IEEE Symposium Conference Record Nuclear Science 2004.
DOI: 10.1109/nssmic.2004.1462365
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A small Time Projection Chamber (TPC) has been read out by means of a Medipix2 readout chip as direct anode. A Micromegas foil was placed 50 μm above the chip, and electron multiplication occurred in the gap. With a He/isobutane 80/20 mixture, gas multiplication factors up to tens of thousands were achieved, resulting in an efficiency for detecting single electrons of better than 90%. We recorded many frames containing 2D images with tracks from cosmic muons. Along these tracks, electron clusters were observed, as well as δ-rays. Some applications of this new device are presented.