GEM basic test and R&D plan

Takuya Yamamoto （ Saga Univ. ）

Introduction

GEM is used for the sensor part of TPC.

Beam test that examined a basic performance of GEM was done.

GEM

10cm

140μm

CERN GEM

5μ ｍ（ Cu ）

5μ ｍ（ Cu ）

50μ ｍ（ KAPTON ）

70μ ｍ

60μ ｍ

Fuchigami GEM

70μ ｍ

Outline of BEAM TEST

Compares of CERN and Fuchigami. •Used and tested at Hiroshima Univ. Refer

150MeV Electron Beam

•Three GEM was installed in the chamber.

•The gas used the P-10 gas.

•Reading PAD was used the one of PrototypeTPC.

•The trigger counter was set up back and forth.

2mm

6mm

Dielectric board

GEM3GEM2GEM1

PAD

Drift area

（ Cathode）

（ Anode）GND

213V/cm

The space between PAD is all 0.3 mm.

235mm

Transfer area 2kV/cm1.5mm

Induction area 3kV/cm1mm

Eve

nts

C.O.G. [mm]

（ Fuchigami GEM ： Layer ４ 　（ VGEM ＝ 330 （ V ） ）

Residual

Eve

nts

Track [mm]

180

100200

400

- 3 40- 3 40

Residual [mm]

Eve

nts

0－ 2 2

0－ 2 2

Residual [mm]

1000

σ　≒ 320 ［ μｍ］m

σ　≒ 380 ［ μｍ］m

Residual ＝ C.O.G. － Track [μm]E

ven

ts

350

Fuchigami GEM

290μ ｍ

CERN GEM

340μｍ

Each of Layer4

Positional resolution

Fuchigami

CERN

Track / Residual

Fuchigami GEM ： Layer ４ （ VGEM ＝ 330V ） CERN GEM ： Layer4 （ VGEM ＝ 330V ）Track [mm] Track [mm]

CERNFuchigami

Res

idu

al [

mm

]

Res

idu

al [

mm

]

00

Systematic behavior is seen

2

- 2

2

- 2

0-3 4 0-3 4

Size of electron distribution

• Response Function

Rat

io o

f ch

arge

（％）

100

50

0

Distance from PAD to Track（mm）0-4 4

Distribution of charge seen from each pad of one layer.

0

Distance from PAD to Track（mm）0-4 4

100

50

CERN GEM ： Layer4 （ VGEM=330V ）Fuchigami GEM ： Layer ４ （ VGEM ＝ 330V ）

Fuchigami CERNR

atio

of

char

ge （％）

Difference of pulse height

CERN

Fuchigami

sumADC

even

ts

ADC counts

1count = About 0.25pC

● 　 CERN

〇　 Fuchigami

The gain of Fuchigami GEM is about 0.8 times CERN GEM.Fuchigami GEM ： Layer4 （ VGEM ＝ 320V ）

CERN GEM ： Layer4 （ VGEM=320V ）

Pad raw No.(Layer)

Result of BEAM TEST

•Obtained Position resolution

•Fuchigami 　 About 290[μｍ ]

•CERN 　　 　 About 340[μｍ ]

（ Non Magnetic field）

In SN influences

•Fuchigami GEM operated as well as CERN GEM , too

•Some problems happened during Beam test

•The durability of GEM

Discharged GEM（ CERN）

Normal

Damaged

In developing

Durability of GEM

When HV is raised and beam ON, GEM is discharged.

When the numbers of ions collected in the hole increase too much,

and copper is transformed.

As a result, it energizes between both electrodes.

Hypothesis

Development of GEM①

•To investigate the cause of the electrical discharge, the segment does GEM.

10cm

Possible to impress HV to nine separate GEM

Development of GEM②

•We try Nickel coated GEM.

Nickel

Development of GEM③

•The load of one hole is decreased by increasing the number of holes. 9cm

3cm

•The diameter of the hole is 30μm.

•Laser etched by 50μm pitch.

Some surfaces are uneven because of the heat of the laser.