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BERETTA, MATTIA. "Application and development of scintillation based detectors for the investigation of neutrino physics in double beta decay experiments." Doctoral thesis, Università degli Studi di Milano-Bicocca, 2020. http://hdl.handle.net/10281/261929.
Texte intégralRésumé :
L’attività di ricerca da me svolta durante il dottorato di ricerca è stata legata all’applicazione e sviluppo di rivelatori a scintillazione criogenici, pensati per la ricerca del decadimento doppio beta senza emissione di neutrini (0νββ). Ho analizzato due possibili implementazioni di questa tecnica: rivelatori ad alte prestazioni basati sulla lettura della luce di scintillazione e rivelatori bolometrici a scintillazione con doppia lettura. Il rivelatore per 0νββ basato sulla scintillazione che ho studiato è costituito da cristalli scintillanti, contenenti l’isotopo candidato al 0νββ, accoppiati otticamente a rivelatori a deriva in silicio (Silicon Drift Detectors, SDD), utilizzati come lettori di luce e operati a 120K. Il mio lavoro è stato dedicato alla caratterizzazione degli SDD, per mezzo di misure dirette con raggi X e misure di scintillazione. Le misure con raggi X sono state utilizzate per caratterizzare gli SDD progettati appositamente per questa applicazione dalla Fondazione Bruno Kessler (FBK), che sono i dispositivi di questo tipo con singolo anodo più grandi mai prodotti. I risultati ottenuti mostrano il livello estremamente basso di rumore elettronico raggiunto da questi rivelatori, dimostrando che questa caratteristica non ne limita le prestazioni. Le misure di scintillazione, invece, sono state realizzate accoppiando un cristallo di CdWO4 al SDD, permettendo di valutare la risoluzione energetica del rivelatore complessivo. Con diverse misure, ho dimostrato che la risoluzione energetica è limitata dalla efficienza di raccolta di carica del SDD, non uniforme sulla superficie del rivelatore. Per risolvere questo problema, una nuova serie di SDD che correggono questa caratteristica è stata progettata e prodotta da FBK.
Al fianco di questo sviluppo tecnico, ho lavorato come membro della collaborazione CUPID-0 all’analisi dei dati raccolti dall’esperimento. CUPID-0 è un rivelatore bolometrico a scintillazione composto da 26 cristalli di ZnSe, 24 dei quali arricchiti in 82Se, un candidato al 0νββ. Combinando la buona risoluzione energetica del canale di calore con l’identificazione delle particelle resa possibile dal segnale di luce, CUPID-0 è stato in grado di raggiungere il fondo più basso mai raggiunto da un esperimento bolometrico per la ricerca del 0νββ. Grazie a questo risultato, è stato possibile estrarre il miglior limite sulla vita media del 0νββ del 82Se, dimostrando le alte prestazioni di questo approccio sperimentale. Con il mio lavoro ho ottenuto un ulteriore miglioramento della risoluzione energetica, correggendo la correlazione tra luce e calore. Anche grazie a questo nuovo passaggio di analisi, un nuovo limite sulla vita media del 0νββ del 82Se è stato ottenuto, utilizzando tutti i dati raccolti nella prima fase dell’esperimento. Ho anche contribuito alla definizione del modello del fondo dell’esperimento, sviluppando un sistema di analisi per caratterizzare le contaminazioni superficiali dei cristalli. Sfruttando i risultati del modello di fondo, ho poi potuto mettere un limite alla violazione della simmetria di Lorentz nelle interazioni dei neutrini, ottenuto analizzando la forma dello spettro del decadimento doppio beta a due neutrini del 82Se.
Il lavoro da me svolto mi ha consentito di acquisire esperienza nell’operazione e analisi dati di scintillatori operati a temperature criogeniche, spendibili sulle diverse tecniche sperimentali che ho approfondito e estendibili ad altre applicazioni basate su questo tipo di rivelatori.<br>The research activity during my PhD has been devoted to the application and development of cryogenic scintillation detectors for the search of neutrinoless double beta decay (0νββ). I investigated two implementations of this design: high performance detectors based on the light output readout and the double-readout scintillating bolometers. The scintillation based 0νββ detector that I investigated is based on scintillating crystals, containing a 0νββ candidate, optically coupled to Silicon Drift Detectors (SDDs) operated as light detectors at 120K. My work was dedicated to the characterization of the SDD detectors, performing both X-ray and scintillation measurements. The X-ray measurements served as a testing ground for the devices designed and produced for this application by Fondazione Bruno Kessler (FBK), which are the biggest single anode SDDs ever built. The obtained results showed that these devices have excellent noise performances, proving that the electronic noise is not a limiting factor in this application. The scintillation measurements performed with a CdWO4 crystal coupled with a SDD, instead, allowed to evaluate the attainable energy resolution. With different measurement, I showed that the energy resolution is limited by the variable charge collection efficiency of the SDD surface. To solve this problem, a new series of SDDs with uniform efficiency is going to be designed and produced at FBK.
Alongside this technical development, I worked as a member of the CUPID-0 collaboration in the data analysis. CUPID-0 is a scintillating bolometer composed by 26 ZnSe crystals, 24 of which are enriched in 82Se, a 0νββ candidate. Combining the good energy resolution given by the heat channel readout and the particle identification given by the light signal, CUPID-0 was able to reach the lowest background ever reached by a bolometric experiment in the region of interest for the 0νββ. Consequently, the best limit on the 0νββ of 82Se could be extracted, showing the efficiency of this technological approach. I obtained an ulterior enhancement of the attainable energy resolution in the heat channel, by the means of the light/heat correlation correction. With this new analysis step, a new limit was obtained on the 0νββ half-life of 82Se, calculated with the total statistic of the first phase of the experiment. I also worked in the definition of the background model for the CUPID-0 experiment, developing an analysis routine to characterize the surface contamination of crystals. Exploiting the result of the background model I could put a limit on the Lorentz violation in the neutrino sector, analyzing the shape of the 2νββ spectrum. My research work allowed me to acquire a solid know-how on scintillators operated at cryogenic temperatures, expendable in between the two technological routes I have followed and extendable to other scintillation-based applications.
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Šalomoun, Vojtěch. "Studium teplotních parametrů nanostrukturovaného senzoru pro detekci IR." Master's thesis, Vysoké učení technické v Brně. Fakulta elektrotechniky a komunikačních technologií, 2016. http://www.nusl.cz/ntk/nusl-241151.
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Theodoro, Victor Cominato. "Estudo espectral das instabilidades MHD no tokamak TCABR." Universidade de São Paulo, 2013. http://www.teses.usp.br/teses/disponiveis/43/43134/tde-18112014-153714/.
Texte intégralRésumé :
Neste trabalho foram estudadas instabilidades magnetohidrodinâmicas (MHD) utilizando um novo sistema bolométrico que foi instalado no tokamak TCABR para medidas da evolução temporal da potência irradiada. Este novo sistema conta com 24 cordas verticais, capazes de mapear toda uma secção poloidal da coluna de plasma com resolução espacial de aproximadamente 2 cm e uma resolução temporal de 20 µs. Como se sabe, as instabilidades MHD degradam o connamento do plasma e modicam a topologia das superfícies magnéticas, causando a perda da energia do plasma. Por conta disso, compreender essas instabilidades é fundamental para o sucesso dos futuros reatores de fusão nuclear. As perturbações (oscilações) causadas pelas instabilidades MHD modulam diversos parâmetros macroscópicos do plasma como a densidade, a temperatura e a potência irradiada. Então, utilizando o diagnóstico bolométrico, é possível medir as oscilações no perl de potência irradiada e, a partir deles, extrair informações importantes para determinar a origem e as características de tais instabilidades. No tokamak TCABR, as instabilidades foram caracterizadas através da análise espectral dos 24 sinais provenientes do novo sistema bolométrico. Para auxiliar a caracterização das instabilidades, um programa foi desenvolvido em Matlab para simular as medidas das perturbações no perl de potência irradiada. Através do mesmo procedimento de análise espectral, os resultados simulados foram comparados aos experimentais de forma que os parâmetros simulados, como largura e posição das ilhas magnéticas, fossem ajustados aos experimentais. Através dessa metodologia de análise, que combina simulação e experimento, foi possível caracterizar diversas instabilidades como o precursor dos dentes de serra e ilhas magnéticas de modos m = 2 e m = 3.<br>In this dissertation, magnetohydrodynamic (MHD) instabilities were investigated using a new bolometric system that was installed in the TCABR tokamak for radiation power measurements. This diagnostic is composed by 24 vertical chords that provide a full view of the poloidal cross section of the plasma column and provides spatial and temporal proles with approximately 2 cm space and 20 µs time resolution. As it is well known, the MHD instabilities degrade the plasma connement and modify the magnetic topology, leading to energy loss from the plasma. Therefore, the understanding of these instabilities is essential for the success of the controlled thermonuclear fusion reactors. The MHD instabilities also cause perturbations (oscillations) in various macroscopic parameters, such as plasma density, temperature, and radiated power. Therefore, the oscillations in the radiated power prole measured by the bolometric diagnostic system provide a possibility to investigate the origin and features of the instabilities. In the TCABR tokamak, the instabilities were characterized by spectral analysis of the 24 vertical chords of the bolometric signals. In addition, a Matlab program was developed to simulate the integral characteristic of the oscillations in the radiated power measured by the bolometric system. The spectral analysis of the simulated signals is then compared with the spectral analysis of the bolometric signals. The simulated parameters, island width and radial position, were then adjusted to t the experimental spectrum results. Using this method of analysis, which combines experiment and simulation, it was possible to characterize various instabilities, such as sawtooth precursor and m = 2 and m = 3 magnetic islands.
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Hollister, Matthew Ian. "SCUBA-2 instrument : an application of large-format superconducting bolometer arrays for submillimetre astronomy." Thesis, University of Edinburgh, 2009. http://hdl.handle.net/1842/3855.
Texte intégralRésumé :
This thesis concerns technical aspects related to the design and operation of the submillimetre common-user bolometer array 2 (SCUBA-2) instrument, a new wide-field camera for submillimetre astronomy currently undergoing commissioning on the James Clerk Maxwell Telescope on Mauna Kea, Hawaii. Offering unprecedented sensitivity and mapping capabilities, SCUBA-2 is expected to make a major impact in surveys of the sky at submillimetre wavelengths, a largely unexplored part of the electromagnetic spectrum, and provide better understanding of the formation and evolution of galaxies, stars and planets by providing large, unbiased samples of such objects. SCUBA-2 uses large arrays of bolometers, with superconducting transition edge sensors (TESs) as the temperature-sensitive element. TES devices are a relatively new technology, utilising the sharp resistance change between the normal and superconducting states to make a sensitive thermistor. Kilopixel arrays of such devices are multiplexed using superconducting quantum interference devices (SQUIDs). This thesis derives the key detector performance parameters, and presents analysis of engineering data to confirm the detector performance on array scales. A key issue for bolometric instruments for far infrared and submillimetre astronomy is the need to operate at extremely low temperatures in the sub-kelvin and millikelvin ranges to achieve the necessary detector sensitivity. This work describes the design, testing and performance of the liquid cryogen-free millikelvin cryostat, the first such instrument to be deployed for astronomy. Subsequent chapters detail the design and testing of a magnetic shielding scheme for the instrument, an important aspect of the operation of superconducting devices. Based on experience with the construction and testing of this instrument, a number of potential improvements for future instruments are presented and discussed.
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Campbell, E. S. "Millimetre and submillimetre bolometric interferometry." Thesis, University of Cambridge, 2005. http://ethos.bl.uk/OrderDetails.do?uin=uk.bl.ethos.597259.
Texte intégralRésumé :
I start by presenting simulations of the noise performance of Superconductor-Insulator-Superconductor (SIS) direct detectors, combined with op-amp based readout electronics. This involves the combination of non-linear device modelling, with a detailed noise model of both the SIS junction and the readout-electronics. Using this model, I show that an SIS direct detector can be competitive in terms of noise performance with a transition edge sensor, provided the junction is biased well below the gap, and that the gap is tailored to the observing frequency. I then describe a set of experiments aimed at measuring the noise performance of a tantalum aluminium SIS device combined with op-amp based readout. I compare the results of these experiments with the predictions of my model, and show that they are in excellent agreement. Using the modelling software I have developed, I predict the lowest noise equivalent power achievable with this device as being 1.3 x 10<sup>-17</sup>W/√Hz, over a video bandwidth of 5 kHz. The expected dynamic range is 91 dB. I also describe the development and testing of the first submillimetre, single-chip, beam combining interferometer. This uses a superconducting chip, on which both the beam combination and detection occur. Two designs of chip were tested, one using a directional coupler for the beam combination, the other using a 90° hybrid. Both designs resulted in the measurement of fringe patterns that agree remarkably well with theory. The final part of this work concerns the development of a new modal theory of interferometry. The aim of this work was to accurately describe the partially coherent behaviour of multi-moded bolometric interferometers. My first attempt uses an approach based on the eigenmodes of the optical system. This was successful, but it became apparent that a more elegant solution existed. This alternative approach introduces the concept of eigenfields. These are the fundamental field distributions associated with an optical system. The can be found using the singular value decomposition, and, as I demonstrate, they allow the accurate simulation of multi-modal bolometric interferometers.
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Leder, Alexander Friedrich Sebastian. "Rare-event searches with bolometers." Thesis, Massachusetts Institute of Technology, 2018. http://hdl.handle.net/1721.1/119106.
Texte intégralRésumé :
Thesis: Ph. D., Massachusetts Institute of Technology, Department of Physics, 2018.<br>Cataloged from PDF version of thesis.<br>Includes bibliographical references (pages 173-185).<br>Rare-event searches have played an integral part in the pursuit of physics beyond the Standard Model, offering us the chance to bridge the disparity between our current understanding and observed phenomena such as Dark Matter (DM) or the nature of neutrino masses. Over the last 30 years, these experiments have grown larger and more sophisticated, allowing us to probe new and exciting theories of the universe. At the same time, we have started to apply the technologies and techniques used in rare-event searches to areas of applied physics, for example; reactor monitoring using Coherent Elastic Neutrino Nucleon Scattering (CEvNS) with Ricochet. In this thesis, I will discuss the hardware and analysis techniques required to design, construct, and extract results from these low background, rare-event searches. In particular, I will discuss the hardware and analysis related to the Cryogenic Dark Matter Search (CDMS), CEvNS detection with Ricochet and the measurement of the effective nuclear quenching factor g, via shape analysis of the highly forbidden In-115 beta spectrum. The latter measurement has far reaching consequences for all neutrino-less double beta decay experiments, independent of isotope.<br>by Alexander Friedrich Sebastian Leder.<br>Ph. D.
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Brien, Thomas. "The silicon cold-electron bolometer." Thesis, Cardiff University, 2015. http://orca.cf.ac.uk/77064/.
Texte intégralRésumé :
This thesis describes the development and testing of two cold-electron bolometers using highly-doped silicon as the absorber. These detectors exhibit both high sensitivity and low time constants. High sensitivity is achieved due to the weak thermal-link between the electrons and the phonons in the silicon absorber at low temperature (< 1 K). Schottky barriers form naturally between the highly-doped silicon absorber and the superconducting contacts. Selective tunnelling of electrons across these Schottky barriers allows the electron temperature in the silicon absorber to be cooled to below the thermal bath temperature. This direct electron-cooling acts as thermoelectric feedback, reducing the time constant of a cold-electron bolometer to below 1 µs. In this work, the underlying physics of these devices is discussed and two devices are presented: one with a highly-doped silicon absorber and the other with strained highly-doped silicon used as the absorber. The design of these detectors is discussed and results are found from numerous characterisation experiments, including optical measurements. These measurements show that a prototype device, using a strained and highly-doped silicon absorber, has a noise-equivalent power of 6.6 × 10^-17 W/rtHz. When photon noise (which dominated this measurement) and noise from the amplifier are disregarded, the underlying device-limited noise-equivalent power is 2.0 × 10^-17 W/rtHz. By measuring the photon noise, the time constant of this detector has been determined to be less than 1.5 µs. When compared to the device using unstrained silicon, it is clear that the straining of the silicon absorber, which reduces the electron-phonon coupling, produces a notable improvement in detector performance. Furthermore, a novel amplifier-readout technique, whereby the outputs of two matched amplifiers are cross correlated is introduced; this technique reduces the input-referred amplifier noise from 1 nV/rtHz to 300 pV/rtHz.
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Youngblood, Brian Joaquin. "Bolometer diagnostics on Alcator C-mod." Thesis, Massachusetts Institute of Technology, 2004. http://hdl.handle.net/1721.1/33629.
Texte intégralRésumé :
Thesis (S.M.)--Massachusetts Institute of Technology, Dept. of Nuclear Engineering, 2004.<br>Includes bibliographical references (leaves 75-76).<br>Bolometry is a diagnostic technique common to most tokamak fusion experiments. Bolometers are so widespread because they provide an important measure of the energy lost from confined plasmas as radiation, as well as being relatively simple and resilient in their construction. Here the bolometric diagnostics of the Alcator C-mod tokamak, their function, limitations, and the details of their calibration, operation, and maintenance are covered. In addition, the results of a variety of investigations into the behavior of C-mod plasmas as observed by bolometers are presented and discussed. The measurements dealt with are either measurements of total power radiated by the plasma or measurements of radial emissivity profiles. Measurements of the first kind are suitable for studying the effects of factors like net input power while measurements of the second kind are useful for studying the effects of factors like local temperature profiles and plasma composition.<br>by Brian Joaquin Youngblood.<br>S.M.
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GAEL, MARIE-MAGDELEINE. "Thermalisation de l'energie dans un bolometre pour la detection d'ions." Paris 7, 1997. http://www.theses.fr/1997PA077139.
Texte intégralRésumé :
Cette these porte sur l'etude de deux aspects du fonctionnement des bolometres en vue d'application a la detection d'ions : les mecanismes physiques de thermalisation de l'energie deposee et etude de la resolution en energie du detecteur. Du reseau des caracteristiques courant-tension des thermometres nous deduisons les modalites de circulation de la chaleur dans le detecteur. Nous analysons ainsi la fuite thermique vers le bain et nous caracterisons le couplage electrons-phonons du materiau des thermometres. L'etude du bolometre en regime dynamique nous permet de rendre compte du processus de thermalisation de l'energie deposee par l'ion. Les thermometres sont non seulement des outils de mesure de la temperature mais aussi le lieu de thermalisation de l'energie. Nous montrons que le couplage electrons-phonons varie en t#5. La capacite calorifique des thermometres, quant a elle est proportionnelle a la temperature, ce qui implique une variation du temps de reponse du bolometre en t#-#4. Ce temps de reponse est le facteur limitant de rapidite dans nos experiences. Nous montrons aussi dans cette these la forte sensibilite de la forme des signaux en fonction de la position du point d'impact sur l'absorbeur. Nous obtenons une resolution de l'ordre de 45 kev pour les alphas de 5. 5 mev d'une source d'americium. La resolution apparait limitee par les fluctuations de ligne de base du bolometre dues a des vibrations mecaniques dans la gamme de frequences constitutives des signaux. L'elimination de ces parasites est necessaire pour affiner la resolution en energie.
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Leong, Jonathan Ryan Kyoung Ho. "Characterization of the Polarization and Frequency Selective Bolometric Detector Architecture." Case Western Reserve University School of Graduate Studies / OhioLINK, 2009. http://rave.ohiolink.edu/etdc/view?acc_num=case1232487119.
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Siringo, Giorgio. "PolKa a polarimeter for submillimeter bolometer arrays /." [S.l.] : [s.n.], 2003. http://deposit.ddb.de/cgi-bin/dokserv?idn=967819733.
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Aslam, Shahid. "High-temperature superconducting bolometers for space applications." Thesis, University of Oxford, 2006. http://ethos.bl.uk/OrderDetails.do?uin=uk.bl.ethos.437380.
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Stritzinger, Maximilian. "Type Ia supernovae bolometric properties and new tools for photometric techniques /." [S.l.] : [s.n.], 2005. http://deposit.ddb.de/cgi-bin/dokserv?idn=979066697.
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Walker, Gareth Robert. "Integration and optimisation of sensitive bolometric detectors with pulse-tube cryocoolers." Thesis, Cardiff University, 2007. http://orca.cf.ac.uk/54582/.
Texte intégralRésumé :
The integration of 300 mK semiconductor bolometers and 4 K hot-electron bolometers with commercial pulse tube cryocooler (PTC) systems has been investigated. The process also involved the integration of a two-stage 4He-3He adsorption refrigerator with the PTC to produce a cryogen free sub-Kelvin system. Thermometry electronics with an onboard computer and an internet interface have been developed that allow for remote and/or automatic operation. Methods to reduce excess noise seen in the 300 mK bolometer have been investigated to demonstrate the possibility of using high sensitivity bolometric detectors in this system for astrophysics and Earth observation instruments. In order to minimise the microphonic induced noise and thermal fluctuations from the pulse tube operation an AC biasing circuit was used. The origin of excess noise components in the bolometer readout have been identified and quantified as a function of both mechanical and electrical configurations of the cold components. With the optimum configuration thermal fluctuation noise, rather than microphonic induced noise dominates, reducing the bolometer sensitivity by approximately two times compared to the same device operated in a liquid helium cooled cryostat. Clearly the performance could be improved by increasing the thermal isolation of the sorption refrigerator from the pulse tube temperature oscillations. The hot-electron bolometer behaved nominally up to 6 kHz when operated in the cryogen free cryostat. Dynamic audio frequency noise deteriorated the detector's performance above 6 kHz and has been attributed to the movement of the helium gas through the PTC's valves and orifices during its thermodynamic cycle. Restrictions of the signal analyser mean that it is unclear whether this microphonic noise is present above 1 MHz.
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Heidenblut, Torsten. "Herstellung und Charakterisierung von Hochtemperatursupraleiter-Bolometern auf gepufferten Siliziumnitrid-Membranen." [S.l. : s.n.], 2001. http://deposit.ddb.de/cgi-bin/dokserv?idn=961538058.
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Decharat, Adit. "Integration and Packaging Concepts for Infrared Bolometer Arrays." Licentiate thesis, KTH, School of Electrical Engineering (EES), 2009. http://urn.kb.se/resolve?urn=urn:nbn:se:kth:diva-10690.
Texte intégralRésumé :
<p> </p><p>Infrared (IR) imaging devices based on energy detection has shown a dramatic development in technology along with an impressive price reduction in recent years. However, for a low-end market as in automotive applications, the present cost of IR cameras is still the main obstacle to broadening their usage. Ongoing research has continuously reduced the system cost. Apart from decreasing the cost of infrared optics, there are other key issues to achieve acceptable system costs, including wafer-level vacuum packaging of the detectors, low vacuum level operation, and the use of standard materials in the detector fabrication. This thesis presents concepts for cost reduction of low-end IR cameras.</p><p> The thesis presents a study of detector performance based on the thermal conductance design of the pixel. A circuit analog is introduced to analyze the basic thermal network effect from the surrounding environment on the conductance from the pixel to the environment. A 3D simulation model of the detector array conductance has been created in order to optimize the performance of the arrays while operated in low vacuum. In the model, Fourier's law of heat transfer is applied to determine the thermal conductance of a composite material pixel. The resulting thermal conductance is then used to predict the performance of the detector array in low vacuum.</p><p> The investigations of resist as the intermediate bonding material for 3D array integration are also reported in the thesis. A study has been made of the nano-imprint resists series mr-I 9000 using a standard adhesive wafer bonding scheme for thermosetting adhesives. Experiments have been performed to optimize the thickness control and uniformity of the nano-imprint resist layer. The evaluation, including assessment of the bonding surface uniformity and planarizing ability of topographical surfaces, is used to demonstrate the suitability of this resist as sacrificial material for heterogeneous detector array integration<em>. </em><em></em></p><p> Moreover, the thesis presents research in wafer-level packaging performed by room temperature bonding. Sealing rings, used to create a cavity, are manufactured by electroplating. The cavity sealing is tested by liquid injection and by monitoring the deflection of the lid membrane of the cavities. A value for the membrane deflection is calculated to estimate the pressure inside the cavities. </p>
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Kim, Joo-Hyung. "Micromachined epitaxial colossal mognetoresistors for uncooled infrared bolometer." Doctoral thesis, KTH, Microelectronics and Information Technology, IMIT, 2005. http://urn.kb.se/resolve?urn=urn:nbn:se:kth:diva-535.
Texte intégralRésumé :
<p>High quality perovskite manganites, La1<sub>-x</sub>A<sub>x</sub>MnO<sub>3</sub> (A = Ca, Sr, Ba) are very attractive materials due to their great application potential for magnetic memory, uncooled infrared (IR) microbolometer and spintronics devices. This thesis presents studies of the growth and material characterization (including structural, electrical, magnetic and noise) of epitaxial manganite films on Si and GaAs. Furthermore, investigations about strain effect on structural and electrical properties of manganites, and finally fabrication of self-supported free standing microstructures for uncooled IR bolometer are also demonstrated.</p><p>To obtain high quality epitaxial manganite films on semiconductor substrates at room temperature, using a combination of La<sub>0.67</sub>Sr<sub>0</sub>.<sub>33</sub>MnO<sub>3 </sub>(LSMO) and La<sub>0.67</sub>Ca<sub>0.33</sub>MnO<sub>3 </sub>(LCMO) compounds, La<sub>0.67</sub>(Sr,Ca)<sub>0.33</sub>MnO<sub>3</sub> (LSCMO) films were successfully grown on Si substrates with Bi<sub>4</sub>Ti<sub>3</sub>O<sub>12</sub>(BTO)/CeO<sub>2</sub>/YSZ buffers by pulsed laser deposition (PLD) technique. Crystallographic relations between layers shows cube-on-cube for BTO/CeO2/YSZ/Si and diagonal-on-side for LSCMO films on BTO layer. 4.4 %K<sup>-1 </sup>maximum temperature coefficient of resistivity (TCR = 1/ρ·dρ/dT) and 2.9 %kOe<sup>-1</sup> colossal magnetoresistance (CMR) were obtained at room temperature. Assuming of a prototype of temperature sensor, 1.2 μK/√Hz of noise equivalent temperature difference (NETD) and 2.9×10<sup>8</sup> cm√Hz/W of detectivity are expected to achieve at 294 K, 30 Hz. For GaAs substrates, using MgO buffer layer, LCMO films shows 9.0 %K<sup>-1</sup> of TCR at 223 K while LSMO exhibits 2 %K<sup>-1</sup> at 327 K.</p><p>Systematic strain effects on structural and electrical properties of La<sub>0</sub>.<sub>75</sub>Sr<sub>0.25</sub>MnO<sub>3</sub> LSMO) films on BTO/CeO2/YSZ-buffered Si, Si<sub>1-x</sub>Ge<sub>x</sub>/Si (compressive strain, x = 0.05-0.20) and Si<sub>1-y</sub>C<sub>y</sub>/Si (tensile, y = 0.01) were investigated. The strain induced from Si<sub>1-x</sub>Ge<sub>x</sub>/Si and Si<sub>0.99</sub>C<sub>0.01</sub>/Si has a tendency to decrease the roughness of CMR films compared to Si sample. High resistivity and low TCR values are observed for Si<sub>0.8</sub>Ge<sub>0</sub>.<sub>2</sub>/Si and Si<sub>0.99</sub>C<sub>0.01</sub>/Si samples due to excessive strains whereas Si<sub>0</sub>.<sub>9</sub>Ge<sub>0.1</sub>/Si and Si<sub>0.95</sub>Ge<sub>0.05</sub>/Si show slight improvements of films quality and TCR value.</p><p>To fabricate LSCMO manganite bolometer on Si, wet etching with KOH and BHF and dry etching methods with Ar ion beam etching (IBE) were studied. For KOH wet etching, LSCMO films show high chemical resistance with lower than 0.2 nm/min of etch rate. BHF wet etching shows high etching selectivity over photoresist mask and silicon substrates. The etch rates for LSCMO and BTO layers are 22 and 17 nm/min. For Ar IBE, LSCMO films and oxide buffer layers show similar etch rates, 16-17 nm/min that are lower compared to 24 nm/min for Si.</p><p>Free standing, self-supported heteroepitaxial LSCMO/BTO/CeO<sub>2</sub>/YSZ membranes for bolometer pixels on Si was successfully fabricated by Ar IBE and ICP etching techniques using a preannealed photoresist. The structural investigation by TEM revealed the sharp interfaces between layers. The electrical property of the free standing membrane was slightly degraded due to strain release and multi-step etching effect. These results demonstrate feasibility to use heteroepitaxial oxide structures as a thermally isolated membrane with conventional photoresist patterning.</p>
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Kim, Joo-Hyung. "Micromachined epitaxial colossal magnetoresistors for uncooled infrared bolometer /." Stockholm, 2005. http://urn.kb.se/resolve?urn=urn:nbn:se:kth:diva-535.
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Lu, Ming-Lin Ziv 1975. "Micro bolometers and readout circuits for infrared sensing." Thesis, McGill University, 2002. http://digitool.Library.McGill.CA:80/R/?func=dbin-jump-full&object_id=79249.
Texte intégralRésumé :
There are two major types of detectors for IR imaging and sensing: photon detector and thermal detector. Photon detector converts photon energy directly into electrical signal. Thermal detector, on the other hand, has a temperature-sensitive electrical property and its temperature can be easily altered by incident IR radiation. To reduce noise, both photon detector and previous generation bolometer require cooling. A new generation of uncooled bolometer emerged recently and will be the focus of this study.<br>Micromachining processes were used to fabricate bolometers and bolometric material test vehicles. Both surface micromachining and bulk micromachining were attempted. The surface micromachined bolometers were created by the MUMPs process. The material of the bolometer structures was polysilicon. From the measurements carried out, it was shown that the present polysilicon bolometers have a TCR of 0.123%/K and a thermal conductivity of 2 * 10-6 W/K.<br>For the bulk micromachined bolometers, Bismuth bolometers were deposited on silicon dioxide membranes on top of a silicon wafer. The silicon dioxide membranes were made by overetching the bulk. A TCR of -0.21%/K, thermal conductance of 4.58 * 10-5 W/K and a responsivity of 0.4 V/W were measured.<br>A 4 by 4 readout circuit was fabricated by TSMC 0.35 mum CMOS process. It consists of pixel biasing, pixel selection, and output amplifying stage. Two do voltage offset correction methods were proposed and examined. The proposed do voltage offset correction methods could minimize the offset voltage to 113 muV.
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Lentz, William Alexander 1976. "Characterization of noise in uncooled IR bolometer arrays." Thesis, Massachusetts Institute of Technology, 1998. http://hdl.handle.net/1721.1/28199.
Texte intégralRésumé :
Thesis (M.Eng.)--Massachusetts Institute of Technology, Dept. of Electrical Engineering and Computer Science, 1998.<br>Includes bibliographical references (p. 81-82).<br>by William Alexander Lentz.<br>M.Eng.
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Öktem, Bülent Abukay Doğan. "High temperature superconducting YBa2Cu3O7 thin flims and bolometers/." [s.l.]: [s.n.], 2006. http://library.iyte.edu.tr/tezler/master/fizik/T000555.pdf.
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Marnieros, Stefanos. "Couches minces d'isolant d'anderson application a la bolometrie a tres basse temperature." Paris 11, 1998. http://www.theses.fr/1998PA112119.
Texte intégralRésumé :
Les bolometres fonctionnant a tres basse temperature mesurent l'energie deposee par ses effets thermiques. Universels, ayant les records de sensibilite dans plusieurs champs de recherche, ils ont permis de realiser ou d'envisager des experiences dont la portee scientifique est majeure : recherche directe des wimps comme candidats pour la matiere noire non baryonique, etude approfondie du corps noir cosmologique dans les prochaines experiences spatiales (planck surveyor, first). J'ai travaille a l'elaboration, la caracterisation et la comprehension au niveau de leurs proprietes fondamentales de couches minces de nb#xsi#1#-#x qui relevent de la problematique de la transition metal-isolant de mott-anderson. Des bolometres de masse consequente (de 25 a 250 g) ont ete realises avec ces couches minces comme senseurs thermometriques. J'ai montre que ces couches sont sensibles aux phonons balistiques hors d'equilibre qui portent transitoirement l'energie deposee apres l'impact d'une particule dans le detecteur. Conformement au modele de fonctionnement athermique des bolometres que j'ai adapte et optimise pour notre configuration, j'ai pu montrer experimentalement que la sensibilite du detecteur est pratiquement independante de la masse de l'absorbeur. Ce travail ouvre donc la perspective de bolometres massifs de haute sensibilite, ainsi que celle de bolometres dotes d'une capacite de localisation des impacts et de discrimination des evenements.
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Richter, Heiko Helmut. "Entwicklung von Hot-Electron-Bolometer-Mischern für Terahertz-Heterodynempfänger." [S.l.] : [s.n.], 2005. http://deposit.ddb.de/cgi-bin/dokserv?idn=975329480.
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Greenspan, Jonathan. "The fabrication and characterization of metal thin film bolometers." Thesis, National Library of Canada = Bibliothèque nationale du Canada, 1998. http://www.collectionscanada.ca/obj/s4/f2/dsk1/tape11/PQDD_0023/MQ50612.pdf.
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Viklund, Jonas. "Developing of an ultra low noise bolometer biasing circuit." Thesis, Uppsala universitet, Fasta tillståndets elektronik, 2016. http://urn.kb.se/resolve?urn=urn:nbn:se:uu:diva-296698.
Texte intégralRésumé :
Noise in electronic circuits can sometimes cause problems. It is especially problematic in for example high sensitive sensors and high end audio and video equipment. In audio and video equipment the noise will make its way into the sound and picture reducing the overall quality. Sensors that are constructed to sense extremely small changes can only pick up changes larger than the noise floor of the circuit. By lowering the noise, sensors can achieve higher accuracy. This thesis presents an ultra low noise solution of the biasing circuitry to the bolometer used in one of FLIR Systems high end cameras. The bolometer uses different adjustable direct current voltage sources and is extremely sensitive to noise. The purpose is to improve the picture quality and the thermal measurement resolution. A prototype circuit was constructed and in the end of the thesis a final circuit with successful result will be presented.
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Gimbal-Zofka, Yann. "Development and study of luminescent bolometers for neutrino physics." Thesis, Linnéuniversitetet, Institutionen för fysik och elektroteknik (IFE), 2017. http://urn.kb.se/resolve?urn=urn:nbn:se:lnu:diva-60660.
Texte intégralRésumé :
This Master thesis aims at designing, assembling and operating a prototypal luminescentbolometer containing a candidate with high Q-value (116Cd and 100Mo)for the study of the neutrinoless double- decay. The crystal is scintillating (with 116CdWO4 and Li2MoO4 compounds). The prototype is designed according to a simple thermal model and cooled down to 18 mK. Data analysis of the 116CdWO4 crystal determines the energy resolution (intrinsicand in the ROI) and the alpha/beta discrimination power. It includes a full interpretation of the background energy spectrum in terms of environmental radioactivity and an evaluation of the crystal radiopurity by the detection of internal contamination of the detector. An evaluation of the potential of a future experiment based on the 116CdWO4developed prototype is performed, ascertaining the feasibility of large scale experiments to search for neutrinoless double beta decay. The use of the thermal model of the detector response to interpret its bolometric behaviour and the study of future optimizations of the detector performance concludes this project.
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Baubert, Jean Benoît Martin. "Superconducting hot electron bolometers on thin membranes for SHAHIRA." Paris 6, 2005. http://www.theses.fr/2005PA066617.
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GORET, PASCAL. "Developpements de bolometres pour la recherche de matiere noire." Paris 6, 1993. http://www.theses.fr/1993PA066102.
Texte intégralRésumé :
Cette these presente un travail effectue dans le cadre d'un projet de developpement de bolometres (cristaux et thermometres) pour la recherche de matiere noire non baryonique. L'etude du fonctionnement statique d'un bolometre de 24 g de saphir a permis de modeliser les resistances thermiques existant entre les differents constituants de ce bolometre. Cette connaissance represente un des elements essentiels pour la comprehension du signal delivre par le detecteur. La comparaison des techniques d'amplification du signal (en courant et en tension) a montre que, pour une meme temperature du cryostat, le maximum du rapport signal sur bruit ne depend pas seulement de la temperature du thermometre, mais egalement du mode d'amplification utilise. La derniere partie est consacree a l'analyse des premieres mesures bolometriques en site souterrain a basses energies, realisees en novembre 1991 au laboratoire souterrain de modane. Les resultats obtenus montrent que le niveau de bruit de fond atteint est essentiellement du a la radioactivite des parties du cryostat a dilution utilise, les plus proches du detecteur. Ces resultats confirment egalement l'un des points forts des bolometres, qui mesurent toute l'energie deposee dans le cristal, a savoir le faible seuil en energie (3 kev)
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Bernert, Matthias. "Analysis of the H-mode density limit in the ASDEX Upgrade tokamak using bolometry." Diss., Ludwig-Maximilians-Universität München, 2013. http://nbn-resolving.de/urn:nbn:de:bvb:19-162625.
Texte intégralRésumé :
The high confinement mode (H-mode) is the operational scenario foreseen for ITER, DEMO and future fusion power plants. At high densities, which are favourable in order to maximize the fusion power, a back transition from the H-mode to the low confinement mode (L-mode) is observed. This H-mode density limit (HDL) occurs at densities on the order of, but below, the Greenwald density.
In this thesis, the HDL is revisited in the fully tungsten walled ASDEX Upgrade tokamak (AUG). In AUG discharges, four distinct operational phases were identified in the approach towards the HDL.
First, there is a stable H-mode, where the plasma density increases at steady confinement, followed by a degrading H-mode, where the core electron density is fixed and the confinement, expressed as the energy confinement time, reduces. In the third phase, the breakdown of the H-mode and transition to the L-mode, the overall electron density is fixed and the confinement decreases further, leading, finally, to an L-mode, where the density increases again at a steady confinement at typical L-mode values until the disruptive Greenwald limit is reached.
These four phases are reproducible, quasi-stable plasma regimes and provide a framework in which the HDL can be further analysed.
Radiation losses and several other mechanisms, that were proposed as explanations for the HDL, are ruled out for the current set of AUG experiments with tungsten walls.
In addition, a threshold of the radial electric field or of the power flux into the divertor appears to be responsible for the final transition back to L-mode, however, it does not determine the onset of the HDL.
The observation of the four phases is explained by the combination of two mechanisms: a fueling limit due to an outward shift of the ionization profile and an additional energy loss channel, which decreases the confinement.
The latter is most likely created by an increased radial convective transport at the edge of the plasma.
It is shown that the four phases occur due to a coupling of these two mechanisms.
These observations are in line with studies made at AUG with carbon walls, although in those discharges the energy loss was most likely caused by the full detachment of the divertor.
The density of the HDL depends only weakly on the plasma current, unlike the Greenwald limit, and can be increased by high heating power, again unlike the Greenwald limit.
The triangularity of the plasma has no influence on the density of the HDL, though improves the performance of the plasma, since the onset of the degrading H-mode phase occurs at higher densities.
It is explicitly shown that the HDL and also the L-mode density limit are determined by edge parameters.
Using pellet fueling, centrally elevated density profiles above the Greenwald limit can be achieved in stable H-modes at a moderate confinement.
Future tokamaks will have intrinsic density peaking. Consequently, they will most likely operate in H-modes above the Greenwald limit.<br>Für den Betrieb von zukünftigen Fusionsexperimenten, wie ITER und DEMO, ist das H-Mode-Operationsregime vorgesehen, das sich gegenüber dem L-Mode-Regime durch einen verbesserten Energieeinschluss auszeichnet. Dabei werden hohe Dichten angestrebt um die Fusionsleistung zu maximieren. Bei zu hohen Dichten findet jedoch ein Übergang in das L-Mode-Regime statt. Dieses H-Mode-Dichtelimit (HDL) tritt in der Nähe des Greenwald Limits (GWL) auf, welches eine obere Dichtegrenze für den Betrieb von Tokamaks darstellt.
Im Rahmen dieser Doktorarbeit wurde das H-Mode-Dichtelimit am Tokamak ASDEX Upgrade (AUG) im Betrieb mit einer Wolframwand experimentell untersucht. Verschiedene existierende Erklärungsansätze für das Auftreten des HDL, wie zum Beispiel der Einfluss von Strahlungsverlusten, wurden für die durchgeführten Experimente ausgeschlossen.
Eine systematische Untersuchung zeigt, dass das HDL durch vier verschiedene, reproduzierbare und quasi-stabile Plasmazustände, die mit ansteigender Plasmadichte aufeinander folgen, charakterisiert wird. Die erste Phase ist eine stabile H-Mode, bei der die Dichte bei konstantem Druck ansteigt. Darauf folgt ein degradierendes H-Mode-Regime, bei dem die zentrale Dichte konstant ist und der Energieeinschluss verschlechtert wird. Die dritten Phase ist der Zusammenbruch des H-Mode-Regimes und somit das eigentliche HDL. Dabei wird der erhöhte H-Mode-Temperaturgradient am Rand abgebaut. In dieser Phase bleibt das gesamte Dichteprofil jedoch konstant. Mit der vierten Phase hat das Plasma das L-Mode-Regime erreicht, bei dem die Dichte bei einem konstanten, niedrigen Energieeinschluss wieder ansteigt.
Grenzwerte des radialen elektrischen Feldes und die Leistungsschwelle der H-Mode erklären potentiell den Übergang in die L-Mode, können aber für das Einsetzen des HDL ausgeschlossen werden.
Die vier Phasen werden durch eine Kombination von zwei Effekten erklärt: ein Absinken der Ionisationsrate im eingeschlossenen Plasma und ein zusätzlicher, bei hohen Dichten auftretender Energieverlustkanal. Diverse Beobachtungen deuten darauf hin, dass der Verlustkanal durch einen erhöhten konvektiven Transport am Rand des Plasmas entsteht.
In dieser Arbeit wurden die vier Phasen auch in AUG Plasmen mit Kohlenstoffwand nachgewiesen. Die Unterschiede zwischen den Beobachtungen bei beiden Wandmaterialien werden auf eine Änderung des Energieverlustkanals zurückgeführt. Dieser Verlustkanal wurde bei Kohlenstoff durch das Ablösen des Plasmas von der Wand erklärt. Dieser Effekt konnte für Wolfram jedoch ausgeschlossen werden.
Im Gegensatz zum GWL hängt die Dichte des HDLs im Betrieb mit Wolframwand nur schwach vom Plasmastrom ab. In dieser Arbeit wurde allerdings eine deutliche Abhängigkeit von der Heizleistung nachgewiesen. Die Triangularität des Plasmas hat keine Auswirkung auf die Dichte des HDL, kann aber die Einschlussgüte des Plasmas bei hohen Dichten deutlich erhöhen, da die degradierende Phase später einsetzt.
Es wird gezeigt, dass man das HDL und das GWL mit zentral erhöhten Dichteprofilen überschreiten kann. Das beweist, dass beide Limits durch Parameter am Rand bestimmt werden. Hochtemperaturplasmen, wie in ITER und DEMO, werden voraussichtlich intrinsisch zentral erhöhte Dichteprofile haben und sollten entsprechend der vorgestellten Ergebnisse bei Dichten oberhalb des GWL in H-Mode betrieben werden können.
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Khalife, Hawraa. "CROSS and CUPID-Mo : future strategies and new results in bolometric search for 0νββ". Thesis, université Paris-Saclay, 2021. http://www.theses.fr/2021UPASP002.
Texte intégralRésumé :
La désintégration double-beta sans émission de neutrino est une transition nucléaire hypothétique et rare (T₁/₂>10²⁶ ans). Son observation fournirait de précieuses informations sur la nature des neutrinos. En particulier, cela démontrerait que ceux-ci sont des particules de Majorana et qu’il n’y a pas conservation du nombre de lepton. Cette désintégration peut être étudiée avec des bolomètres dont l’absorbeur contient l’isotope susceptible de se désintégrer, mais la possibilité d’analyser ce processus rare dépend crucialement du niveau de bruit de fond dans la région d’intérêt. Une nouvelle R&D a récemment débuté au sein du projet CROSS (Cryogenic Rare-event Observatory with Surface Sensitivity) visant au développement de bolomètres cryogéniques incluant les isotopes prometteurs ¹⁰⁰Mo and ¹³⁰Te. Ces bolomètres sont capables de discriminer les interactions α et β de surface via l’exploitation des propriétés d’un matériau supraconducteur (film d’Al) ou d’un métal normal (film de Pd) déposé sur les faces du cristal (Li₂MoO₄ and TeO₂). Ces films jouent le rôle de modificateurs de forme pour les impulsions. Les résultats des tests sur des prototypes fabriqués et testés au CSNSM (Orsay, France) ont montré la capacité de films d’Al (de Pd) de quelques μm (nm) d’épaisseur déposés à la surface du cristal de discriminer les événements de surface des événements bulk, avec un niveau de réjection compatible avec celui exigé par les expériences finales. Alors que le film d’Al ne peut identifier que les particules α de surface, avec des films métalliques normaux, nous avons été capables de séparer également les composantes β de surface. Ceci constitue une avancée importante dans la technologie bolométrique pour la décroissance double beta qui pourrait atteindre, avec cette technologie, un indice de bruit de fond de l’ordre de 10⁻⁵ événements/(keV kg an). De plus, la présente thèse expose les résultats de l’expérience CUPID-Mo, un démonstrateur de CUPID, une expérience d’une tonne de prochaine génération pour la détection du 0νββ. CUPID-Mo utilise des bolomètres scintillants en Li₂MoO₄ qui discriminent entre les α et les β/γ, permettant ainsi de rejeter la contribution dominante au bruit de fond (particules α). L’expérience a permis d’atteindre une nouvelle limite sur le temps de demi-vie de la désintégration 0νββ dans le ¹⁰⁰Mo : T₁/₂> 1.5 x 10²⁴ ans à 90% C.I<br>Neutrinoless double-beta decay is a hypothetical rare nuclear transition (T₁/₂>10²⁶ yr). Its observation would provide an important insight about the nature of neutrinos ascertaining that they are Majorana particles and demonstrating that the lepton number is not conserved. This decay can be investigated with bolometers embedding the double beta decay isotope, the possibility to investigate this rare process is strongly influenced by the background level in the region of interest. A new R&D has recently begun within the CROSS project (Cryogenic Rare-event Observatory with Surface Sensitivity) aiming at the development of bolometric detectors, embedding the promising isotopes ¹⁰⁰Mo and ¹³⁰Te, capable of discriminating surface α et β interactions by exploiting the properties of superconducting material (Al film) or normal metal (Pd film) deposited on the crystal faces (Li₂MoO₄ and TeO₂). These films work as pulse-shape modifiers. The results of the tests on prototypes performed at CSNSM (Orsay, France) showed the capability of a few- μm (nm)-thick Al (Pd) film deposited on the crystal surface to discriminate surface from bulk events, with the required rejection level of the surface background. While Al film can only identify surface α particles, with normal-metal films we were able to separate also the β surface component. This is a breakthrough in bolometric technology for double beta decay that could lead to reach a background index in the range 10⁻⁵ counts/(keV kg yr). In addition, the thesis covers the CUPID-Mo experiment, a demonstrator of CUPID, the next-generation ton-scale cryogenic 0νββ experiment. CUPID-Mo employs Li₂MoO₄ scintillating bolometers that allows to discriminate between α and β/γ, thus rejecting the dominant contribution on the background that consists in α particle interactions. The experiment achieved a new limit on the half-life of 0νββ decay in ¹⁰⁰Mo of T₁/₂> 1.5 x 10²⁴ yr at 90% C.I., the best ever obtained worldwide on this isotope
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Stever, Samantha Lynn. "Characterisation and modelling of the interaction between sub-Kelvin bolometric detectors and cosmic rays." Thesis, Université Paris-Saclay (ComUE), 2019. http://www.theses.fr/2019SACLS009/document.
Texte intégralRésumé :
Nous avons étudié l'effet des rayons cosmiques dans les détecteurs en utilisant un bolomètre de germanium composite NTD à basse température, et une source de particules alpha comme source générique d'impulsions. Nous avons caractérisé ce bolomètre en constatant que la forme de son impulsion était due à la combinaison de sa réponse impulsionnelle (la somme de deux exponentielles doubles), et des effets liés à la position découlant de la thermalisation des phonons balistiques en phonons thermiques dans son absorbeur. Nous avons établi un schéma décrivant la forme de l'impulsion dans ce bolomètre en comparant une impulsion mathématique générique à une seconde description basée sur la physique thermique. Nous constatons que la thermalisation des phonons balistiques, suivie de la diffusion thermique, jouent un rôle important dans la forme de l'impulsion, en parallèle avec le couplage électrothermique et les effets électriques dépendant de la température. Nous avons modélisé les impulsions en observant que leur comportement peut être reproduit en tenant compte de la réflexion de phonons balistiques sur le bord de l’absorbeur, avec un couplage thermique fort au capteur central du bolomètre. Compte tenu de ces résultats, nous étudions également les effets des rayons cosmiques sur l’instrument Athena X-Ray Integral Field Unit (X-IFU), en produisant des timelines simulées et en testant la hausse de la valeur moyenne de la température (RMS) sur la plaquette du détecteur. Nous montrons que le flux thermique attendu des rayons cosmiques est au même ordre de grandeur que le maximum autorisé ΔTRMS ce qui constitue une menace sur le budget de la résolution énergétique de l'instrument<br>We have studied the effect of cosmic rays in detectors using a composite NTD germanium bolometer at low temperatures and an alpha particle source as a generic source of pulses. We have characterised this bolometer, finding that its pulse shape is due to a combination of its impulse response function (the sum of two double exponentials), and position-dependent effects arising from thermalisation of ballistic phonons into thermal phonons in its absorber. We have derived a scheme for describing the pulse shape in this bolometer, comparing a generic mathematical pulse shape with a second description based on thermal physics. We find that ballistic phonon thermalisation, followed by thermal diffusion, play a significant role in the pulse shape, along with electro-thermal coupling and temperature-dependent electrical effects. We have modelled the pulses, finding that their behaviour can be reproduced accounting for ballistic phonon reflection off the absorber border, with a strong thermal coupling to the bolometer’s central sensor. With these findings, we also investigate the effects of cosmic rays on the Athena X-Ray Integral Field Unit (X-IFU), producing simulated timelines and testing the average RMS temperature increase on the detector wafer, showing that the expected cosmic ray thermal flux is within the same order of magnitudeas the maximum allowed ΔTRMS, posing a threat to the instrument’s energy resolution budget
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Stockhausen, Axel [Verfasser]. "Optimization of Hot-Electron Bolometers for THz Radiation / Axel Stockhausen." Karlsruhe : KIT Scientific Publishing, 2013. http://www.ksp.kit.edu.
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MacDermid, Kevin. "Design and testing of tuning algorithms for the E and B EXperiment (EBEX)." Thesis, McGill University, 2008. http://digitool.Library.McGill.CA:80/R/?func=dbin-jump-full&object_id=116095.
Texte intégralRésumé :
Detection of B-mode polarization from the cosmic microwave background would provide compelling evidence for the inflationary paradigm and has thus become a principal goal for experimental cosmologists during the last 5-10 years. A number of high sensitivity experiments have been developed and many are under construction, including the E and B EXperiment (EBEX), a balloon-borne experiment scheduled to take data in 2010. The design of EBEX is presented here, including the scientific motivation for the experiment, and an overview of all its components, with particular attention paid to the read out electronics for its array of over 1300 biometries detectors. In the read out of such a large array of bolometers, which must be kept at ∼250mK, running many signals down the same wire (i.e. multiplexing) is vital. The digital frequency multiplexing (dfmux) electronics designed and tested at McGill addresses this as well as providing the control required to tune the bolometers and super conducting quantum interference devices (SQUIDs) used in readout. How these electronics accomplish both of these goals is described with an in-depth description of the recently designed tuning algorithms required to take the detectors from initialization to fully-operational. Finally, some tests of the readout system on cold bolometers in a test cryostat are presented. These measurements are encouraging with 98% success rate of automated tuning on a test sample of 47 bolometers. Improvements to achieve a 100% success rate have been proposed and will be implemented for the upcoming integration of the bolometer camera with the telescope in November 2008. A test-flight for the experiment is planned for spring 2009, and the science flight for 2010 from Antarctica.
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Eames, Sara Jennifer. "Novel light absorbing species for a wavelength-selective high-temperature superconducting bolometer /." Full text (PDF) from UMI/Dissertation Abstracts International, 2000. http://wwwlib.umi.com/cr/utexas/fullcit?p3004256.
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Longhin, Mattia. "Semiconducting bolometric detectors : material optimization and device design for future room temperature THz imaging arrays." Paris 6, 2009. http://www.theses.fr/2009PA066076.
Texte intégralRésumé :
L’application à grande échelle des technologies liées au rayonnement terahertz (THz) est encore aujourd’hui limitée par leur complexité et les coûts élevés. Dans ce mémoire, nous proposons des détecteurs bolométriques économiques fonctionnant à température ambiante pour application à l’imagerie THz. Dans ce contexte, nous avons tout d’abord étudié le dépôt de films minces de la phase semiconductrice de l’oxyde YBaCuO et optimisé les caractéristiques structurales et électriques des films minces pour les rendre compatibles avec une technologie CMOS. Nous avons ensuite initié et mis en œuvre de nouveaux procédés de technologie pour fabriquer des bolomètres à partir des films minces semiconducteurs. En particulier, nous nous sommes occupés du couplage entre l’antenne THz et l’élément sensible. Finalement, de premiers dispositifs correspondant à différentes configurations possibles du détecteur ont été réalisés et testés.
36
Zolotarova, Anastasiia. "Study and selection of scintillating crystals for the bolometric search for neutrinoless double beta decay." Thesis, Université Paris-Saclay (ComUE), 2018. http://www.theses.fr/2018SACLS293/document.
Texte intégralRésumé :
L'observation de la désintégration double bêta sans émission de neutrino (0ν2β) fournirait des informations essentielles sur la nature du neutrino et son échelle de masse absolue. Ce processus consiste en la transformation simultanée de deux protons en deux neutrons avec l'émission de deux électrons et aucun neutrino. Cette transition n'est possible que si les neutrinos sont égaux aux antineutrinos (nature Majorana du neutrino). Les recherches pour une désintégration à ce point rare représentent un défi technique complexe, car les expériences de prochaine génération visent des sensibilités de l'ordre de 10^27-10^28 ans afin d'avoir un potentiel de découverte élevé. Cette thèse est focalisée sur les projets LUMINEU et CUPID-Mo, développant la technique des bolomètres scintillants pour la recherche de désintégration 0ν2β avec le radio-isotope 100Mo.Les bolomètres sont des détecteurs cryogéniques mesurant l'énergie des particules déposées via un changement de température dans l'absorbeur. Si des cristaux scintillants sont utilisés comme absorbeurs, les signaux lumineux peuvent être enregistrés avec un bolomètre auxiliaire, sensible à l'énergie totale déposée par les photons de scintillation. Une telle configuration permet de séparer les particules α des γ/β, en rejetant le fond le plus difficile. La technologie des bolomètres scintillants est décrite en détail comme une option pour une future expérience cryogénique à l'échelle d'une tonne, appelée CUPID, qui peut couvrir complètement la région de masses de neutrinos dans la hiérarchie inversée<br>Neutrinoless double beta (0ν2β) decay is a process of great interest for neutrino physics: its observation would provide essential information on neutrino nature and its absolute mass scale. This process consists of the simultaneous transformation of two protons into two neutrons with the emission of two electrons and no neutrino, implying the violation of the total lepton number. Such transition is possible only if neutrinos are equal to antineutrinos (Majorana particles). The searches for such a rare decay are becoming a complicated technical challenge, as next generation of 0ν2β experiments aim at sensitivities of the order of half-life at 10^27-10^28 yr. This thesis is focused on LUMINEU and CUPID-Mo projects, developing the scintillating bolometers technique for 0ν2β decay search with 100Mo with Li2MoO4 crystals. Bolometers are cryogenic detectors measuring the deposited particle energy as a change of temperature in the absorber. The use of scintillating crystals allows to perform discrimination of α particles from γ/β ones due to different light output of these two particle types, rejecting the most challenging background. The scintillating bolometers technology is described in details as an option for a future ton-scale cryogenic experiment, named CUPID, which can completely cover the inverted hierarchy region of neutrino masses
37
Raccanelli, Andrea. "HUMBA the hundred millikelvin bolometer array for 2 mm continuum observations /." [S.l.] : [s.n.], 2003. http://deposit.ddb.de/cgi-bin/dokserv?idn=968777686.
Texte intégral
38
Taele, Benedict Molibeli. "III-V semiconducting hopping bolometers for detecting nonequilibrium phonons and astroparticles." Thesis, Lancaster University, 2000. http://ethos.bl.uk/OrderDetails.do?uin=uk.bl.ethos.322851.
Texte intégral
39
Northeast, David Bernard. "Hot electron bolometer sensors for millimetre-wave and terahertz wave detection." Thesis, Stellenbosch : University of Stellenbosch, 2011. http://hdl.handle.net/10019.1/6468.
Texte intégralRésumé :
Thesis (MScEng (Electrical and Electronic Engineering))--Univerity of Stellenbosch, 2011.<br>ENGLISH ABSTRACT: The design and simulation of hot electron bolometer sensors for the detection
of millimeter and terahertz wave radiation is presented. These devices can be
used for the formation of images or for spectroscopy in these frequency ranges.
Many molecules resonate and have absorption spectra over these ranges, allowing
for the identi cation, non-destructively and at a distance, of the constitution
of many di erent materials. The penetrating ability of the radiation
makes mm-wave and THz wave detectors ideal for security imaging. The design
and simulation of these devices predicts performance as mixers and as
interferometers. Manufacturing processes used while fabricating these thin
lm devices are outlined and experimental results are reported.<br>AFRIKAANSE OPSOMMING: Hierdie tesis bespreek die ontwerp en simulasie van warm-elektron bolometers
vir die waarneming van millimetergolf- en terahertz-straling. Sodanige
toestelle kan in bogenoemde frekwensiebereike gebruik word vir beeldvorming
of spektroskopie. Aangesien heelwat molekules binne hierdie bande resoneer,
kan die samestelling van 'n verskeidenheid materiale oor 'n afstand en op
'n nie-vernietigende wyse gedenti seer word. Die deurdringingsvermo van
millimetergolf- en terahertz-straling maak sulke detektors ideaal vir beeldvorming
in veiligheidstoepassings. Met die ontwerp en simulasie van hierdie
toestelle word gewys wat hul werkverrigting as mengers en interferometers kan
wees. Die prosesse wat gebruik is om hierdie dun lmtoestelle mee te vervaardig
word ook bespreek en eksperimentele resultate word aangebied.
40
Otto, Ernst. "Development of superconducting bolometer device technology for millimeter-wave cosmology instruments." Thesis, University of Oxford, 2013. http://ora.ox.ac.uk/objects/uuid:30a1103a-ea7a-4b08-ba92-665cbd9740e0.
Texte intégralRésumé :
The Cold-Electron Bolometer (CEB) is a sensitive detector of millimeter-wave radiation, in which tunnel junctions are used as temperature sensors of a nanoscale normal metal strip absorber. The absorber is fed by an antenna via two Superconductor-Insulator-Normal metal (SIN) tunnel junctions, fabricated at both ends of the absorber. Incoming photons excite electrons, heating the whole electron system. The incoming RF power is determined by measuring the tunneling current through the SIN junctions. Since electrons at highest energy levels escape the absorber through the tunnel junctions, it causes cooling of the absorber. This electron cooling provides electro-thermal feedback that makes the saturation power of a CEB well above that of other types of millimeter-wave receivers. The key features of CEB detectors are high sensitivity, large dynamic range, fast response, easy integration in arrays on planar substrates, and simple readout. The high dynamic range allows the detector to operate under relatively high background levels. In this thesis, we present the development and successful operation of CEB, focusing on the fabrication technology and different implementations of the CEB for efficient detection of electromagnetic signals. We present the CEB detector integrated across a unilateral finline deposited on a planar substrate. We have measured the finline-integrated CEB performance at 280-315 mK using a calibrated black-body source mounted inside the cryostat. The results have demonstrated strong response to the incoming RF power and reasonable sensitivity. We also present CEB devices fabricated with advanced technologies and integrated in log-periodic, double-dipole and cross-slot antennas. The measured CEB performance satisfied the requirements of the balloon-borne experiment BOOMERANG and could be considered for future balloon-borne and ground-based instruments. In this thesis we also investigated a planar phase switch integrated in a back-to-back finline for modulating the polarization of weak electromagnetic signals. We examine the switching characteristics and demonstrate that the switching speed of the device is well above the speed required for phase modulation in astronomical instruments. We also investigated the combination of a detector and a superconducting phase switch for modulating the polarization of electromagnetic radiation.
41
Bacchus, Ian Dean. "On the development of a far-infrared bolometric detector using a 2DEG as the absorbing medium." Thesis, Cardiff University, 2008. http://orca.cf.ac.uk/54649/.
Texte intégralRésumé :
This thesis describes the development of a far-infrared bolometric detector using a two-dimensional electron gas (2DEG) as the detecting medium. The 2DEG is formed at a AlGaAs/GaAs heterojunction made of layers of undoped GaAs and AlGaAs and highly doped (5 x lO126 3) AlGaAs. A 2DEG layer grown in this way in a molecular beam epitaxy (MBE) system is generally within 100 nm of the surface of the wafer and is subsequently patterned by etching away the surrounding wafer material and leaving a mesa containing the buried 2DEG. Ohmic contact to the 2DEG is achieved either through a diffusion of charge carriers into the contact region. Using a 2DEG as the absorbing medium in bolometers will yield detectors that are fast, sensitive, and frequency selective. The low electron densities in 2DEGs (1011 cm<super>-2</super>) allow large-area devices with extremely low thermal conductance between the electrons and the semiconductor lattice (e.g. Appleyard, et al. 1). The fast time constant (on the order of 1 ps) of the electron relaxation time in the 2DEG would allow for very high bandwidth spectroscopy. This thesis presents an overview of the use of 2DEG bolometers and a detailed study of their properties relevant for use as THz HEBs or CEBs. Chapter 1 briefly outlines the importance of Terahertz astronomy. Chapter 2 presents an introduction to bolometer theory. Chapter 3 provides a description of the electrical, thermal, and magnetic properties of 2DEGs. Chapter 4 outlines the equations governing the operation of 2DEG HEBs and CEBs and contains computer-simulated data. Chapter 5 describes our device fabrication, testing methods, and gives the results of our measurements. Finally, this thesis concludes with a discussion of the results of the tests and possible interpretations in terms of different physical models for electron-photon interactions in the 2DEG.
42
Moeen, Mahdi. "Design, Modelling and Characterization of Si/SiGe Structures for IR Bolometer Applications." Licentiate thesis, KTH, Integrerade komponenter och kretsar, 2015. http://urn.kb.se/resolve?urn=urn:nbn:se:kth:diva-159762.
Texte intégralRésumé :
This thesis presents SiGe(C)/Si(C) multi quantum well (MQW) layers individually or in combination with Si(C) Schottky diodes as material structures to detect infrared (IR) radiation. The performance of devices was investigated in terms of SiGe/Si periodicity and quality of SiGe/Si interface. The structures were grown by chemical vapour deposition using GeH4 and SiH4 sources at 650 °C and processed into pixel arrays with sizes of 25×25, 100×100 and 200×200 μm2. The device response to thermal variations was expressed by temperature coefficient of resistance (TCR) and the signal-to-noise-ratio was evaluated by noise measurements. The strain relaxation in SiGe layers was investigated by implementing oxygen at the interface of SiGe/Si or during SiGe growth. A minor amount of 10 ppb oxygen at the interface can be detected by noise measurements while the material characterizations could reveal defects for significantly higher defect density. Oxygen and water contaminations should be accounted for in low temperature epitaxy (350-650 °C) of the layers. Furthermore, an empirical model was developed to describe the kinetics of the SiGe growth using Si2H6 and Ge2H6 as precursors at low temperature. The model takes into account the energy for dissociation of gas molecules, diffusion of the molecules from the gas boundaries toward the substrate and the incorporation of absorbed molecules. A good consistency was observed between the experimental and calculated data.<br><p>QC 20150211</p>
43
Miao, Wei. "Investigation of hot electron bolometer mixers for submillimeter multi-pixel receiver applications." Paris 6, 2010. http://www.theses.fr/2010PA066077.
Texte intégralRésumé :
Les bolomètres à électrons chauds (HEB) supraconducteurs sont aujourd'hui les composants les plus sensibles pour la détection cohérente dans le domaine des ondes THz. Ce travail est centré sur l’étude et le développement des mélangeurs de type HEB à refroidissement par phonons dans une configuration quasi-optique permettant l’application multi pixels. D’abord, nous avons étudié un nouveau concept de mélangeur HEB sur membrane comprenant des éléments de couplage en quasi-optique associés à des micro-miroirs. Le comportement du mélangeur HEB sur membrane a été modélisé en utilisant le modèle "hot spot" récemment développé. Les propriétés de couplage du signal incident à cette structure incluant membranes et micro-mirroirs ont été calculées. Certains résultats obtenus par simulation ont été validés par des mesures sur des modèles à l’échelle développés spécifiquement. Nous avons également étudié les propriétés de rayonnement des mélangeurs HEB en quasi-optique utilisant des substrats épais associés à des lentilles. Deux types de configurations ont été étudiées: en mono pixel et en multi pixels. Une approche hybride combinant l’optique géométrique et l’optique physique a été adoptée pour simuler la structure quasi-optique, car une approche électromagnétique globale aurait nécessité des moyens de calcul extrêmement puissants à cause du rapport très élevé entre la dimension de la lentille et la longueur d’onde submillimétrique. Finalement, un modèle de "hot spot" amélioré est présenté. Les prédictions des caractéristiques statiques ainsi que les performances de sensibilité ont été comparées avec les mesures sur un mélangeur en mono pixel et un bon accord a été obtenu
44
Gaertner, Siegfried. "Systeme de lecture des bolometres optimise pour la mission spatiale planck surveyor." Toulouse 3, 1997. http://www.theses.fr/1997TOU30250.
Texte intégralRésumé :
Cette these presente des recherches et developpements technologiques concernant les systemes de lecture des bolometres utilisant une modulation electrique et un traitement numerique du signal realise avec des processeurs spatialisables (transputers). Ces etudes ont permis de definir, realiser et tester un systeme optimise pour la mission spatiale planck surveyor de l'esa, dediee principalement aux mesures des fluctuations angulaires du corps noir cosmologique. Cette these comprend cinq parties distinctes : 1. Description scientifique et technique de planck surveyor 2. Presentation du bolometre, de son fonctionnement et des divers choix techniques possibles pour concevoir le systeme electronique de lecture. Le systeme defini est compose d'un bolometre et d'une capacite de polarisation (permettant de fixer le courant traversant le detecteur et d'eviter le bruit de johnson d'une resistance), assembles en pont et modules par deux tensions equilibres afin de s'affranchir du bruit en 1/f des amplificateurs et d'avoir une dynamique du signal raisonnable. Tout le systeme est numerique ce qui permet, grace a un transputer, de realiser la detection synchrone et de controler les parametres de la modulation : connaissance de la puissance recue par chaque bolometre et determination en cours de mission de leur point optimal de fonctionnement de sensibilite 3. Description du systeme developpe et de ses performances sur des bolometres refroidis a 100 mk 4. Resultats des observations astrophysiques realisees avec ce systeme sur le photometre sol diabolo 5. Presentation d'un prototype spatialisable du systeme de lecture des bolometres, optimise pour planck surveyor, concu a partir d'une synthese des performances du systeme developpe et respectant les contraintes scientifiques et techniques de cette mission spatiale : systeme bas bruit jusqu'a 0. 1 hz, consommation electrique inferieure a 40 watts et encombrement inferieur a 40 litres.
45
Martin, Michel. "Étude expérimentale de bolomètres rapides à jonctions tunnel métal normal-isolant-supraconducteur." Grenoble INPG, 1996. http://www.theses.fr/1996INPG0206.
Texte intégralRésumé :
Nous etudions des bolometres bases sur des jonctions tunnel metal normal - isolant - supraconducteur en vue de leur application a la mesure d'energie d'ions retrodiffuses. La fabrication et l'etude de tels bolometres est montre en detail. On s'attache particulierement a l'influence des parametres physiques sur la mesure de temperature.
46
MacKenzie, Todd. "Extra-galactic and survey science with the submillimeter common user bolometer array-2." Thesis, University of British Columbia, 2011. http://hdl.handle.net/2429/38054.
Texte intégralRésumé :
We have carried out a pilot study for the SCUBA-2 'All-Sky' Survey, SASSy, a wide and shallow mapping project at 850 μm, designed to find rare objects, both Galactic and extragalactic. Two distinct sets of exploratory observations were undertaken, and used to test the SASSy approach and data reduction pipeline. The first was a 0.5° x 0.5° map around the nearby galaxy NGC 2559. The galaxy was easily detected at 156 mJy, but no other convincing sources are present in the map. Comparison with other galaxies with similar wavelength coverage indicates that NGC 2559 has relatively warm dust. The second observations cover 1 deg² around the W5-E Hɪɪ region. As well as diffuse structure in the map, a filtering approach was able to extract 27 compact sources with signal-to-noise greater than 6. By matching with data at other wavelengths we can see that the SCUBA-2 data can be used to discriminate the colder cores. Together these observations show that the SASSy project will be able to meet its original goals of detecting new bright sources which will be ideal for follow-up observations with other facilities.
We have also carried out a study of MS 0451-03, a massive galaxy cluster at z=0.5, strongly lensing a group of galaxies at z=3. Imaging with SCUBA, and more recently with SCUBA-2, shows a prominent arc of submm emission, but lacks the resolution to break up this lensed structure into individual sources. ALMA, even in Early Science mode, has the ability to finally resolve the giant submm arc. A lensing reconstruction will allow us to relate the submm sources to lensed objects detected in other wavebands. The cluster-scale lensing and the extent of the galaxy group make this a relatively simple system to investigate. Lessons learned here could help us understand the effects of differential lensing on the spectral energy distribution in more complicated galaxy-scale lens systems.
47
Hirahara, Ann Satoko 1972. "Fabrication of sensitive high-temperature superconducting bolometers on a yttria-stabilized zirconia membrane." Thesis, Massachusetts Institute of Technology, 1995. http://hdl.handle.net/1721.1/32172.
Texte intégralRésumé :
Thesis (M.S.)--Massachusetts Institute of Technology, Dept. of Materials Science and Engineering, 1995.<br>Vita.<br>Includes bibliographical references (leaves 37-38).<br>by Ann Satoko Hirahara.<br>M.S.
48
Tenconi, Margherita. "Development of luminescent bolometers and light detectors for neutrinoless double beta decay search." Thesis, Paris 11, 2015. http://www.theses.fr/2015PA112224/document.
Texte intégralRésumé :
L'étude de la double désintégration bêta sans neutrinos joue un rôle important dans plusieurs questions en physique des particules et cosmologie. Ce processus nucléaire hypothétique viole la conservation du nombre leptonique par deux unités et jusqu'à présent il est le seule moyen pratique pour dévoiler la nature du neutrino : sa détection implique forcement que neutrino et antineutrino sont la même particule. En outre, le taux de décroissance est sensible à la masse efficace de Majorana du neutrino, du coup à l'échelle absolue des valeurs propres de la masse et leur hiérarchie. La marque expérimentale de la DDB0ν est un pic monochromatique dans le spectre énergétique de la somme des deux électrons émis. Le but des expériences de prochaine génération est une sensibilité sur la masse efficace du neutrino de l'ordre de dizaines de meV, c'est-à-dire demi-vies de l'ordre de 10²⁷-10²⁸ années : en pratique, il s'agit de construire des sources de quelques centaines de kg d'isotope candidat, au moins, et les sonder par des détecteurs très efficients, tout en gardant le bruit de fond dans la région énergétique d'intérêt au niveau d'un coup/tonne/an. Les bolomètres luminescents sont une technique prometteuse vu leur excellentes résolutions énergétiques, haute efficacité de détection, ample choix pour les matériaux et extensibilité modulaire à grande échelle; de plus, grâce à la détection simultanée de chaleur et lumière produites par l'interaction des particules, il est possible de discriminer les contaminations α, dangereuse source de bruit aux énergies d'intérêt pour plusieurs noyaux candidats à la DDB0ν. Cette thèse a été effectuée dans le contexte de l'expérience LUMINEU : une expérience pilote qui a pour but la construction d'une expérience de prochaine génération basée sur les bolomètres scintillants en molybdate de zinc, pour l'étude de l'isotope candidat ¹⁰⁰Mo. En vue de la construction d'une expérience à grande échelle, il est nécessaire d'effectuer des caractérisations systématiques pour s'assurer des performances et de la reproductibilité des détecteurs et leurs composantes. La disponibilité d'installations expérimentales en surface, facilement accessibles, est souhaitable pour des tests routiniers : j'ai mené la plupart des expériences au CSNSM, où j'ai aussi travaillé à l'installation d'un nouvel cryostat à dilution basé sur la technologie du Pulse-Tube. Une partie de ma thèse a concerné l'étude de détecteurs bolométriques de lumière aux absorbeurs en germanium et thermomètres NTD (thermistors Neutron Transmutation Doped) : une structure standard pour LUMINEU a été établie et on a mesuré les performances des bolomètres telles que sensibilité, résolution énergétique, bruit de base et reproductibilité. Les résultats sont satisfaisants en vue d'un emploi dans une expérience avec bolomètres scintillants, bien que la configuration soit très sensible à la microphonie. En outre, j'ai testé avec succès des détecteurs bolométriques de lumière exploitants l'effet Neganov-Luke, qui augmente le rapport signal-bruit au niveau compatible avec la détection de la lumière Cherenkov pour la discrimination des événements. Une autre partie a vu la caractérisation des bolomètres scintillants en molybdate de zinc avec masse allant jusqu'à environ 300 g : couplés aux capteurs de lumière susmentionnés et lus par thermistors NTD, ils ont été refroidis en surface au CSNSM et en endroit souterrain à Modane, dans l'installation de l'expérience EDELWEISS pour la Matière Noire. Grâce à la détection simultanée de lumière et chaleur, les interactions des particules β/γ sont séparées des contaminations α. Les résultats démontrent que la caractérisation de bolomètres massifs, presque la taille cible des détecteurs finaux, est possible même en surface, en dépit du rayonnement cosmique. En outre, ces tests ont permis d'optimiser la compatibilité de l'installation de Modane avec les exigences des bolomètres scintillants pour la recherche de la DDB0ν<br>Neutrinoless Double Beta Decay (0νDBD) is regarded as an important key in the decryption of some hot astroparticle and cosmological enigmas: it violates lepton number by two units and it is currently the only known practical way to shed light on the neutrino nature, being possible only in case of a Majorana neutrino, identical to its antiparticle. Moreover, the 0νDBD rate is sensitive to the effective neutrino mass, so it would be useful to define the absolute neutrino mass scale and hierarchy. The experimental footprint of 0νDBD is a monochromatic peak in the sum energy spectrum of the two emitted electrons. Next-generation experiments aim at reaching a sensitivity on the effective neutrino mass of the order of ten meV, corresponding to half lives in the range 10²⁷-10²⁸ years: this means to be able to gather, at least, a few hundred kilograms of 0νDBD candidate isotope source and to efficiently scrutinize it with very sensitive detectors. Meanwhile, background levels in the energy region of interest of the 0νDBD signal should be lowered to less than one count/ton/y. Cryogenic luminescent bolometers are a promising technique for 0νDBD search, as they feature excellent energy resolutions, high detection efficiency, flexibility in the material choice and easy scalability to large modular experiments; furthermore, the simultaneous read-out of heat and light signals produced by particle interactions provides an active discrimination method against the dangerous α contaminations, populating the 0νDBD energy region of several interesting candidate isotopes. The work presented in this dissertation was carried out in the context of the LUMINEU project: a pilot experiment focused on zinc molybdate scintillating bolometers, to define the strategies for the construction of a next-generation experiment based on the 0νDBD candidate ¹⁰⁰Mo. In view of the construction of a large 0νDBD experiment, involving hundreds of modules, systematic cryogenic measurements have to be performed to ensure good performance and reproducibility of the detectors and their components. Aboveground facilities are preferred for routinary tests because of their easier accessibility: most of the tests were carried out at CSNSM, where I also worked on the setup of a new cryogenic apparatus, based on the Pulse-Tube technology. One part of my thesis work saw the study of bolometric light detectors based on germanium absorbers and Neutron Transmutation Doped (NTD) thermometers: a proper design was developed in view of LUMINEU and the devices were characterized in terms of sensitivity, energy resolution, baseline noise and reproducibility. The results are compatible with a 0νDBD search final experiment, though this detector configuration is very sensitive to vibrational noise. In addition, the feasibility of bolometric light detectors based on NTD thermometers and Neganov-Luke amplification was investigated, demonstrating that this technique can actually boost the signal-to-noise gain to a level compatible with event discrimination based on Cherenkov light detection. Another part of my work dealt with the test of scintillating zinc molybdate bolometers of mass up to ~300 g, coupled to the aforementioned light detectors and operated both in the aboveground facilities at CSNSM and underground at Modane, in the cryostat of the EDELWEISS Dark Matter search experiment. Good event discrimination capability was achieved: thanks to double read-out of heat and light, it is possible to identify α particles, the threatening background for 0νDBD interests, against β/γ interactions. The results proved the possibility to pre-characterize aboveground detectors of mass close to the one of a final experiment module, despite the high cosmic rays rates. Besides, the measurements opened the way to the mutual compatibility of the underground setup, conceived for another kind of experiment, and LUMINEU 0νDBD search detectors
49
Priestley, Kory James. "Use of First-Principle Numerical Models to Enhance the Understanding of the Operational Analysis of Space-Based Earth Radiation Budget Instruments." Diss., Virginia Tech, 1997. http://hdl.handle.net/10919/30662.
Texte intégralRésumé :
NASA's Clouds and the Earth's Radiant Energy System (CERES) program is a key component of the Earth Observing System (EOS). The CERES Proto-Flight Model (PFM) instrument is to be launched on NASA's Tropical Rainfall Measuring Mission (TRMM) spacecraft in November, 1997. Each CERES instrument will contain three scanning thermistor bolometer radiometers to monitor the longwave, 5.0 to >100 microns, and shortwave, 0.3 to 5.0 microns, components of the Earth's radiative energy budget.
High-level, first-principle dynamic electrothermal models of the CERES radiometric channels have been completed under NASA sponsorship. These first-principle models consist of optical, thermal and electrical modules. Optical characterization of the channels is ensured by Monte-Carlo-based ray-traces. Accurate thermal and electrical characterization is assured by transient finite-difference formulations. This body of research presents the evolution of these models by outlining their development and validation. Validation of the models is accomplished by simulating the ground calibration process of the actual instruments and verifying that the models accurately predict instrument performance. The result of this agreement is a high confidence in the model to predict other aspects of instrument performance.<br>Ph. D.
50
Zhang, Chang. "Radiative Heat Transfer in Free-Standing Silicon Nitridemembranes in the Application of Thermal Radiation Sensing." Thesis, Université d'Ottawa / University of Ottawa, 2020. http://hdl.handle.net/10393/41409.
Texte intégralRésumé :
Thin-film silicon nitride (SiN) membranes mechanical resonators have been widely used for many fundamental opto-mechanical studies and sensing technologies due to their extremely low mechanical dissipation (high mechanical Q-factor). In this work, we experimentally demonstrate an opto-mechanical approach to perform thermal radiation sensing, using a SiN
membrane resonator. An important aspect of this work is to develop a closed-form analytical heat transfer model for assessing the thermal coupling conditionbetween free-standing membranes and their environment. We also derive analytical expressions for other important intrinsic thermal quantities of the membrane, such as thethermal conductance, the heat capacity and the thermal time constant. Experimental results show good agreement with our theoretical prediction. Of central importance, we show that membranes of realistic dimensions can be coupled to their environment more strongly via radiation than by solid-state conduction. For example, membranes with 100nm thickness (frequently encountered size) are predicted to be radiation dominated when their side length exceeds 6 mm. Having radiation dominated thermal coupling is a key ingredient for reaching the fundamental detectivity limit of thermal detectors. Hence, our work proves that SiN membranes are attractive candidates for reaching the fundamental limit. We also experimentally exhibit the high temperature responsivity of the SiN membranes resonance, in which we shift a 88.7 KHz resonance by over 1 KHz when temperature increment on the membrane is approximately 2 K.