The absorption length, λabs, of light with wavelengths between 0.95 and 1.30 μm in silicon irradiated with 24 GeV/c protons to 1 MeV neutron equivalent fluences up to 8.6×1015 cm−2 has been measured. ...It is found that λabs decreases with fluence due to radiation-induced defects. A phenomenological parametrization of the radiation-induced change of λabs as a function of wavelength and neutron equivalent fluence at room temperature is given. The observation of the decrease of λabs with irradiation is confirmed by edge-TCT measurements on irradiated silicon strip detectors. Using the measured wavelength dependence of λabs, the change of the silicon band-gap with fluence is determined.
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 × 1016cm−2 1MeV neutron equivalent at 3.0cm distance from the beam are expected for an integrated luminosity of 3000fb−1. In the last decades, the pixel pitch has constantly been reduced to cope with the experiments’ 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 100 × 25µm2 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 ϕeq=3.6×1015 cm−2. The measurements were performed with a 5GeV electron beam. A spatial resolution of 3.2±0.1µm is found for non-irradiated sensors, at the optimal angle for charge sharing. The resolution is 5.0±0.2µm for a proton-irradiated sensor at ϕeq=2.1×1015 cm−2 and a neutron-irradiated sensor at ϕeq=3.6×1015 cm−2. The extrapolated resolution to infinite beam momentum, where the contribution of multiple scattering can be neglected, has also been evaluated.
Position reconstruction for segmented detectors Ebrahimi, A.; Feindt, F.; Garutti, E. ...
Nuclear instruments & methods in physics research. Section A, Accelerators, spectrometers, detectors and associated equipment,
10/2021, Letnik:
1014
Journal Article
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The topic of the paper is the position reconstruction from signals of segmented detectors. With the help of a simple simulation, it is shown that the position reconstruction using the ...centre-of-gravity method is strongly biased, if the width of the charge (or e.g. light) distribution at the electrodes (or photo detectors) is less than the read-out pitch. A method is proposed which removes this bias for events with signals in two or more read-out channels and thereby improves the position resolution. The method also provides an estimate of the position–response function for every event. Examples are given for which its width as a function of the reconstructed position varies by as much as an order of magnitude.
A fast Monte Carlo program is described which simulates the signals from a silicon pixel detector traversed by charged particles under different angles, and the results obtained with the proposed reconstruction method and with the centre-of-gravity method are compared. The simulation includes the local energy-loss fluctuations, the position-dependent electric field, the diffusion of the charge carriers, the electronics noise and charge thresholds for clustering, A comparison to test-beam-data is used to validate the simulation.
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.
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.
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.
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