arXiv subjects

F. Feindt

Publications and source records attributed to F. Feindt.

3 recordsLinked to original sources

arXiv2023

Monolithic MHz-frame rate digital SiPM-IC with sub-100 ps precision and 70$~\mu$m pixel pitch

This paper presents the design and characterization of a monolithic integrated circuit (IC) including digital silicon photomultipliers (dSiPMs) arranged in a 32$~\times~$32 pixel matrix at 70$~\mu$m pitch. The IC provides per-quadrant time stamping and hit-map readout, and is fabricated in a standard 150-nm CMOS technology. Each dSiPM pixel consists of four single-photon avalanche diodes (SPADs) sharing a quenching and subsequent processing circuitry and has a fill factor of 30$~\%$. A sub-100$~$ps precision, 12-bit time-to-digital converter (TDC) provides timestamps per quadrant with an acquisition rate of 3$~$MHz. Together with the hit map, the total sustained data throughput of the IC amounts to 4$~$Gbps. Measurements obtained in a dark, temperature-stable environment as well as by using a pulsed laser environment show the full dSiPM-IC functionality. The dark-count rate (DCR) as function of the overvoltage and temperature, the TDC resolution, differential and integral nonlinearity (DNL/INL) as well as the propagation-delay variations across the matrix are presented. With aid of additional peripheral test structures, the main building blocks are characterized and key parameters are presented.

physics.ins-det↗

arXiv2021

Position resolution with 25 um pitch pixel sensors before and after irradiation

Pixelated silicon detectors are state-of-the-art technology to achieve precise tracking and vertexing at collider experiments, designed to accurately measure the hit position of incoming particles in high rate and radiation environments. The detector requirements become extremely demanding for operation at the High-Luminosity LHC, where up to 200 interactions will overlap in the same bunch crossing on top of the process of interest. Additionally, fluences up to 2.3 10^16 cm^-2 1 MeV neutron equivalent at 3.0 cm distance from the beam are expected for an integrated luminosity of 3000 fb^-1. In the last decades, the pixel pitch has constantly been reduced to cope with the experiment's needs of achieving higher position resolution and maintaining low pixel occupancy per channel. The spatial resolution improves with a decreased pixel size but it degrades with radiation damage. Therefore, prototype sensor modules for the upgrade of the experiments at the HL-LHC need to be tested after being irradiated. This paper describes position resolution measurements on planar prototype sensors with 100x25 um^2 pixels for the CMS Phase-2 Upgrade. It reviews the dependence of the position resolution on the relative inclination angle between the incoming particle trajectory and the sensor, the charge threshold applied by the readout chip, and the bias voltage. A precision setup with three parallel planes of sensors has been used to investigate the performance of sensors irradiated to fluences up to F_eq = 3.6 10^15 cm-2. The measurements were performed with a 5 GeV electron beam. A spatial resolution of 3.2 +\- 0.1 um is found for non-irradiated sensors, at the optimal angle for charge sharing. The resolution is 5.0 +/- 0.2 um for a proton-irradiated sensor at F_eq = 2.1 10^15 cm-2 and a neutron-irradiated sensor at F_eq = 3.6 10^15 cm^-2.

physics.ins-det↗

arXiv2019

Influence of radiation damage on the absorption of near-infrared light in silicon

The absorption length, $\lambda_{abs}$, of light with wavelengths between 0.95 and 1.30$~\mu$m in silicon irradiated with 24$~$GeV/c protons to 1$~$MeV neutron equivalent fluences between 0 and $8.6 \times 10^{15}~$cm$^{-2}$ has been measured. It is found that $\lambda_{abs}$ decreases with fluence due to radiation-induced defects. A phenomenological parametrisation of the radiation-induced change of $\lambda_{abs}$ as a function of wavelength and neutron equivalent fluence at room temperature is given. The observation of the decrease of $\lambda_{abs}$ with irradiation is confirmed by edge-TCT measurements on irradiated silicon strip detectors. Using the measured wavelength dependence of $\lambda_{abs}$, the change of the silicon band-gap with fluence is determined.

physics.ins-det↗