CTA report 152:Comparison of photon detection performance

of photomultiplier tube and silicon photomultiplier for Medium Sized Telescopes

Anatolii Zenin, Hiroyasu Tajima, Akira Okumura, Yuki Nakamura

ISEE, Nagoya University

OutlineIntroduction

• CTA and Cherenkov imaging• Motivation• PMT and SiPM• Medium-sized telescope

2

Main Part

• Setup and analysis technique• Measurement results

• Discussion

CTA and atmospheric Cherenkov imaging

3

Cherenkov Photons

Electromagnetic Cascade

Very-high-energyGamma Ray(20 GeV –300 TeV)

LST:20 GeV ~ 150 GeV

SST:5 TeV ~ 300 TeV

MST:150 GeV ~ 5 TeV

K. Bernlöhr

MotivationAdvantages of SiPM:

• Background-tolerant, no degradation over time

• Stable quantum efficiency and photon detection efficiency

• Can be operated with 60V

• Lightweight, compact

4

PMT and SiPMTo ensure that the performance of SiPM cameras will not be inferior to the current PMT cameras, we have to compare:

•QE / PDE

•Sensitivity to signal

•Sensitivity to noise

•High NSB (moonlight) tolerance and performance under high NSB conditions

•Overall telescope performance (the end goal of this work)

5

PMT and SiPM sensitivity comparison (not to scale)

200 300 400 500 600 700wavelength, nm

0

0.5

1

1.5

2

2.5

3

3.5

4

4.5

5

arb.

uni

t

100 GeV γ Cherenkov spectrum

La PalmaNSB spectrum

CTA PMT QECTA SiPM PDE

Medium-sized telescope

6

Cutoff angle 26˚≤αc≤28˚

(technical requirement)

ROBAST simulation of MST optical system

αc

Measurement setup

7

PMT on a rotation stage

Readout module (TARGET) on a rotation stage

8

365 nm

Analysis technique

Crosstalk does not affect 0pe peaks in SiPM

PMT charge spectrum sample

h_spec1Entries 39900Mean 15.31Std Dev 18.79

40− 20− 0 20 40 60 80 mV)×Integral Value (ns

0

100

200

300

400

500

600

700

800

Entri

es

h_spec1Entries 39900Mean 15.31Std Dev 18.79

200− 0 200 400 600 800 1000 1200 1400 1600 ns)×Charge (mV

1

10

210

310

410 Signal + dark count

Only dark count

noise

SiPM charge spectrum sample

P (k) =�k

k!e��

<latexit sha1_base64="oeIIB7kHc47mJxUDmVkUPZ7sMuE=">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</latexit><latexit sha1_base64="oeIIB7kHc47mJxUDmVkUPZ7sMuE=">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</latexit><latexit sha1_base64="oeIIB7kHc47mJxUDmVkUPZ7sMuE=">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</latexit><latexit sha1_base64="oeIIB7kHc47mJxUDmVkUPZ7sMuE=">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</latexit>

� = � lnP (0)<latexit sha1_base64="zWnPk8B8mEXbQb2nXx/pjxwn5fk=">AAAB/nicdVDLSsNAFJ3UV62vqLhyM1iEujAkpdB2IRTduKxgH9CEMplM2qGTSZiZCCUU/BU3LhRx63e482+cphVU9MDA4ZxzuXeOnzAqlW1/GIWV1bX1jeJmaWt7Z3fP3D/oyjgVmHRwzGLR95EkjHLSUVQx0k8EQZHPSM+fXM393h0Rksb8Vk0T4kVoxGlIMVJaGppHLtPhAMELeA5dxrN2xT6bDc2ybTWbjWq1BnNSc5wFceoN6Fh2jjJYoj00390gxmlEuMIMSTlw7ER5GRKKYkZmJTeVJEF4gkZkoClHEZFelp8/g6daCWAYC/24grn6fSJDkZTTyNfJCKmx/O3Nxb+8QarChpdRnqSKcLxYFKYMqhjOu4ABFQQrNtUEYUH1rRCPkUBY6cZKuoSvn8L/SbdqObbl3NTKrctlHUVwDE5ABTigDlrgGrRBB2CQgQfwBJ6Ne+PReDFeF9GCsZw5BD9gvH0CUKSUbw==</latexit><latexit sha1_base64="zWnPk8B8mEXbQb2nXx/pjxwn5fk=">AAAB/nicdVDLSsNAFJ3UV62vqLhyM1iEujAkpdB2IRTduKxgH9CEMplM2qGTSZiZCCUU/BU3LhRx63e482+cphVU9MDA4ZxzuXeOnzAqlW1/GIWV1bX1jeJmaWt7Z3fP3D/oyjgVmHRwzGLR95EkjHLSUVQx0k8EQZHPSM+fXM393h0Rksb8Vk0T4kVoxGlIMVJaGppHLtPhAMELeA5dxrN2xT6bDc2ybTWbjWq1BnNSc5wFceoN6Fh2jjJYoj00390gxmlEuMIMSTlw7ER5GRKKYkZmJTeVJEF4gkZkoClHEZFelp8/g6daCWAYC/24grn6fSJDkZTTyNfJCKmx/O3Nxb+8QarChpdRnqSKcLxYFKYMqhjOu4ABFQQrNtUEYUH1rRCPkUBY6cZKuoSvn8L/SbdqObbl3NTKrctlHUVwDE5ABTigDlrgGrRBB2CQgQfwBJ6Ne+PReDFeF9GCsZw5BD9gvH0CUKSUbw==</latexit><latexit sha1_base64="zWnPk8B8mEXbQb2nXx/pjxwn5fk=">AAAB/nicdVDLSsNAFJ3UV62vqLhyM1iEujAkpdB2IRTduKxgH9CEMplM2qGTSZiZCCUU/BU3LhRx63e482+cphVU9MDA4ZxzuXeOnzAqlW1/GIWV1bX1jeJmaWt7Z3fP3D/oyjgVmHRwzGLR95EkjHLSUVQx0k8EQZHPSM+fXM393h0Rksb8Vk0T4kVoxGlIMVJaGppHLtPhAMELeA5dxrN2xT6bDc2ybTWbjWq1BnNSc5wFceoN6Fh2jjJYoj00390gxmlEuMIMSTlw7ER5GRKKYkZmJTeVJEF4gkZkoClHEZFelp8/g6daCWAYC/24grn6fSJDkZTTyNfJCKmx/O3Nxb+8QarChpdRnqSKcLxYFKYMqhjOu4ABFQQrNtUEYUH1rRCPkUBY6cZKuoSvn8L/SbdqObbl3NTKrctlHUVwDE5ABTigDlrgGrRBB2CQgQfwBJ6Ne+PReDFeF9GCsZw5BD9gvH0CUKSUbw==</latexit><latexit sha1_base64="zWnPk8B8mEXbQb2nXx/pjxwn5fk=">AAAB/nicdVDLSsNAFJ3UV62vqLhyM1iEujAkpdB2IRTduKxgH9CEMplM2qGTSZiZCCUU/BU3LhRx63e482+cphVU9MDA4ZxzuXeOnzAqlW1/GIWV1bX1jeJmaWt7Z3fP3D/oyjgVmHRwzGLR95EkjHLSUVQx0k8EQZHPSM+fXM393h0Rksb8Vk0T4kVoxGlIMVJaGppHLtPhAMELeA5dxrN2xT6bDc2ybTWbjWq1BnNSc5wFceoN6Fh2jjJYoj00390gxmlEuMIMSTlw7ER5GRKKYkZmJTeVJEF4gkZkoClHEZFelp8/g6daCWAYC/24grn6fSJDkZTTyNfJCKmx/O3Nxb+8QarChpdRnqSKcLxYFKYMqhjOu4ABFQQrNtUEYUH1rRCPkUBY6cZKuoSvn8L/SbdqObbl3NTKrctlHUVwDE5ABTigDlrgGrRBB2CQgQfwBJ6Ne+PReDFeF9GCsZw5BD9gvH0CUKSUbw==</latexit>

Poisson distribution:

Can extract mean value from pedestal:

9

365 nm

Photoelectron distribution in SiPM

0 1 2 3 4 5 6 7 8x

0

1

2

3

4

5

6

7

8y

0

200

400

600

800

1000

1200

1400

phot

on c

ount

0.0027222 0.00747551 0.0469161 0.09266 0.0896353 0.0360592 0.00623342 0.000213355

0.0471951 0.0805923 0.0508806 0.0415147 0.0400246 0.0471579 0.0808369 0.0388827

0.0817675 0.0739368 0.0170783 0.0146918 0.0229714 0.02124 0.0693322 0.0787186

0.0509001 0.0145181 0.0176383 0.0133915 0.01318 0.0485025 0.0478063

0.0667145 0.0487292 0.0168159 0.011876 0.0162426 0.0156332 0.0485464 0.0633529

0.080206 0.0730602 0.0395963 0.0324879 0.0133267 0.034744 0.077408 0.0757741

0.0181476 0.0732873 0.0366851 0.0603641 0.0581927 0.0318337 0.0642246 0.013782

0.00291888 -0.00117109 0.0395916 0.0910576 0.0869906 0.0381313 -0.000498826 0.00173501

0 1 2 3 4 5 6 7 8x

0

1

2

3

4

5

6

7

8y

0

0.01

0.02

0.03

0.04

0.05

0.06

0.07

0.08

0.09

mea

n PE

SiPM photo

SiPM geometry

PE distribution in data

Simulated photon distribution

0 5 10 15 20 25 30 35 40 angle, deg.θ

0

0.5

1

1.5

2

2.5

3λ PMT simulationPMT experimentSiPM simulationSiPM expermiment

465 nm

10

Measurement resultsResults for azimuthal angle φ = 0

(see the figure on the left)

cutoffangle

PreliminaryOur simulation can not reproduce absolute values, so it is normalized to fit on-axis SiPM

data

There are still some issues with the measurement setup and analysis

It is likely that consideration in terms of only geometrical optics is not good enough to

simulate SiPM behavior properly

0 5 10 15 20 25 30 35 40 angle, deg.θ

0

0.5

1

1.5

2

2.5

3

3.5λ PMT simulationPMT experimentSiPM simulationSiPM expermiment

375 nm

Preliminary

cutoffangle

Discussion

11

• Although the results are not final, our measurement technique is usable and only needs a little polishing

• There are still some difficulties with the setup, but that will be solved in a short time

• Relative performance is not consistent with the simulation, likely due to interference effects in Si3N4 and SiO2 layers and on silicon surface

• Cutoff angle for SiPM configuration has to be checked

To do

12

Several things have to be done before making any solid conclusions:

• Design a new light concentrator to remove the gaps and optimize the cutoff angle (in progress)

• Compare the performance of PMT and SiPM by a simple ray-tracing simulation(after designing a new light concentrator)

• Perform a full telescope simulation with CORSIKA and sim_telarray and study how NSB affects new cameras(the final step)