Radiation imaging with glass Micromegas
Résumé
Optically recording scintillation light emitted by MicroPattern Gaseous Detectors (MPGDs) with imaging sensors is a versatile and performant readout modality taking advantage of modern high granularity imaging sensors. To allow scintillation light readout of a detector based on MicroMesh Gaseous Structure (Micromegas) technology, we have integrated a Micromegas on a glass substrate with a transparent anode. In addition to optical detection of scintillation light emitted during electron avalanche multiplication between the micromesh and the anode, this setup also achieves a good energy resolution. A glass Micromegas detector was operated in an Ar/CF$_4$ gas mixture and showed a response comparable to conventional Micromegas detectors. The spectrum of the emitted scintillation light was recorded and shown to be equivalent to the one obtained with other gaseous detectors in the same gas mixture. Optically read out images were recorded with CCD cameras and integrated X-ray radiographic imaging with good spatial resolution was demonstrated. A spatial resolution of 440 μ m (10% MTF) was found. Single X-ray photon detection with a high-sensitivity camera was achieved, which potentially permits energy-resolved X-ray fluorescence imaging.
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