M.A. Chefdeville

A Radiation Imaging Detector Made by Postprocessing a Standard CMOS Chip

An unpackaged microchip is used as the sensing element in a miniaturized gaseous proportional chamber. This letter reports on the fabrication and performance of a complete radiation imaging detector based on this principle. Our fabrication schemes are based on wafer-scale and chip-scale postprocessing. Compared to hybrid-assembled gaseous detectors, our microsystem shows superior alignment precision and energy resolution, and offers the capability to unambiguously reconstruct 3D radiation tracks on the spot.

Applications of GridPix detectors

GridPix detectors provide an excellent tracking and vertex determination for internal radioactive sources with a 4p angular acceptance. In both WIMP search and neutrinoless double beta decay experiments, we expect that GridPix detectors have the ability to significantly improve the measurements.

New results from GridPix detectors

GridPix detector prototypes have been made using a TimePix pixel chip and a PSI 46 pixel chip. A system of discharge protection has been successfully tested. GridPix detectors have been tested using cosmic rays, a 90Sr source and the T9 test beam facility at CERN. GridPix detectors perform well for 3D track reconstruction, dE/dx measurements and transition radiation detection.

Results from MPGDs with a protected timepix or medipix-2 pixel sensor as active anode

The functioning of a high-resistive, hydrogenated amorphous Silicon layer as a protection against discharges for Micoomegas-based pixel readout gaseous detectors, has been investigated. Chips, protected with a 3 mum thick layer, still broke, but a 20 mum thick layer has proven to be adequate. Images from discharge events disclose their geometrical parameters, enabling to further optimize the discharge protection.

A miniaturized multiwire proportional chamber using CMOS wafer scale post-processing

This paper presents the technology of a new microsystem consisting of a CMOS chip with integrated high voltage electrodes, to be used as a detector for ionizing radiation. Its application ranges from particle detection in nuclear and high-energy physics to X-ray detection for materials research and medical purposes. In this paper, the process integration is detailed and system trade-off considerations are reported

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.