good agreement

5 10 15 20 25 30

Rate [Hz]

50 100 150 200 250 300

3

10 ×

(FBARPTime>10.000000 && FBARPTime<20.000000) FBAR Rate E>2.000000MeV

FBARModID

5 10 15 20 25 30

ratio (phys / tmon)

0.9 1 1.1 1.2

E > 2MeV, 10 < FBARPTime < 20 E > 2MeV, 10 < FBARPTime < 20 FBARModID Rate [Hz] Ratio (phys./tmon) Outer Channels Inner Channels 300 ×103

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SLIDE 19

Ryota Shiraishi 2019.12.23 Kuno-Yamanaka Group Year-End Presentation 2019

Rates in 35 - 50 clock timing

19

Energy Threshold FBAREne > 2MeV Rate = #events/(∆T×#triggered) ∆T = ∆T2

10 10 20 30 40 50 60 70

Rate [Hz]

FBAR Rate ch0 (E>2.000000MeV)

100 200 300 400 500 600

3

10 ×

FBAR Rate ch0 (E>2.000000MeV)

FBARPTime [clock]

10 − 10 20 30 40 50 60 70

ratio (phys / tmon)

0.5 1 1.5

∆T2

FBAR Rate ch0 (E>2 MeV)

FBARPTime [clock] Rate [Hz] Ratio (phys./tmon)

Ratio = Phys./TMON = 1.1 ~ 1.2

− : Physics − : TMON

5 10 15 20 25 30

Rate [Hz]

50 100 150 200 250 300

3

10 ×

(FBARPTime>35.000000 && FBARPTime<50.000000) FBAR Rate E>2.000000MeV (FBARPTime>35.000000 && FBARPTime<50.000000) FBAR Rate E>2.000000MeV

FBARModID

5 10 15 20 25 30

ratio (phys / tmon)

0.9 1 1.1 1.2

FBARModID Rate [Hz] Ratio (phys./tmon) E > 2MeV, 35 < FBARPTime < 50 Outer Channels Inner Channels 300 ×103

➞ A little bit worse than earlier timing