Present Status of GEM Detector Development for Position Counter

1. Introduction2. GEM3. Readout Board4. Fabrication Test5. Large GEM6. Readout Electronics7. Summary

Kunihiro FujitaResearch Center for Nuclear Physics, Osaka University

IntroductionIntroductionIntroductionIntroduction

• Application to Nuclear Physics Experiment– Coherent Pion Production

• Requirements– high position resolution (< 100um)– radiation tolerance (> 1Mcps)

• Concept– GEM– Readout Board with Micro Pattern Strips

Sci 1Sci 2

GEM detectorposition 1

position 2

charged particle

trigger

tracking

overview of the detector system

GEMGEMGEMGEM

100mm

140μm

• Fabrication procedure– Wet etching (supplied by CERN)

⇒ high quality and low cost ~ 700,000yen/10sheet– Plasma etching ( by Fuchigami Micro Co., Ltd.)

⇒ large size is difficult– Laser etching ( by Fuchigami Micro Co., Ltd.)

⇒ larger size needs higher cost ~ 3,700,000yen/20sheet

lowest cost and stable operation ⇒ We decide to use CERN-GEM

Drift (3 kV/cm)GEM 1

Readout Board (GND)

ΔV ~400V

aramid carbon (6μm)

GEM 2

GEM 3E

Flexible Printed Circuit500 channel

100mm

100mm

Readout Board (ROB)Readout Board (ROB)Readout Board (ROB)Readout Board (ROB)

electron microscope image and schematic image

Cu (4um)Kapton (50um)

Cu (4um)G10 (100um)400um

• Readout Board– high position resolution– 2 dimensional readout

• components– double layers of perpendicular copper strips

• fabrication procedure– close to one of used for GEM

• wet etching ~ Raytech, CERN• laser etching ~ Raytech

340um

80um

prototype

Fabrication procedure of ROBFabrication procedure of ROBFabrication procedure of ROBFabrication procedure of ROB

• Raytech– Wet etching– Laser etching

• CERN• Cost

– 1,000,000/3sheet•Problem

–Over etching–Mountain shape

•only 50um kapton

Fabrication testFabrication testFabrication testFabrication test

• Components– 3GEM electrode– 128ch bundled Micro Strip

• test procedure– 55Fe source– Charge amp. → Camac ADC– calibration for gain

• result is consistent with CERN & CNS

Triple GEM effective gain

340 350 360 370 380 390 400 410ΔVgem

Eff

ecti

ve G

ain

ArCO2

ArC4H10

the measured amplification factor in each gas.

[1] S. Bachmann et al., NIM A 438 (1999) 376.[2] M. Inuzuka et al., NIM A 525 (2004) 529.pulse height distribution.

prototype chamber

Large Size GEMLarge Size GEMLarge Size GEMLarge Size GEM

soldering

pattern 1

307.2

GEM holes (standard)triangular pattern

size: 70umpitch: 140um cross section

200um separation

H.V.

divide50.2

• Active area– 307.2x 50.2 mm2

• What should be solved– discharge propagation

• over 80cm2

– H.V. terminal• Solution

– 2-segmented– protection resistance– 3 patterns of H.V. terminal

10M

pattern 2pattern 3

discharge signals on anodes S. Bachmann et al., NIMA 479(2002)294

ConnectionConnectionConnectionConnection

• Propose– charge transfer from ROB to Readout electronics

• Components– Flexible Printed Circuit Board– its connector

• Advantages– low noise transfer– wire bonding less

Front-end Card

Readout ElectronicsAnalog-LSI

half-pitch connector

FPC connector

Readout Board

FPC

easy to debug

• Requirements– huge number of readout channel → ~2000ch– high counting rate → ~1M count s-1 (detector total)– high trigger rate → ~100 kcps– small space → installed in the magnet

• Concept– multi channel processing– high speed digitization and data transfer– small number of modules and low cost– easy to debug and connect to other devices

small number of modules and signal lines

high speed data takingComputer

analog

digital

digital

radiation hard environment

GEMdetector

ADCs for each channel?

Development of Readout SystemDevelopment of Readout SystemDevelopment of Readout SystemDevelopment of Readout System

multi channel readout

Readout Electronics Readout Electronics (Space Wire)(Space Wire)Readout Electronics Readout Electronics (Space Wire)(Space Wire)

• Components– multi channel processing analog LSI ← sampling/hold, shaping, and multiplex– Flash ADC ← high speed digitization– Space Wire Protocol (IEEE 1355) ← simple and high speed data transfer protocol– Complex Programmable Logic Device ← reconfigurable logic unit

• Advantages– multi channel LSI and serial data transfer ← small number of modules and cables– high speed data transfer ← MAX 400Mbps– easy to fit to other detectors ← by reconfigure CPLD only– low cost/channel ← small number of module– Space Wire is simple protocol ← performed by only one CPLD chip

sample & hold

sequential read

Space Wire protocol(LVDS)

Space Wire host

Computer

single line

block diagram

control / data

GEMdetector

analog LSI

Va32_Rich2

~2000ch 4 lane 1 lane

Flash ADC

CPLD

Connector Board(hub)

Fig8. Energy distribution in the NaI measured by the M-PMT(H6568-Mod).

40K　 17%（FWHM）

40K　 17%（FWHM）

Sum

2.2 keV/ch

2.2 keV/ch

Energy Spectrum by using New Readout SystemLeft figure shows the photon yield at each channel of one M-PMT. Right figure shows energy spectrum obtained from summing up the photon yields.This result shows that a newly developed read-out system can be used to read-out Multi-channels detectors.

Example and ApplicationExample and ApplicationExample and ApplicationExample and Application

• multi channel readout– silicon strip detector [3]– CdTe detector [3,4]– multi-anode phototube [5]

• easy to fit other detector– replacement the detector– performed by reconfiguring FPGA

[3] T. Mitani et al., IEEE Trans. Nucl. Sci., 50 (2003) No.4 1048[4] H. Tajima et al., IEEE Trans. Nucl. Sci., 51 (2004) No.3 842[5] H. Nakamura, NDM03 poster session.

readout system for M-PMT

PC

IFC

SpaceWireVME

M-PMT

VA32_HPD11

11 kΩ

47pF51Ω

51Ω

1.65V

Digital

Analog

FlashADCSpaceWire

Digital & Analog

BiasBoard

Fig7. New Read-out System form a M-PMT.

New Readout SystemFigure7 shows the new read-out system.In this system, signals of maximum 1024-channles from a detector can be read.

Digital & Analog

Analog LSI

energy distribution measured by the M-PMT.

GEM

reconfigure

CPLD

FADC & CPLD board

SummarySummarySummarySummary

• We develop GEM Position detector for tracking of charged particle

• Stable operation with high gain• High resolution will be performed by Micro

Pattern Readout Board• Readout Electronics is consist of Multi-Channel

LSI and Serial data link system• Now, Hardware is almost ready• Experiment ~ will be performed in next April