The first beam test of a monolithic particle pixel detector in high-voltage CMOS technology

Abstract

The results of beam- and irradiation tests preformed on a monolithic particle pixel detector in high-voltage CMOS technology will be presented for the first time. All tested detectors are implemented in a 0.35 μ m technology, they utilize high-voltage n-well/p-substrate diodes as pixel sensors and rely on charge drift in diode depletion layers as the main signal generating mechanism. The detector prototype tested in the beam is a system on a chip that contains a 128×128 matrix with 21 × 21 μ m 2 large pixels, source-follower based- rolling shutter readout and on-chip ADCs that digitize the signal amplitudes with 8-bit precision. Test beam measurements have been performed using EUDET infrastructure. The measured MIP cluster signals are typically 2200 e, spatial resolution approximately 7 μ m (RMS), signal-to-noise ratio of a single pixel is 12.3 and detection efficiency more than 85%. To test the radiation tolerance, several detector chips have been irradiated with neutrons up to 10 14 n eq/cm 2 and with X-rays up to 500 kGy (50 Mrad), they are still functional and the experimental results obtained with these chips will be presented as well.