Recent R&D work on Micromegas detector

Liang Guan University of Science and Technology of China

Center for particle physics and technology Joint Laboratory of Technologies of Particle Detection and Electronics April,2010 @ NanChang University

Outline



Introduction



Simulation



Prototypes fabrication



Test Results



Summary

Liang Guan April,2010 NanChang University

1

Introduction

Liang Guan April,2010 NanChang University

2

Development of Micromegas

Traditional Gaseous detector MWPC faces problems: • Rate capability restrained by space charge effect • Spatial resolution limited by wire pitch Micromegas Working principle Micromegas ( Micro Me sh ga seous s tructure)  Invented in1996 by Y. Giomataris et al,CEA Saclay, France Liang Guan Nuclear Instruments and Methods in Physics Research A 376 (1996) April,2010 NanChang University

3

Development of Micromegas

 high rate capability > 10 8 mm -2 s -1  space resolution ~ 12m m  energy resolution  time resolution  radiation hardness  simple structure Y. Giomatarisa NIM A 419 (1998) J. Derre& et al. NIM A 459 (2001) Liang Guan A. Delbart et al. NIM A 461 (2001) April,2010 NanChang University Leszek Ropelewski (CERN) et al.

94th LHCC Committee Meeting, July 2 2008

4

Introduction: Application of Micromegas

40cm*40cm 7cm*7cm

COMPASS CAST

34 cm x 36 cm

NA48/KABES beam spectrometer The T2K ND-280 TPC Future application: ILC TPC, LHC upgrade, Neutron detection…

Liang Guan April,2010 NanChang University

5

Simulation

Liang Guan April,2010 NanChang University

6

Gas Properties

• Ramsauer Dip in Argon+Isobutane Magboltz • Electron thermic energy Ar 90 <- 95

Ar/iC 4 H 10 90/10 Ar/iC 4 H 10 96/4

~0.24eV

Ar 100% 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 Liang Guan April,2010 NanChang University

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Gas Properties

• Drift velocity Magboltz Ar90% Iso10% Liang Guan April,2010 NanChang University

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Gas Properties

• Excitation rate & Penning transfer Argon: 15.7eV

Isobutane: 10.67eV

Magboltz 1 atm Pressure Liang Guan April,2010 NanChang University

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Field, Drift, ionization

Electron drift velocity R-T relation [Drift Gap:3mm, Avalanche Gap:120mm, Vava= -500V, field ratio 200] Liang Guan April,2010 NanChang University

10

Signal

• Track, cluster, drift lines 5.9 keV x-ray Ar/iC 4 H 10 90/10 Vmesh=400 Field ratio 200 • Weighting field Reciprocity theorem

n N

  1

Q n V n N

 

n

 1

Q n V n

Ramo theorem

Q

1  

q V

0

V w

 

q

 [

x

(

t

)]

V w

250 m m Signal on 5 readout pads 100 m m Pad 1 Pad 2 Pad 3 Pad 4 Pad 1 Pad 5 Liang Guan April,2010 NanChang University

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Prototypes

Liang Guan April,2010 NanChang University

12

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 Lithography & woven mesh Liang Guan Microbulk Standard lithography and kapton etching April,2010 NanChang University InGrid CMOS compatible InGrid technology

13

Thermo-bond film

An novel idea to construct amplification gap in Micromegas: use Thermo-bond film Proposed by Prof. T.C. Zhao 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: 80 m m,125 m m,155 m m,160 m m…  good mechanical property: tensile strength@break--several thousand psi  softening temperature 100-200℃  dielectric property: dielectric constant ~2.4, volume resistivity>10 17 ohm/mil  excellent metal adhesion  uniform adhesive thickness Liang Guan April,2010 NanChang University

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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 The detection of low cross section or rare processes (dark matter, double beta decay…) • Possible to make multi-layer parallel mesh chamber • Quick, Easy fabrication, Economical Liang Guan April,2010 NanChang University

15

Prototype Fabrication

sensitive area: 45mm*45mm Thermo-bond film thickness: 155mm (width for each side:7mm), also tried other films… Avalanche, drift mesh: 350LPI woven wire mesh Drift region: 9mm Avalanche region thickness: 130mm Readout: 9 Pads(15mm*15mm) connected in parallel Drift electrode

350LPI mesh Mesh stretching Thermal attaching Frame Assembling

Liang Guan “Bulk” avalanche region April,2010 NanChang University

16

Experimental Setup

Sketch map of testing system

55 Fe HV Supplier

g

Gas input Gas output

R

Drift mesh -HV Avalanche mesh -HV Readout Pad Ortec142AH Ortec 855 spectroscopy amplifier Computer MCA

Pulse Electronic calibration Pulse: rise time<10ns ,duration>100 m s,Period>3ms Liang Guan April,2010 NanChang University Calibration for 10 times Head amp.

17

Test Results

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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 April,2010 NanChang University

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Electron transparency

By Guo Junjun Liang Guan Field ratio: E ava /E drift Ar80 Ar90 Ar94 Ar95 * For high field ratio-> Diffusion, attachment in drift region April,2010 NanChang University

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Gas Gain

G



N



N

0 N: electron # collected at the anode N 0 : # of electrons generated in the conversion (drift) gap by 5.9KeV g : Electron transparency (assume 100% for 350LPI mesh) Gain as a function of mesh HV Energy linearity

155

m

m

 Gas gain of more than2*10 4 has been achieved Liang Guan

21

Energy resolution

Best energy resolution 13.7% (FWHM) Photo-peak ratio: K a /K b 1.109(Exp) 1.102(Theory)  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 S. Behrends and A.C. Melissinos, NIM A 1889 (1981) Liang Guan April,2010 NanChang University

22

Summary

 Simulation study: Ramsauer Dip in Argon/iC 4 H 10 , penning transfer etc.  A novel idea: use thermo-bond films avalanche mesh from anode plane. to separate  Gas Gain> 3.7*10 4 , 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 April,2010 NanChang University

23

Thank you !

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Liang Guan April,2010 NanChang University

Penning transfer

Penning transfer---sim &exp

Gas comp.

Ar+Iso5 Ar+Iso6 Ar+Iso7 Ar+Iso8 Ar+Iso9 Ar+Iso10 Ar* (%) 35.03

35.22

35.91

37.84

38.03

38.67

* Higher Isobutane concentration lead to higher penning transfer prob.

Penning transfer Ar+Iso10% (38% Ar*)

Where penning transfer start

Ar+Iso10% Ar+Iso20% (40% Ar*)

Where penning transfer start

Ar+Iso20%

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Mesh parameters Mesh 350LPI (tabby) 400LPI (tabby) 400LPI (diagonal) 500LPI (diagonal) Wire diameter ( m m) 24 21.7

26.4

21.7

Hole size ( m m) 47.2-48.2

40.5-41.1

34.2-36.4

27.7-29.9

Liang Guan April,2010 NanChang University

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signal Liang Guan April,2010 NanChang University