Дисертації з теми "Active detectors"

Thesis (Ph. D.)--Massachusetts Institute of Technology, Dept. of Physics, 2003.
Includes bibliographical references (p. 239-243).
As the first generation of laser interferometric gravitational wave detectors near operation, research and development has begun on increasing the instrument's sensitivity while utilizing existing infrastructure. In the Laser Interferometer Gravitational Wave Observatory (LIGO), significant improvements are being planned for installation in 2007 to increase the sensitivity to test mass displacement, hence sensitivity to gravitational wave strain, by improved suspensions and test mass substrates, active seismic isolation, and higher input laser power. Even with the highest quality optics available today, however, finite absorption of laser power within transmissive optics, coupled with the tremendous amount of optical power circulating in various parts of the interferometer, result in critical wavefront deformations which will cripple the performance of the instrument. Discussed is a method of active wavefront correction via direct thermal actuation on optical elements of the interferometer; or, "thermally adaptive optics". A simple nichrome heating element suspended off the face of an affected optic will, through radiative heating, remove the gross axisymmetric part of the original thermal distortion. A scanning heating laser- will then be used to remove any remaining non-axisymmetric wavefront distortion, generated by inhomogeneities in the substrate's absorption, thermal conductivity, etc. This work includes a quantitative analysis of both techniques of thermal compensation, as well as the results of a proof-of-principle experiment which verified the technical feasibility of each technique.
by Ryan Christopher Lawrence.
Ph.D.

Collisions between personnel on foot and heavy equipment or materials on a construction site can be characterized as a contact collision. These types of incidents are a common occurrence on a work site. Technology is needed to improve work zone safety by alerting workers that are in danger of collisions pro-actively and in real-time. Developing this technology may assist in collecting previously un-recorded data on "near-misses" (close-calls). An approach is presented in this paper that is based on wireless radio frequency technology to alert workers in real-time when they are in danger. Various experiments are described that have been conducted in order to gain better understanding of the technology's potential, including measuring equipment blind spots and alert (or safety) zones. Blind spots areas are measured for six common construction vehicles to help determine the required (or minimum) alert distance (safety zone) for the equipment. A computer program was developed in-house to automatically calculate the percentage of blind spots on 2-dimensional planes and in the overall 3-dimensional volume. The blind spots results directly indicate the necessary safety zones for the equipment. The proximity device results show that technology demonstrated the capability of collecting important safety data while pro-actively detecting hazardous situations and warning workers and equipment operators during imminent potential hazardous events. Furthermore, the presented research can lead to improve the overall safety performance in construction and elsewhere through improved learning and education by providing relevant information to decision makers at all levels.

A thorough investigation has been carried out in order to determine the suitability of diamond and silicon carbide for active interrogation applications. This included electrical and radiological characterisation of single crystal diamond (D-SC) and polycrystalline diamond (D-PC) detectors; epitaxial silicon carbide (SiC-EP) and semi-insulating silicon carbide (SiC-SI); all compared against the performance of a commercial silicon PIN photodiode (Si-PIN) from Hamamatsu. This work aided in determining whether the detectors were suitable for radiation detection purposes, as well as obtaining the operational criteria for use. Characterisation work was also conducted on semi-insulating silicon carbide detectors from three different suppliers, as well as on detectors fabricated via different techniques. This work demonstrated the robustness of the material, as the charge collection properties were unaffected by contact fabrication technique. Changes in current-voltage characteristics were observed for different contact fabrication methods, but were generally still low (≈nA) over the ranges tested (±500V). Following this work the performance of selected detectors was measured against criteria for the AWE active interrogation project. Radiation dose dependent performance deterioration was observed in the SiC-SI and D-PC detectors, with decreased charge collection efficiency (-45±4%) and intrinsic efficiency (-40% at -400V) observed respectively. It is not clear as to whether these effects are a result of bulk material damage or contact/surface/mount damage, but an increase in the current-voltage relationship was also observed on these detectors, as well as the Si-PIN (SiC-SI≈+25% and D-PC≈+20% at -400V; Si- PIN≈+300% at -25V). Instability of the peak position and/or counting rate with irradiation time was observed in D-SC, D-PC and all the semi-insulating SiC (polarisation effect). For D-SC this was primarily with alpha particles and stability would be maintained after a period of time, with that period decreasing as the incident flux increases. For D-PC and the semi-insulating SiC, this effect was observed on most radiation types tested (alpha, beta, X-ray, gamma, neutron and protons) with polarisation rate increasing as the the number of charge carriers created per incident particle increased. However, it has been shown that combinations of ambient light and 0V bias could depolarise a semi-insulating SiC detector and even decrease its polarisation rate for future irradiations. D-SC, SiC-EP and semi-insulating SiC material were also shown to operate from -60◦C to +100◦C. For D-SC and SiC-EP the charge collection efficiency was similar (±10%) over the entire range, apart from at +100◦C for D-SC where it was ≈50% down. For SiC-SI, the charge collection efficiency peaked at room temperature, but became more stable at +100◦C (lower polarisation rate). All the detectors demonstrated the ability to detect and discriminate between both different energy neutrons and ionising photon (gamma) energies using simple energy threshold discrimination. Comparison of the endpoint energy for AmBe (< 4.1MeV >) and Cf-252 (< 2.1MeV >) or mono-energetic 1MeV and 5MeV neutrons, give ratios (Emax(High Energy)/Emax(Low Energy)) of ≈3.5, 2.5, 5.0, 4.9 and 2.0 for D-SC, D-PC-, SiC-EP, SiC-SI and Si-PIN respectively. Similarly comparison of the endpoint energy for Co-60 gammas (1.2MeV and 1.3MeV) and AmBe neutron (Emax(AmBe)/Emax(Co − 60)) give ratios of 8.1, 16.0, 6.4, 6.9 and 9.1 respectively. It was also shown that the neutron-gamma detection ability can be improved through simple design optimisation techniques, including: the use of high atomic number filtration to reduce gamma detection; hydrogenous proton conversion layers to improve neutron detection; and large area detection arrays to improve counting statistics.

Active interrogation of cargo containers employing monoenergetic photons offers an expeditious low-dose approach in pursuit of shielded special nuclear materials. Cherenkov detectors can be used for a variety of purposes, including imaging of the cargo contingent upon gamma ray energies used in interrogation. If the gamma ray energies are sufficiently well separated, as the case in $^{11}$B(d,n-$\gamma$)$^{12}$C reaction resulting in 4.4 MeV and 15.1 MeV photons, spectral analysis using Cherenkov detectors is possible. Applying an array of custom designed Cherenkov detectors reduce undesired low energy background, both natural and scatter from the application environment, while producing the capability of high contrast transmission imaging. Spectral analysis of the image can be used to confirm the presence of high-Z materials by analyzing the relative transmission of the two main energies emitted by exploiting the large difference in Compton Scatter and pair production cross sections. These detectors require a special approach to design and energy calibration due to the lack of resolution in order for spectral analysis to take place. This thesis addresses the design and utility of Cherenkov detectors for active interrogation with monoenergetic photons as well as the results of computational and experimental studies of their energy calibration and application to imaging with material identification.

In this thesis we have presented a thorough study on the optical and sensoristic properties of SRSN Mu-disks, in an isolated configuration and when coupled to a passive Si3N4 waveguide placed underneath. The whole structure of the device have been previously simulated in order to study the behavior of the supported WGM when subject to a geometrical variation (i.e.: radius, thickness, shape of the edge of the isolated Mu-disk): the obtained results granted the realization of Mu-resonators with Q factor exceeding 104. The coupled structure have been then simulated with the main goal of maximizing the WGM intensity transmitted at the end of the WG. This task has been fulfilled through a careful optimization of the geometrical parameters (i.e.: X-Gap and Z-Gap). The subsequent step, involving the fabrication process of the sample - realized in the Centro Nacional de Microelectronica (CNM) of Bellaterra - has been carried out using standard CMOS compatible process. The deposition and the implantation of the Si3N4 has been performed by means of LPCVD technique, while for the SiO2 deposition the PECVD. Finally the optical elements has been defined by means of a two level photolithographic mask. On the produced samples we have performed a superficial analysis (SEM, AFM) with the aim of evaluate the presence of geometrical imperfections and estimation of the superficial roughness. Furthermore the EFTEM analysis revealed the absence of Si-nc inside the active layer. Using the Cut-back technique, low losses under 1 dB/cm have been found in both VIS and IR spectral range in the passive WG of different width. On the other hand, applying the SES technique on an Si-rich WG structure we have been able to extract the losses value of active material in a wide and continuous range of wavelength, defined inside the PL spectrum. As a result of a careful optimization of the active SRSN in terms of PL intensities and optical losses, we have been able to produce bright and high Q isolated Mu-disks, achieving maximum values about 1.4x104 in a wide spectral range in the VIS and emitting up to few nW on a single resonance. The reported Q values are the best ever reported in circular Si-based light emitting Mu-cavities and are just limited by the spectral resolution of our experimental setup. The coupled structures demonstrated Q values up to 1.48x103, which are susceptible to be greatly improved through optimization of the fabrication process. Through a prof of concept , we have demonstrated that these structures are very sensible to the surrounding material and are able to detect refractive index changes with sensitivities of 51.79 nm/RIU and minimum measured refractive index change of 1.15x10-3 RIU.
En esta tesis, realizada en el departament d' Electrònica de la Universitat de Barcelona se ha presentado un estudio detallado the las propiedades ópticas y sensoras de estructuras resonantes tipo micro-disco fabricados íntegramente en nitruro de silicio enriquecido con silicio (SRSN). El estudio se ha llevado a cabo bien en estructuras aisladas o en una configuración acoplada con una guía de onda passiva situada debajo de la cavidad. La totalidad de la estructura ha sido simulada con el fin de estudiar el comportamiento de los modos resonantes WGM soportados cuando se cambian las condiciones de contorno geómetricas y del material. Los resultado obtenidos han permitido la realización de estructuras resonantes con factores de calidad superiores a 104. El objetivo de las simulaciones ha sido el de maximizar la intensidad transmitida de los modos soportados (WGM) al final de la guía de onda. Este hito ha sido cumplido gracias a la optimización de los parámetros geómetricos relativos (el X-gap y el Z-gap). Una vez producidas las muestras, se procedió a la realización de un análisis de superficie (SEM, AFM) para evaluar la rugosidad efectiva de las estructuras y las eventuales imperfecciones geométricas. Como resultado de la optimización del material activo en términos de intensidad de fotoluminiscencia y pérdidas ópticas, se consiguieron realizar cavidades resonantes de alta emisión luminosa y buenos factores de calidad. En un nuevo montaje experimental de u-PL desarrollado íntegramente para el estudio de estos dispositivos, se obtuvieron valores máximos de Q = 1.4x104 en un rango espectral ancho en el visible. La potencia emitida en cada resonancia ha sido medida y cuantificada en un valor de nW. Este valor permite la utilización de detectores de silicio integrados. Con el fin de evaluar la sensitividad del dispositivo, se han llevado a cabo medidas de u-PL cambiando el entorno del microdisco y monitorizando el desplazamiento espectral que sufre una determinada resonancia. El resultado de estas medidas muestra un desplazamiento de 1.37 nm como consecuencia de un índice de refracción de An = 0.0038 RIU (refractive index unit).

El Gran Colisionador de Hadrones (LHC) tiene previsto aumentar su luminosidad hasta siete veces su valor actual con el objetivo de ampliar su actual programa de física. Esta mejora se conoce con el nombre de High Luminosity LHC (HL-LHC) y está prevista para el año 2024-2026. El actual Inner Detector (ID) del detector de ALTAS será completamente reemplazado por uno nuevo para ajustarse a los rigurosos requisitos que impone el HL-LHC. Nuevos detectores de píxeles están siendo investigados para su utilización en todo el ID cuando el HL-LHC entre en operación. La utilización de sensores de píxeles tipo monolítico dentro del ID de ATLAS supondría una nueva era para los detectores de píxeles en física de altas energías debido a sus muchas ventajas con respecto a las tecnologías que se usan actualmente. Las principales ventajas son: mejor resolución espacial, menor densidad, mayor rendimiento, y menor coste. En este contexto, un nuevo tipo de sensor monolítico conocido como Depleted Monolithic Active Pixel Sensor on silicon-on-insulator ha sido investigado en esta tesis. El capítulo 1 describe el LHC, el experimento ATLAS, y las mejoras previstas para el HL-LHC. Este capítulo también describe los requerimientos y desafíos del futuro Inner Detector, al ser el subdetector más cercano al punto de interacción. El capítulo 2 describe la base de los detectores de partículas en física de altas energías. Este capítulo abarca la interacción de partículas con la materia, los conceptos básicos para la construcción de un detector de píxeles, y la resolución de momento transverso, vértice, y parámetro de impacto de un detector. El capítulo 3 describe los daños que la radiación produce en detectores de silicio, tanto en la electrónica como en el sensor, cuyo impacto es crucial en el rendimiento de los detectores especialmente para experimentos en el HL-LHC. El capítulo 4 revisa la evolución y tendencias en detectores de pixeles, abarcando desde los ya bien establecidos pixel híbridos, hasta los CMOS píxeles. La sección dedicada a los CMOS píxeles describe los diferentes tipos que se están considerando en ATLAS: High resistivity CMOS, high voltage CMOS, y monolíticos CMOS-on-SOI. Este ultimo compone el núcleo de estudio de esta tesis y es descrito en detalle. Los siguientes capítulos detallan el programa de caracterización y medidas realizado en el contexto de esta tesis. El capitulo 5 se centra en la caracterización del daño creado por la radiación en la electrónica hasta las dosis esperadas en el ID de ATLAS durante su operación en el HL-LHC. Las propiedades del detector, como son las corrientes de fuga, el cociente entre señal y ruido, la colección de carga y la profundidad de depleción, son descritas en el capitulo 6. El Capítulo 7 describe la caracterización de sensores monolíticos CMOS-on-SOI en un haz de piones, donde la colección de carga, el reparto de carga entre píxeles, la resolución espacial, y la eficiencia son discutidas. Este trabajo concluye con un resumen, con vistas al futuro de las tecnologías monolíticas CMOS-on-SOI en la física de altas energías.
A major upgrade of the Large Hadron Collider (LHC) called High Luminosity LHC (HL-LHC) is scheduled for 2024-2026. This will lead to an increase of the luminosity by seven times the current value and to the extension of the currently ongoing physics programme. A completely new Inner Detector for the ATLAS experiment needs to be developed to withstand the extremely harsh environment at the HL-LHC. New pixel detector concepts are being investigated as a possible candidate to the inner and outer layers of the HL-LHC ATLAS Inner Detector. The use of monolithic pixel sensors in the ATLAS Inner Tracker would lead to a new era of pixel detectors as a consequence of its many advantages with respect to the current technologies. The achievement of smaller spatial resolution, lower density, bigger production yield and throughput, and smaller budget cost are the main arguments to pursue this technology. In this context, a novel Depleted Monolithic Pixel Active Detector built on a thick film Silicon-On-Insulator has been fully investigated in this thesis. Chapter 1 introduces LHC and the ATLAS experiment as well as their foreseen scenarios at the HL-LHC upgrade. This naturally motivates the stringent requirements and challenges of the closest sub-detector to the interaction point, the Inner Detector. Chapter 2 describes the basis of a tracking detector for high energy physics applications, detailing the interactions of particles with matter to the formation of a pixel detector from a semiconductor material. Then the momentum, vertex, and impact parameter resolution of a tracking detector are calculated leading to a set of requirements for the detector design. Chapter 3 describes the radiation damage in silicon detectors whose impact to the detector performance is crucial specially for HL-LHC experiments. The radiation damage in the electronics and in the silicon bulk is treated. Chapter 4 revises the current developments and trends on pixel detectors from the well established hybrid pixel technologies to the commercial CMOS pixels. The commercial CMOS pixels section describes the current technologies being considered at ATLAS: high resistivity, high voltage CMOS (currently built as hybrid and as monolithic), and monolithic CMOS-on-SOI. The latter one composes the core of study of this thesis and is described in great detail. The final chapters are dedicated to the description of the validation programme performed to the CMOS-on-SOI technology, together with characterization methods used, measurements performed, and results analysis description. Chapter 5 focuses on the measurements performed to characterize the radiation hardness of the technology against the ionizing radiation expected in the HL-LHC ATLAS detector. The crucial charge collection properties to fulfil the ATLAS detector requirements were measured and are described in Chapter 6. These measurements include leakage current, signal-to-noise ratio, collected charge, and depletion depth on unirradiated and irradiated samples. Additionally, different techniques as radioactive sources, pion beams, and laser beams were used in order to calculate the depletion depth. Chapter 7 describes the characterization of the monolithic CMOS-on-SOI in a pion beam test. The measured charge collection, charge sharing, spatial resolution, and tracking efficiency are discussed. Within the summary, an outlook towards the future of depleted monolithic active pixel sensors on silicon-on-insulator technology for high energy physics is presented.

Thesis (M. S.)--Mechanical Engineering, Georgia Institute of Technology, 2004.
Dr. William P. King, Committee Member ; Dr. F. Levent Degertekin, Committee Member ; Dr. Thomas R. Kurfess, Committee Chair.

For designing detectors for infrequently occurring objects in wide-area satellite imagery, we are faced with the challenge that such objects are difficult to find for the purpose of generating the needed training data. As a result, a human agent must expend an inordinate length of time in order to produce a sufficient number of labeled training data. In this dissertation, we reduce this annotation burden by drawing upon the research that has been carried out recently in the area of active learning, whereby the machine searches for human annotation those unlabeled samples that can actually improve the detector. The search is iterative: Starting with a small number of human-supplied strongly positive and negative samples, our framework scans the images and tests the candidate samples against the current decision surfaces. Only those samples that are too close to the decision surfaces are sent to the human for annotation and the new samples thus labeled used to update the decision surfaces. We have applied this framework to create detectors for pedestrian crosswalks and transmission-line towers in a cloud-based implementation in areas of over 150,000 sq km in Australia. We should also mention that a stepping stone to this work was our earlier, more direct approach to detector design in which the class discrimination features are specified by the human. This approach, which was also an exercise in exploiting volunteer-generated road maps for detecting objects that are on or along the roads, was used to create a crosswalk detector and applied to a 180,000 sq km area in Australia.

Thesis (M. Phil.)--Hong Kong University of Science and Technology, 2003.
Includes bibliographical references (leaves 67-69). Also available in electronic version. Access restricted to campus users.

ALICE (A Large Ion Collider Experiment) is a general-purpose, heavy-ion detector at the CERN LHC designed to study the physics of strongly interacting matter, and in particular the properties of the Quark-Gluon Plasma (QGP), using Pb-Pb collisions at unprecedented energy densities. During the first three years of operation, it has demonstrated very good capabilities for measurements at high energy Pb-Pb collisions. But there are certain measurements like high precision measurements of rare probes over a wide range of momenta, which would require high statistics and are not satisfactory or even possible with the current experimental setup. These measurements would help to achieve the long term physics goals of ALICE and would go a long way forward in understanding and characterizing the Quark Gluon Plasma (QGP). To enhance its physics capabilities, ALICE has formulated an upgrade of its detectors, motivated by an upgrade of the LHC during the LHC Long Shutdown 2 (2018-2020). The LHC upgrade features which primarily motivated the ALICE upgrade programme are, in particular, Pb-Pb collisions with a high interaction rate of up to 50 kHz corresponding to an instantaneous luminosity, L = 6 × 1027cm−2s−1 and, the installation of a narrower beam pipe. Accordingly, ALICE would require detector upgrades to cope with the upgrade scenario. These upgrades should help to improve tracking and vertexing capabilities, radiation hardness and allow readout of all interactions to accumulate enough statistics for the upgrade physics programme. The objective is to accumulate 10 nb−1 of Pb–Pb collisions, recording about 1011 interactions. Within this upgrade strategy, the Inner Tracking System (ITS) upgrade forms an important cornerstone, providing improved vertexing and readout capabilities. The new ITS will have a barrel geometry consisting of seven layers of Monolithic Active Pixel Sensors (MAPS) with high granularity which would cater to the material budget, readout and radiation hardness requirements for the upgrade. The geometry is optimized for high efficiency, both in standalone tracking and ITS-TPC combined tracking. TowerJazz 0.18 μm technology is selected for designing the pixels for ITS upgrade. This technology provides attractive features like the option to implement a deep pwell allowing the implementation of a full CMOS process in the pixel. The ongoing research and development on these pixels investigates different design strategies and would converge towards the final design of the detector by the end of 2014. Several prototypes have been designed to investigate and validate the different design strategies and the different components of the pixel detector using this technology. The work presented in this thesis can be categorized in two parts. The first part concerns the results of characterization of some of the pixel prototype circuits developed for the ITS upgrade, in particular MIMOSA32, MIMOSA32Ter and Explorer-1. The second part discusses the detector performance studies of the upgraded ITS. MIMOSA32 and MIMOSA32Ter were one of the first prototypes designed with the TowerJazz technology in the upgrade programme. The motivation was to validate the technology. This thesis includes the results of tests and characterization of pixel structures of these prototypes and qualifies the technology in terms of charge collection and radiation tolerance and the usage of the deep p-well structure. This provides a starting point for future prototypes where the deep p-well could be implemented in a full CMOS process, thus allowing in-pixel sophisticated signal processing circuits. The Explorer prototypes are developed at CERN with the main motivation towards developing a detector with low power density, lower than the maximum permissible limits for the upgrade programme. This would provide a margin to reduce the material budget of the detection layers, improving the detector performance. The Explorer prototypes are designed to study the ratio of the collected charge to the input capacitance (Q/C), in particular, its dependence on the size of the collection diode and its distance to the adjacent p-well of the input transistors. The Explorer prototypes allows the application of a back-bias voltage which has an effect on the signal collection properties. In a pixel detector, improvement of the Q/C ratio enhances the signal amplitude at the collection node of the pixel circuit which is connected to the analog frontend. This would help in optimizing the analog frontend to improve the signal to noise ratio of the detector, which has a direct consequence in minimizing the power consumption of the detector. This thesis includes the test and characterization of Explorer-1 prototype circuits with different starting materials. The results show that Q/C improves with higher back bias voltage and increased spacing between the collection electrode and the adjacent p-well. With these results, the future prototypes of Explorer could concentrate on Optimizing the size of the input transistors to study its effects on the Random Telegraph Signal noise. In parallel, optimization of the signal processing circuits would also be carried out in other prototypes. The second part of the thesis studies the performance of a baseline configuration of the upgraded detector in terms of impact parameter resolution, momentum resolution and tracking efficiency both in standalone tracking mode and ITS-TPC combined tracking. The performance is compared with the current ITS to study the improvements in the upgraded ITS. The performance is affected by the radial position and material budget of the layers and the detector intrinsic resolution. The detector specifications in this regard are still evolving specially for the Outer Barrel (the outermost four layers). The studies show the effects of variation of the specifications in terms of material budget and intrinsic resolution on the detector performance. This would help to finalize the detector specifications for an optimized detector performance. The thesis also concludes that a reduction in the beam pipe radius (lower than the baseline upgrade scenario) would not affect detector performance but may facilitate the installation of the Inner Barrel. Redundancy studies show that the presence of a dead layer can degrade the detector performance significantly. This defines a key requirement of easy and rapid accessibility to the detector in the design of the upgraded ITS. The ITS upgrade timeline foresees the finalization of the final pixel architecture in late 2014. Mass production of the final circuit is planned for 2015. The construction of the detector modules, tests, assembling and pre-commissioning will be carried out throughout 2016-2017 followed by the installation of the detector in the ALICE cavern in 2018.

ALICE (A Large Ion Collider Experiment) is the heavy-ion experiment at the Large Hadron Collider (LHC) at CERN. As an important part of its upgrade plans, the ALICE experiment will schedule the installation of a new Inner Tracking System (ITS) during the Long Shutdown 2 (LS2) of the LHC. The new ITS layout will consist of seven concentric layers, ¿ 12.5 Gigapixel camera covering about 10m2 with Monolithic Active Pixel Sensors (MAPS). This choice of technology has been guided by the tight requirements on the material budget of 0.3% X/X0 per layer for the three innermost layers and backed by the significant progress in the field of MAPS in recent years. The technology initially chosen for the ITS upgrade is the TowerJazz 180 nm CMOS Technology. It offers a standard epitaxial layer of 15 - 18 µm with a resistivity between 1 and 5 k¿ cm¿1 and a gate oxide thickness below 4 nm, thus being more robust to Total Ionizing Dose (TID). The main subject of this thesis is to implement a novel digital pixel readout architecture for MAPS. This thesis aims to study this novel readout architecture as an alternative to the rolling-shutter readout. However, this must be investigated through the study of several chip readout architectures during the R&D phase. Another objective of this thesis is the study and characterization of TowerJazz, if it meets the Non-Ionizing Energy Loss (NIEL) and Single Event Effects (SEE) of the ALICE ITS upgrade program. Other goals of this thesis are: ¿ Implementation of the top-down flow for this CMOS process and the design of multiple readouts for different prototypes up to the assembly of a full-scale prototype. xvii Abstract ¿ Characterization of the radiation hardness and SEE of the chips submitted to fabrication. ¿ Characterization of full custom designs using analog simulations and the generation of digital models for the simulation chain needed for the verification process. ¿ Implementation and study of different digital readouts to meet the ITS upgrade program in integration time, pixel size and power consumption, from the conceptual idea, production and fabrication phase. Chapter 1 is a brief overview of CERN, the LHC and the detectors complex. The ALICE ITS will be explained, focusing on the ITS upgrade in terms of detector needs and design constraints. Chapter 2 explains the properties of silicon detectors and the detector material and the principles of operation for MAPS. Chapters 3 and 4 describe the ALPIDE prototypes and their readout based on MAPS; this forms the central part of this work, including the multiple families of pixel detectors fabricated in order to reach the final design for the ITS. The ALPIDE3/pALPIDE3B chip, the latest MAPS chip designed, will be explained in detail, as well focusing in the matrix digital readout. In chapter 5 the noise measurements and its characterization are presented including a brief summary of detector response to irradiation with soft X-rays, sources and particle beams.
El sub detector ITS (Inner Tracking System) del detector ALICE (A Large Ion Collider Experiment) es un detector de vértice y es el detector mas cercano al punto de interacción. Se encuentra conformado por 3 tipos de subdetectores, dos capas de pixel de silicio (Silicon Pixel Detectors), 2 capas de acumulación de silicio (Silicon Drift Detectors) y 2 capas de banda de Silicio (Silicon Strip Detectors). La función primaria del ITS es identificar y rastrear las partículas de bajo momentum transversal. El detector ITS en sus dos capas más internas están equipadas con sensores de silicio basados en píxeles híbridos. Para reemplazar esta tecnología de Píxeles, el detector ITS actual será reemplazado por un nuevo detector de una sola tecnología, ampliando su resolución espacial y mejorando el rastreo de trazas. Este nuevo detector constará de siete capas de sensores de píxeles activos monolíticos (MAPS), las cuales deberán satisfacer los requerimientos de presupuesto de materiales y ser tolerantes a mayores niveles de radiación para los nuevos escenarios de incrementos de luminosidad y mayores tasas de colisiones. Los sensores MAPS que integran el sensor de imagen y los circuitos de lectura se encuentran en la misma oblea de silicio, tienen grandes ventajas en una buena resolución de posición y un bajo presupuesto material en términos de bajo coste de producción. TowerJazz ofrece la posibilidad de una cuádruple-WELL aislando los transistores pMOS que se encuentran en la misma nWELL evitando la competencia con el electrodo de recolección, permitiendo circuitos mas complejos y compactos para ser implementados dentro de la zona activa y además posee una capa epitaxial de alta resistividad. Esta tecnología proporciona una puerta de óxido muy delgado limitando el daño superficial por la radiación haciéndolo adecuado para su uso denxiii Resúmen tro del experimento ALICE. En los últimos cuatro años se ha llevado a cabo una intensiva I+D en MAPS en el marco de la actualización del ITS de ALICE. Varios prototipos a pequeña escala se han desarrollado y probado exitosamente con rayos X, fuentes radioactivas y haces de partículas. La tolerancia a la radiación de ALICE ITS es moderada con una tolerancia de irradiación TID de 700 krad y NIEL de 1 × 1013 1 MeV neqcm¿2 , MAPS es una opción viable para la actualización del ITS. La contribución original de esta tesis es la implementación de una nueva arquitectura digital de lectura de píxeles para MAPS. Esta tesis presenta un codificador asíncrono de direcciones (arquitectura basada en la supresión de ceros transmitiendo la dirección de los píxeles excitados denominada PADRE) para la arquitectura ALPIDE, el autor también hizo una contribución significativa en el ensamblaje y veri- ficación de circuitos. PADRE es la principal investigación del autor, basada en un codificador de prioridad jerárquica de cuatro entradas y es una alternativa a la arquitectura de lectura rolling-shutter. Además de los prototipos a pequeña escala, también se han desarrollado prototipos a escala completa a las necesidades del detector ITS (15 mm y 30 mm) empleando un nuevo circuito de lectura basado en la versión personalizada del circuito PADRE. El pALPIDEfs fue el primer prototipo a escala completa y se caracterizó obteniendo un tiempo de lectura de la matriz por debajo de 4 µs y un consumo de energía en el orden de 80 mWcm¿2 . En general, los resultados obtenidos representan un avance significativo de la tecnología MAPS en cuanto al consumo de energía, velocidad de lectura, tiempo de recolección de carga y tolerancia a la radiación. El sensor pALPIDE2 ha demostrado ser una opción muy atractiva para el nuevo detector ITS, satisfaciendo los requerimientos en términos de eficiencia de detección, fake-hit rate y resolución de posición, ya que su rendimiento no puede alcanzarse mediante prototipos basados en la arquitectura de lectura tradicionales como es
El subdetector ITS (Inner Tracking System) del detector ALICE (A Large Ion Collider Experiment) és un detector de vèrtex i és el detector mes proper al punt d'interacció. Es troba conformat per 3 tipus de subdetectors, dues capes de píxel de silici (Silicon Pixel Detectors), 2 capes d'acumulació de silici (Silicon Drift Detectors) i 2 capes de banda de Silici (Silicon Strip Detectors). La funció primària del ITS és identificar i rastrejar les partícules de baix moment transversal. El detector ITS en les seues dues capes més internes estan equipades amb sensors de silici basats en píxels híbrids. Per a reemplaçar aquesta tecnologia de Píxels, el detector ITS actual serà reemplaçat per un nou detector d'una sola tecnologia, ampliant la seua resolució espacial i millorant el rastreig de traces. Aquest nou detector constarà de set capes de sensors de píxels actius monolítics (MAPS), les quals hauran de satisfer els requeriments de pressupost de materials i ser tolerants a majors nivells de radiació per als nous escenaris d'increments de lluminositat i majors taxes de col·lisions. Els sensors MAPS que integren el sensor d'imatge i els circuits de lectura es troben en la mateixa hòstia de silici, tenen grans avantatges en una bona resolució de posició i un baix pressupost material en termes de baix cost de producció. TowerJazz ofereix la possibilitat d'una quàdruple-WELL aïllant els transistors pMOS que es troben en la mateixa nWELL evitant la competència amb l'elèctrode de recol·lecció, permetent circuits mes complexos i compactes per a ser implementats dins de la zona activa i a més posseeix una capa epitaxial d'alta resistivitat. Aquesta tecnologia proporciona una porta d'òxid molt prim limitant el dany superficial per la radiació fent-ho adequat per al seu ús dins de l'- experiment ALICE. En els últims quatre anys s'ha dut a terme una intensiva R+D en MAPS en el marc de l'actualització del ITS d'ALICE. Diversos prototips a petita escala s'han desenvolupat i provat ix Resum reeixidament amb rajos X, fonts radioactives i feixos de partícules. La tolerància a la radiació d'ALICE ITS és moderada amb una tolerància d'irradiació TID de 700 krad i NIEL d'1× 1013 1MeV neqcm¿2 , MAPS és una opció viable per a l'actualització del ITS. La contribució original d'aquesta tesi és la implementació d'una nova arquitectura digital de lectura de píxels per a MAPS. Aquesta tesi presenta un codificador asíncron d'adreces (arquitectura basada en la supressió de zeros transmetent l'adreça dels píxels excitats denominada PADRE) per a l'arquitectura ALPIDE, l'autor també va fer una contribució significativa en l'assemblatge i verificació de circuits. PADRE és la principal recerca de l'autor, basada en un codificador de prioritat jeràrquica de quatre entrades i és una alternativa a l'arquitectura de lectura rolling-shutter. A més dels prototips a petita escala, també s'han desenvolupat prototips a escala completa a les necessitats del detector ITS (15 mm i 30 mm) emprant un nou circuit de lectura basat en la versió personalitzada del circuit PADRE. El pALPIDEfs va ser el primer prototip a escala completa i es va caracteritzar obtenint un temps de lectura de la matriu per sota de 4 µs i un consum d'energia en l'ordre de 80 mWcm¿2 . En general, els resultats obtinguts representen un avanç significatiu de la tecnologia MAPS quant al consum d'energia, velocitat de lectura, temps de recol·lecció de càrrega i tolerància a la radiació. El sensor pALPIDE2 ha demostrat ser una opció molt atractiva per al nou detector ITS, satisfent els requeriments en termes d'eficiència de detecció, fake-hit rate i resolució de posició, ja que el seu rendiment no pot aconseguir-se mitjançant prototips basats en l'arquitectura de lectura tradicionals com és el rolling-shutter dissenyat en la mateixa tecnologia. Per aquesta raó, la R+D en els prototips ALPIDE ha continuat amb l'objectiu d'optimitza
Marín Tobón, CA. (2017). PADRE pixel read-out architecture for Monolithic Active Pixel Sensor for the new ALICE Inner Tracking System in TowerJazz 180 nm technolog [Tesis doctoral no publicada]. Universitat Politècnica de València. https://doi.org/10.4995/Thesis/10251/86154
TESIS

The U.S. construction industry continues to rank as one of the most dangerous work environments when compared to other industrial sectors. Construction companies are required to record and report lagging safety leading indicators including fatalities, injuries, and illnesses. Safety leading indicators provide an opportunity to identify construction site hazards and hazardous worker behavior before a fatality, injury, or illness occurs. Further improvements are also necessary for construction safety through the use of technology. The application of advanced or emerging technologies can have a significant role in enhancing construction worker safety performance. This research seeks to report and analyze safety leading indicators, specifically near misses. Furthermore, technologies capable of providing alerts in real-time to construction equipment operators and ground workers during hazardous proximity situations are reviewed. A testing method for proximity detection and alert devices for the construction environment is presented. Operator visibility, including impacts of design components, is also measured and analyzed. One major contribution of this research is the creation of a near miss reporting program ready for implementation for construction companies. Other research contributions include understanding of impacts of design on operator visibility, scientific evaluation data of proximity sensing technology, and a test method for proximity detection and alert system deployed in the construction environment. Research findings can be disseminated for improved construction worker safety education and training.

This thesis work fits in the Newtonian noise (NN) cancellation framework for gravitational-wave (GW) detectors of 2nd and 3rd generation. At frequencies below 20 Hz the NN affects GW detectors by generating gravity gradients that mask the GW signals that we want to measure. My work can be divided in three main tasks: the optimization of a seismic array for the NN cancellation in underground detectors, the optimization of a seismic array for Advanced Virgo + (which, respect to the former one, relied on seismic measurements and not on a seismic model) and the evaluation of the NN and the seismic field at the KAGRA site. I will briefly summarize in the following the main results of these three works. In the first work I performed a global optimization for finding the optimal locations of an array of sensors for the NN cancellation for underground detectors. Since we need to search for the optimal positions of N sensors in a 3D space, the computational efforts required are very demanding. At the present time, seismic correlations in the relevant frequency band for ET from 3Hz to 20Hz are not available. So we modelled the seismic field as isotropic and homogeneous. With this work I was able to assess the feasibility of applying active NN reduction in underground detectors and reaching a factor 10 of noise reduction with 15 sensors at 10 Hz. In 2019 this work was published. The second work I made during my PhD was conceptually similar to the previous one but very different in the approach used to solve it. Exploiting a theoretical model in Virgo was not an option given its complicated structure. I then used Virgo's seismic data to run the optimization of sensor locations. The main challenge here was that I had to perform a gaussian process regression over a 4D space, and not enough data were available for this purpose. I found a way to bypass the regression over the 4D space by exploiting the convolution theorem. This allowed me to perform the regression over a space with reduced dimension, i.e., in 2D. The global optimization algorithm was then run hundreds of times in order to statistically prove the global minimum, exactly as done in the work for the underground optimization. The results proved that with 15 seismometers we can reach a noise reduction factor of 3-7, which is enough for the aimed sensitivity of the next observing runs. The results of this work were then used to set the array that will be used to cancel the NN in Advanced Virgo +. This work has been published in 2020. This approach could also be useful in future, where it will be needed to optimize underground seismic arrays with real seismic data. Finally, in the third work I used seismic data collected in the Kamioka mine (where the gravitational-wave detector KAGRA is hosted) to investigate the seismic noise caused by the infrastructure and to calculate a NN budget. These are important aspects that need to be investigated in view of the 3rd generation GW detector Einstein Telescope. The data indicated that the infrastructure noise starts to be important well above 10 Hz, where the NN loses its impact on the detector and where the seismic isolation system is capable of killing the noise. Moreover, I used the data from three seismometers to perform a beamforming analysis and find the seismic velocities and the seismic wave main directions. The extracted values were then used as a reference for the estimation of the NN budget. For completeness, I also estimated the NN budget coming from surface Rayleigh waves. This was made by exploiting the data of the F-net network, in Japan. I then showed that the NN from surface and body waves can be neglected for KAGRA.

A very fascinating region for investigating the origins of cosmic rays is the toe of the ultra-high energy cosmic ray (UHECR) spectrum, above ≈ 50 EeV. The potential for small magnetic deflections at these energies is coupled with the presence of flux suppression, which may be a sign of the sources’ maximum acceleration potential or may have an explanation for the interactions of cosmic rays with background photons, effectively restricting the region of interest in the search for UHECR sources to a relatively small bubble around us. In this thesis, I present the latest dataset of cosmic rays at the highest energies collected by the Pierre Auger Observatory, the largest experiment dedicated to UHECR science ever built, and the anisotropy searches carried out using it. I have carried out blind, model-independent searches for overdensities, astrophysical structural correlation analysis, and cross-correlation investigations with catalogs of candidate sources. For UHECRs with energy greater than 38 EeV, the results show evidence of a deviation from isotropy at an angular scale of ≈ 25◦ at the 4σ level. Additionally in this thesis for the first time, I present the possibility of using ancient minerals as paleo-detectors to study the history of the flux of cosmic rays in the past by detecting the tracks left in the mineral structure by the interactions between ions and energetic secondary cosmic rays present in the extensive airshowers.

The ALICE experiment at CERN has planned an upgrade of the Inner Tracking System (ITS), named ITS3, for the LHC Long Shutdown 3, in 2025. The cornerstone of the upgrade is a new CMOS pixel sensor built in 65 nm technology and in bent-cylindrical configuration, replacing the inner layers of the existing detector, the ITS2. The ITS3 will reach much better tracking and vertexing performance, thanks to the improved spatial resolution and the much reduced material budget with respect to the previous Inner Tracking System. The aim of this thesis is to report on the analysis of the data collected at beam tests on new ALPIDE chips (used for ITS2, based on Monolithic Active Pixel Sensor, MAPS) which have been bent in a cylindrical configuration as foreseen for the ITS3. This is the first bending proof of concept for a silicon detector. In particular, data from beam test taken in 2020 have been studied through a data analysis framework that I have personally written to accomplish this task; the complexity of the data analysis is driven by the fact that each ALPIDE chip has a total of 1024x512 pixel MAPS and by the bent geometry of the sensor. In this thesis, the promising performances obtained by studying the sensor total efficiency and spatial resolution in different experimental configurations will be presented and discussed.

High-temperature piezoelectric wafer active sensors (HT-PWAS) have been developed for structure health monitoring at hazard environments for decades. Different candidates have previously been tested under 270 °C and a new piezoelectric material langasite (LGS) was chosen here for a pilot study up to 700 °C. A preliminary study was performed to develop a high temperature sensor that utilizes langasite material. The Electromechanical impedance (E/M) method was chosen to detect the piezoelectric property. Experiments that verify the basic piezoelectric property of LGS at high temperature environments were carried out. Further validations were conducted by testing structures with attached LGS sensors at elevated temperature. Additionally, a detection system simulating the working process of LGS monitoring system was developed with PZT material at room temperature. This thesis, for the first time, (to the best of author’s knowledge) presents that langasite is ideal for making piezoelectric wafer active sensors for high temperature structure health monitoring applications.

For the X-ray astronomy project Advanced Telescope for High ENergy Astrophysics (Athena) wafer-scale DEpleted P-channel Field Effect Transistor (DEPFET) detectors are proposed as Focal Plane Array (FPA) for the Wide Field Imager (WFI). Prototype structures with different pixel layouts, each consisting of 64 x 64 pixels, were fabricated to study four different DEPFET designs. This thesis reports on the results of the electrical and spectroscopic characterization of the different DEPFET designs. With the electrical qualification measurements the transistor properties of the DEPFET structures are investigated in order to determine whether the design intentions are reflected in the transistor characteristics. In addition, yield and homogeneity of the prototypes can be studied on die, wafer and batch level for further improvement of the production technology with regard to wafer-scale devices. These electrical characterization measurements prove to be a reliable tool to preselect the best detector dies for further integration into full detector systems. The spectroscopic measurements test the dynamic behavior of the designs as well as their spectroscopic performance. In addition, it is revealed how the transistor behavior translates into the detector performance. This thesis, as the first systematic study of different DEPFET designs on die and detector level, shows the limitations of the current DEPFET assessment methods. Thus, it suggests a new concise characterization procedure for DEPFET detectors as well as guidelines for expanded testing in order to increase the general knowledge of the DEPFET. With this study of four different DEPFET variants not only designs suitable for Athena mission have been found but also improvement impulses for the starting wafer-scale device production are provided.

Space radiation exposure to astronauts will need to be carefully monitored on future missions beyond low earth orbit. NASA has proposed an updated radiation risk framework that takes into account a significant amount of radiobiological and heavy ion track structure information. These models require active radiation detection systems to measure the energy and ion charge Z.

However, current radiation detection systems cannot meet these demands. The aim of this study was to investigate several topics that will help next generation detection systems meet the NASA objectives. Specifically, this work investigates the required spatial resolution to avoid coincident events in a detector, the effects of energy straggling and conversion of dose from silicon to water, and methods for ion identification (Z) using machine learning.

The main results of this dissertation are as follows: 1. Spatial resolution on the order of 0.1 cm is required for active space radiation detectors to have high confidence in identifying individual particles, i.e., to eliminate coincident events. 2. Energy resolution of a detector system will be limited by energy straggling effects and the conversion of dose in silicon to dose in biological tissue (water). 3. Machine learning methods show strong promise for identification of ion charge (Z) with simple detector designs.

Les applications de détection infrarouge active sont nombreuses dans le domaine de la défense et la sécurité. Cependant ces systèmes sont actuellement peu utilisés en pratique à cause de leur portée limitée. Un moyen d’augmenter cette portée est d’améliorer la sensibilité des détecteurs infrarouges qui possèdent des bruits bien plus élevés que leurs équivalents dans le visible. L’idée principale de cette thèse est d’utiliser l’optique non linéaire pour effectuer une conversion de fréquence du signal infrarouge à détecter vers de plus basses longueurs d’ondes et ainsi bénéficier des performances des détecteurs fonctionnants à ces longueurs d’ondes. Les développements récents en cristaux donnent un intérêt nouveau à ces techniques pour certains cas applicatifs identifiés au cours de cette thèse. L’étude détaillée de la conversion multimode à la fois temporelle et spatiale, a permis de proposer une méthode simple et originale pour dépasser l’état de l’art en terme de nombre d’éléments résolus convertis. Pour quantifier précisément les avantages de ces conversions, une étude théorique et numérique de la conversion multimode a été menée et deux séries d’expériences ont été conduites. La première concerne la détection ponctuelle de signaux moyen-infrarouge pour des applications de spectroscopie par conversion dans un cristal d’OP-GaAs. La deuxième concerne la détection de cibles par imagerie active dans le proche infrarouge par conversion dans un cristal de PPLN vers une caméra CMOS. Les performances en sensibilité obtenues sont dans les deux expériences meilleures d’un ordre de grandeur que les détections directes avec les détecteurs habituellement utilisés
There is a wide range of applications in active infrared detection technologies in defense and security. However, the limited range available by these systems limits their developments. Increasing sensors sensitivity is a key milestone to improve this range. Indeed, noise in infrared detectors is much higher than for visible detectors due to some physical and technological issues. The key idea of this manuscript is to use nonlinear optical technologies to convert the infrared signal to detect into the visible spectrum and use all the benefits of silicon based sensors. Recent advances in optical crystals and in pump laser regimes bring renewed interest to upconversion detection for some specific application cases identified in this thesis. A novel and easy method to improve the number of converted modes has been proposed after a careful study of multimode conversion both temporally and spatially. In order to give figures on detection improvement using upconversion, we conducted a theoretical and numerical study of the multimode conversion as well as two sets of experiments. The first one, using conversion in an OP-GaAs crystal and a monodetector addresses mid-infrared spectroscopy applications. The second one addresses active imaging applications for target recognition and identification in the near-infrared. By using a PPLN crystal, the near-infrared image is detected on a low noise CMOS camera. A key milestone of this work is the sensitivity improvement of such a detection. Sensitivities obtained in each experiment are one order of magnitude better than with direct detection using common infrared sensors

This work deals with methods of segmentation of biomedical image signals. It describes, sums up and compares representative methods of digital image processing. Segmentation based on parametric representation is one of the mentioned methods. So as the basic parameter can be chosen for example luminance and the final binary image is obtained by thresholding. Next described method is segmentation based on edge representation. This method can be divided into edge detection by the help of edge detectors and of Hough transformation. Edge detectors work with the first and second derivation. The following method is region-based segmentation, which can be used for a image with noise. This category can be divided into three parts. The first one is segmentation via splitting and merging regions, when the image is split and the created regions are tested on a defined condition. If the condition is satisfied, the region merges and doesn’t continue splitting. The second one is region growing segmentation, when adjacent pixels with a similar intensity of luminance are grouped together and create a segmentated region. Third one is watershed segmentation algorithm based on the idea of water diffusion on uneven surface. The last group of methods is segmentation via flexible and active contours. Here is described an active shape model proceeding from a possibility to deform models so that they match with sample shapes. Next I also describe method Snakes, where occurs gradual contour shaping up to the edge of the object in the image. For the final editing is used mathematical morphology of segmentated images. I aimed to meet methods of image signals segmentation, to cover the chosen methods as a script in programming language Matlab and to check their properties on images.

Les travaux de recherche de cette thèse portent sur deux parties: l'évaluation de l'auto-absorption des rayonnements gamma et l'étude de la fonction de réponse des capteurs à pixels actifs pour la dosimétrie en temps réel. Dans le processus d'analyse quantitative de la radioactivité par spectrométrie gamma, l'étalonnage en rendement de détection de la chaîne est une étape essentielle. Outre le problème des interférences, l'atténuation des photons dans l'échantillon et l'effet de sommation en cas de cascade de transitions gamma sont les deux principaux facteurs déterminants dans ce type d'analyse. Dans ce contexte des mesures expérimentales et des calculs de simulation Monte Carlo, ont été réalisés pour étudier le phénomène de la self-absorption et évaluer les effets de matrice dans le cas des échantillons volumineux. Cette étude a permis de corriger les analyses par spectrométrie gamma des phosphates marocains. La deuxième partie de la thèse consiste à appliquer des capteurs CMOS de type MIMOSA, dérivés de ceux développés par l'IReS et le LEPSI pour la physique des particules, à la détection de rayonnements de neutrons et alpha, pour en faire des dosimètres léectroniques impulsionnels personnels. Ces appareils doivent permettre de suivre en temps réel les concentations du radon dans des environnements variés. Des codes ont été élaborés pour l'acquisition et l'analyse des données enregistrées par un système conçu pour cette application. Des tests ont été effectués pour la détection du radon et descendants émanant d'une source de Radium. Les résultats de ces tests ont été comparés aux mesures obtenues par d'autres techniques passives et actives. Des calculs de simulation Monte Carlo de la fonction de réponse du système aux neutrons rapides à l'aide du code MCNP ont été effectués.

This thesis presents the practical and novel work in the area of optimal placement of actuators and sensors for sound-structure interaction systems. The work has been done by the author during his PhD candidature. The research is concentrated in systems with non-ideal boundary conditions as in the case in practical engineering applications. An experimental acoustic cavity with five walls of timber and a thin aluminium sheet fixed tightly on the cavity mouth is chosen in this thesis as a good representation of general sound-structure interaction systems. The sheet is intentionally so fixed that it does not satisfy ideal boundary conditions. The existing methods for obtaining optimal sensor-actuator location using analytic models with ideal boundary conditions are of limited use for such problem with non-ideal boundary conditions. The method presented in this thesis for optimal placement of actuators and sensors is motivated by energy based approach and model uncertainty inclusion. The optimal placement of actuator and sensor for the experimental acoustic cavity is used to construct a robust feedback controller based on minimax LQG control design method. The controller is aimed to reduce acoustic potential energy in the cavity. This energy is due to the structure-borne sound inside the sound-structure interaction system. Practical aspects of the method for optimal placement of actuator and sensors are highlighted by experimental vibration and acoustic noise attenuation for arbitrary disturbance using feedback controllers with optimal placement of actuator and sensor. The disturbance is experimentally set to enter the system via a spatial location different from the controller input as would be in any practical applications of standard feedback disturbance rejections. Experimental demonstration of the novel methods presented in this thesis attenuate structural vibration up to 13 dB and acoustic noise up to 5 dB for broadband frequency range of interest. This attenuation is achieved without the explicit knowledge of the model of the disturbance.

Seating is an integral part of work environment. When people are at work, they often sit in chairs for long periods of time without changing postures. This results in reduced blood circulation in the body, especially in the buttock-thigh area causing muscle fatigue, pain and discomfort. Ergonomically designed task chairs adopt a passive approach to guiding people into better postures by providing adjustability inside the chair. However most people do not adjust their chairs because they fail to sense the need for changing posture. They are left to sensing the need to change posture through guesswork or extreme discomfort. This thesis proposes a new system to address this problem by sensing static posture in a seated person with the use of electronic sensors embedded in the seat, and by providing interactive feedback to static posture via sound, light and tactile channels. The new technology is an sensing-feedback mechanism embedded in a chair, that allows people to receive postural information and make body adjustments periodically to avoid pain and discomfort caused by prolonged seating.The feedback mechanism was tested with four subjects to determine its efficacy in generating posture change through pressure relief and user feedback was gathered in order to design the final prototype.

L'IRM-LINAC est un appareil de radiothérapie guidée par l'imagerie combinant un accélérateur linéaire (LINAC) et un imageur par résonance magnétique (IRM), permettant un meilleur suivi de la tumeur. Des problématiques dosimétriques, associées à la présence du champ magnétique statique, ont été soulevées dans la littérature. L'objectif de la thèse est de développer des outils dosimétriques et des protocoles robustes utilisables sur les IRM-LINAC afin d'améliorer la connaissance des doses délivrées aux patients traités avec ces appareils. La première partie du travail se concentre sur la détermination des facteurs d'ouverture du collimateur (FOC) en petits champs sur cet appareil et sur l'étude de la réponse des détecteurs. Comme aucune variation significative de réponse n'a été observée pour des films EBT3 exposés à différentes durées en présence du champ magnétique (0,35 T), ce détecteur 2D à haute résolution a été utilisé pour réaliser plusieurs séries de mesures de FOC sur un IRM-LINAC MRidian qui ont ensuite été comparées aux mesures par détecteurs actifs (chambres d'ionisation, diodes, microdiamant) ainsi qu'aux données du TPS. Un bon accord est observé entre les FOC mesurés et ceux calculés par le TPS pour les tailles de champ supérieures ou égales à 2,5x2,5 cm², une sous-estimation du FOC TPS est observée pour les tailles de champ inférieures (champ 0,83x0,83 cm² : 6% pour les films, et 4% en moyenne pour les détecteurs actifs solides). Après application des facteurs correctifs du TRS483, les mesures par détecteurs actifs convergent vers celles obtenues avec les films. Ces écarts avec le TPS tendent à suggérer la nécessité d'un ajustement plus robuste de l'algorithme du TPS pour les petits champs. Les mesures sont complétées par des simulations Monte-Carlo réalisées avec le code Geant4 pour établir des facteurs correctifs en présence d'un champ magnétique pour les détecteurs actifs. La seconde partie porte sur la faisabilité de lecture par IRM de gels dosimétriques TruView (ModusQA), fabriqués au laboratoire, pour évaluer des distributions de dose. Ces gels caractérisés par lecture IRM (mesure du temps de relaxation T2), ont montré une linéarité de la réponse en dose jusqu'à 7 Gy ainsi qu'une sensibilité faible comparativement à la littérature. Une sensibilité thermique importante et une inhomogénéité du gel entre la surface du gel et le gel situé plus en profondeur ont été observées pour des gels non-irradiés, et des protocoles ont été mis en place pour s'en affranchir. La faisabilité d'utilisation de gels dosimétriques pour la réalisation de contrôle qualité patient sur l'IRM-Linac a été démontrée, une amélioration de la sensibilité du gel est nécessaire afin d'obtenir une dosimétrie fiable avec ce protocole
MR-LINAC are radiotherapy devices that combine a linear accelerator (LINAC) and a magnetic resonance imager (MRI), allowing an improved tumor tracking. Dosimetric issues associated with the presence of the static magnetic field have been discussed in the literature. The aim of this thesis is to develop dosimetric tools and robust protocols for use on MRI-LINACs to enhance the knowledge of the doses delivered to patients treated with these devices. The first part of the work focuses on determining output factors (OF) in small fields on this device and studying detectors' responses. No significant variation in response was observed for EBT3 films exposed to different durations in the presence of the magnetic field (0.35 T). This high-resolution 2D detector was then used to perform several series of OF measurements on an MRidian MR-LINAC, which were then compared with measurements using active detectors (ionization chambers, diodes, microdiamond) as well as with data from the treatment planning system (TPS). A good agreement was observed between the measured OF and those calculated by the TPS for field sizes larger than or equal to 2.5x2.5 cm²; an underestimation of the TPS OF was observed for smaller field sizes (0.83x0.83 cm²: 6% for films and f 4% on average for solid active detectors). After applying TRS483 correction factors, measurements with active detectors converge with those obtained with films. These discrepancies with the TPS suggest the need for a more robust adjustment of the TPS algorithm for small fields. Measurements were complemented by Monte Carlo simulations using the Geant4 code to establish correction factors in the presence of a magnetic field for active detectors. The second part focuses on the feasibility of MRI reading of TruView dosimetric gels (ModusQA) manufactured in the laboratory to evaluate dose distributions. These gels, characterized by MRI reading (measuring T2 relaxation time), exhibited a dose-response linearity up to 7 Gy, along with relatively low sensitivity compared to the literature. Significant thermal sensitivity and gel inhomogeneity between the gel surface and deeper layers were observed in non-irradiated gels, and protocols were implemented to address these issues. The feasibility of using dosimetric gels for patient quality control in MR-Linac has been demonstrated, but an enhancement of gel sensitivity is required to achieve reliable dosimetry with this protocol

L'astronomie des rayons g de haute (E > 100MeV, HE) et de très haute énergie (E 100GeV, VHE) ont effectué des progrès considérables en moins d'une décennie. Le nombre de sources émettrices dans ce régime d'énergie a augmenté de plus d'un ordre de grandeur, de nouvelles classes d'émetteurs ont été découvertes et des nouvelles sous-classes ont été établies basées sur l'émission gamma, et les sources connues sont à présent résolues à des échelles spatiales ou temporelles sans précédent révélant de nouvelles propriétés. Les noyaux actifs de galaxie (AGN) sont l'une des classes d'émetteurs les plus énergétiques, dont le pic de puissance émis dans le spectre électromagnétique peut dans certains cas dépasser la capacité de mesure des instruments actuels, et dont l'investigation requiert la maîtrise simultanée du ciel g HE et VHE qu'apportent les expériences Cerenkov au sol (atmospheric Cerenkov telescope, ou ACT) et le satellite Fermi.

Aktive galaktische Kerne (AGN) gehören zu den besten Quellkandidaten der hochenergetischen kosmischen Strahlung. Es wird erwartet, dass hochenergetische Neutrinos durch Interaktion der kosmischen Strahlung mit Materie oder Photonfeldern in der Nähe der Quellen erzeugt werden. Der resultierende Neutrinofluss kann dieselbe Zeitvariabilität aufweisen wie elektromagnetische Strahlung die von diesen Quellen emittiert wird. Diese Zeitvariabiltät kann in Neutrinoanalysen zusätzlich zu Energie-und Ortsinformationen benutzt werden, um die Detektionswahrscheinlichkeit zu erhöhen. Im Rahmen dieser Arbeit werden zwei neue Methoden entwickelt, welche benutzt werden um nach Neutrino-flares in Aktiven Galaktischen Kernen zu suchen: Die Multi-flare und Multi-flare-Stacking-Methode. Die Multi-flare-Methode ist so entworfen, dass sie nicht nur sensitiv auf einen hellen Flare ist, sondern auch auf weitere schwächere Flares welche normalerweise individuell nicht detektiert werden können. Die Multi-Flare-Methode benötigt keine Zeitkoinzidenz mit Ausbrüchen im elektromagnetischen Spektrum. Sie ist auch sensitiv auf unkorrelierter Neutrinoemission mit unterschiedlicher Dauer der einzelnen Flares, was in einigen Emissionsmodellen vorkommt. Die Multi-Flare-Stacking-Methode ist eine Erweiterung der Multi-Flare-Methode auf zusätzliche Quellen. In ihr werden mehrere schwache, variable Quellen, welche individuell zu schwach sein können um detektiert zu werden, zusammen mit der Stackingmethode analysiert. Die beiden Analysemethoden werden auf eine vorselektierte Liste von Aktiven Galaktischen Kernen angewandt. Hierfür werden drei Jahre Daten des IceCube Neutrinoteleskops verwendet (Mai 2009-June-2012). Kein statistisch signfikanter Neutrinoflare wurde gefunden und obere Fluenzgrenzen f ̈ur jede der Quellen werden ausgerechnet. Diese Grenzen sind im Durchschnitt um einen Faktor zwei besser als vorherige Obergrenzen von Analysen einzelner Flares.
Active Galactic Nuclei are among the best candidate sources for high-energy cosmic rays. High-energy neutrinos are expected to be produced in these sources via interactions of cosmic rays with matter or photon fields present in the source vicinity. The resulting neutrino flux may exhibit time variability on the same time scales than the ones observed in the electromagnetic radiation that is emitted from these sources. Time variability can be taken into account in high-energy neutrino searches in order to increase their detection probability with respect to search methods that include only energy and spatial information. In this work, two new methods are developed to look for high-energy neutrino flares emitted from Active Galactic Nuclei: the Multi-flare and Multi-flare stacking method. The Multi-flare method is designed to be sensitive not only to one bright flare emitted from a single source, as considered in other existing search methods, but also to several weak flares that might not be detected individually. This is achieved by developing a likelihood stacking approach that analyzes the cumulative neutrino emission from several flares. This method does not assume a-priori time coincidences with photon flares observed in the electromagnetic spectrum, allowing uncorrelated neutrino emission with different flare durations as considered in some emission models. The Multi-flare stacking method is an extension of the Multi-flare method to include several sources that might be too weak for individual detection. The two search methods are applied to a pre-selected list of Active Galactic Nuclei using data of the IceCube Neutrino Observatory (May-2009 to May 2012). No statistically significant neutrino flares are detected and fluence upper limits are calculated for each selected source. These limits are on average a factor of two better than previous upper limits from single-flare searches.

This work deals with the design of a CMOS pixel sensor prototype (called MIMOSA 31) for the outer layers of the International Linear Collider (ILC) vertex detector. CMOS pixel sensors (CPS) also called monolithic active pixel sensors (MAPS) have demonstrated attractive performance towards the requirements of the vertex detector of the future linear collider. MIMOSA 31developed at IPHC-Strasbourg is the first pixel sensor integrated with 4-bit column-level ADC for the outer layers. It is composed of a matrix of 64 rows and 48 columns. The pixel concept combines in-pixel amplification with a correlated double sampling (CDS) operation in order to reduce the temporal and fixed pattern noise (FPN). At the bottom of the pixel array, each column is terminated with an analog to digital converter (ADC). The self-triggered ADC accommodating the pixel readout in a rolling shutter mode completes the conversion by performing a multi-bit/step approximation. The ADC design was optimized for power saving at sampling frequency. Accounting the fact that in the outer layers of the ILC vertex detector, the hit density is inthe order of a few per thousand, this ADC works in two modes: active mode and inactive mode. This thesis presents the details of the prototype chip and its laboratory test results.

L'expérience CBM (Compressed Baryonic Matter), l'une des expériences majeures du futur accélérateur FAIR (Darmstadt, Allemagne), a pour objectif d'étudier le diagramme des phases de la matière nucléaire dans la région des hautes densités baryoniques nettes et des températures modérées. Un des principaux thèmes de physique de cette expérience est l'étude de la production et de la propagation des particules à charme ouvert, comme les mésons D (particules constituées d'un quark charmé et d'un quark léger), dans les collisions d'ions lourds. La mesure de ces mésons charmés nécessite l’utilisation d’un détecteur de vertex d’excellente précision. La présente thèse est une contribution à la conception et au développement de ce détecteur, appelé MVD (Micro Vertex Detector). Elle porte sur trois aspects principaux. Le premier, concerne la caractérisation expérimentale de la réponse des capteurs MAPS (Monolithic Active Pixel Sensors), constituant les stations du détecteur MVD, au passage des particules chargées. Le second, porte sur le développement d'un modèle permettant de décrire de façon réaliste la réponse du détecteur MVD. En fin, le troisième aspect consiste en une étude détaillée de la faisabilité des mesures des particules à charme ouvert dans les collisions noyau-noyau. Les résultats obtenus montrent que la mesure des particules à charme ouvert est faisable et permettent d’évaluer les performances attendues et les limites de l’expérience
The CBM experiment (Compressed Baryonic Matter), one of the main experiments of the future FAIR accelerator facility (Darmstadt, Germany), aims in studying the phase diagram of nuclear matter in the region of high baryonic densities and moderate temperatures. Among the core physics goals is the study of the production and propagation of open charm particles, like D-mesons (particles containing one charm quark and one light quark) in heavy ion collisions. The measurements of these charmed mesons require the use of an excellent precision vertex detector. The present thesis is a contribution to the design and development of this detection device called MVD (Micro Vertex Detector). It is focused on three different parts. The first one concerns the experimental characterisation of the response of MAPS (Monolithic Active Pixel Sensors) sensors, composing the MVD detector stations, to the passage of charged particles. The second deals with the development of a realistic detector response model for the MVD detector. The last part focuses on a detailed feasibility study of open charm particle measurements in heavy ion collisions. The results demonstrate the feasibility of open charm particle measurements and allow assessing the expected performances and the limitations of the experiment

Mestrado em Engenharia Electrónica e Telecomunicações
Este documento descreve um trabalho desenvolvido no âmbito da tese de Mestrado, ano lectivo de 2007-08, do Mestrado Integrado de Engenharia Electrónica e Telecomunicações da Universidade de Aveiro. O trabalho realizado foi no sentido de desenvolver um sistema de detecção de obstáculos móveis baseado em ultra-sons, para aplicar num veículo cujo principal objectivo é participar na prova Eco-Maratona Shell. Pretendia-se com este sistema detectar veículos em aproximação pela retaguarda e avisar ao piloto através de mecanismos de apoio. Pretendia-se também determinar qual a velocidade de aproximação e qual o quadrante de aproximação em relação ao eixo de direcção do Ícaro. Durante a realização deste projecto, grande parte dos esforços foram no sentido de construir um sistema de detecção de obstáculos que permitisse apenas, a aquisição de ecos provenientes de direcções paralelas ao solo, focalizando o máximo de energia possível em torno dos 0 graus. A autonomia do sistema também foi tida em conta, pois o sistema foi idealizado para um veículo automóvel, tendo como única fonte energética a bateria. Deste trabalho, resultou um protótipo para o sistema de detecção com bastantes potencialidades para a aplicação. No entanto ainda carece de testes efectuados em movimento, isto é, em condições reais, para colmatar qualquer problema detectado.
Ultra-sounds are a path to detect obstacles, but there are various ways to use them to that goal. In this work, we evaluate some devices based in ultra-sonic transducers and compare them to achieve a good performance in obstacle detection and distance determination as well. A Shell Eco-Marathon driver must have the perception of the rear distance object , this is given by ears and eyes. The vision of the rear objects is given by the car mirrors, but in this case is also given by a led´s panel, the earing perception is given by sounds produced in function of the direction of the rear object. This system is to be applied to a car and must be autonomous, there are a group of devices to reach a system based only on the car battery in terms of energy.

Improvements in the control of prosthetic hands can provide a future solution for amputated people, improving their motor skills and in general their quality of life. The prosthesis controlled by electromyography (EMG) are studied for their greater potential, but the technology is still unprepared for mass usage. The control is too unstable due to various phenomena related to the inconstancy of bioelectric signals and changes in the human body posture during the execution of tasks. This thesis is focused on the creation of a fault detector able to detect these instabilities and correct the prosthesis’s future behaviour. Machine learning algorithms and methodologies were employed for this objective. The approach is then tested on four healthy subjects with a preliminary experiment.

Cette thèse est une contribution au document intitulé "Detector Baseline Document (DBD)" décrivant le conceptde détecteur ILD envisagé auprès du collisionneur linéaire international électron-positon ILC (acronyme del'anglais International Linear Collider).Les objectifs de physique de l'ILD nécessitent un détecteur de vertex (VXD) particulièrement léger, rapide et trèsgranulaire permettant d'atteindre une résolution sans précédent sur le paramètre d'impact des trajectoiresreconstruites des particules produites dans les interactions étudiées. Le principal objectif de cette thèse est demontrer comment optimiser les paramètres du VXD dans le cas ou il est composé de Capteurs à Pixels Actifsfabriqués en technologie industrielle CMOS (CAPS). Ce travail a été réalisé en étudiant la sensibilité desperformances d'étiquetage des saveurs lourdes et de la précision sur les rapports d'embranchement hadroniquedu boson de Higgs aux différents paramètres du VXD.Le cahier des charges du VXD, particulièrement ambitieux, a nécessité le développement d'une nouvelletechnologie de capteurs de pixels de silicium, les CAPS, dont le groupe PICSEL de l'IPHC est à l'origine. Lavitesse de lecture et l'influence des paramètres qui régissent la fabrication des capteurs en fonderie ont étéétudiées dans cette thèse, et des prototypesde CAPS ont été caractérisés sur faisceau de particules. Enfin, les performances de trajectométrie d'un VXDcomposé de CAPS a été évalué avec des études de simulation
This thesis is a contribution to the " Detector Baseline Document ", describing the ILD detector which is intendedfor the International Linear Collider (ILC).The physics goals of the ILD call for a vertex detector (VXD) particularly light, rapid and very granular allowing toreach an unprecedented resolution on the impact parameter of the tracks that reconstruct the particles producedin the studied interactions. The principle goal of this thesis is to show how to optimise the parameters of the VXDin the case that is composed of Active Pixel Sensors manufactured in industrial CMOS technology (CAPS). Thiswork has been realised by studying the sensitivity of the performance of the heavy flavour tagging and theprecision on the hadronic branching fractions of the Higgs boson as a function of different sets of VXDparameters.The specifications of the VXD, particularly ambitious, call for the development of a novel silicon pixel sensorstechnology, the CAPS, which was pioneered by the PICSEL group of IPHC. The readout speed and the influenceof the fabrication parameters have been studied in this thesis, and CAPS prototypes have been characterised intest beams. Finally, the tracking performance of a CAPS based VXD has been evaluated with simulation studies

Abstract Research on X-ray imaging sensors and systems have been carried out for several decades. To make these X-ray scanners smaller with better performance and higher operating speed is an important subject for scientific research and industrial applications. This thesis covers a whole X-ray line-scan camera system. Special attention is given to the smart sensor micromodule design and processing technology. The smart sensor micromodule is an integrated sensor card that includes both silicon X-ray sensor array and signal-processing integrated circuits, which can perform the functions of both an optical sensor and an analog signal processor. Digital signal processing (DSP) made by application specific integrated circuits (ASICs) is also covered in this thesis. Processing technology of the photodiode array, design of the integrated circuit, design and packaging of the micromodules are presented in this thesis. The mechanism of photodiode leakage current is studied in detail. Measured results show that the leakage current level of the photodiode array achieves 80 pA/cm2 under zero bias condition, which outperforms the best photodiode reported so far. The algorithm of the digital signal processing is also studied. The X-ray scanning system can achieve 2 m/s scanning speed with a spatial resolution of 400 mm.

With the growth of successes in pattern recognition and signal processing, mobile robot applications today are increasingly equipping their hardware with microphones to improve the set of available sensory information. However, if the robot, and therefore the microphone, ends up in a poor location acoustically, then the data will remain noisy and potentially useless for accomplishing the required task. This is compounded by the fact that there are many bad acoustic locations through which a robot is likely to pass, and so the results from auditory sensors often remain poor for much of the task. The movement of the robot, though, can also be an important tool for overcoming these problems, a tool that has not been exploited in the traditional signal processing community. Robots are not limited to a single location as are traditionally placed microphones, nor are they powerless over to where they will be moved as with wearable computers. If there is a better location available for performing its task, a robot can navigate to that location under its own power. Furthermore, when deciding where to move, robots can develop complex models of the environment. Using an array of sensors, a mobile robot can build models of sound flow through an area, picking from those models the paths most likely to improve performance of an acoustic application. In this dissertation, we address the question of how to exploit robotic movement. Using common sensors, we present a collection of tools for gathering information about the auditory scene and incorporating that information into a general framework for acoustical awareness. Thus equipped, robots can make intelligent decisions regarding control strategies to enhance their performance on the underlying acoustic application.

Fumonisins, carcinogenic mycotoxins produced by various Fusarium species, occur naturally in maize and maize-based food products. They are hazards for animal and human health as they cause cancer in rodents and have been associated with oesophageal cancer and neural tube defects in humans. The most abundant naturally occurring fumonisins analogues in maize are fumonisin B1, B2 and B3 (FB1, FB2 and FB3). For analytical determination, they mostly require suitable extraction, clean-up and pre or post-column derivatization together with reversed-phase HPLC separation. o- Phthaldialdehyde (OPA) had been adopted as the most widely used derivatization reagent for fumonisins as they lack useful chromophores or fluorophores. Alternative derivatization reagents, naphthalene-2,3- dicarboxaldehyde (NDA) and dansyl chloride (DnS-Cl), were investigated in this study

The upgrade of the ALICE vertex detector, the Inner Tracking System (ITS), is scheduled to be installed during the next long shutdown period (LS2 in 2019-2020) of the CERN Large Hadron Collider (LHC). The current ITS will be replaced by seven concentric layers of Monolithic Active Pixel Sensors (MAPS) with total active surface of ~10 m^2, thus making ALICE the first LHC experiment implementing MAPS detector technology on a large scale. The scope of this thesis is twofold; to report on the activity on the development and the characterisation of a MAPS for the ITS upgrade and to study the charge collection process using a first-principles Monte Carlo simulation. The performance of a MAPS depends on a large number of design and operational parameters, such as collection diode geometry, reverse bias voltage, and epitaxial layer thickness. I have studied this dependence by measuring the INVESTIGATOR chip response to X-rays emitted by an 55-Fe source and to minimum ionising particles. In particular, I have examined the influence of the parameters considered in the design of the MAPS for the ITS upgrade, on the Q/C ratio, i.e. the ratio of the collected charge in a single pixel and the pixel input capacitance. The ALPIDE chip, based on TowerJazz 180 nm CMOS Imaging Process, has been developed for the ITS upgrade. I have performed extensive laboratory studies on the full-scale prototypes as well as on the final sensor. I have studied in detail the analogue front-end response in terms of timing characteristics using an infrared laser beam. I have significantly contributed to the measurements of the prototype and final sensors under charged particle beams. The laboratory and test-beam measurements allowed me to verify the compliance of the ALPIDE sensor to the ITS upgrade requirements. The layers of the new ITS will be azimuthally segmented into the independent units called staves, which integrate the ALPIDE sensors and the mechanical and electrical support elements. The NA61/SHINE collaborations offered the opportunity to test an ITS stave in the Pb--Pb collision environment of their experiment. I have integrated a stave consisting of nine ALPIDE sensors in the NA61 experiment and tested its performance in terms of detection efficiency and spatial resolution at the multiplicities comparable to those expected in the ITS after the LS2. While the successful operation of the sensors for the ITS upgrade has been confirmed, a great deal still remains to be understood about the charge collection process of MAPS. The exact response of MAPS is challenging to model due to contributions from both epitaxial layer and substrate, a typically only partially depleted active volume, and complex well structures. Transient TCAD simulations provide a good description but are not sufficiently fast to be used in the experiments simulations. Therefore, I have developed a fast tool to model the response of ALICE ITS MAPS. The basic concept is a first principles MC simulation, using electric fields extracted from a TCAD simulation to model the charge carrier drift. That is, the more complex part is handled by a TCAD simulation while preserving the speed of a MC simulation with only one free parameter. The tool is versatile, any MAPS architecture can be simulated once the proper external electric field is provided. So far, I have simulated the response of the INVESTIGATOR (analogue output) and ALPIDE (digital output) chips. An excellent agreement between data and simulation has been achieved, both for 55-Fe X-rays and minimum ionising particles.

This study is aimed at investigating the feasibility of using the radiometric technique as an alternative to traditional methods for determining soil physico-chemical parameters which are important for terroir characterization. In-situ and ex-situ radiometric analyses of soil from three vineyard blocks of Simonsig Wine Estate in the Stellenbosch district (Western Cape, South Africa) were studied. A mobile MEDUSA gamma-ray detection system comprising a CsI(Na) crystal (length 15 cm, diameter 7 cm) and associated electronics mounted on a portable trolley were used for partial terroir characterisation. Thereafter activity concentrations of 40K, 232Th series and 238U series in soil (top ~30 cm) from the measured MEDUSA spectra (0 – 3 MeV) were extracted by means of the full-spectrum analysis (FSA) method. A lead-shielded HPGe detector was used for analyzing collected soil samples while soil physico-chemical parameters were analysed using standard methods at research and commercial laboratories.

The natural ²
³
⁸U, ²
³
²
Th and ⁴°
K radioactive content of vineyard soil was measured with an in-situ gamma-ray detector. The activity concentration measured with the in-situ detector are normalized using the laboratory-determined activity concentrations of several samples from the vineyard site. To determine the activity concentration of a particular soil sample, the gamma-ray photopeak detection efficiencies are required. In this work, the detection efficiencies were derived for each soil sample using gamma-ray photopeaks associated with the radionuclide of ²
³
⁸U, ²
³
²
Th present in the sample, and the ⁴°
K, 1460.8 keV gamma-ray peak, from KCl salt.

Hybrid pixel detectors have been demonstrated to provide excellent quality detection of ionising photon radiation, particularly in X-ray imaging. Recently, there has been interest in developing a hybrid pixel detector specifically for photon dosimetry. This thesis is on the design, implementation, and preliminary characterisation of the Dosepix readout chip. Dosepix has 256 square pixels of 220 mm side-length, constituting 12.4 mm2 of photo-sensitive area per detector. The combination of multiple pixels provides many parallel processors with limited input flux, resulting in a radiation dose monitor which can continuously record data and provide a real-time report on personal dose equivalent. Energy measurements are obtained by measuring the time over threshold of each photon and a state machine in the pixel sorts the detected photon event into appropriate energy bins. Each pixel contains 16 digital thresholds with 16 registers to store the associated energy bins. Preliminary measurements of Dosepix chips bump bonded to silicon sensors show very promising results. The pixel has a frontend noise of 120 e-. In low power mode, each chip consumes 15 mW, permitting its use in a portable, battery-powered system. Direct time over threshold output from the hybrid pixel detector assembly reveal distinctive photo-peaks correctly identifying the nature of incident photons, and verification measurements indicate that the pixel binning state machines accurately categorise charge spectra. Personal dose equivalent reconstruction using this data has a flat response for a large range of photon energies and personal dose equivalent rates.

The thesis presents the investigation on how to increase the sensitivity of the narrowed sensors of radiation. Also the thesis also deals with the attempts to analyze the influence of the microwave radiation on to the narrowed semiconductor formations and to reveal the physical nature of the observed effects as well as to determine the influence of structure of the samples on the detected signal magnitude. The work solves the following major tasks: the characteristics of the narrowed semiconductor heterostructures depending on the quality of the modulation layers and on the parameters of the semiconductor materials as well as the characteristics, depending on the selectively doped structure, on the conductivity of the highly doped semiconductor layer, and on the thickness of the separating layer, and the type of metallization of the gate. In order to achieve the goal there were produced and investigated narrowed different heterostructures (AlGaAs/GaAs, AlGaAs/InGaAs/GaAs) and n-GaAs structures. The thesis consists of four chapters, the final one is the generalization of the results. The first chapter (introductory) deals with the actuality of the problem, the aim and the tasks are stated, the novelty of the scientific research is described, the reports of the author are presented together with the publications, and the structure of the thesis. The second chapter is assigned to the review of the literature. It presents the principals of electromagnetic radiation detection... [to full text]
Disertacijoje nagrinėjama, kaip padidinti susiaurintų spinduliuotės jutiklių jautrį. Taip pat disertacijoje siekiama ištirti mikrobangų spinduliuotės poveikį susiaurintiems puslaidininkiniams dariniams ir atskleisti stebimų efektų fizinę prigimtį bei nustatyti bandinių struktūros įtaką detektuojamo signalo dydžiui. Darbe sprendžiami tokie pagrindiniai uždaviniai: tiriamos įvairialyčių susiaurintų puslaidininkinių darinių savybės, priklausančios nuo darinių sluoksnių kokybės ir puslaidininkinių medžiagų parametrų bei analizuojamos savybės, priklausančios nuo stipriai legiruoto puslaidininkinio sluoksnio laidumo, nuo skiriamojo sluoksnio storio ir nuo sklendės pobūdžio metalizacijos. Siekiant užsibrėžto tikslo, buvo gaminami ir tiriami susiaurinti skirtingi įvairialyčiai dariniai (AlGaAs/GaAs, AlGaAs/InGaAs/GaAs) ir n-GaAs dariniai. Disertaciją sudaro penki skyriai, kurių paskutinis – rezultatų apibendrinimas. Pirmajame (įvadiniame) skyriuje nagrinėjamas problemos aktualumas, formuluojamas darbo tikslas bei uždaviniai, aprašomas mokslinis darbo naujumas, pristatomi autoriaus pranešimai, disertacijos struktūra. Antrasis skyrius skirtas literatūros apžvalgai. Jame apžvelgiami elektromagnetinės spinduliuotės detektavimo principai, aptariamos šiluminės ir bigradientinės elektrovaros susidarymo priežastys, AlGaAs/GaAs įvairialytė sandūra, selektyvusis legiravimas bei puslaidininkinių prietaisų fizikinės galimybės. Trečiajame skyriuje pateikta eksperimento tyrimo metodika. Išsamiai... [toliau žr. visą tekstą]

Ce travail traite des aides optroniques aux déplacements des non-voyants. Préalablement à ce travail, deux " détecteurs de passage " ont été développés au Laboratoire Aimé Cotton le " Tom Pouce " et le " Télétact ". Le " Tom Pouce " est simple d'utilisation mais présente des limitations pour détecter les passages étroits à des distances supérieures à trois mètres ainsi que pour éviter les poteaux fins. Le " Télétact " permet de gérer l'ensemble des situations mais le nombre d'utilisateurs est limité par l'effort cognitif important que demande son utilisation ainsi que sa fragilité.Le but principal de cette thèse est d'améliorer les capteurs ainsi que leur façon de représenter l'espace afin d'avoir un dispositif facile d'utilisation détectant tous les passages.Dans un premier temps, l'hypothèse que la forme de la zone de protection idéale devrait être d'aspect cylindrique est émise. La réalisation approchée de cette forme à partir de capteurs infrarouges est analysée théoriquement et validée expérimentalement. Deux dispositifs le " Tom Pouce II " et le " Minitact " utilisant ce concept ont été proposés à des non-voyants et ont reçu un accueil favorable. Dans un second temps, les capteurs laser télémétriques du " Télétact " ont été revus afin d'améliorer leurs performances permettant entre autres une moindre sensibilité aux contraintes mécaniques. Une nouvelle forme d'association des capteurs infrarouges et laser permet de gérer l'ensemble des configurations de passages, y compris en chicane, avec une interface tactile ayant seulement trois niveaux d'alerte correspondant à trois zones de protection (moins de 2 mètres de profondeur sur 10 cm de large, entre 2 et 6 mètres sur plus de 50 cm de large, plus de 6m de profondeur et 1m de large ) avec un effort cognitif très réduit par rapport au " Télétact " initial utilisant 32 sons différents. Des outils pour pouvoir analyser objectivement les performances des dispositifs dans des environnements contrôlés ont été mis au point afin de pouvoir ajuster finement les formes des zones de protection. Un dernier point concerne les possibilités d'identification des obstacles, l'imagerie est explorée mais s'avère immature, actuellement seules les " astuces d'utilisation " des capteurs sont opérationnelles.

ACTAR TPC (ACtive TARget and Time Projection Chamber) est une cible active de nouvelle génération construite au GANIL (Grand Accélérateur d'Ions Lourds). Les cibles actives sont des cibles gazeuses où le gaz permet de détecter le passage de particules chargées selon le principe des chambres à projection temporelle (TPC). La TPC d'ACTAR est formée d'une anode segmentée de 16384 pixels carrés de 2 mm de côté. La haute densité de voies est gérée par le système électronique GET (General Electronics for TPCs). Ce système digitalise également les signaux sur un intervalle de temps donné, pour une reconstruction 3D complète des évènements. Un démonstrateur huit fois plus petit a d'abord été construit pour vérifier le fonctionnement de l’électronique et la conception mécanique. La finalisation d’ACTAR TPC s’est basée sur les résultats du démonstrateur, qui a été testé avec des faisceaux de 6Li, de 24Mg et de 58Ni. Le commissioning d'ACTAR TPC a été effectué dans le cas de la diffusion résonante sur cible de protons avec des faisceaux de 18O et de 20Ne.Un algorithme de reconstruction des traces mesurées dans la TPC permet d'en extraire les angles et les énergies des ions impliqués dans les réactions. Les résultats sont comparés à des données connues pour déterminer les performances du système de détection. Les résolutions obtenues sur le commissioning à partir de calculs en matrice R valident l'utilisation d'ACTAR TPC pour de futures expériences. Par ailleurs, la diffusion résonante 6Li + 4He réalisée avec le démonstrateur a permis d'étudier les états d’agrégat alpha dans le 10B. Deux résonances à 8.58 MeV et 9.52 MeV sont observées pour la première fois en diffusion élastique dans cette voie de réaction
ACTAR TPC (ACtive TARget and Time Projection Chamber) is a next generation active target that was designed and built at GANIL (Grand Accélérateur d'Ions Lourds). Active targets are gaseous targets in which the gas is also used to track charged particles following the principles of time projection chambers (TPC). The TPC of ACTAR has a segmented anode of 16384 2 mm side square pixels. The high density of pixels is processed using the GET (General Electronics for TPCs) electronic system. This system also digitizes the signals over a time interval, enabling a full 3D event reconstruction. An eight time smaller demonstrator was first built to verify the electronics operation and the mechanical design. ACTAR TPC's final design was based on results obtained with the demonstrator which was tested using 6Li, 24Mg and 58Ni beams. The commissioning of ACTAR TPC was then carried out for the case of resonant scattering on a proton target using 18O and 20Ne beams. A track reconstruction algorithm is used to extract the angles and energies of the ions involved in the reactions. Results are compared to previous data to determine the detection system performances. Comparing the commissioning data with R matrix calculations, excitation functions resolutions in different cases are obtained. The use of ACTAR TPC is validated for future experiments. Furthermore, alpha clustering was studied in 10B through the resonant scattering 6Li + 4He, carried out with the demonstrator. Two resonances at 8.58 MeV and 9.52 MeV are observed for the first time in elastic scattering with this reaction channel