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Low energy measurement with Helium micromegas µTPC

Low energy measurement with Helium micromegas µTPC. Olivier Guillaudin Frédéric Mayet, Daniel Santos, Charbel Koumeir , Cyril Grignon Laboratoire de Physique Subatomique et de Cosmologie Grenoble – Université Joseph Fourier - CNRS/IN2P3. MIMAC Collaboration.

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Low energy measurement with Helium micromegas µTPC

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  1. Low energy measurement with Helium micromegas µTPC Olivier Guillaudin Frédéric Mayet, Daniel Santos, Charbel Koumeir , Cyril Grignon Laboratoire de Physique Subatomique et de Cosmologie Grenoble – Université Joseph Fourier - CNRS/IN2P3

  2. MIMAC Collaboration LPSC (Grenoble) : D. Santos, F. Mayet, C. Koumeir, C. Grignon Technical coordinator : O. Guillaudin Team : O. Bourrion, G. Bosson, J-P. Richer, Ch. Fourel, T. Lamy, P. Sole, J.P. Scordilis, J. Angot, A. Pelissier CEA-IRFU (Saclay): I. Giomataris, P. Colas, J. Pancin IRSN (Cadarache) : A. Allaoua, L. Lebreton O. Guillaudin Low energy measurement with Helium micromegas - Paris - December 2008

  3. Outline Final Goal : ionization measurement for low energy Helium ion • Calibrated Detector with X-Rays for Helium/Isobutane gaz mixture • A calibrated ion source (from 1 to 50 keV) • Gain Curve • Energy Resolution for X-Rays and low energy 3He and 4He ions • Quenching factor for MIMAC R&D project (Key point for Dark Matterto compute recoil energy ) O. Guillaudin Low energy measurement with Helium micromegas - Paris - December 2008

  4. Detector : Bulk µMegas Standard bulk micromegas fabricated at CERN-TS/DEM • Stainless steel mesh • 325 line/inch = 78 μm pitch • Wire diameter ~25 μm • Amplification gap = 128 μm • 100mm x 100mm active area • Pilar peach 2 mm • Drift gap: 3 cm HV ISEG • Ripple : 2 mV (p-p) • Resolution on voltage setting (10 mV) • LabView interface (voltage, current) Gain Reproductibility O. Guillaudin Low energy measurement with Helium micromegas - Paris - December 2008

  5. Calibration with Helium / Isobutane mixture • Classical radioactive source : • 55Fe (5.97 keV) • Helium transparency for X > 2 keV High flux source (multicell detector!) • Production of fluorescence X-Rays on different targets with a Miniature X-Ray Generator (inside chamber) • Peak X-ray flux equivalent to a 2 mCi source (during few sec) • Target and X-ray • Al : 1.486 keV • Ti : 4.504 keV • Fe : 6.4 keV • Cu : 8.1 keV O. Guillaudin Low energy measurement with Helium micromegas - Paris - December 2008

  6. Al (1,486 keV) Ti (4,504 keV) Multi-Target Spectrum • Target : Aluminium + Titanium • 700 mbar Helium + 5% Isobutane • E Drift = 130 V/cm • HV Detector = 430 V • Gain = 1,2 104 • Energy Resolution FWHM • Aluminium 1,486 keV = 32,9 % • Titanium 4,504 keV = 19,6 % O. Guillaudin Low energy measurement with Helium micromegas - Paris - December 2008

  7. Multi-Target Spectrum • Target : Aluminium + Iron • 1000 mbar Helium + 5% Isobutane • E Drift = 130 V/cm • HV Detector = 430 V Al (1,486 keV) Fe (6,4 keV) • Gain = 1,1 104 • Energy Resolution FWHM • Aluminium 1,486 keV = 29,4 % • Iron 6,4 keV = 15,3 % O. Guillaudin Low energy measurement with Helium micromegas - Paris - December 2008

  8. Gain and Energy resolution • Detector operated in sealed mode for 1 day (after outgazing during night) • Gain variation about ~ -0,2% / h O. Guillaudin Low energy measurement with Helium micromegas - Paris - December 2008

  9. He ions ECR ion source configuration(Design and build at LPSC SSI Team) • p, 3He and 4He from 1 to 50 keV • From 5 to 10 000 ions/s WIEN Filter (ion selection) Plasma source (gaz + HV) Henzel Lens Faraday Cup Membrane between vaccuum and gaz detector (Si3N4 or µm hole) Bulk Micromegas O. Guillaudin Low energy measurement with Helium micromegas - Paris - December 2008

  10. STOP He ions Mobile channeltron Ion source calibration with Si3N4 membrane Time of flight under vacuum Low energy secondary electron START Helium atom VACUUM Metallized Silicon Nitride membrane 50 nm • Neutral atom after the Silicon nitride membrane • Method : measuring time of flight for 2 positions of the STOP channeltron O. Guillaudin Low energy measurement with Helium micromegas - Paris - December 2008

  11. STOP He ions Mobile channeltron Ion source calibration with Si3N4 membrane Time of flight under vacuum Low energy secondary electron START Helium atom VACUUM Metallized Silicon Nitride membrane • Neutral atom after the Silicon nitride membrane • Method : measuring time of flight for 2 positions of the STOP channeltron O. Guillaudin Low energy measurement with Helium micromegas - Paris - December 2008

  12. Time of Flight Results • Ion : 4He • Membrane • 50 nm Si3N4 • 10 nm Al • Others • Proton • 3He 4He 13,4 keV O. Guillaudin Low energy measurement with Helium micromegas - Paris - December 2008

  13. 55Fe (5,9keV) 18 % FWHM 26 % FWHM STRAGGLING!!! Al (1,486 keV) 29,4 % FWHM Ionisation measurementwith Si3N4 Interface Calibration Helium + 5% Isobutane Pressure : 1 bar • 4He • Initial ion energy : 20 keV • 13,4 keV after membrane O. Guillaudin Low energy measurement with Helium micromegas - Paris - December 2008

  14. 16 % FWHM Ionisation measurement1 µm Hole Interface Helium + 5% Isobutane Pressure : 1 bar Initial Ion energy : 13,4 keV Count rate : 25 cps/s Same resolution as X-Ray Energy resolution improvement with the hole O. Guillaudin Low energy measurement with Helium micromegas - Paris - December 2008

  15. 1 µm hole 10 mm O. Guillaudin Low energy measurement with Helium micromegas - Paris - December 2008

  16. Quenching factor @ 700 mbars Quenching factor measurement • Helium + 5% Isobutane • Pressure : 700 mbar • Count rate : 25 cps/s (no space charge effect) • Threshold :300 eV (ioni.) or 1 keV (recoil) 4He New Micromegas (192 µm gap) for low pressure (< 500 mbar) O. Guillaudin Low energy measurement with Helium micromegas - Paris - December 2008

  17. Energy resolution Ion vs X-Ray • Better resolution for X-Rays • Does not depend on pressure • Ion measurement down to 1 keV O. Guillaudin Low energy measurement with Helium micromegas - Paris - December 2008

  18. H2 1+ He 1+ 38,58 keV 38,60 keV He 2+ Ionisation and ion charge (with hole) Ion : He 1+ Eacc = 50 keV Ec = 50 keV Ion : He 2+ Eacc = 25 keV Ec = 50 keV Ionisation do not depend of state of charge O. Guillaudin Low energy measurement with Helium micromegas - Paris - December 2008

  19. Henzel Lens 2 Magnetic dipole Henzel Lens 1 Faraday Cup New ECR ion source for Fluorine quenching factor measurement • Possibility to separate • p • 3He • 4He • 14N • 19F • Gaz : CF4 O. Guillaudin Low energy measurement with Helium micromegas - Paris - December 2008

  20. MIMAC : µTPC chamber Ionisation and Track cathod Drift space : 15 cm Micromegas +pixellized anod (x,y) MIMAC ASIC O. Guillaudin Low energy measurement with Helium micromegas - Paris - December 2008

  21. He ions The TPC chamber Faraday cube • Design to be connected to the ECR ion source • Variable drift lenght to study diffusion effect on track O. Guillaudin Low energy measurement with Helium micromegas - Paris - December 2008

  22. Thanks for your attention O. Guillaudin Low energy measurement with Helium micromegas - Paris - December 2008

  23. Drift velocity vs. Pressure O. Guillaudin Low energy measurement with Helium micromegas - Paris - December 2008

  24. Diffusion of primary electrons O. Guillaudin Low energy measurement with Helium micromegas - Paris - December 2008

  25. MIMAC source spectrum at 14kV O. Guillaudin Low energy measurement with Helium micromegas - Paris - December 2008

  26. Recoil energy distribution after a polypropilene foil of 0.44μg/cm2for acceleration energies of 45 and 50 keV O. Guillaudin Low energy measurement with Helium micromegas - Paris - December 2008

  27. Time of flight measurement of the ion coming out of the MIMAC source at 50 kV O. Guillaudin Low energy measurement with Helium micromegas - Paris - December 2008

  28. He3 -TOF measurement O. Guillaudin Low energy measurement with Helium micromegas - Paris - December 2008

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