東京大学におけるＭＳＧＣの開発 東京大学 二河久子 藤田薫、高田夕佳、高橋浩之 2007/01/27 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 for  1)Large sensitive area (1~1.5m 2 cost  2)High position cost ~0.6mm for normal size: 10cm 2 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 strip grid electrode M-MSGC Multi Wire Proportional counter Microfablication technology photolithography EB lithography ⇒ High-counting Rate 100 ~ 400  m Anode pitch ⇒ High position resolution MSGC Discharges due to surface streamers Problem favorable electric field with intermediate grid electrodes MSGC A G1 G2 G3 G4 C 400  m M-MSGC Narrow pitch of electrodes

M-MSGC:Original design The longest MSGC: 64cm Global Local Method High position resolution 1-3mm FWHM Low cost 700mm 2 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/ L/20 20 L/400 + Local with GLG method 1)Global-Local Grouping 1-Dimensional MSGC

Signal to Noise ratio Position resolution (mm) Comparison of GLG and usual charge division Advantage of use GLG For total length 640mm Simple Charge division GLG method １００ １０ 1mm 10mm 1)Global-Local Grouping 1-Dimensional MSGC

FWHM ： Global: 13mm, Local: 1.6mm 1)Global-Local Grouping 1-Dimensional MSGC 14 keV PF Ar(70%)+CH 4 (30%) ＠１ atm Gas gain 3500 Position resolution for 14 keV X-rays

Beam Scan Results for 32cm along Gas gain )Global-Local Grouping 1-Dimensional MSGC

X-ray Beam scan result 1)Global-Local Grouping 1-Dimensional MSGC

Multi layer 64mm 2 0.8mm pitch Position resolution ： 0.8mm Split 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 Tokyo Plate 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 G1 and G3 and

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 Rate Previous work (i) Linear response ～ 10 8 cps/mm 2 Dynamic range measured in a charge-integrating mode Gas Gain: 100

Dynamic range measurement using a beam parallel to anode strip 3) Fine-pitch MSGC Previous work (ii) Linear response ～ cps/mm 2 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 300~400  m Towards Fine-pitch M-MSGC side view Plate without grids 3) Fine-pitch MSGC radiation Charge Anode Glass substrate Anode Glass substrate Coarse pitch Fine pitch cathode radiation Charge

50 um pitch : Nano strip Gas Counter (NSGC ） Grid 2 50 um Anode Grid1 Cathode Metal Chromium Anode pitch 50 um Anode width 800 nm Gap Anode-Grid 6um others 5 um Effective area 2mm x 20 mm 3) Fine-pitch MSGC Gaps 6,5,5,5,6,=32 Width 3,3,5,2,3,3=18

3) Fine-pitch MSGC Measured using 16 CH Preamp U-Tokyo ASIC Time[sec] Amplitude [a.u.] Charge-sensitive preamplifier output signal

Anode Cathode 1  sec Time[sec] Amplitude [a.u.] 3) Fine-pitch MSGC

FWHM 15% Ar escape peak Channel number 3) Fine-pitch MSGC Pulse height spectrum for 8keV X-rays Counts/Channel 8 keV X-rays φ100  PF Ar(70%)+CH 4 (30%) ＠１ atm Gas 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