2,132 research outputs found
Front-End electronics and integration of ATLAS pixel modules
For the ATLAS Pixel Detector fast readout electronics has been successfully
developed and tested. Main attention was given to the ability to detect small
charges in the order of 5,000 electrons within 25 ns in the harsh radiation
environment of LHC together with the challenge to cope with the huge amount of
data generated by the 80 millions channels of the Pixel detector. For the
integration of the 50 micron pitch hybrid pixel detector reliable bump bonding
techniques using either lead-tin or indium bumps has been developed and has
been successfully tested for large scale production.Comment: Talk at the VERTEX2003 conference, Lake Windermere, UK, September
2003, 8 pages, LaTeX, 6 eps figure
Readout Concepts for DEPFET Pixel Arrays
Field effect transistors embedded into a depleted silicon bulk (DEPFETs) can
be used as the first amplifying element for the detection of small signal
charges deposited in the bulk by ionizing particles, X-ray photons or visible
light. Very good noise performance at room temperature due to the low
capacitance of the collecting electrode has been demonstrated. Regular two
dimensional arrangements of DEPFETs can be read out by turning on individual
rows and reading currents or voltages in the columns. Such arrangements allow
the fast, low power readout of larger arrays with the possibility of random
access to selected pixels. In this paper, different readout concepts are
discussed as they are required for arrays with incomplete or complete clear and
for readout at the source or the drain. Examples of VLSI chips for the steering
of the gate and clear rows and for reading out the columns are presented.Comment: 8 pages, 9 figures, submitted to Nucl. Instr. and Methods as
proceedings of the 9th European Symposium on Semiconductor Detectors, Elmau,
June 23-27, 200
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
X-ray analog pixel array detector for single synchrotron bunch time-resolved imaging
Dynamic x-ray studies may reach temporal resolutions limited by only the
x-ray pulse duration if the detector is fast enough to segregate synchrotron
pulses. An analog integrating pixel array detector with in-pixel storage and
temporal resolution of around 150 ns, sufficient to isolate pulses, is
presented. Analog integration minimizes count-rate limitations and in-pixel
storage captures successive pulses. Fundamental tests of noise and linearity as
well as high-speed laser measurements are shown. The detector resolved
individual bunch trains at the Cornell High Energy Synchrotron Source (CHESS)
at levels of up to 3.7x10^3 x-rays/pixel/train. When applied to turn-by-turn
x-ray beam characterization single-shot intensity measurements were made with a
repeatability of 0.4% and horizontal oscillations of the positron cloud were
detected. This device is appropriate for time-resolved Bragg spot single
crystal experiments.Comment: 9 pages, 11 figure
Evolution des méthodes de protection des procédés industriels contre les effets des explosions : le projet DELFINE)
National audienceClassical methods for vent sizing are based on experimental correlations coming from academic test situations, sometime quite different from real industrial conditions. Thus, they do not take into account the variation of turbulence in industrial enclosures, which may alter drastically the explosion violence. The DELFINE installation presently in construction will allow studying dust explosions in real working conditions of a dust collector. Preliminary experiments in an instrumented small size filter are presented, which allow characterizing the turbulence level in every work phase of the system. It appears that the turbulence level is generally lower than in the standard conditions for vent testing, even during reverse jet cleaning. It should offer perspective for optimization of the venting areas for dust collectors. Explosion tests in real conditions on the DELFINE installation will be performed to try to confirm these first observations.Les industries de la chimie, du bois et de l'agroalimentaire concentrent plus de 80% des explosions de poussières recensées en France au cours des 100 dernières années [1]. Pour cette raison il existe aujourd'hui un secteur industriel qui propose des solutions de maîtrise des risques d'explosion de poussière et met sur le marché, qui des technologies de protection, qui des appareils équipés de ces technologies dès la conception. Si des normes relatives à ces stratégies industrielles ont été proposées comme pendant à la Directive ATEX [2], il a été observé qu'elles étaient loin de couvrir la réalité des procédés industriels. Cela est perçu comme un obstacle majeur à l'ingénierie de la sécurité des procédés puisqu'on ne possède pas de " méthodes d'ingénieur " suffisantes. L'objectif du projet DELFINE qui réunit les moyens de FIKE Corp. (producteur de systèmes de protection), de DELTA NEU (producteur de process industriels de filtration) et de l'INERIS (Expert de la phénoménologie de l'explosion) est de promouvoir des méthodes de dimensionnement des systèmes de protection en commençant par la technologie des évents. On présente dans cette communication les résultats obtenus au plan de la modélisation phénoménologique du développement des explosions dans les systèmes industriels (réseaux d'enceintes et de canalisations) et les premiers résultats expérimentaux obtenus à l'échelle réelle au moyen d'une boucle d'essai de dépoussiérage spécialement conçue pour le projet
Radiation hardness of CMS pixel barrel modules
Pixel detectors are used in the innermost part of the multi purpose
experiments at LHC and are therefore exposed to the highest fluences of
ionising radiation, which in this part of the detectors consists mainly of
charged pions. The radiation hardness of all detector components has thoroughly
been tested up to the fluences expected at the LHC. In case of an LHC upgrade,
the fluence will be much higher and it is not yet clear how long the present
pixel modules will stay operative in such a harsh environment. The aim of this
study was to establish such a limit as a benchmark for other possible detector
concepts considered for the upgrade.
As the sensors and the readout chip are the parts most sensitive to radiation
damage, samples consisting of a small pixel sensor bump-bonded to a CMS-readout
chip (PSI46V2.1) have been irradiated with positive 200 MeV pions at PSI up to
6E14 Neq and with 21 GeV protons at CERN up to 5E15 Neq.
After irradiation the response of the system to beta particles from a Sr-90
source was measured to characterise the charge collection efficiency of the
sensor. Radiation induced changes in the readout chip were also measured. The
results show that the present pixel modules can be expected to be still
operational after a fluence of 2.8E15 Neq. Samples irradiated up to 5E15 Neq
still see the beta particles. However, further tests are needed to confirm
whether a stable operation with high particle detection efficiency is possible
after such a high fluence.Comment: Contribution to the 11th European Symposium on Semiconductor
Detectors June 7-11, 2009 Wildbad Kreuth, German
Physiology-based IVIVE predictions of tramadol from in vitro metabolism data
To predict the tramadol in vivo pharmacokinetics in adults by using in vitro metabolism data and an in vitro-in vivo extrapolation (IVIVE)-linked physiologically-based pharmacokinetic (PBPK) modeling and simulation approach (SimcypA (R)).
Tramadol metabolism data was gathered using metabolite formation in human liver microsomes (HLM) and recombinant enzyme systems (rCYP). Hepatic intrinsic clearance (CLint(H)) was (i) estimated from HLM corrected for specific CYP450 contributions from a chemical inhibition assay (model 1); (ii) obtained in rCYP and corrected for specific CYP450 contributions by study-specific intersystem extrapolation factor (ISEF) values (model 2); and (iii) scaled back from in vivo observed clearance values (model 3). The model-predicted clearances of these three models were evaluated against observed clearance values in terms of relative difference of their geometric means, the fold difference of their coefficients of variation, and relative CYP2D6 contribution.
Model 1 underpredicted, while model 2 overpredicted the total tramadol clearance by -27 and +22%, respectively. The CYP2D6 contribution was underestimated in both models 1 and 2. Also, the variability on the clearance of those models was slightly underpredicted. Additionally, blood-to-plasma ratio and hepatic uptake factor were identified as most influential factors in the prediction of the hepatic clearance using a sensitivity analysis.
IVIVE-PBPK proved to be a useful tool in combining tramadol's low turnover in vitro metabolism data with system-specific physiological information to come up with reliable PK predictions in adults
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