The detection of single electrons by means of a Micromegas-covered   MediPix2 pixel CMOS readout circuit
  A small drift chamber was read out by means of a MediPix2 readout chip as direct anode. A Micromegas foil was placed 50 $\mu$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 delta-rays. 
M. Campbell, M. Chefdeville, P. Colas, A.P. Colijn, A. Fornaini, Y.   Giomataris, H. van der Graaf, E.H.M Heijne, P. Kluit, ...