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.Comment: 15 pages, 9 included postscript figures, 5 separate jpeg figures, submitted to Nucl. Instr. and Meth. A. A complete postscript version with high resolution figures 1, 3, 11, 12 and 14 can be found at http://www.nikhef.nl/~i06/RandD/final/letter4.p

Soft X-ray sensitivity of a photon-counting hybrid pixel detector with a silicon sensor matrix

We have tested a CMOS pixel readout circuit bump-bonded to a high resistivity silicon sensor to study the noise properties of the system and to determine the lower limit in energy for the detection of X-rays at room temperature. Our test shows that single photon counting is possible down to about 5 keV, and we obtain a mean total noise equivalent to142 electrons on the electronics input

The Silicon Trackers transient detector description

This note describes the new transient detector description model of the two Atlas silicon trackers: the Pixel and the SCT detectors, as it will be used for Data Challenge 0