Study of scintillation light from microstructure based detectors

In a previous work it has been pointed out that scintillation light, extending up to the infrared, emitted in microstructure based gaseous detectors (microstrips, microgaps, GEMs, etc.) can be used for non destructive testing of these detectors when they are associated to a CCD readout system. The choice of the gas mixture is an important issue, in so far as its emission spectrum should overlap efficiently the sensitivity region of the CCD (400-1100 nm). In the present work we report on a systematic study for several gas mixtures which includes measurements of the total light yields as a function of the electric field and of the spectrometric distribution of the light emitted, in the wavelength region between 250 and 930 nm. Results are presented for pure argon and argon and xenon based gas mixtures. A comparison is made between the results obtained with the CCD coupled to a GEM detector and with a gaseous scintillation proportional counter.