Development of Binary Readout CMOS Monolithic Sensors for MIP Tracking

Abstract

Recently, CMOS Monolithic Active Pixels Sensors (MAPS) have become strong candidates for pixel detectors used in high energy physics experiments. A very good spatial resolution lower than 5 mum can be obtained with these detectors. A recent fast MAPS chip, designed in AMS CMOS 0.35 mum Opto process and called MIMOSA16 (HiMAPS2), was submitted to foundry in June 2006. The chip is a 128times32 pixels array where 8 columns have analog test outputs and 24 columns have their outputs connected to offset compensated discriminator stages. The pixel array is addressed row-wise. The array is divided in four blocks of pixels with different charge-to-voltage conversion factors and is controlled by a serially programmable sequencer. The sequencer operates as a pattern generator which delivers control signals both to the pixels and to the column-level discriminators. Discriminators have a common adjustable threshold. This chip is the basis of the final sensor of the EUDET-JRA1 beam telescope which will be installed at DESY in 2009. In this paper, laboratory tests results using a <sup xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">55</sup> Fe source together with beam tests results obtained at CERN using Minimum Ionizing Particles (MIPs) are presented.