Intermediate Digital Monolithic Pixel Sensor for the EUDET High Resolution Beam Telescope

Abstract

<para xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink"> A high resolution beam telescope, based on CMOS Monolithic Active Pixels Sensors (MAPS), is being developed under the EUDET collaboration, a coordinated detector R&amp;D program for a future international linear collider. A very good spatial resolution <formula formulatype="inline"><tex Notation="TeX">$≪5\ \mu$</tex></formula>m, a fast readout time of 100 <formula formulatype="inline"> <tex Notation="TeX">$\mu$</tex></formula>s for the whole array (136<formula formulatype="inline"><tex Notation="TeX">$\, \times \,$</tex></formula>576 pixels) and a high granularity can be obtained with this technology. A recent fast MAPS chip, designed in AMS CMOS 0.35 <formula formulatype="inline"><tex Notation="TeX">$\mu$</tex></formula>m Opto process with 14 <formula formulatype="inline"> <tex Notation="TeX">$\mu$</tex></formula>m epitaxial layer and called MIMOSA22, was submitted to foundry. MIMOSA22 has an active area of 26.5 mm<formula formulatype="inline"> <tex Notation="TeX">$^{2}$</tex></formula> with a pixel pitch of 18.4 <formula formulatype="inline"><tex Notation="TeX">$\mu$</tex></formula>m arranged in an array of 576 rows by 136 columns where 8 columns have analog test outputs and 128 have their outputs connected to offset compensated discriminator stages. The pixel array is divided in seventeen blocks of pixels, with different amplification gain, diode size, pixel architecture and is addressed row-wise through a serially programmable (JTAG) sequencer. Discriminators have a common adjustable threshold with internal DAC. MIMOSA22 is the last chip (IDC-Intermediate Digital Chip), before the final sensor of the EUDET-JRA1 beam telescope, which will be installed on the 6 GeV electron beam line at DESY. In this paper, laboratory test results on analog and digital parts are presented. Test beam results, obtained with a 120 GeV pion beam at CERN, are also presented. In the last part of the paper, results on irradiated chips are given. </para>