Atsuhiko Ochi Kobe University 25/06/2013 New Small Wheel MicroMegas Mechanics and layout Workshop

 About sputtering micromegas  First operation test for sputtering micromegas.  The mechanical structure ideas for large size production  Future plan 25/04/2013 A. Ochi, MMM workshop2

 Screen printing is used for current prototypes CERN and Japan) ◦ 400 μm pitch was available, but less pitch is very difficult (in our experience)  We have proposed new technique : Sputtering with lift off process ◦ Less than half pitch of readout strips can be formed  We will not need to take care the alignment between resistive strips and readouts. (We have to confirm it) 25/04/2013 A. Ochi, MMM workshop3 Readout strips Resistive strips

 The resistive strips are formed using sputtering and liftoff technology  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 25/04/2013 A. Ochi, MMM workshop4 Substrate (polyimide) Photo resist (reverse pattern of surface strips) Substrate (polyimide) Metal/Carbo n sputtering Substrate (polyimide) Developing the company (Laytech company (Be-Sputter company (Laytech inc.)

 Sputtering company  They have large sputtering chamber ◦ Φ1800 X H2000 ◦ 1m X 4.5m (flexible board) can be sputtered  They have special technology for uniform sputtering for large area 25/04/2013 5A. Ochi, MMM workshop

 About sputtering micromegas  First operation test for sputtering micromegas.  The mechanical structure ideas for large size production  Future plan 25/04/2013 A. Ochi, MMM workshop6

 Two prototype chambers with 10cm x 10cm have been just delivered on 3 weeks before, and last Thursday.  These are first prototypes of MPGD using sputtering technique for resistive electrodes. 25/04/2013 A. Ochi, MMM workshop7

 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. 25/04/2013 A. Ochi, MMM workshop8

 Beam time: June (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. 25/04/2013 A. Ochi, MMM workshop9

 Pulse height distribution of 5.9 keV X-ray. ◦ Anode = 540V, Drift = - 300V ◦ Drift spacing: 5mm ◦ Gas: Ar(93%) + CO2(7%) ◦ Estimated gain ~  HV current log under intense neutron. ◦ Same as above conditions ◦ Neutron intense is about 10 5 cps/cm 2. ◦ 0.01V correspond to 1 μA  ~600nA of base current was found while beam ON. 25/04/2013 A. Ochi, MMM workshop10 1 μA

 No difference is observed on the resistive strips condition between before and after neutron test 25/04/2013 A. Ochi, MMM workshop11

 About sputtering micromegas  First operation test for sputtering micromegas.  The mechanical structure ideas for large size production  Future plan 25/04/2013 A. Ochi, MMM workshop12

 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) ◦ There is no problem for making 10cm x 10cm 25/04/2013 A. Ochi, MMM workshop13 Flexible foil (polyimide) Rigid PCB (epoxy) Resistive strips (sputtered) Readout strips Bonding film Mesh Pillar

 We can divide the production process of resistive strip from that of readout board. ◦ Resistive strip is formed on thin foil ◦ Because of fine pitch, < 200 micron, we don’t need fine alignment between resistive strips and readout strips.  Dividing those processes will make the yield of production growing up. 25/04/2013 A. Ochi, MMM workshop14 Readout board Resistive Strip foil

 Currently, industrial company says ◦ 50cm X 1m  Proposed design for 2m X 1m test chamber ◦ Consists of 4 resistive strip films.  More inputs are needed for designing strip line and film shape. 25/04/2013 A. Ochi, MMM workshop15

 Small size … it’s OK.  Large size … ◦ Principally, we have not to care the fine alignment of polyimide film gluing. ◦ we should research the affect of polyimide gap.  Does it become instability operation? ◦ How to deal with the boarder of the resistive film? ◦ We need more inputs for deal with this gap 25/04/2013 A. Ochi, MMM workshop16 PCB board Polyimide film Readout strip Resistive strip

 About sputtering micromegas  First operation test for sputtering micromegas.  The mechanical structure ideas for large size production  Future plan 25/04/2013 A. Ochi, MMM workshop17

 Controlling surface resistivity ◦ We need input for optimal resistivity to be set  Making lower resistivity, we need long deposition time. ◦ In this summer  Produce and test one more small test chamber ◦ To apply floating mesh method, lower resistivity. ◦ September - October  Tests for basic properties ◦ Position / Timing resolution  Using Cosmic muon, charged beam line ◦ Stability for ling time operation  Under intense neutron ◦ August - October  Large resistive foil test production ◦ Foil production  September - October ◦ Together with PCB readout and making large chamber  October - November 25/04/2013 A. Ochi, MMM workshop18

 We have operate sputtering MicroMEGAS successfully.  There is no defect after intense neutron operation. ◦ Of course, We need more studies for longtime operation and aging.  The production process attaching rigid PCB and polyimide film ◦ For small chamber … no problem so far. ◦ We need some idea for large size chamber. 25/04/2013 A. Ochi, MMM workshop19