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