マイクロメッシュを用いた高増幅率型 μ-PIC の開発

Development of -PICusing micro mesh

1. Introduction2. Test operation of prototype3. Simulation studies4. Summary

神戸大学　　越智 敦彦、桂華 智裕Kobe Univ. Atsuhiko Ochi, Tomohiro Keika

400m

Mesh

Introduction

• Micro pixel chamber (-PIC)– Position resolution ( - 100m)– Timing resolution ( < 100ns)– High rate capability

( > 107c/sec/mm2)

• With micro mesh– Higher gain in stable

operation (>104)

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 will

attain safely

• Reduction of positive ion distribution across detection volume

Applications

• Replacement of -PIC with GEM– Real time imaging device for

• X-ray• Gamma-ray• Charged particle• Neutron• etc.

• TPC– Low ion diffuse

Prototype test• Micro mesh was mounted on -PIC

– Supported by plastic film / nylon wire• Support structure is future tasks

– Distance between -PIC and wire• About 300m

– Micro mesh is connected to HV controller

• Operation gas– Ar:C2H6 = 90:10

0.5mm

Micro scope picturesfor same place(different focus point)

Micro mesh mount on -PIC by hand.Size of -PIC = 3cm x 3cm.Efficient area using mesh = 2mm x 3cm

Test parameters

• Only signal pulses (gain) were measured– Gain dependency on

• Anode voltage (=Va)• Mesh voltage (=Vm)• Drift voltage (=Vd)

10 m

10 m100m

Drift Plane

Cathode

Anode 信号

Vd

Va

MeshVm

0

2000

4000

6000

8000

10000

12000

14000

16000

420 430 440 450 460 470 480 490 500

no meshVm=0VVm=-50VVm=-100VVm=-150V

Gain curve (Va, Vm dependence)

• Vd-Vm = 100V (Vd=2kV for no mesh plot)• Gas: Ar(90%)+C2H5(10%)• Source: Fe55 (5.9kV)

Va [V]

Gain

Collection efficiency problem

• Collection efficiencies for electrons– Depend on Vd-Vm … smaller is better

Without MeshWith mesh (Vm=0V)

Va=450V Va=450V

Vd [V] Vd [V]

Gain Gain

Current status of development

• Came up with the new idea -PIC with micro mesh

• Prototypes were made and tested– Gas multiplicity of it is more than 3 times– More studies are needed for tuning up the parameters

• Simulation studies Keika will talk

• There are many issue to study– How to hold the mesh on detector?– Optimization of geometries and operation voltage?– 2 dimensional readout and larger detection area– We have to get the budget for this project !!!

• There is no budget about this project yet !!