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Recent R&D workRecent R&D work on Micromegas detectoron Micromegas detector
Liang Guan
University of Science and Technology of China
April,2010 @ NanChang University
Center for particle physics and technology
Joint Laboratory of Technologies of Particle Detection and Electronics
April,2010 NanChang University 1
OutlineOutline
Introduction
Simulation
Prototypes fabrication
Test Results
Summary
Liang Guan
April,2010 NanChang University 2
Introduction
Liang Guan
3April,2010 NanChang University
Traditional Gaseous detector MWPC faces problems:
• Rate capability restrained by space charge effect
• Spatial resolution limited by wire pitch
Micromegas (Micro Mesh gaseous structure)
Invented in1996 by Y. Giomataris et al,CEA Saclay, France
Nuclear Instruments and Methods in Physics Research A 376 (1996)
Development of Micromegas
Micromegas Working principle
Liang Guan
4April,2010 NanChang University
Development of Micromegas
high rate capability > 108 mm-2s-1
space resolution ~m
energy resolution
time resolution
radiation hardness
simple structureY. Giomatarisa NIM A 419 (1998)
J. Derre& et al. NIM A 459 (2001) Leszek Ropelewski (CERN) et al.94th LHCC Committee Meeting, July 2 2008
A. Delbart et al. NIM A 461 (2001)
Liang Guan
5April,2010 NanChang University
Introduction: Application of Micromegas
COMPASS CAST
40cm*40cm 7cm*7cm
NA48/KABES beam spectrometer The T2K ND-280 TPC
Future application: ILC TPC, LHC upgrade, Neutron detection…
34 cm x 36 cm
Liang Guan
April,2010 NanChang University 6
Simulation
Liang Guan
7April,2010 NanChang University
de Broglie wavelength of electron can be compared with the radius of noble gas atom undergo a phase shift when passing through the strong attractive field around the atom and results in low interaction cross-section, long mean free path
~0.24eV
• Ramsauer Dip in Argon+Isobutane • Electron thermic energy
Gas Properties
Ar 90 <- 95
Ar 100%
Ar/iC4H10 90/10
Magboltz
Ar/iC4H10 96/4
Liang Guan
8April,2010 NanChang University
Gas Properties
Ar90% Iso10%
• Drift velocityMagboltz
Liang Guan
April,2010 NanChang University
Gas Properties
• Excitation rate & Penning transfer 1 atm Pressure
Argon: 15.7eVIsobutane: 10.67eV
Magboltz
Liang Guan 9
10April,2010 NanChang University
Field, Drift, ionization
[Drift Gap:3mm, Avalanche Gap:120mm, Vava= -500V, field ratio 200]
R-T relationElectron drift velocity
Liang Guan
11April,2010 NanChang University
Signal
Pad 1 Pad 2 Pad 3 Pad 4 Pad 5
Signal on 5 readout pads
5.9 keV x-ray
• Track, cluster, drift lines • Weighting field
N
nnn
N
nnn VQVQ
11
Reciprocity theorem
Ramo theorem
ww V
txq
V
VqQ
)]([01
Pad 1
Ar/iC4H10 90/10
Vmesh=400
Field ratio 200
Liang Guan
250m 100m
April,2010 NanChang University 12
Prototypes
Liang Guan
13April,2010 NanChang University
Review
Different materials
mesh: grid by chemical etching, electroformed … (stainless steel, copper, nickel, gold… )
woven wires (nickel, copper, stainless steel)
spacer: quartz fibers, pillars by photo-lithography (mainly used), Kapton ring, fishing line…
Different technologies
Bulk MicrobulkStandard lithography and kapton etching
InGrid Lithography & woven mesh CMOS compatible InGrid technology
Liang Guan
14April,2010 NanChang University
Thermo-bond film
An novel idea to construct amplification gap in Micromegas: use Thermo-bond film
Thermo-bond film adhesive bonding film, flexible & insulating usually made of a substrate sandwiched by two bond lines or only two bond lines attached together side by side solid at room temperature, melt & becomes adhesive after heat is applied.
Features various thickness: 80m,125m,155m,160m… good mechanical property: tensile strength@break--several thousand psi softening temperature 100-200℃ dielectric property: dielectric constant ~2.4, volume resistivity>1017ohm/mil excellent metal adhesion uniform adhesive thickness
Proposed by Prof. T.C. Zhao
Liang Guan
15April,2010 NanChang University
Thermo-bond film
Motivation and prospects
• Possible to use such kind of film to build detector without internal solid state support structure
No internal dead area
Nuclear medical imaging
• Possible to make detector with large sensitive area
• Possible to make multi-layer parallel mesh chamber
• Quick, Easy fabrication, Economical
The detection of low cross-section or rare processes (dark matter, double beta decay…)
Liang Guan
16April,2010 NanChang University
Prototype Fabrication
350LPI mesh
Mesh stretching
Thermal attaching
sensitive area: 45mm*45mmThermo-bond film thickness: 155mm (width for each side:7mm), also tried other films…Avalanche, drift mesh: 350LPI woven wire mesh Drift region: 9mmAvalanche region thickness: 130mm Readout: 9 Pads(15mm*15mm) connected in parallel
Drift electrode
“Bulk” avalanche region
Frame Assembling
Liang Guan
17April,2010 NanChang University
Experimental Setup
Drift mesh -HV
Avalanche mesh -HV
Readout Pad
Ortec142AH
Ortec 855 spectroscopy amplifier
MCA
ComputerHV
Supplier
55Fe
Gas input
Gas output
R
Sketch map of testing system Electronic calibration
Pulse: rise time<10ns ,duration>100s,Period>3ms
Calibration for 10 times Head amp.
Pulse
Liang Guan
April,2010 NanChang University 18
Test Results
Liang Guan
19April,2010 NanChang University
HV Plateau & Counting rate
Test at Ar96% Iso4% gas mixture, MCA cut:150th channel, test time: 100s Test at Ar96% Iso4% gas mixture, Vmesh=400, Vdrift=613, Head Amp=20
Liang Guan
20April,2010 NanChang University
Electron transparency
Ar80 Ar90 Ar94 Ar95
Liang Guan
By Guo Junjun * For high field ratio-> Diffusion, attachment in drift region
Field ratio: Eava/Edrift
21
Gas Gain
Energy linearity
Gain as a function of mesh HV
155m
Gas gain of more than2*104 has been achieved
0N
NG
N: electron # collected at the anode
N0: # of electrons generated in the conversion (drift) gap by 5.9KeV
Electron transparency (assume 100% for 350LPI mesh)
Liang Guan
22April,2010 NanChang University
1.109(Exp)
13.7% (FWHM)
Photo-peak ratio:
1.102(Theory)
Best energy resolution
K
Energy resolution for 5.9 keV x-ray can be better than 20% over one order of magnitude in gain
Deterioration of energy resolution for argon-rich gas mixture: influence of polyatomic molecular
Energy resolution
S. Behrends and A.C. Melissinos, NIM A 1889 (1981)
Liang Guan
23April,2010 NanChang University
Summary
Simulation study: Ramsauer Dip in Argon/iC4H10, penning transfer etc.
A novel idea: use thermo-bond films to separate avalanche mesh from anode plane.
Gas Gain>3.7*104, Energy resolution better than 13.7%.
Continues efforts should be made to systemically study performances of detectors with other films. Also try to make large size prototypes.
Liang Guan
Thank you !
April,2010 NanChang University
Back up
Liang Guan
Penning transfer
Penning transfer---sim &exp
Gas comp. Ar* (%)
Ar+Iso5 35.03
Ar+Iso6 35.22
Ar+Iso7 35.91
Ar+Iso8 37.84
Ar+Iso9 38.03
Ar+Iso10 38.67
* Higher Isobutane concentration lead to higher penning transfer prob.
Penning transfer
Where penning transfer start
Ar+Iso10% (38% Ar*)
Ar+Iso10%
Ar+Iso20% (40% Ar*)
Ar+Iso20%Where penning transfer start
April,2010 NanChang University
Back up
Liang Guan
Mesh Wire diameter (m)
Hole size (m)
350LPI (tabby) 24 47.2-48.2
400LPI (tabby) 21.7 40.5-41.1
400LPI (diagonal) 26.4 34.2-36.4
500LPI (diagonal) 21.7 27.7-29.9
Mesh parameters
April,2010 NanChang University
Back up
signal
Liang Guan