1. マイクロメッシュを用いた 三次元電場構造型μ-PICの開発
神戸大学　　越智 敦彦、本間康浩、桂華 智裕、
　　　　　　　　故島陽太、守谷健司、道前武
1. Introduction
2. Test operation of prototype
3. Summary
日本物理学会2007年春季大会　26 Mar. 2007

2. Introduction Micro pixel chamber (m-PIC) With micro 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 will　be attained safely
104-5
Reduction of positive ion distribution across detection volume
~ 1% (simulation)

4. Applications Replacement of m-PIC with GEM TPC
Real time imaging device for
X-ray
Gamma-ray
Charged particle
Neutron
etc.
TPC
Low ion diffuse
No gating method needed

5. Prototype test Micro mesh was mounted on m-PIC Operation gas
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. Test parameters Only signal pulses (gain) were measured
Gain dependency on
Anode voltage (=Va)
Mesh voltage (=Vm)
Drift voltage (=Vd)
10 mm
100mm
Drift Plane
Cathode
Anode 信号 Vd Va
Mesh Vm

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

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. 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