experience with resistive coatings at saclay n.
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Experience with resistive coatings at Saclay

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Experience with resistive coatings at Saclay - PowerPoint PPT Presentation

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Experience with resistive coatings at Saclay

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  1. Experiencewithresistivecoatingsat Saclay P. Colas • Use of resistivecoatings for: • Spreading the charge to improveresolutionwhilelimiting the number of electronicreadoutchannels • Stabilizing Micromegas detectors (spark suppression) • Protectingintegrated circuits • Numerous techniques triedsince a decade • Characterization of coverlays : measurement of surface resistivity, bulkresistivity and thru-resistivity and Carleton, Nikhef, Neuchatel

  2. ILC-TPC : charge spreading Resistivebulk Micromegas Continuous RC circuit spreads the charge -> resolutionimprovement 60 µ resolutionat 0 drift with 3 mm pads ! Experience with resistive coatings

  3. Also the resistive foil stabilizes Micromegas: no more breakdown, stable current Argon/Isobutane 90/10 Cr (SiO2)ncermet P.C., M. Dixit, I. Giomataris 2005 LC workshop, Stanford Experience with resistive coatings

  4. Standard Micromegas Resistive Micromegas MAMMA beam test, 15 kHz hadron beam, October 2009 Experience with resistive coatings

  5. ResistivedepositsalsoprotectTimePix Chips fromsparks (10 microns of aSi:H, 4-7 microns of SixNy (H. VdGraaf, N. Wyrsch) Experience with resistive coatings

  6. Experience with resistive coatings

  7. Deposition of thinlayers (10 µ thick) of a-SiH (1013W.cm) Neuchatel, N. Wyrsch Possibility to add a doped layer on top Experience with resistive coatings

  8. Weusedseveral techniques to measureresistivities. • May depend on voltage, pressure of the contact,… • Oftenseediscrepancies, inhomogeneities, unstabilities • Thru-resistivitysometimesinconsistentwith surface resistivity 4-point probe (Neuchatel) Circular probe Conducting tape, insulatingsubstrate lxLresistivesample = L/l ’squares’ Measureresistance, divide by number of squares Experience with resistive coatings

  9. Diagnostic tools : thermal image of the prototype with a high-resistivity layer and a lower-resistivity layer on top (N. Wyrsch, EPFL, Neuchatel) Hot spots due to leakagecurrent Experience with resistive coatings

  10. Experience with resistive coatings