1. Edoardo Cardelli – Dipartimento di Fisica – Università di Cagliari Università degli Studi di Cagliari Dipartimento di Fisica Detector Quality Control Edoardo Cardelli

2. Overview Edoardo Cardelli – Dipartimento di Fisica – Università di Cagliari Introduction Motivations Gas Leak Test Measurement Principle Setup An example X-Ray Test Setup Uniformity measurement

3. Introduction Edoardo Cardelli – Dipartimento di Fisica – Università di Cagliari Quality control measurements are necessary to guarantee the requested detector performances Gas Leak Rate The chamber leak rate below a few mbar/day allows to keep the gas mixture humidity below a few hundredth ppm V with a 100 cc/min gas flow, to reduce possible ageing effects due to HF formation Test X-Ray Necessary to verify that the gain uniformity is at the level of 10-20%. This is important because the detector has a digital readout and all the channel thresholds are set to the same value. Large gain non-uniformities would reduce the detector operating pleateau

4. Gas leak Test : setup (I) Edoardo Cardelli – Dipartimento di Fisica – Università di Cagliari The gas leak rate measurement of a chamber is referred to the pressure of one reference chamber (same volume, no leak) The chambers are inflated in parallel up to an overpressure of ~ 5 mbar The difference of pressure, Δp, from the probe S2 returns the gas leak rate of the chamber under test The probe S1 returns the relative pressure of the chamber under test N2N2 S1S2 P atm TP Ref Chamber Chamber to test

5. Gas leak Test : setup (II) Edoardo Cardelli – Dipartimento di Fisica – Università di Cagliari

6. Pressure and temperature sensors Gas leak of the Chamber Edoardo Cardelli – Dipartimento di Fisica – Università di Cagliari Equal value of T/p We can measure the gas leak rate by measuring the pressure Δp at time instants with equal p/T value. The result fit make gas leak rate of the chamber

7. Pressure and temperature are used to correct the HV supply in order to keep a constant detector gain X Ray Test: system setup Edoardo Cardelli – Dipartimento di Fisica – Università di Cagliari With a 4 mm collimator 20% of the beam illuminates 2 adjacent pads – this is important to limit border effects The detector can be moved in the XY plane by means of two stepping motors to measure the average sensitivity of each pad X Ray tube Y X Sleds Collimator Gain Uniformity We measure the current collected on the pads when the detector is illuminated with a high intensity X-Ray Tube (the iron target gives two energy peaks at E = 6.4 keV and E 2 = 7.1 keV) The current is proportional to the detector gain We measure the current collected on the pads when the detector is illuminated with a high intensity X-Ray Tube (the iron target gives two energy peaks at E 1 = 6.4 keV and E 2 = 7.1 keV) The current is proportional to the detector gain

8. Entries I(nA) Edoardo Cardelli – Dipartimento di Fisica – Università di Cagliari X-Ray Test: A Measurement Entries I(nA) The current collected on the pads is read-out with a Keithley 6517A electrometer with sensitivity <<1 nA Mean Current Distribution on pads The Gain uniformity is about 15 % including edge effects Edge effect  part of the X-Ray beam is outside the detector sensitive area X Y I(nA) Current Distribution on pads Mean Current Distribution on pads without edge effect The Gain uniformity ~8 %

9. Conclusions Edoardo Cardelli – Dipartimento di Fisica – Università di Cagliari The triple-GEM detector quality control tools are now operational in our construction site The gas leak measurement setup allows to reach the requested sensitivity in 12-24 hours The X-Ray setup allows to monitor the detector gain uniformity with an accuracy better than 10% (or even better if we exclude the pads on the detector perimeter) with a test time of 1-2 min / pad, equivalent to 3.25-6.5 hours total run time

11. Conclusions Edoardo Cardelli – Dipartimento di Fisica – Università di Cagliari Charging Up on one Pad

12. Edoardo Cardelli – Dipartimento di Fisica – Università di Cagliari Charging Up on of the Pads Time (seconds) Charging Up on 12 Pads