東京大学におけるＭＳＧＣの開発

東京大学二河久子

niko@sophie.q.t.u-tokyo.ac.jp

藤田薫、高田夕佳、高橋浩之

2007/01/27 MPGD@ 佐賀大学

Outline

Introduction

1) Global-Local Grouping 1-Dimensional MSGC

2) Global-Local Grouping 2-Dimensional MSGC

3) Fine-pitch MSGC

Conclusions

Introduction

Multi-grid-type MSGC(M-MSGC) is being developed for1)Large sensitive area (1~1.5m2)@low cost2)High position resolution @low cost ~0.6mm for normal size: 10cm2 1.5mm~2mm for large area, ~0.6mm

3)High counting rate ~20kHz/module, ~1MHz possible with 4 anode readout

Why MSGC? - Uniformity of plate pattern = realize uniform gas gain

- Low cost

- We can develop MSGC design and its plate by ourselves with Electron Beam lithography (ADVANTEST F5112) at our univ.

1)&2): especially for Neutron scattering experiment

(it needs quantitative data : detection of the position)

0) Multi-grid type MSGC

Cathode strip

anode stripgrid electrode

M-MSGC

Multi Wire Proportional counterMicrofablication technology

photolithographyEB lithography

⇒High-counting Rate 100 ~ 400 m Anode pitch ⇒High position resolution

MSGC

Discharges due to surface streamers

Problem

favorable electric fieldwith intermediate grid electrodes

MSGC

AG1G2

G3G4

C

400m

M-MSGC

Narrow pitch of electrodes

M-MSGC:Original designThe longest MSGC: 64cmGlobal Local MethodHigh position resolution 1-3mm FWHMLow cost

700mm2 designs are arranged on one plate.

Signals are read from cathodes ：no necessity of decoupling condensers

1)Global-Local Grouping 1-Dimensional MSGC

For Large sensitive

Conceptual drawing:top view

Local

Anode

Global

What is Global-Local Grouping Method?

1)Global-Local Grouping 1-Dimensional MSGC

Conventional M-MSGC

⇒Position = Global:2 and Local1

(top view)

“Position resolution” and “Signal to noise ratio”

Conventional type

Anode

Cathode

L

L

L

Cathode Local

Cathode Global

L’

S/N worsens, but L becomes smaller!!

Signal to Noise ratio

Position resolution

L/40

20

40

L/20

20 L/400

+ Localwith GLG method

1)Global-Local Grouping 1-Dimensional MSGC

Signal to Noise ratio

Pos

itio

n re

solu

tion

(m

m)

Comparison of GLG and usual charge division　　　

Advantage of use GLG

For

tota

l len

gth

640m

m

Simple Charge division

GLG method

１００１０

1mm

10mm

1)Global-Local Grouping 1-Dimensional MSGC

0

200

400

600

800

1000

0 200 400 600 800 1000

local 4mm scan

local1local2local3local4local5local6local7

cou

nts

channel

FWHM ：　 Global: 13mm, Local: 1.6mm

0

100

200

300

400

500

600

700

800

0 200 400 600 800 1000

adjacent global signals

global1global2

cou

nts

channel

1)Global-Local Grouping 1-Dimensional MSGC

14 keV X-rays @KEK PFAr(70%)+CH4(30%) ＠１ atmGas gain 　 3500

Position resolution for 14 keV X-rays

Beam Scan Results for 32cm alongGas gain 4000

300

400

500

600

700

800

900

1000

0 50 100 150 200 250 300 350

globallocal

channel

position(mm)

1)Global-Local Grouping 1-Dimensional MSGC

X-ray Beam scan result

1)Global-Local Grouping 1-Dimensional MSGC

Multi layer64mm2 0.8mm pitchPosition resolution ： 0.8mmSplit anode and GLG Method for cathode

simpler electronics (1/5) ：Read out :36 channels + amps ⇒ 　 0.8mm pitch, 2D individual readout(usually as the same design,160 channels+ amps are needed for individual readout)

Concept & Design :University of TokyoPlate manufacture : TOSHIBA

2) Global-Local Grouping 2-Dimensional MSGC

For High position resolution

Source: Sr-90

2) Global-Local Grouping 2-Dimensional MSGC

Quick reports with test plate(G2 and G4 are open.)

Bias Voltage: anode@630VG1 and G2@280VG3 and G4@45V

Global position

Local position

X-ray Beam scan result (anode) Position resolution~0.8mm

2) Global-Local Grouping 2-Dimensional MSGC

3) Fine-pitch MSGC

For High Counting RatePrevious work (i)

Linear response 　～ 108 cps/mm2

Dynamic range measured in a charge-integrating mode

1.0E+00

1.0E+01

1.0E+02

1.0E+03

1.0E+04

1.0E+05

1.0E+06

1.0E+04 1.0E+05 1.0E+06 1.0E+07 1.0E+08 1.0E+09

Counting rate(cps/ mm2)

Curr

ent(

pA)

0.048msec0.68msec5.37msec19msec

Integration time

Gas Gain: 100

Dynamic range measurement using a beam parallel to anode strip

3) Fine-pitch MSGCPrevious work (ii)

Linear response 　～ 1011 cps/mm2

3 digits improved

Gas Gain: 100

For higher counting rate, fine-pitch M-MSGC is considered

Fine pitch MSGC can enhance the counting rate characteristics

Design : Fine-pitch 　 < 　 Electron mean pass in gas 300~400m

Towards Fine-pitch M-MSGC

side view Plate without grids

3) Fine-pitch MSGC

radiationCharge

Anode

Glass substrate

Anode

Glass substrate

Coarse pitch Fine pitch

cathode

radiationCharge

50 um pitch : Nano strip Gas Counter (NSGC ）

Grid 2

50 um

Anode Grid1

Cathode

MetalChromiumAnode pitch　50 umAnode width800 nmGap　Anode-Grid 6umothers　 5 umEffective area2mm x 20 mm

3) Fine-pitch MSGC

Gaps 6,5,5,5,6,=32Width 3,3,5,2,3,3=18

3) Fine-pitch MSGC

Measured using 16 CH Preamp U-Tokyo ASIC

Time[sec]

Am

pli

tud

e　

[a.u

.]Charge-sensitive preamplifier output signal

Anode

Cathode

1sec

Time[sec]

Am

pli

tud

e　

[a.u

.]

3) Fine-pitch MSGC

FWHM 15%

Ar escape peak

Channel number

3) Fine-pitch MSGC

Pulse height spectrum for 8keV X-raysC

ount

s/C

hann

el

8 keV X-rays φ100 m@KEK PFAr(70%)+CH4(30%) ＠１ atmGas gain 　 280

Conclusions 1) Global-Local Grouping 1-Dimensional MSGC

Confirmed basic characteristics.Next step, build up several plates array alignment.

2) Global-Local Grouping 2-Dimensional MSGC

Under manufacturing of the Plate…

3) Fine-pitch MSGC

We have made a very fine-pitch M-MSGC as the first trial of nano-strip gas counter

Fabricated detector was successfully operated at a gas gain 280