Speaker
Description
Silicon Photomultipliers (SiPMs) are state-of-the-art photon detectors used in particle
physics, medical imaging, and beyond. They are sensitive to even single photons in the
optical wavelength regime and achieve time resolutions in the order of 10 ps, which makes
them candidates for timing detectors in tracking systems. The Geiger-discharge triggered
in the sensitive elements of a SiPM, Single-Photon Avalanche Diodes (SPADs), yields
signal amplitudes independent of the energy deposited by a photon or ionizing particle.
This intrinsically digital nature of the signal motivates its digitization already on a SPAD
level.
A digital SiPM (dSiPM) developed at Deutsches Elektronen Synchrotron (DESY), and
produced in a LFoundries 150-nm CMOS technology is presented, introducing embedded
CMOS circuitry for on-chip signal processing. Key features of the DESY dSiPM are
hit position information on a pixel level, and hit time stamps per quadrant and 3 MHz
readout frame. The pixels comprise four SPADs and have a pitch of 70 μm. The four
time stamps are provided by 12 bit Time-to-Digital Converters (TDCs) with a resolution
below 100 ps.
The chip is investigated in the laboratory to determine dark count rate, breakdown
voltage, and TDC characteristics. Test-beam measurements demonstrate synchronous
integration in a detector system, spatial hit resolution on a pixel level, and are used to
study minimum-ionizing particle detection efficiency and time resolution.
| Submission declaration | Original and unplublished |
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