The Preliminary Test and Plansof GEM Detector in Tsinghua

Rensheng Wang (王仁生 )Tsinghua U. (清华大学 )

The Third Workshop on Haron Physics in China and Opportunities with 12GeV JLab

Collaborators: Zhi-Gang Xiao, Zhao Zhang, Wei-Hua Yan, Han Yi, Ai-Xing Wang

Outline:

Brief introduction to GEM detectorThe set up of testSome results of testNear future plansSummary

GEM at Tsinghua• TPC read-out based on GEM (See Talk by

Yulan LI)• 16 channel CSA and shaping amplifier

(by Zhi Deng)• … …

To start with a small GEM prototype, trying to study the energy resolution, space resolution and signal properties (like cluster size and broadening) varying with the high voltage, strip width and gas mixture. By comparing these measurements with  the large prototype in the next step, we will know the effect of the large readout board size on the signal propagation.

Brief introduction to GEM detector

-HV

Drift /Sensitive(~1-3kv/cm)

Transfer(~1-3kv/cm)

Induction(~1-3kv/cm)

Cathode

GEM1(300v-500v)

GEM2(300v-500v)

Anode/Readout strip

~2-30 mm

~1-2mm

~1-6mm

The set up of testGEM foil (CERN):50mm*50mm

300um

400um

100um

200um

The set up of test

Operating conditions:1,Atomosphere pressure；2,Active gases： Ar&Co2 : 75/25—90/10

Drift /Sensitive

Transfer

Induction

Cathode

GEM1

GEM2

Anode/Readout strip

2.625mm

2.25mm

1.625mm

-HV(1300V-1900V)1MΩ

13MΩ

20MΩ22MΩ

20MΩ

16MΩ

… …

Charge-SensitivePreamplifier(16 channels)

Main Amplifier ADC

CFD

DAQ

Logical ORfoutGG8020

The result of testThis test includes two sections:

16 in 1 : 16 adjacent strips are connected to one input, to test: energy resolution, effective gain;16 in 16 : 16 adjacent strips are connected individually with 16 preamplifiers input, to test:

Diagnose spectrum of signal;the energy resolution;the signal characters, such as the cluster size, high central moment … …

… …… …

Charge Amplifier

Charge Amplifier

… …

… …

16 in 1

… …… …

Charge Amplifier

Fe55

Homemade

16 in 1

Charge Amplifier

… …

… …

Fe55

16 in 16

16 in 16

16 in 16Energy Resolution:

16 in 16Cluster size of signal of main peak

-HV

1710

1750

Ar 75 80 85

16 in 1616

i ii=1

16

ii=1

x ax =

a

16

2i i

2 i=116

ii=1

( ) a[ ]

a

x xE x

Therein: is the position of fired strip; is the amplitude of signal; is the position, calculated from centroid; x

ixia

16 in 16Second central moment/Variance

-HV

1710

1750

Ar 75 80 85

Near Future PlansFurther detailed test, such as :

Beam test at Jlab?A prototype for SoLID

Space resolution;VME DAQ (1024 channels-ordered) ;Simulation;Timing performance;Proportionality of signal;

… …

GEM

Silicon strip

Cosmic raySource

~45cm

~48cm

~20cm

SummaryGEM-Detector prototype test has been started in Tsinghua; The performance of the tested prototype is consistent with literature report : 1),energy resolution is about 20%-30% for Fe55 depending notably on read-out strip parameters, insignificantly on gas-mixture or HV; 2), 2nd Moment of the signal distribution, increasing slightly with decreasing quenching gas, is larger for the 400um strip space configuration; Next step is to build a prototype for SoLID;

Thanks！