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Construction and Quality control of large scale GEM detectors. On behalf on the collaboration GEM for CMS. Status. Prototype II. Prototype I. New NS2 technic assembly 4 prototypes produced. NS2 assembly technic. Readout connector. 10 to 15mm. GND. O-ring. Free to slide . GND.
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Construction and Quality control of large scale GEM detectors On behalf on the collaboration GEM for CMS
Status Prototype II Prototype I New NS2 technicassembly 4 prototypes produced
NS2 assemblytechnic Readout connector 10 to 15mm GND O-ring Free to slide GND Drift electrode External screws to adjust stretching GEM attaching structure (4 pieces defining gaps) Embedded nut O-ring Rui De Oliveira GEM workshop IV
Install pullingscrews • Install 50 pullingscrews
Closingwithreadoutboard • Colsingwith the readoutboard 50 screws.
Producing 6 new NS2 Large scale detectors External frame Produced in severalpieces, thengluedtogether. GEM foils ready, waiting for the readout and drift boards. Assemblynextweek.
GEM foils quality control • Sector to test from -50V to -500V by step of 50V. • High voltage applied on the top, bottom and first neighborssectorsconnected to ground. • Measuring the leakagecurrent
Expectedleakagecurrent • Kaptonresisitvity ~1019ohm.m • Air resistivity ~1016ohm.m • R// = Rkaptonx Rair / (Rkapton+Rair) • R//(60µm)~1016 x 60.10-6= 6. 1011ohm • Iexpected~ 500/ R//(60µm)= 0.8 nA Leakagecurrent RKapton Rair HV (-500V)
RESULTS HV (Volts) HV (Volts) GEM1 I (nA) I (nA) HV (Volts) HV (Volts) GEM2 I (nA) I (nA)
Gain Uniformity Control Set up
Eta Sector 4 Peak Position (ADC counts) 15 slices ->1 slice ~ 3cm X Position (mm)
Eta Sector 5 Peak Position (ADC counts) X Position (mm)
Eta Sector 6 Peak Position (ADC counts) X Position (mm)
Eta Sector 7 Peak Position (ADC counts) X Position (mm)
Eta Sector 8 Peak Position (ADC counts) X Position (mm)
Uniformity Plot PeakPosition Variation (%)
Conclusion • Construction of 6 large scale production prototypes isgoing on • Improvements made on mechanicalassembly (NS2 technic and flat boards) • Powerfulltool to check gain uniformityisavailable