Imaging with the invisible light

Abstract

We describe a UV photodetector with single photon (electron) counting and imaging capability. It is based on a CsI photocathode, a GEM charge multiplier and a self-triggering CMOS analog pixel chip with 105 k pixels at 50 pm pitch. The single photoelectron produced by the absorption of a UV photon is drifted to and multiplied inside a single GEM hole. The coordinates of the GEM avalanche are reconstructed with high accuracy (4 mu m rms) by the pixel chip. As a result the map of the GEM holes, arranged on a triangular pattern at 50 pm pitch, is finely imaged. (C) 2007 Published by Elsevier B.V

The gas electron multiplier (GEM): Operating principles and applications

“…In the course of development of the X-ray polarimeter (see the next section), and using a large scale integrated ASIC readout chip having $ 22,000 hexagonal pixels, 50 mm in diameter and a custom thin GEM foil with $ 30 mm holes at a 50 mm pitch, an intrinsic position accuracy for UV photons of $ 5 mm rms has been demonstrated, as it can be inferred by the self-portrait image in Fig. 61 [119].…”

Gaseous photodetectors with solid photocathodes

“…The coordinate characteristics of GEM-based GPDs with CsI photocathodes were studied in [14,119]. In [14], a spatial resolution of 55 μm for single photons upon readout to the anode in the form of parallel strips was obtained.…”

A UV sensitive integrated Micromegas with Timepix readout

“…In [4] a Micromegas device with a single anode is coupled to a CsI reflective photocathode. A CMOS imaging chip coupled to a non-integrated gaseous electron multiplier (GEM) with CsI photocathode was described in [5]. This work presents the first fully monolithic embodiment of such a UV-photon imaging detector.…”