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PID meeting @Nagoya Univ. 31. Aug.2002 Contents 1. Introduction 2. PMT structure & Set up 3. Basic performance 4. Experiment results Gain Time resolution 5. Summary R&D on Fine-mesh multi-anode PMT with T.T.S.=100 ps under B1T T.Hokuue Nagoya University, Japan Fine-mesh PMT L24 - Multi-anode

R&D on Fine-mesh multi-anode PMT with T.T.S.=100 ps under B 1T

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R&D on Fine-mesh multi-anode PMT with T.T.S.=100 ps under B  1T. Contents Introduction PMT structure & Set up Basic performance Experiment results Gain Time resolution Summary. T.Hokuue. Nagoya University, Japan. Multi-anode. Fine-mesh PMT. L24 - . - PowerPoint PPT Presentation

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Page 1: R&D on Fine-mesh  multi-anode PMT  with T.T.S.=100 ps under B  1T

PID meeting @Nagoya Univ. 31.Aug.2002

Contents1. Introduction2. PMT structure & Set up3. Basic performance4. Experiment results

– Gain– Time resolution

5. Summary

R&D on Fine-mesh multi-anode PMT

with T.T.S.=100 ps under B1TT.HokuueNagoya University, Japan

Fine-mesh PMTL24 -

Multi-anode

Page 2: R&D on Fine-mesh  multi-anode PMT  with T.T.S.=100 ps under B  1T

PID meeting @Nagoya Univ. 31.Aug.2002

IntroductionTOP counter : a new type of Cherenkov Ring Imaging detector

Single-photon sensitive with high efficiency Position sensitive : x 1 mm

Operate under magnetic field : B = 1.5T(at Belle )

Linear-array Multi-anode Fine-mesh PMT Nucl. Instrum. Meth. : A460,326-335,2001.

Hybrid Avalanche PhotoDiode (HAPD) Nucl. Instrum. Meth. : A463,220-226,2001.

Transit time spread : TTS = 100 ps

Our candidates

Requirements

Page 3: R&D on Fine-mesh  multi-anode PMT  with T.T.S.=100 ps under B  1T

PID meeting @Nagoya Univ. 31.Aug.2002

A fine-mesh PMT exhibits a good position resolution and moderate time resolution for high multiple-photons, but not for single-photon.

We focused our effort to enhance the multiplication gain.

Under the magnetic field:

Page 4: R&D on Fine-mesh  multi-anode PMT  with T.T.S.=100 ps under B  1T

PID meeting @Nagoya Univ. 31.Aug.2002

PMT structures

We made 3 different fine-mesh PMTs

Base: Multi-anode Fine-mesh PMT (R6135-L24X) made by Hamamatsu Photonics Company(HPK),Japan

• Common structure : - 24 anodes (readout

channels)- anode size 26.50.8 mm- # of stages of fine-mesh dynode 24 () or 19 ()

PMT Type

Distance L (mm)

H.V divider network ratio

Mesh Size (lines/inch),pitch

- 2.5-3 1:1: :1 2000 ,12.5m- 1 2:1: :1 2000 ,12.5m- 1 2:1: :1 2500 ,9m

Page 5: R&D on Fine-mesh  multi-anode PMT  with T.T.S.=100 ps under B  1T

PID meeting @Nagoya Univ. 31.Aug.2002

1. Shorter distance between photo-cathode and first dynode2. H.V divider network ratio3. Finer mesh size

1. Shorter distance between photo-cathode and the first dynode

Transit time:

E1: the applied voltage across LL = 2.5-3 mm t 660 psL = 1 mm t 270 ps

L = 2.5-3 mmL = 1 mm

Page 6: R&D on Fine-mesh  multi-anode PMT  with T.T.S.=100 ps under B  1T

PID meeting @Nagoya Univ. 31.Aug.2002

3. Finer mesh size

2. H.V divider network ratio

T.T.S. 100 ps (1: 1: 1:1) T.T.S. 70 ps (2: 2: 1:1)(ex.) Line-forcused PMT (R5900-L16)

1:1: … :1 2:1: … :1

2000 lines/inch (12.5m pitch) 2500 lines/inch (9m pitch)

The radius reduces with field strength.• The secondary electrons would

get to hit fewer dynodes

Using the finer mesh would undo this reduction somewhat!!

reduced multiplication gain

Page 7: R&D on Fine-mesh  multi-anode PMT  with T.T.S.=100 ps under B  1T

PID meeting @Nagoya Univ. 31.Aug.2002

Set up• Set up

L24 -

Page 8: R&D on Fine-mesh  multi-anode PMT  with T.T.S.=100 ps under B  1T

PID meeting @Nagoya Univ. 31.Aug.2002

Basic performance• Signal shape (-)

1. Single-photon sensitive

B = 0.4 T , H.V = 2400 V

The exhibits a quite clear single-photon peak.

Efficiency : 52 % (-)

• ADC distributions

Rise time 1ns

63 % (-)85% (-)

Page 9: R&D on Fine-mesh  multi-anode PMT  with T.T.S.=100 ps under B  1T

PID meeting @Nagoya Univ. 31.Aug.2002

Basic performance2. Position sensitive

You can see clearly the field effect at weak field!!

- setting 1mm-wide slit on PMT’s surface• Anode-distributions(-

)• Signal spread in root-mean-square

The resolution of 0.5mm is dominated by the slit width of 1mm.True resolution might be much better than this.

Page 10: R&D on Fine-mesh  multi-anode PMT  with T.T.S.=100 ps under B  1T

PID meeting @Nagoya Univ. 31.Aug.2002

Gain • Multiplication Gain • Relative gain

The : Gain 5 10 (B = 1.5T, H.V= 3400V)6

H.V = 1600 V

The exhibits less reduction and the highest gain at 0.2T.The : Gain 8 10 (B = 1.5 T, H.V= 2000 V)5

Gain/Gain(B=0T)

Page 11: R&D on Fine-mesh  multi-anode PMT  with T.T.S.=100 ps under B  1T

PID meeting @Nagoya Univ. 31.Aug.2002

Time resolution• ADC-sliced time resolution (-,) & time-walk correction

0.4T,1.5kV 0.6T,1.7kV 1.0T,2.2kV

T.T.S 150 ps at ADC = 175-th ch at

T.T.S 100 ps at B 1T

0.4T,2.4kV

T.T.S 100 ps at ADC = 180-190 ch

-

-

150 ps at B = 1.5T

type

Page 12: R&D on Fine-mesh  multi-anode PMT  with T.T.S.=100 ps under B  1T

PID meeting @Nagoya Univ. 31.Aug.2002

• Gain vs. T.T.S.

Increment of gain by factor of 10

has rather steeper relation than

improve T.T.S of

30 ps (-)45 ps (-)

The time resolution under various conditions are plotted for and PMTs.

Both PMTs indicate that the multiplication gain of 3-5 10 are required to have a time resolution of 100ps.

7

Page 13: R&D on Fine-mesh  multi-anode PMT  with T.T.S.=100 ps under B  1T

PID meeting @Nagoya Univ. 31.Aug.2002

• Multi-photons2-photons TTS 80 ps3-photons TTS 70 ps4-photons TTS 60 ps

• T.T.S. with Multi-photons (-)

We already obtained high time resolution for multiple-photons.

Page 14: R&D on Fine-mesh  multi-anode PMT  with T.T.S.=100 ps under B  1T

PID meeting @Nagoya Univ. 31.Aug.2002

- By developing fine-mesh 24-anodes PMT

Summary

Time resolution : 100 ps (B1T)150 ps (B=1.5T)

- To have a 100 ps resolution under B=1.5T multiplication gain of

3-5 10 is required 7

- For higher gain and better T.T.S.

by using finer mesh dynodes by increasingly applied H.V. on the first dynode

- For Multiple-photons …

by reducing distance between the first dynode and photo-cathode