Recent R&D work on Micromegas detector

1. Recent R&D workon 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

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

3. Introduction Liang Guan April,2010 NanChang University 2

4. 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 (MicroMesh gaseous structure) • Invented in1996 by Y. Giomataris et al,CEA Saclay, France Nuclear Instruments and Methods in Physics Research A 376 (1996) Liang Guan April,2010 NanChang University 3

5. Development of Micromegas • high rate capability > 108 mm-2s-1 • space resolution ~12mm • energy resolution • time resolution • radiation hardness • simple structure Y. Giomatarisa NIM A 419 (1998) A. Delbart et al. NIM A 461 (2001) Leszek Ropelewski (CERN) et al. 94th LHCC Committee Meeting, July 2 2008 J. Derre& et al. NIM A 459 (2001) Liang Guan April,2010 NanChang University 4

6. Introduction: Application of Micromegas 7cm*7cm 40cm*40cm 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

7. Simulation Liang Guan April,2010 NanChang University 6

8. Gas Properties • Ramsauer Dip in Argon+Isobutane • Electron thermic energy Ar 90 <- 95 Magboltz Ar/iC4H10 90/10 Ar 100% ~0.24eV Ar/iC4H10 96/4 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 7

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

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

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

12. Signal • Track, cluster, drift lines • Weighting field 5.9 keV x-ray Reciprocity theorem Ar/iC4H10 90/10 Vmesh=400 Field ratio 200 Ramo theorem Pad 1 250mm 100mm Signal on 5 readout pads Pad 3 Pad 4 Pad 5 Pad 1 Pad 2 Liang Guan April,2010 NanChang University 11

13. Prototypes Liang Guan April,2010 NanChang University 12

14. 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 Microbulk InGrid Bulk Lithography& woven mesh Standard lithography and kapton etching CMOS compatible InGrid technology Liang Guan April,2010 NanChang University 13

15. 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: 80mm,125mm,155mm,160mm… • 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 Liang Guan April,2010 NanChang University 14

16. Thermo-bond film Motivation and prospects • Possible to use such kind of film to build detector without internal solid state support structure • Possible to make detector with large sensitive area The detection of low cross-section or rare processes (dark matter, double beta decay…) No internal dead area Nuclear medical imaging • Possible to make multi-layer parallel mesh chamber • Quick, Easy fabrication, Economical Liang Guan April,2010 NanChang University 15

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

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

19. Test Results Liang Guan April,2010 NanChang University 18

20. 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 19

21. Electron transparency Field ratio: Eava/Edrift Ar80 Ar90 Ar94 Ar95 * For high field ratio-> Diffusion, attachment in drift region By Guo Junjun Liang Guan April,2010 NanChang University 20

22. Gas Gain Energy linearity N: electron # collected at the anode N0: # of electrons generated in the conversion (drift) gap by 5.9KeV g e:Electron transparency (assume 100% for 350LPI mesh) 155mm Gain as a function of mesh HV • Gas gain of more than2*104 has been achieved Liang Guan 21

23. Energy resolution 13.7% (FWHM) Best energy resolution 1.102(Theory) Photo-peak ratio: Ka/Kb 1.109(Exp) • 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

24. 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 April,2010 NanChang University 23

25. Thank you !

26. Back up Liang Guan April,2010 NanChang University

27. Penning transfer

28. Penning transfer---sim &exp * Higher Isobutane concentration lead to higher penning transfer prob.

29. Penning transfer Ar+Iso10% (38% Ar*) Ar+Iso20% (40% Ar*) Where penning transfer start Where penning transfer start Ar+Iso10% Ar+Iso20%

30. Back up Mesh parameters Liang Guan April,2010 NanChang University

31. Back up signal Liang Guan April,2010 NanChang University