138 research outputs found
Simulations of CMOS pixel sensors with a small collection electrode, improved for a faster charge collection and increased radiation tolerance
CMOS pixel sensors with a small collection electrode combine the advantages
of a small sensor capacitance with the advantages of a fully monolithic design.
The small sensor capacitance results in a large ratio of signal-to-noise and a
low analogue power consumption, while the monolithic design reduces the
material budget, cost and production effort. However, the low electric field in
the pixel corners of such sensors results in an increased charge collection
time, that makes a fully efficient operation after irradiation and a timing
resolution in the order of nanoseconds challenging for pixel sizes larger than
approximately forty micrometers. This paper presents the development of
concepts of CMOS sensors with a small collection electrode to overcome these
limitations, using three-dimensional Technology Computer Aided Design
simulations. The studied design uses a 0.18 micrometer process implemented on a
high-resistivity epitaxial layer.Comment: Proceedings of the PIXEL 2018 Worksho
Front end electronics for pixel detector of the PANDA MVD
ToPix 2.0 is a prototype in a CMOS 0.13 ¹m technology of the front-end chip for the hybrid pixel sensors that will equip the Micro-Vertex Detector of the PANDA experiment at GSI. The Time over Threshold (ToT) approach has been employed to provide a high charge dynamic range (up to 100 fC) with a low power dissipation (15 ¹W/cell). In an area of 100¹m£100¹m each cell incorporates the analog and digital electronics necessary to amplify the detector signal and to digitize the time and charge information. The ASIC includes 320 pixel readout cells organized in four columns and a simplified version of the end of column readout
Test-beam Performance Results of the FASTPIX Sub-Nanosecond CMOS Pixel Sensor Demonstrator
Within the ATTRACT FASTPIX project, a monolithic pixel sensor demonstrator
chip has been developed in a modified 180 nm CMOS imaging process technology,
targeting sub-nanosecond timing precision for single ionising particles. It
features a small collection electrode design on a 25 micrometers-thick
epitaxial layer and contains 32 mini matrices of 68 hexagonal pixels each, with
pixel pitches ranging from 8.66 to 20 micrometers. Four pixels are transmitting
an analog output signal and 64 are transmitting binary hit information. Various
design variations are explored, aiming at accelerating the charge collection
and making the timing of the charge collection more uniform over the pixel
area. Signal treatment of the analog waveforms, as well as reconstruction of
digital position, time and charge information, is carried out off-chip. This
contribution introduces the design of the sensor and readout system and
presents performance results for various pixel designs achieved in recent test
beam measurements with external tracking and timing reference detectors. A time
resolution below 150 ps is obtained at full efficiency for all pixel pitches.Comment: 14 pages, 15 figures, submitted to NIMA (special issue for ULITIMA
2023 conference
Comparison of small collection electrode CMOS pixel sensors with partial and full lateral depletion of the high-resistivity epitaxial layer
Large area silicon pixel trackers are currently under development for the High Luminosity upgrade of the LHC detectors. They are also foreseen for the detectors proposed for the future high energy Compact Linear Collider CLIC. For the CLIC tracker a single hit resolution of 7 μm, a timing resolution of a few nanoseconds and a material budget of 1–2 % of radiation length per detection layer are required. Integrated CMOS technologies are promising candidates to reduce the cost, facilitate the production and to achieve a low material budget. CMOS sensors with a small size of the collection electrode benefit from a small sensor capacitance, resulting in a large signal to noise ratio and a low power consumption.
The Investigator is a test-chip developed for the ALICE Inner Tracking System upgrade, implemented in a 180 nm CMOS process with a small collection electrode on a high resistivity epitaxial layer. The Investigator has been produced in different process variants: the standard process and a modified process, where an additional N-layer has been inserted to obtain full lateral depletion. This paper presents a comparison of test-beam results for both process variants, focuses on spatial and timing resolution as well as efficiency measurements
High-rate, high-resolution single photon X-ray imaging: Medipix4, a large 4-side buttable pixel readout chip with high granularity and spectroscopic capabilities
The Medipix4 chip is the latest member in the Medipix/Timepix family of
hybrid pixel detector chips aimed at high-rate spectroscopic X-ray imaging
using high-Z materials. It can be tiled on all 4 sides making it ideal for
constructing large-area detectors with minimal dead area. The chip is designed
to read out a sensor of 320 x 320 pixels with dimensions of 75 {\mu}m x 75
{\mu}m or 160 x 160 pixels with dimensions of 150 {\mu}m x 150 {\mu}m. The
readout architecture features energy binning of the single photons, which
includes charge sharing correction for hits with energy spread over adjacent
pixels. This paper presents the specifications, architecture, and circuit
implementation of the chip, along with the first electrical measurements
Forward-central two-particle correlations in p-Pb collisions at root s(NN)=5.02 TeV
Two-particle angular correlations between trigger particles in the forward pseudorapidity range (2.5 2GeV/c. (C) 2015 CERN for the benefit of the ALICE Collaboration. Published by Elsevier B. V.Peer reviewe
Event-shape engineering for inclusive spectra and elliptic flow in Pb-Pb collisions at root(NN)-N-S=2.76 TeV
Peer reviewe
Elliptic flow of muons from heavy-flavour hadron decays at forward rapidity in Pb-Pb collisions at root s(NN)=2.76TeV
The elliptic flow, v(2), of muons from heavy-flavour hadron decays at forward rapidity (2.5 <y <4) is measured in Pb-Pb collisions at root s(NN)= 2.76TeVwith the ALICE detector at the LHC. The scalar product, two- and four-particle Q cumulants and Lee-Yang zeros methods are used. The dependence of the v(2) of muons from heavy-flavour hadron decays on the collision centrality, in the range 0-40%, and on transverse momentum, p(T), is studied in the interval 3 <p(T)<10 GeV/c. A positive v(2) is observed with the scalar product and two-particle Q cumulants in semi-central collisions (10-20% and 20-40% centrality classes) for the p(T) interval from 3 to about 5GeV/c with a significance larger than 3 sigma, based on the combination of statistical and systematic uncertainties. The v(2) magnitude tends to decrease towards more central collisions and with increasing pT. It becomes compatible with zero in the interval 6 <p(T)<10 GeV/c. The results are compared to models describing the interaction of heavy quarks and open heavy-flavour hadrons with the high-density medium formed in high-energy heavy-ion collisions. (C) 2015 CERN for the benefit of the ALICE Collaboration. Published by Elsevier B.V.Peer reviewe
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