Abstract. The use of pixel readout chips as highly segmented anodes of gaseous detectors offers high granularity and low noise at the input of each channel. This readout can be applied to TPCs for high energy particle tracking as well as for low energy recoil detection where a small charge is created in the gas volume. Detectors combining GEM or Micromegas amplification stages with pixel readout chips will be presented and their tracking capabilities described.
IntroductionThe use of pixel readout chips as highly segmented anodes of micro-patterned gaseous detectors offers a few tens of microns granularity and a low noise at the input of each channel allowing the detection in three dimensions of single electrons with a potentially very good spatial resolution, with high rate capability and efficiency.These detectors are well suited for the detection of polarized photons and axions, as both radiations eventually end in a few-keV photo-electron conversion. The photo-electron being absorbed in the gas, its energy can be measured by counting the detected primary electrons; and its track may be resolved thanks to the fine segmentation of the anode. In the same way, the direction and energy of double -ß decay electrons could be measured, as well as the small ionization of low energy nuclear recoils from WIMP or neutrino interactions. This readout can also be applied to TPCs for high energy physic s experiments. In that case, the particle identification (dE/dx) could be improved by counting the primary clusters of electrons along a track and d-rays can be identified and isolated in the analysis. This paper will summarize the progress in Micromegas and GEM based pixelized detectors, describing their combination with the MediPix2 and TimePix pixel readout chips. Meanwhile, emphasis will be put on the on-chip integration of amplification and discharge protection structures.