New gaseous detectors: the application of CMOS pixel chips as direct anode

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 /spl mu/m 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 /spl delta/-rays. Some applications of this new device are presented.