docLarge GEMs - Prototype for totem upgrade
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Large GEMs - Prototype for totem upgrade
Micro pattern gas detectors workshop 16–18 April, nikhef, Amsterdam Large GEMs Serge Duarte Pinto Totem T2 T1 upgrade Challenges Single mask technique Large GEMs Prototype for totem upgrade Manufacturing Performance First foil Gem splicing Coverlay Test Glue press Other ideas Shielding HV distribution Perspectives Serge Duarte Pinto CERN 16 April 2008 GEMs for TOTEM experiment Half round chambers around beam pipe Large GEMs Serge Duarte Pinto Totem T2 T1 upgrade Challenges Single mask technique Manufacturing Performance First foil Gem splicing Coverlay Test Glue press Other ideas Charged particle rate close to beam pipe > 104 Hz/mm2 Expected discharge rate: ∼ 0.1/mm2 /year 2 × 10 chambers side by side Strips & pads for tracking and triggering, respectively Time resolution < 10 ns Space resolution < 100 µm pads radial strips Shielding HV distribution Perspectives TOTEM readout bonding contact Totem T1 upgrade Based on large gem chambers Large GEMs Serge Duarte Pinto Totem T2 T1 upgrade Challenges Single mask technique Manufacturing Performance First foil Gem splicing Coverlay Test Glue press Other ideas Shielding HV distribution Perspectives Ideas for upgrade of totem T1 Large triple gem chambers (∼ 2000 cm2 ) Discs of 2 × 5 chambers, back to back Overlap creates redundancy for alignment, and allows adjustable disc radius Totem T1 upgrade Technical challenges for such large active area Large GEMs Serge Duarte Pinto Totem T2 T1 upgrade Challenges Single mask technique Manufacturing Performance First foil Gem splicing Coverlay Test Glue press Other ideas Shielding HV distribution Perspectives Not trivial to build largest mpgd thus far Double mask technique introduces alignment errors at such dimensions Base material is only 457 mm wide Totem T1 upgrade Technical challenges for such large active area Large GEMs Serge Duarte Pinto Totem T2 T1 upgrade Challenges Single mask technique Manufacturing Performance First foil Gem splicing Coverlay Test Glue press Other ideas Shielding HV distribution Perspectives Not trivial to build largest mpgd thus far Double mask technique introduces alignment errors at such dimensions Ð→ use single mask technique Base material is only 457 mm wide Totem T1 upgrade Technical challenges for such large active area Large GEMs Serge Duarte Pinto Totem T2 T1 upgrade Challenges Single mask technique Manufacturing Performance First foil Gem splicing Coverlay Test Glue press Other ideas Shielding HV distribution Perspectives Not trivial to build largest mpgd thus far Double mask technique introduces alignment errors at such dimensions Ð→ use single mask technique Base material is only 457 mm wide Ð→ splice foils together GEM manufacturing Double mask vs. single mask technique Large GEMs Serge Duarte Pinto Totem T2 T1 upgrade Challenges Single mask technique Manufacturing Double mask 50µm kapton foil 5µm copperclad photoresist coating, masking, exposure metal etching Performance First foil Gem splicing Coverlay Test Glue press Other ideas Shielding HV distribution Perspectives kapton etching metal etching second masking metal etching, and cleaning Single mask Single mask technique Similar performance at lower cost Large GEMs Serge Duarte Pinto First results were not encouraging Ð→ Smt now performs similar to standard gem. delamination Totem T2 T1 upgrade Challenges Single mask technique Single GEM gain curves 1000 Manufacturing Performance SMSC010 First foil SMSC011 Gem splicing SMSC012 SMSC013 Coverlay SMSC014 Test 100 gain Glue press Other ideas Shielding HV distribution Perspectives 10 350 400 450 ΔVGEM (V) 500 550 600 Single mask technique Crucial drying treatment before polyimide etching Large GEMs Serge Duarte Pinto Totem Recent finding that may change fabrication method for double mask gem as well T2 T1 upgrade Challenges Single mask technique Manufacturing Performance First foil Gem splicing Coverlay Test Glue press Other ideas Shielding HV distribution Perspectives Pictures taken from samples of the same foil. Both have been together in the same baths. The bottom one underwent a bake-out before the polyimide etching phase. Single mask technique First large gem foil Large GEMs Serge Duarte Pinto Totem T2 T1 upgrade Challenges Single mask technique Manufacturing Performance First foil Gem splicing Coverlay Test Glue press Other ideas Shielding HV distribution Perspectives Unfortunately, we were not in time to finish the mating foil, to perform a real gluing . . . Single mask technique First large gem foil Large GEMs Serge Duarte Pinto Totem T2 T1 upgrade Challenges Single mask technique Manufacturing Performance First foil Gem splicing Coverlay Test Glue press Other ideas Shielding HV distribution Perspectives Unfortunately, we were not in time to finish the mating foil, to perform a real gluing . . . But a little editing gives the idea! Splicing GEMs Glue foils with pyralux coverlay Large GEMs Serge Duarte Pinto Totem T2 T1 upgrade Challenges Single mask technique Coverlay to glue gems Manufacturing Seam is flat, regular, mechanically and dielectrically strong, and only 2 mm wide. Performance First foil Gem splicing Coverlay Test Glue press Other ideas kapton glue flash Shielding HV distribution Perspectives Ð→ gap Splicing GEMs Test performance near the seam Large GEMs X-ray with ∅0.5 mm collimator Serge Duarte Pinto Rate scan over the seam Totem Behaves normally until at the seam T2 Performance rest of gem surface unaffected T1 upgrade Challenges Single mask technique Manufacturing Performance First foil Gem splicing Coverlay 3500 3000 2500 Test Glue press Other ideas Shielding 2000 1500 HV distribution Perspectives 1000 500 0 rate (Hz) Splicing GEMs A glue press to splice large gems Large GEMs Serge Duarte Pinto Totem T2 T1 upgrade Challenges Single mask technique Manufacturing Performance First foil Gem splicing Coverlay Test Glue press Other ideas Shielding HV distribution Perspectives Old steel bending machine, modified to serve as glue press 240○ C / ∼ 10 MPa 0.5 mm Silicon rubber sheet adjusts to surface roughness Reinforced Teflon sheets serve as anti-adhesive Shielding of GEM chamber Using bypass capacitors Large GEMs Serge Duarte Pinto Use bottom electrodes as shield by applying bypass capacitors Simulations indicate no effect on discharges Totem T2 T1 upgrade Tests thus far confirm that Challenges Single mask technique Tests to confirm shielding benefit are still to be done Manufacturing Performance First foil 100 Gem splicing copper aluminium gold Test Glue press Other ideas Shielding skin depth (microns) Coverlay 10 HV distribution Perspectives 1 1 10 100 frequency (MHz) 1000 10000 High voltage circuitry ZIF sockets instead of solderings Large GEMs Serge Duarte Pinto Totem T2 T1 upgrade Challenges Single mask technique Manufacturing Performance First foil Gem splicing Coverlay Test Glue press Other ideas Shielding HV distribution Perspectives Compact and easy to shield No hand solderings Allows more benefit of conformal coating. Can be instantly replaced Perspectives For large area gems Large GEMs Serge Duarte Pinto Totem T2 T1 upgrade Challenges Single mask technique Conclusions Single mask technique proved viable and cheap alternative Splicing method allows to go beyond limits of base material These techniques open the way for large area mpgds Manufacturing Performance First foil Gem splicing Coverlay Test Glue press Other ideas Shielding HV distribution Perspectives Perspectives Finalise odds & ends of mechanical design Decide on readout structure Finish hv circuitry layouts Prototype ready for testbeam spring 2008 Single mask technique Attempt to avoid conical shape Large GEMs Serge Duarte Pinto Agitation of etching liquid Totem T2 T1 upgrade Challenges Single mask technique Manufacturing Performance First foil Gem splicing Coverlay Test Glue press Other ideas Shielding HV distribution Perspectives Kapton etching is not conical, but neither cylindrical, and overall badly controlled Etching of bottom copper gives sharp edges, prone to discharge Gain insufficient to measure spectrum with single gem delamination Single mask technique Measurement with double gem setup Large GEMs Serge Duarte Pinto Spectrum of double gem, 9keV X-rays and Ar/CO2 800 Data: DUBGEM_B Model: Gauss Totem 700 T2 T1 upgrade 600 Challenges Single mask technique 500 Manufacturing First foil Gem splicing Coverlay 400 #pulses Performance Chi^2/DoF = 280.63393 R^2 = 0.99198 y0 xc1 w1 A1 xc2 w2 A2 0 ±0 572.658 ±0.20863 92.71802 ±0.44728 76925.88382 ±311.84627 399.66063 ±1.35265 94.14457±3.66577 13803.05807 ±425.50997 300 200 Test Glue press Other ideas 100 0 Shielding HV distribution Perspectives -100 0 200 400 600 800 1000 1200 pulse height (a.u.) Energy resolution is not very bad: σE E = 8.6%. Single mask technique Back to conical holes Large GEMs Serge Duarte Pinto Totem T2 T1 upgrade Challenges Single mask technique Manufacturing Performance First foil Gem splicing Coverlay Test Glue press Other ideas Shielding HV distribution Perspectives Less agitation during kapton etching Extra intermediate cleaning treatment Passive etching of bottom copper (adds to clearance on top) ∅ ∼ 97µm ∅ ∼ 68µm Single mask technique Results for latest samples Large GEMs Serge Duarte Pinto Large holes toward cathode Totem T2 700 Data: SMSC2LG_B Model: Gauss 600 Chi^2/DoF = 295.55124 R^2 = 0.99036 500 y0 xc1 w1 A1 xc2 w2 A2 Challenges Single mask technique # pulses T1 upgrade 400 300 0 ±0 641.62387 102.79563 77255.93976 428.15782 108.68438 14554.19156 ±0.22945 ±0.48366 ±305.82933 ±1.47466 ±3.64984 ±384.39431 Manufacturing Performance 200 First foil 100 Gem splicing Coverlay Test 0 200 400 Glue press Other ideas Shielding HV distribution Perspectives 600 800 pulse height (a.u) Can be operated up to ∆Vgem = 630V ! Gain ∼ 1340, still moderate due to large hole diameter σE E = 7.8% Charging-up of ∼ 15% Single mask technique Results for latest samples Large GEMs Serge Duarte Pinto Small holes toward cathode Works only up to ∆Vgem = 560V Totem Gain ∼ 345 T2 T1 upgrade σE E Challenges Single mask technique Charging-up of ∼ 50%! Manufacturing Performance 600 First foil Data: SMSC2SU4_B Model: Gauss Gem splicing 500 Chi^2/DoF = 295.67233 R^2 = 0.9874 Coverlay Test HV distribution Perspectives # pulses Shielding This strong charging-up appears to be opposite to previous measurements with conical gems. . . 400 y0 xc1 w1 A1 xc2 w2 A2 Glue press Other ideas = 7.1% 300 200 0 ±0 768.06409 ±0.2863 112.0422 ±0.59848 71721.82005 ±326.39791 514.45662 ±1.98794 143.4565 ±5.06313 17324.18433 ±478.9598 100 0 0 200 400 600 pulse height (a.u.) 800 1000
