1 July GEM R&D Activity in USTC Yi Zhou University of Science & Technology of China

2 Outline  The NS2 Self-stretching Technique  The 30cm×30cm GEM of USTC

3 The self-stretching technique Readout PCB GEMs Drift NS1 is relaying on the elastic properties of the periphery frame The screw is pushing the frame before the stretching. The screw is pulling out the console Detector Base NS1 NS2 L. Franconi, A. Marinov, R. De Oliveira Status of no-stretch no-spacer GEM assembly

4 The advantages of NS2  The whole construct progress is driving the screws, it is very easy and very fast, so that we can assemble a detector in 2 hours ；  All the GEM foils are self-stretched, the detector doesn’t need support frames anymore. It means that there is no dead area inside the detector, no glue aging and gas flow problems anymore ；  All the screws can be released and tightened again, so that any part of the detector is replaceable, it means that the cost of the GEM project can be greatly decreased ；

5 3D model of NS2 GEM

6 10M R GEM1 R GEM2 R GEM3 10M 100k Drift d I =2mm d T2 =2mm d T1 =2mm d D =3mm HV 100k 2.2nF Connection of HV divider & filter R D =1M R GEM1 =0.55M R T1 =1M R GEM2 =0.5M R T2 =1M R GEM3 =0.45M R I =1M Low Pass Filter

7 The temperature of the dividers HV=4500V

8 Inefficiency estimate LCR Meter Capacity of 10cm×10cm GEM foil: ~4.5nF  After each discharge, the GEM sector need recharge, if the protected resistor is 10MΩ, the recharge time is about: T = 4.5nF × 10MΩ ≈ 45ms  this 45ms charging time causes the inefficiency. If we require the inefficiency < 1%, we need P×Φ×S×T < 1%, we have: Here: P: the discharge probability; Φ: the flux of the beam; S: the area of a GEM sector; T: the recharge time(~45ms)

9 Foil assemblage

10 Gas tight test

11 Detector assemblage

12 HV discharge problem & solution

13 GEM system

14 Signal of 30cm×30cm GEM from Rui

15 We need the Cu-target X-ray tube

16 Ultrasonic bath for detector clean

17 Summary & near future work  System calibration for gain measurement;  uniformity test for gain and energy resolution;  Setup the clean system;  The NS2 self-stretching technique is a very efficient way for the GEM detector construction;  The HV part on the GEM detector should be sealed; Summary: Near future work: