What we did up to now: Summary of the measurements performed up to now with the gas setup built for the THGEMs coated with the CsI. Photocurrent measurements (Leszek’s chamber) with several gas mixtures (Ne, Ar, CH 4, NeCH 4 X/100-X, ArCH 4 X/100-X, ArCO 2 70/30) at different pressures (i.e. atm pressure, 0.2 bar, 30 mbar) for a dummy THGEM coated with CsI and with a dummy THGEM as a drift (see Jarda’s presentation GDD 32 meeting); Quick characterization (drift and voltage scans) for a double structure THGEM (C7 type: d=0.4 mm, p=0.8 mm, t=0.4 mm, rim=0.01 mm) used as a single structure with 55 Fe source flushing the gas at atmospheric pressure and with several gas mixtures (NeCH 4 90/10, CF4, ArCH 4 X/100-X, ArCO 2 70/30); Optimization of the voltage on the double THGEM structure for few gas mixtures at atmospheric pressure with 55 Fe source; Drift scan with the UV light (Oriel Lamp) on the double THGEM used as a single and as a double structure just with the Ar/CO 2 gas mixture (70/30); Single Photon spectrum acquisition and estimation of the rate of the photons from the current measured onto the anode.

Same setup, several & different purposes Gas mixer Avantes – UV lamp picoammeters 55 Fe Double THGEM C7 Leszek’s chamber Dummy/dummy Quartz window of the double THGEM chamber (type C7) Oriel Lamp Three positions of the shutter: 1.completly open, 2.closed (some internal reflections), 3.Open + filter 3.0 OD N 2 inlet Hidden N2 exhaust Setup for photocurrent measurements and optimization of performance for the double THGEM structure with the iron source Setup for UV light meas. with the double THGEM structure Filter 0.5 OD Narrow Filter Filter 3.0 OD

Some examples about performed meas. THGEM: C7 d=0.4 mm pitch =0.8 mm t=0.4 mm rim=0.01 mm drift = wires THGEM 2 THGEM 1 anode d=4.5 mm d=1.6 mm Single Photon spectrum Collection efficiency of electron from CsI Transfer scan of the double THGEM with Iron source