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マイクロメッシュを用いた 高増幅率型 μ-PIC の開発 Development of m -PIC using micro mesh

マイクロメッシュを用いた 高増幅率型 μ-PIC の開発 Development of m -PIC using micro mesh. 神戸大学　　越智 敦彦、桂華 智裕. 1. Introduction 2. Test operation of prototype 3. Simulation studies. Kobe Univ. Atsuhiko Ochi, Tomohiro Keika. 3 rd MPGD workshop @ Saga Univ. 26/Jan/2007. Introduction. Mesh. 400 m m.

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マイクロメッシュを用いた 高増幅率型 μ-PIC の開発 Development of m -PIC using micro mesh

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  1. マイクロメッシュを用いた高増幅率型μ-PICの開発Development of m-PICusing micro mesh 神戸大学　　越智 敦彦、桂華 智裕 1. Introduction 2. Test operation of prototype 3. Simulation studies Kobe Univ. Atsuhiko Ochi, Tomohiro Keika 3rd MPGD workshop @ Saga Univ. 26/Jan/2007

  2. Introduction Mesh 400mm • Micro pixel chamber (m-PIC) • Position resolution ( - 100mm) • Timing resolution ( < 100ns) • High rate capability ( > 107c/sec/mm2) • With micro mesh • Higher gain in stable operation (>104)

  3. Effect using micro mesh • Higher Electric field around the anode • Vertical direction against detection flat • Without increase of e-field near cathode edge •  Higher gas gain willbe attained safely • 104-5 • Reduction of positive ion distribution across detection volume

  4. Applications • Replacement of m-PIC with GEM • Real time imaging device for • X-ray • Gamma-ray • Charged particle • Neutron • etc. • TPC • Low ion diffuse

  5. Prototype test • Micro mesh was mounted on m-PIC • Supported by plastic film / nylon wire • Support structure is future tasks • Distance between m-PIC and wire • About 300mm • Micro mesh is connected to HV controller • Operation gas • Ar:C2H6 = 90:10

  6. Micro scope pictures for same place (different focus point) 0.5mm Micro mesh mounted on m-PIC by hand. Size of m-PIC = 3cm x 3cm. Efficient area using mesh = 2mm x 3cm

  7. Drift Plane Vd Mesh Vm 10mm Cathode 100mm 10mm Anode Va 信号 Test parameters • Only signal pulses (gain) were measured • Gain dependency on • Anode voltage (=Va) • Mesh voltage (=Vm) • Drift voltage (=Vd)

  8. Gain curve (Va, Vm dependence) Gain • Vd-Vm = 100V (Vd=2kV for no mesh plot) • Gas: Ar(90%)+C2H5(10%) • Source: Fe55 (5.9kV) Va [V]

  9. Collection efficiency problem • Collection efficiencies for electrons • Depend on Vd-Vm … smaller is better Gain Gain Va=450V Va=450V Without Mesh With mesh (Vm=0V) Vd [-V] Vd [-V]

  10. Current status of development • Came up with the new idea • m-PIC with micro mesh • Prototypes were made and tested • Gas multiplicity of it is more than 3 times • Gain of 2 x 104 were attained • With prototype mesh (distance is about 300mm) • More studies are needed for tuning up the parameters • Simulation studies  Keika will talk

  11. Optimization of parameters for μ-PIC with micro mesh マイクロメッシュμ-PICの最適動作パラメーターの探索 2007.1.26-27 MPGD workshop @Saga Univ. Kobe Univ.M2Tomohiro Keika 神戸大学　桂華　智裕

  12. micromesh Height Cathode Anode Simulation Study • Optimization for detector parameters • Structure • Operation voltage 3D simulation Parameters • Height of micro mesh • Mesh Voltage (Vm) • Drift Voltage (Vd) • （Anode Voltage is fixed） We optimize the height of micro mesh using a simulation.

  13. About simulation software Maxwell3D • 3D field simulator made by Ansoft Co. America • Make a 3D structure geometry • Calculate electromagnetic field using a finite element method (FEM) • (Supported by Cosmic Ray Group at Kyoto Univ.) Garfield • 2D・3D field simulator made by CERN • Feed maps made by Maxwell3D to Garfield • Calculate electromagnetic field , gas gain and so on.

  14. Height of micro mesh Micro mesh 100μm or Polyimide Cathode 200μm or 500μm Anode Geometry drawing We compare the three patterns. 100μm 200μm 500μm Height

  15. Effect using micro mesh Micro mesh Anode Anode No micro mesh (Va=450V) Micro mesh 100μm (Va=450V,Vm=-100V) Color display of electric field

  16. Comparison of the results by Maxwell3D and by observed value How to calculate gas gain • Calculated using the first Townsend coefficient • Collection-efficiency • No space-charge effect, ion-electron recombination Focus: increasing or decreasing trend of the results Gas gain of μ-PIC without micro mesh is （Va=450V,Vd=-5000V） →It is the comparative data.

  17. Select these parameters to compare the electric field near micro mesh. Dependences of gas gain on Anode Voltage and Height of micro mesh 条件：Va=450V,Vm-Vd=100V 赤：Mesh100um Gain 青：Mesh200um 緑：Mesh500um Supply voltage to micro mesh

  18. Dependences of gas gain on Anode Voltage and Height of micro mesh We had better lower the electric field near micro mesh to prevent electric discharge. 500μm 200μm 赤：メッシュ100um Vm=0V,Vd=-100V 100μm 青：メッシュ200um Vm=-100V,Vd=-200V Electric field 緑：メッシュ500um Vm=-300V,Vd=-400V Distance from the subtrate to micro mesh

  19. Anode:37% Anode:37% No-Anode:3.6% No-Anode:21% Mesh:60% Mesh:41% Collection efficiency Terminal points of electron on the electrode plane or micro mesh. Vm=-200V Vm=0V

  20. Results • Study for the optimization using a 3D simulation. (Qualitative interpretation) • Gain dependency on voltage of meshVm increase Collection efficiency decrease • Estimation of electric field near the micro meshMost desirable fields were obtained in wider (500um) case • In typical case, gain using micro mesh is quite greater than symple u-PIC.simple u-PIC (Va=450V, Vd=-5000V(10mm) ）: 2.2 x 104with micro mesh (Va=450V, Vm=-400V, Distance=500um) :2.0 x 105 Gain rise But Gas gain get more increased

  21. Future prospects • How to hold the mesh on detector? • How to keep the flatness of the mesh? • Wire or leg? • Insulations are attached with micro mesh or m-PIC? • Optimization of geometries and operation voltage? • Collection efficiency ↑and gas gain　↑ • To get consistency of simulation and measurement • 2 dimensional readout and larger detection area • With amplifiers and data acquisition system • We have to get the budget for this project !!! • There is no budget about this project yet !! • We need more than 5M JPY to make new design of m-PIC

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