New gatable MCP-PMTs and their

performances in comparison with

semiconductor type detectors for SLR

applications

2013.11.12-15

Takeshi Taguchi, Masahiro Nakamura

Hamamatsu Photonics K. K.

Abstract

MCP-PMTs(Microchannel Plate Photomultiplier Tubes) and

semiconductor detectors such as APD (Avalanche Photo

Diode) are commonly used for SLR applications.

Performance of these detectors are compared on

parameters such as sensitivity, noise, temporal response,

timing jitter and other characteristics. The MCP-PMTs we

have developed show improvements in especially sensitivity

and noise induced by gating pulse.

We also focus on signal processing technic to optimize

detector performance and introduce other

possible detector modules for future applications. Other

possible applications using MCP-PMTs are discussed as

well for general laser ranging.

Introduction

New Gated MCP-PMTs introduced herein have been

improved in their performances. In particular, sensitivity (=

detection efficiency in this case) and time jitter （resolution)

are superior to the former type, R5916U series.

In comparison with semiconductor type detector, this new

gated MCP-PMT unit shows some advantages on its

performance.

Improvements in

Sensitivity and Time Resolution

Fig. 1 shows structures and operating principles of former

type (R5916U series) and new gated MCP-PMT. R5916U

has a grid electrode between the photocathode and MCP for

gating function but new one does not. In a case of new one,

a gate pulse is directly applied to the photocathode instead

of the grid electrode.

This results in improvement of detection efficiency (30%

UP!) because the grid electrode blocks some photoelectrons

passing through and also generates some time jitter caused

by low potential due to the gate pulse (10 to 50 V but 200 V with the new type) as shown in Fig. 2.

Photons

R R R

R

R R

High Voltage Power Supply

Gate

Driver

Pulse

Generator

Pulse

Generator

R

High Voltage Power Supply

R

Former Type (R5916U Series)

In Comparison with Former Types (R5916U Series)

【Structures(Sensor Head) & Operating Principles】

New Gated MCP-PMT

Fig. 1

Photocathode MCP

Grid

Electrode

Anode

1.E+00

1.E+01

1.E+02

1.E+03

1.E+04

-1200 -1000 -800 -600 -400 -200 0 200 400 600 800 1000 1200

Co

un

ts

Time(ps)

Time Resolution of New Gated MCP-PMT Unit

in comparison with R5916U

New Gatable MCP-PMT Unit

Time Jitter@FWHM = 42.8 ps

But Real Time Jitter is 24.6 ps obtained by deconvolution

Laser Pulse Width = 35 ps @FWHM

R5916U-50

Time Jitter@FWHM =90 ps But Real Time Jitter is 82.9 ps obtained by deconvolution Laser Pulse Width = 35 ps @FWHM

Note: This data was obtained by

Multialkali photocathode types

In Comparison with Former Types (R5916U Series)

【Improved Time Resolution】 Fig. 2

Other Characteristics

【Photocathode Sensitivities】 ①Multialkali ②Ext. Multialkali ③Bialkali

④CsTe ⑤GaAs ⑥Ext. GaAsP

⑦GaAsP

Other Characteristics

【Output Waveform】

-1.2

-1

-0.8

-0.6

-0.4

-0.2

0

0.2

0 100 200 300 400 500 600 700 800

Rela

tive

Ou

tpu

t

Time [ps]

Rise Time: 150 [ps]

Fall Time: 360 [ps] [Note]

Light Source : Laser Diode

Pulse Width: 35 ps @FWHM

Output Waveform of New Gatable MCP-PMT

Photocathode:

Multialkali

Ext. Multiali

Bialkali

Other Characteristics

【Switching Noise Induced by Gate Pulse】

-1

0

1

2

3

4

5

6

0 20 40 60 80 100 120 140 160 180

Puls

e H

eig

ht

[V]

Time [ns]

Gate Input TTL Pulse

Fig. 7-1

-25-20-15-10-505

10152025

0 20 40 60 80 100 120 140 160 180

Ou

tpu

t [m

V]

Time [ns]

Switching Noise on Output

Low enough to discriminate !

R5916U Series New Gated MCP-PMT Unit

HVPS(#C9727)

Option

HVPS

（#C9727)

Included

Gate Driver

Included

Sensor Head

In Comparison with Former Types (R5916U Series)

【Photographs】

Sensor Head

R5916U Series

Sensor

Head

HVPS

C9727

Pulse

Generator

New Gated MCP-PMT

Sensor Head

HVPS

C9727

Gate

Driver

Signal Processing Circuit

Included Option

In Comparison with Former Types (R5916U Series)

【Constructions & Wiring】

Not provided by HPK

AMP C5594 Series

AMP C5594 Series Signal Processing Circuit

Pulse

Generator USB

USB

R5916U-50

(Multialkali)

New Gatable

MCP-PMT

(Multialkali)

New Gatable

MCP-PMT (GaAsP)

Semiconductor

Detector

Spectral Response Range [nm] 160 - 850 160 - 850 280 - 720 350 - 1100

Quantum Efficiency(QE) [%]

@532 nm (Typ.) 8 8 40 20

Effective Area (mm in diameter) 10 10 10 0.2

Gain (Min.) 1.0x105 1.0x105 1.0x105 -

Time Response

[ns] (Typ.)

Rise Time 0.18 0.15 0.18 0.7

Fall Time 0.7 0.4 0.4 -

Time Resolution (Jitter)

@FWHM [ps] (Typ.) 90 1) ≦25 2) 50 2) ＜ 60

Dark Count Rate [s-1] @25 ℃

(Typ.) 1000 1000 10000 9000

Average Anode Current [nA]

(Max.) 100 100 100 -

Gating Time 5 ns -10 μs 100 ns - 50 μs 100 ns - 50 μs -

1) This value includes a jitter of the electronics and the pulse width (35 ps @FWHM) of the light source.

2) These values are obtained by deconvolution for the laser pulse width.

In Comparison with Semiconductor Type Detector

【Specifications】

Signal Processing Technic To minimize a time jitter;

Use CFD (Constant Fraction Discriminator)

Set right level for low discrimination and optimize

a time-walk of CFD

Gated

MCP-PMT

AMP

CFD

Time-Walk Adjustment

Low Level Disc.

Adjustment

Output

/Logic Pulse

Conclusion

New gated MCP-PMT units are now our standard

product.

They show better performance over the former

type, R5916U series. In particular, detection

efficiency and time resolution have been improved.

In comparison with semiconductor detectors, our

new gated MCP-PMTs show some advantages

over the specifications such as sensitivity

(GaAsP), time resolution (Multialkali) and wider

photocathode effective area (0.2 mm in diameter

for semiconductor type ⇒ 10 for ours)