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 ） 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 GEM3 GEM2 GEM1 PAD Drift area （ Cathode ） （ Anode ） GND 213V/cm The space between PAD is all 0.3 mm. 235mm Transfer area2kV/cm 1.5mm Induction area3kV/cm 1mm

Events C.O.G. [mm] （ Fuchigami GEM ： Layer ４ （ V GEM ＝ 330 （ V ） ） Residual Events Track [mm] Residual [mm] Events 0 －2－2 2 0 －2－2 2 Residual [mm] 1000 σ ≒ 320 ［ μ ｍ］ m σ ≒ 380 ［ μ ｍ］ m Residual ＝ C.O.G. － Track [μm] Events 350 Fuchigami GEM 290μ ｍ CERN GEM 340μ ｍ Each of Layer4 Positional resolution Fuchigami CERN

Track / Residual Fuchigami GEM ： Layer ４ （ V GEM ＝ 330V ） CERN GEM ： Layer4 （ V GEM ＝ 330V ） Track [mm] CERN Fuchigami Residual [mm] 0 0 Systematic behavior is seen

Size of electron distribution Response Function Ratio of charge （％） Distance from PAD to Track （ mm ） 0-44 Distribution of charge seen from each pad of one layer. 0 Distance from PAD to Track （ mm ） CERN GEM ： Layer4 （ V GEM =330V ） Fuchigami GEM ： Layer ４ （ V GEM ＝ 330V ） Fuchigami CERN Ratio of charge （％）

Difference of pulse height CERN Fuchigami sumADC events ADC counts 1count = About 0.25pC ● CERN 〇 Fuchigami The gain of Fuchigami GEM is about 0.8 times CERN GEM. Fuchigami GEM ： Layer4 （ V GEM ＝ 320V ） CERN GEM ： Layer4 （ V GEM =320V ） Pad raw No. (Layer)

Result of BEAM TEST Obtained Position resolution Fuchigami About 290[μ ｍ ] CERN About 340[μ ｍ ] （ 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 GEM ① To investigate the cause of the electrical discharge, the segment does GEM. 10cm Possible to impress HV to nine separate GEM

Development of GEM ② We try Nickel coated GEM. Nickel

Development of GEM ③ 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.