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Development of MicroMEGAS using sputtered resistive electrodes for ATLAS upgrade

Development of MicroMEGAS using sputtered resistive electrodes for ATLAS upgrade. Atsuhiko Ochi 1 , Yasuhiro Homma 1 , Tsuyoshi Takemoto 1 , Fumiya Yamane 1 , Yousuke Kataoka 2 , Tatsuya Masubuchi 2 , Yuki Kawanishi 2 , Shingo Terao 2 Kobe University 1 , ICEPP 2.

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Development of MicroMEGAS using sputtered resistive electrodes for ATLAS upgrade

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  1. Development of MicroMEGAS using sputtered resistive electrodes for ATLAS upgrade Atsuhiko Ochi1, Yasuhiro Homma1, Tsuyoshi Takemoto1, Fumiya Yamane1, YousukeKataoka2, Tatsuya Masubuchi2, Yuki Kawanishi2, Shingo Terao2 Kobe University1, ICEPP2 05/07/2013 RD51 workshop @ Zaragoza

  2. Outline • Introduction • Prototype production of sputtered carbon foil • MM prototype and tests • Feasibility for mass production • Summary A. Ochi, RD51 workshop

  3. Requirements for ATLAS NSW MM • High position resolution for one dimension • <100 μm for eta direction.(Resolution of a few cm is allowed for second coordinate.) • Tolerant for high rate HIP particles • ~ 5kHz/cm2 • Resistive layer should be formed as strips • There should be a technology for large size production (~1m) • Mass production should be available • ~2000 board should be produced in half year. • Low cost Mesh (GND) +HV A. Ochi, RD51 workshop

  4. Two option for resistive electrodes • Screen printing • Already several prototypes (@ CERN and Japan) has been produced. • Made from carbon loaded polymer. • Large size (>1m2) is available • 400 μm pitch was available for MAMMA production. • Sputtering with lift off process • New technique. • Just first two prototypes (10cm x 10cm MM) are available at last month. • Fine pattern (~10μm) is available. • Large size (>1m2) is available in industrial facilities. • Production quality is very well. • It is not affected by production environment A. Ochi, RD51 workshop

  5. Liftoff process using sputtering Photo resist (reverse pattern of surface strips) • Very fine structure (a few tens micro meter) can be formed using photo resist. (same as PCB) • Surface resistivity can be controlled by sputtering material and their thickness @PCB company (Laytech inc.) Substrate (polyimide) Metal/Carbon sputtering @Sputtering company (Be-Sputter inc.) Substrate (polyimide) Developing the resists @PCB company (Laytech inc.) Substrate (polyimide) A. Ochi, RD51 workshop

  6. Sputtering facilities • Large size sputtering is available • 4.5m x 1m for flexible film Be-Sputter Co. Ltd. (Kyoto Japan) A. Ochi, RD51 workshop Sample Vacuum chamber (with Ar gas) Rotating drum 4.5 m round Sputtering target

  7. Prototype of resistive strips • Fine strip pitch of 200 μm is formed on 25μm polyimide foil. • More fine structure will be available. • Surface resistivity is controlled in 2M – 10M/sq. • Depend on carbon thickness • Low resistivity (~100k/sq.) will be available with thicker carbon. • (Will be available in next batch) • It keeps strong adhesion and stability of resistivity. Carbon (300-600Å) Tungsten (10-50Å) Substrate (polyimide) A. Ochi, RD51 workshop

  8. Prototype MicroMEGAS production • The readout board consists of • Readout strips (Rigid PCB). • Resistive strip foil (Polyimide film). • Substrate thickness is 60 μm.(25μm polyimide base and 35μm bonding film) • Mesh was formed by bulk MM technique. • There is no problem for making 10cm x 10cm. Mesh Resistive strips (sputtered) Pillar Flexible foil (polyimide) 25μm Bonding film 35μm Readout strips Rigid PCB (epoxy) A. Ochi, RD51 workshop

  9. First operation test for sputtering MicroMEGAS • Two prototype chambers with 10cm x 10cm have been just delivered on June 2013. • These are first prototypes of MPGD using sputtering technique for resistive electrodes. A. Ochi, RD51 workshop

  10. We should check… • To confirm the detector operation using sputtering technologies • Most uncertain issue was, stability of ultra-thin resistive strip (~ 300micron). • We should check whether small sparks and/or big pulse destroy the electrodes or not. • Using intense fast neutron, we can make big pulses and sparks. • Also this condition is similar to ATLAS cavern. • The our first test for sputtering MM is the operation test under fast neutron. • Other properties, i.e. position/timing resolution, should be checked. However, that stability test has top priority. A. Ochi, RD51 workshop

  11. Neutron beamtest • Beam time: June 17-23(until the day before yesterday) • Be(d, n)B reaction was used by tandem electro-static accelerator in Kobe University. • Staffs and students from Kobe Univ. and ICEPP have joined. A. Ochi, RD51 workshop

  12. Signals and spark current • Gain curve of 5.9 keV X-ray. • Drift = -300V • Drift spacing: 5mm • Gas: Ar(93%) + CO2(7%) • HV current log under intense neutron. • Same as above conditions • Neutron intense is about 105 cps/cm2. • 0.01V correspond to 1 μA • ~600nA of base current was found while beam ON. Very preliminary Very preliminary 1 μA A. Ochi, RD51 workshop

  13. Before and after test • No destruction is observed on the resistive strips between before and after neutron test A. Ochi, RD51 workshop

  14. Mass production feasibility • Assumption: • Size of foils: 1000mm x 500mm • Quantity: 3000 • Sputtering: W:10Å, C:600Å • 500 foils / month can be produced • 8 foils can be sputtered simultaneously in one batch. • Sputtering time is estimated 2 hours.(Including overhead, 3 hours / one batch) • 24h/3h x 8 foils x 20days = 1280 foils / month(Applying safety factor >2 500 foils/month ) • It will take half year, for full production. • Cost estimation (Very rough, but probably upper limit) • Sputtering cost:1k CHF / one batch (for spattering 8 foils)130 CHF / foil ) • It is not sure for the cost of liftoff process, but it is estimated around 200 CHF/foil • Total 330 CHF/foil, 1M CHF for full production Electro forming machines Exposure machines in clean room Etching machines PCB/FPC production line in A. Ochi, RD51 workshop

  15. MM PCB production with parallel process • We can divide the production process of resistive strip from that of readout board. • Resistive strip is formed on thin foil • We don’t need fine alignment between resistive strips and readout strips. • Dividing those processes will make the yield of production growing up. Readout board Resistive Strip foil A. Ochi, RD51 workshop

  16. Conclusion • MPGD electrodes using sputtering has been proposed firstly. • First prototype of MicroMEGAS using sputtered resistive electrodes are produced and tested, for ATLAS NSW detector development. • It works as same as conventional resistive strip MicroMEGAS • Gain curve, operation in HIP were tested. It’s OK. • We should check position/timing properties. • There is no damage after spark (big pulse) operation using fast neutron A. Ochi, RD51 workshop

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