44 research outputs found
PROTON RADIOGRAPHY WITH THE PIXEL DETECTOR TIMEPIX
This article presents the processing of radiographic data acquired using the position-sensitive hybrid semiconductor pixel detector Timepix. Measurements were made on thin samples at the medical ion-synchrotron HIT [1] in Heidelberg (Germany) with a 221 MeV proton beam. The charge is energy by the particles crossing the sample is registered for generation of image contrast. Experimental data from the detector were processed for derivation of the energy loss of each proton using calibration matrices. The interaction point of the protons on the detector were determined with subpixel resolution by model fitting of the individual signals in the pixelated matrix. Three methods were used for calculation of these coordinates: Hough transformation, 2D Gaussian fitting and estimate the 2D mean. Parameters of calculation accuracy and calculation time are compared for each method. The final image was created by method with best parameters
Prospects in MPGDs development for neutron detection
The aim of this document is to summarise the discussion and the contributions
from the 2nd Academia-Industry Matching Event on Detecting Neutrons with MPGDs
which took place at CERN on the 16th and the 17th of March 2015. These events
provide a platform for discussing the prospects of Micro-Pattern Gaseous
Detectors (MPGDs) for thermal and fast neutron detection, commercial
constraints and possible solutions. The aim is to foster the collaboration
between the particle physics community, the neutron detector users, instrument
scientists and fabricants
R&D Proposal Development of Micro-Pattern Gas Detector Technologies
Development of advanced gas-avalanche detector technologies and associated electronic-readout systems for applications in basic and applied researc
R&D Paths of Pixel Detectors for Vertex Tracking and Radiation Imaging
This report reviews current trends in the R&D of semiconductor pixellated
sensors for vertex tracking and radiation imaging. It identifies requirements
of future HEP experiments at colliders, needed technological breakthroughs and
highlights the relation to radiation detection and imaging applications in
other fields of science.Comment: 17 pages, 2 figures, submitted to the European Strategy Preparatory
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Ultrafast Radiographic Imaging and Tracking: An overview of instruments, methods, data, and applications
Ultrafast radiographic imaging and tracking (U-RadIT) use state-of-the-art
ionizing particle and light sources to experimentally study sub-nanosecond
dynamic processes in physics, chemistry, biology, geology, materials science
and other fields. These processes, fundamental to nuclear fusion energy,
advanced manufacturing, green transportation and others, often involve one mole
or more atoms, and thus are challenging to compute by using the first
principles of quantum physics or other forward models. One of the central
problems in U-RadIT is to optimize information yield through, e.g.
high-luminosity X-ray and particle sources, efficient imaging and tracking
detectors, novel methods to collect data, and large-bandwidth online and
offline data processing, regulated by the underlying physics, statistics, and
computing power. We review and highlight recent progress in: a.) Detectors; b.)
U-RadIT modalities; c.) Data and algorithms; and d.) Applications.
Hardware-centric approaches to U-RadIT optimization are constrained by detector
material properties, low signal-to-noise ratio, high cost and long development
cycles of critical hardware components such as ASICs. Interpretation of
experimental data, including comparisons with forward models, is frequently
hindered by sparse measurements, model and measurement uncertainties, and
noise. Alternatively, U-RadIT makes increasing use of data science and machine
learning algorithms, including experimental implementations of compressed
sensing. Machine learning and artificial intelligence approaches, refined by
physics and materials information, may also contribute significantly to data
interpretation, uncertainty quantification and U-RadIT optimization.Comment: 51 pages, 31 figures; Overview of ultrafast radiographic imaging and
tracking as a part of ULITIMA 2023 conference, Mar. 13-16,2023, Menlo Park,
CA, US
Characterization of the radiation field in ATLAS using Timepix detectors
Le travail preĢsenteĢ dans cette theĢse porte sur le reĢseau de deĢtecteurs aĢ pixels ATLAS-TPX, installeĢ dans lāexpeĢrience ATLAS afin dāeĢtudier lāenvironement radiatif en utilisant la tech- nologie Timepix. Les travaux sont rapporteĢs en deux parties, dāune part lāanalyse des donneĢes recueillies entre 2015 et 2018, dāautre part lāeĢtude de nouveaux deĢtecteurs pour une mise aĢ niveau du reĢseau.
Dans la premieĢre partie, une meĢthode pour extraire certaines proprieĢteĢs des MIPs (Mini- mum Ionizing Particles) est deĢveloppeĢe, baseĢe sur lāeĢtude des traces laisseĢes par ces particules lorsquāelles traversent les matrices de pixels des deĢtecteurs ATLAS-TPX. Il est montreĢ que la direction des MIPs et leur perte dāeĢnergie (dE/dX) peut eĢtre deĢtermineĢe, permettant dāeĢvaluer leur origine. De plus, la meĢthode pour mesurer les champs de neutrons thermiques et neutrons rapides avec ces deĢtecteurs est expliqueĢe, puis appliqueĢe aux donneĢes. Les flux de neutrons thermiques mesureĢs aux diffeĢrentes positions des deĢtecteurs ATLAS-TPX sont preĢsenteĢs, alors que le signal des neutrons rapides ne se distingue pas du bruit de fond. Ces reĢsultats sont deĢcrits dans une publication, et la facĢ§on dont ils peuvent eĢtre utiliseĢs pour valider les simulations de champs de radiation dans ATLAS est discuteĢe.
Dans la seconde partie, la theĢse preĢsente une eĢtude de deĢtecteurs Timepix utilisant lāarseĢniure de gallium (GaAs) et le tellurure de cadmium (CdTe) comme capteur de radia- tion. Ces semiconducteurs offrent des avantages par rapport au silicium et pourraient eĢtre utiliseĢs dans les prochaines mises aĢ niveau du reĢseau ATLAS-TPX. Comme ils sont connus pour des probleĢmes dāinstabiliteĢ dans le temps et une efficaciteĢ de collection de charge incompleĢte, ils sont testeĢs en utilisant divers types dāirradiation. Ceci est deĢcrit dans deux articles, lāun portant sur un capteur au GaAs de 500 Ī¼m dāeĢpaisseur, lāautre sur un capteur au CdTe de 1 mm dāeĢpaisseur. MalgreĢ lāapparition de pixels bruyants lors des mesures, les deĢtecteurs montrent une bonne stabiliteĢ du signal dans le temps. Par contre, lāefficaciteĢ de
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collection de charge est inhomogeĢne aĢ travers la surface des deĢtecteurs, avec des fluctuations de produits mobiliteĢ-temps de vie (Ī¼Ļ) importantes. Ces reĢsultats montrent quāil est neĢcessaire dāeĢtudier lāinfluence de ces deĢfauts sur les algorithmes de reconnaissance de traces avant lāutilisation du GaAs et CdTe dans les mises aĢ niveau du reĢseau ATLAS-TPX.The work presented in this thesis focuses on the ATLAS-TPX pixel detector network, in- stalled in the ATLAS experiment for studying the radiation environement using the Timepix technology. The achievements are presented in two parts, on one hand the analysis of data acquired between 2015 and 2018, on another hand the study of new detectors for an upgrade of the network.
In the first part, a method to extract properties of MIPs (Minimum Ionizing Particles) is developed, based on the analysis of clusters left by the interaction of these particles in the pixel matrixes of the ATLAS-TPX detectors. It is shown that the direction of MIPs and their energy loss (dE/dX) can be determined, allowing the evaluation of their origin. Moreover, the method for mesuring the thermal and fast neutron fields is explained, and applied to the data. The thermal neutron fluxes at the different detector locations are reported, whereas the fast neutron signal cannot be distingished from the background. Thoses results are described in a publication, and their use for benchmarking simulations of the radiation field in ATLAS is discussed.
In the second part, the thesis presents a study of Timepix detectors equipped with gallium arsenide (GaAs) and cadmium telluride (CdTe) sensors. These semiconductors offer some advantages over silicon and could be used for upgrades of the ATLAS- TPX network. Since they are known to suffer from time instabilities and incomplete charge collection efficiency, they are tested using several types of irradiation. This is described in two publications, one focusing on a 500Ī¼m thick GaAs sensor, another focusing on a 1mm thick CdTe sensor. Despite the appearance of noisy pixels during the measurements, the detectors are found to be reasonably stable in time. However, the charge collection efficiency is found to be inhomogeneous across the sensor surfaces, with significant fluctuations of mobility-lifetime (Ī¼Ļ) products. These results show that
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it is necessary to study the influence of these material defects on the pattern recog- nition algorithms before the integration of such sensors in the ATLAS-TPX upgrades
Applications of Medical Physics
Applications of Medical Physicsā is a Special Issue of Applied Sciences that has collected original research manuscripts describing cutting-edge physics developments in medicine and their translational applications. Reviews providing updates on the latest progresses in this field are also included. The collection includes a total of 20 contributions by authors from 9 different countries, which cover several areas of medical physics, spanning from radiation therapy, nuclear medicine, radiology, dosimetry, radiation protection, and radiobiology