Recent R&D workon Micromegas detector Recent R&D work on Micromegas detector Liang Guan University of Science and Technology of China NanChang University Center for particle physics and technology Joint Laboratory of Technologies of Particle Detection and Electronics

April,2010 NanChang University 1 Outline  Introduction  Simulation  Prototypes fabrication  Test Results  Summary Liang Guan

April,2010 NanChang University 2 Introduction Liang Guan

3 April,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

4 April,2010 NanChang University Development of Micromegas high rate capability > 10 8 mm -2 s -1 space resolution ~  m energy resolution time resolution radiation hardness simple structure Y. Giomatarisa NIM A 419 (1998) J. Derre& et al. NIM A 459 (2001) Leszek Ropelewski (CERN) et al. 94th LHCC Committee Meeting, July A. Delbart et al. NIM A 461 (2001) Liang Guan

5 April,2010 NanChang University Introduction: Application of Micromegas COMPASS CAST 40cm*40cm 7cm*7cm NA48/KABES beam spectrometerThe 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

7 April,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/iC 4 H 10 90/10 Magboltz Ar/iC 4 H 10 96/4 Liang Guan

8 April,2010 NanChang University Gas Properties Ar90% Iso10% Drift velocity Magboltz Liang Guan

April,2010 NanChang University Gas Properties Excitation rate & Penning transfer 1 atm Pressure Argon: 15.7eV Isobutane: 10.67eV Magboltz Liang Guan 9

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

11 April,2010 NanChang University Signal Pad 1Pad 2 Pad 3Pad 4Pad 5 Signal on 5 readout pads 5.9 keV x-ray Track, cluster, drift lines Weighting field Reciprocity theorem Ramo theorem Pad 1 Ar/iC 4 H 10 90/10 Vmesh=400 Field ratio 200 Liang Guan 250  m 100  m

April,2010 NanChang University 12 Prototypes Liang Guan

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

14 April,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: 80  m,125  m,155  m,160  m…  good mechanical property: tensile thousand psi  softening temperature ℃  dielectric property: dielectric constant ~2.4, volume resistivity>10 17 ohm/mil  excellent metal adhesion  uniform adhesive thickness Proposed by Prof. T.C. Zhao Liang Guan

15 April,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

16 April,2010 NanChang University Prototype Fabrication 350LPI mesh Mesh stretching Thermal attaching 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 “Bulk” avalanche region Frame Assembling Liang Guan

17 April,2010 NanChang University Experimental Setup  Drift mesh -HV Avalanche mesh -HV Readout Pad Ortec142AH Ortec 855 spectroscopy amplifier MCA Computer HV Supplier 55 Fe Gas input Gas output R Sketch map of testing system Electronic calibration Pulse: rise time 100  s,Period>3ms Calibration for 10 times Head amp. Pulse Liang Guan

April,2010 NanChang University 18 Test Results Liang Guan

19 April,2010 NanChang University HV Plateau & Counting rate Test at Ar96% Iso4% gas mixture, MCA cut:150th channel, test time: 100sTest at Ar96% Iso4% gas mixture, Vmesh=400, Vdrift=613, Head Amp=20 Liang Guan

20 April,2010 NanChang University Electron transparency Ar80Ar90Ar94Ar95 Liang Guan By Guo Junjun * For high field ratio-> Diffusion, attachment in drift region Field ratio: E ava /E drift

21 Gas Gain Energy linearity Gain as a function of mesh HV 155  m  Gas gain of more than2*10 4 has been achieved N: electron # collected at the anode N 0 : # of electrons generated in the conversion (drift) gap by 5.9KeV   Electron transparency (assume 100% for 350LPI mesh) Liang Guan

22 April,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

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

Thank you !

April,2010 NanChang University Back up Liang Guan

Penning transfer

Penning transfer---sim &exp Gas comp.Ar* (%) Ar+Iso Ar+Iso Ar+Iso Ar+Iso Ar+Iso Ar+Iso * 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 MeshWire diameter (  m) Hole size (  m) 350LPI (tabby) LPI (tabby) LPI (diagonal) LPI (diagonal) Mesh parameters

April,2010 NanChang University Back up signal Liang Guan