Tesis: "Single Photon Detectors"

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Fitzpatrick, Catherine Rose. "Single-photon metrology with superconducting nanowire single-photon detectors". Thesis, Heriot-Watt University, 2013. http://hdl.handle.net/10399/2633.

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Single-photon sources and detectors underpin the development of quantum photonic technologies. This thesis presents research into single-photon devices with a focus on telecom wavelengths. A two-channel superconducting nanowire single-photon detector (SNSPD) system was constructed and characterised. It provides free-running single-photon detection at telecom wavelengths with low dark counts and timing jitter below 90 ps FWHM. The system detection e ciency at 1310 nm is 1 % with a 1 kHz dark count rate, which was competitive when the SNSPD was built in 2009. In this work, the low timing jitter of the SNSPD was bene cial to the development of a two-photon interference experiment. Experiments were carried out with single-photon sources based on self-assembled InAs/GaAs quantum dots in micropillar cavities. Preliminary measurements of the second-order correlation function gave g(²)(τ=0) = 0.12 ± 0.04 with above-band excitation and g(²)( τ = 0) = 0:07 ± 0:05 with near-resonant excitation. These values agree with recent papers reporting improved measurements with near-resonant excitation. Irreparable damage to the sample prevented further investigation. This thesis also presents the design, construction and characterisation of a highresolution single-photon spectrometer for telecom wavelengths. The instrument, a scanning Fabry-Perot interferometer, was optimised for the characterisation of quantum photonic sources. It has a spectral resolution of 550 MHz and a free spectral range of (119.0 ± 0.4) GHz.

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2

Najafi, Faraz. "Superconducting nanowire single-photon detectors : new detector architectures and integration with photonic chips". Thesis, Massachusetts Institute of Technology, 2015. http://hdl.handle.net/1721.1/99836.

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Thesis: Ph. D., Massachusetts Institute of Technology, Department of Electrical Engineering and Computer Science, 2015.
Cataloged from PDF version of thesis.
Includes bibliographical references (pages 153-161).
Superconducting nanowire single-photon detectors (SNSPDs) are a promising technology for long-distance optical communication and quantum information processing. Recent advances in single-photon generation, storage and detection technologies have spurred interest in integration of these components onto a single microchip, which would act as a low-power non-classical optical processor. In this thesis, I will present a method for the scalable integration of SNSPDs with photonic chips. I will show that, using a micron-scale flip-chip process, waveguide-coupled SNSPDs can be integrated onto a variety of material systems with high yield. This technology enabled the assembly of the first photonic chip with multiple adjacent SNSPDs with average system detection efficiencies beyond 10%. Using this prototype, we will show the first on-chip detection of non-classical light. I will further demonstrate optimizations to the detector design and fabrication processes. These optimizations increased the direct fabrication yield and improved the timing jitter to 24 ps for detectors with high internal efficiency. Furthermore, I will show a novel single-photon detector design that may have the potential to reach photodetection dead times below 1ns.
by Faraz Najafi.
Ph. D.

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3

Natarajan, Chandra Mouli. "Superconducting nanowire single-photon detectors for advanced photon-counting applications". Thesis, Heriot-Watt University, 2011. http://hdl.handle.net/10399/2432.

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The ability to detect infrared photons is increasingly important in many elds of scienti c endeavour, including astronomy, the life sciences and quantum information science. Improvements in detector performance are urgently required. The Superconducting Nanowire Single-Photon Detector (SNSPD/SSPD) is an emerging single-photon detector technology o ering broadband sensitivity, negligible dark counts and picosecond timing resolution. SNSPDs have the potential to outperform conventional semiconductor-based photon-counting technologies, provided the di culties of low temperature operation can be overcome. This thesis describes how these important challenges have been addressed, enabling the SNSPDs to be used in new applications. A multichannel SNSPD system based on a closed-cycle refrigerator has been constructed and tested. E cient optical coupling has been achieved via carefully aligned optical bre. Fibre-coupled SNSPDs based on (i) NbN on MgO substrates and (ii) NbTiN on oxidised Si substrates have been studied. The latter give enhanced performance at telecom wavelengths, exploiting the re ection from the Si=SiO2 interface. Currently, the detector system houses four NbTiN SNSPDs with average detection e ciency >20% at 1310 nm wavelength. We have employed SNSPDs in the characterisation of quantum waveguide circuits, opening the pathway to operating this promising platform for optical quantum computing for the first time at telecom wavelengths.

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4

Dauler, Eric A. (Eric Anthony) 1980. "Multi-element superconducting nanowire single photon detectors". Thesis, Massachusetts Institute of Technology, 2009. http://hdl.handle.net/1721.1/46377.

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Thesis (Ph. D.)--Massachusetts Institute of Technology, Dept. of Electrical Engineering and Computer Science, 2009.
This electronic version was submitted by the student author. The certified thesis is available in the Institute Archives and Special Collections.
Includes bibliographical references (p. 140-148).
Single-photon-detector arrays can provide unparalleled performance and detailed information in applications that require precise timing and single photon sensitivity. Such arrays have been demonstrated using a number of single-photon-detector technologies, but the high performance of superconducting nanowire single photon detectors (SNSPDs) and the unavoidable overhead of cryogenic cooling make SNSPDs particularly likely to be used in applications that require detectors with the highest performance available. These applications are also the most likely to benefit from and fully utilize the large amount of information and performance advantages provided by a single-photon-detector array.Although the performance advantages of individual superconducting nanowire single photon detectors (SNSPDs) have been investigated since their first demonstration in 2001, the advantages gained by building arrays of multiple SNSPDs may be even more unique among single photon detector technologies. First, the simplicity and nanoscale dimensions of these detectors make it possible to easily operate multiple elements and to closely space these elements such that the active area of an array is essentially identical to that of a single element. This ability to eliminate seam-loss between elements, as well as the performance advantages gained by using multiple smaller elements, makes the multi-element approach an attractive way to increase the general detector performance (detection efficiency and maximum counting rate) as well as to provide new capabilities (photon-number, spatial, and spectral resolution). Additionally, in contrast to semiconductor-based single-photon detectors, SNSPDs have a negligible probability of spontaneously emitting photons during the detection process, eliminating a potential source of crosstalk between array elements.
(cont.) However, the SNSPD can be susceptible to other forms of crosstalk, such as thermal or electromagnetic interactions between elements, so it was important to investigate the operation and limitations of multi-element SNSPDs. This thesis will introduce the concept of a multi-element SNSPD with a continuous active area and will investigate its performance advantages, its potential drawbacks and finally its application to intensity correlation measurements.This work is sponsored by the United States Air Force under Contract #FA8721-05-C-0002. Opinions, interpretations, recommendations and conclusions are those of the authors and are not necessarily endorsed by the United States Government.
by Eric Dauler.
Ph.D.

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5

Zhu, Di S. M. Massachusetts Institute of Technology. "Superconducting nanowire single-photon detectors on aluminum nitride photonic integrated circuits". Thesis, Massachusetts Institute of Technology, 2017. http://hdl.handle.net/1721.1/108974.

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Thesis: S.M., Massachusetts Institute of Technology, Department of Electrical Engineering and Computer Science, 2017.
Cataloged from PDF version of thesis.
Includes bibliographical references (pages 85-91).
With recent advances in integrated single-photon sources and quantum memories, onchip integration of high-performance single-photon detectors becomes increasingly important. The superconducting nanowire single-photon detector (SNSPD) is the leading single-photon counting technology for quantum information processing. Among various waveguide materials, aluminum nitride (AlN) is a promising candidate because of its exceptionally wide bandgap, and intrinsic piezoelectric and electro-optic properties. In this Master's thesis, we developed a complete fabrication process for making high-performance niobium nitride SNSPDs on AlN, and demonstrated their integration with AlN photonic waveguides. The detectors fabricated on this new substrate material have demonstrated saturated detection efficiency from visible to near-IR, sub-60-ps timing jitter, and ~6 ns reset time. This work will contribute towards building a fully integrated quantum photonic processor.
by Di Zhu.
S.M.

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6

Sunter, Kristen Ann. "Optical Modeling of Superconducting Nanowire Single Photon Detectors". Thesis, Harvard University, 2014. http://nrs.harvard.edu/urn-3:HUL.InstRepos:13106421.

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Superconducting nanowire single photon detectors (SNSPDs) can detect single photons or low levels of infrared light in applications that require high speed and low timing jitter, such as integrated circuit analysis. Most applications also require a high device detection efficiency (DDE), but the DDE of SNSPDs is limited by many factors. A good optical design with an integrated optical cavity and dielectric layers can increase the absorptance of 1550-nm light in the active area to over 90%. Therefore, optical modeling using the transfer matrix method was used to guide the design and fabrication of high-efficiency detectors with a measured DDE of over 70%. In addition, finite element analysis was used to simulate the effect of adding different types of optical antennas to SNSPD designs to increase their active area without compromising their speed, and the fabrication of antennas integrated with nanowires achieved sub-10 nm gaps between features. Thin films of niobium nitride, the starting material of the SNSPDs, were investigated using several techniques for thin film characterization, including x-ray diffraction, Auger electron spectroscopy and x-ray photoelectron spectroscopy. Optical setups based on reflectometry and transmittometry were built to determine the film thickness more accurately than deposition time for optical modeling and to provide feedback on the deposition conditions. The optical setups are able to provide reproducible and precise thickness measurements to within 0.1 nm.
Engineering and Applied Sciences

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7

Bellei, Francesco. "Superconducting nanowire single photon detectors for infrared communications". Thesis, Massachusetts Institute of Technology, 2017. http://hdl.handle.net/1721.1/109008.

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Thesis: Ph. D., Massachusetts Institute of Technology, Department of Electrical Engineering and Computer Science, 2017.
Cataloged from PDF version of thesis.
Includes bibliographical references (pages 113-120).
The ever-increasing data sharing demands of modern technologies forces scientists to adopt new methods that can surpass the approaching limits of classical physics. Quantum optical communications and information, based on single-photon detectors offer the most promising possibility to reach new levels of data rate and communication security. Superconducting nanowire single-photon detectors (SNSPDs) have already been used in the past to demonstrate new protocols of quantum key distribution and are currently the best single-photon detection technology to enable quantum optical communication. With the goal of creating a global quantum communication network, both optical fiber and free-space optical communication technologies have been explored. In addition, the scientific community started pursuing smaller and cheaper cryogenic solutions to enable the use of SNSPDs on a large scale. In this thesis, I describe the design and development of a cryogenic SNSPD receivers in free-space and optical-fiber configurations for 1550-nm-wavelength. The first configuration was created with the goal of enabling optical communication in the mid-IR. I present future steps to achieve this goal. The second configuration was designed to enable a compact and scalable integration of multiple SNSPD channels in the same system. Our approach has the potential of enabling SNSPD systems with more than 64 channels.
by Francesco Bellei.
Ph. D.

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8

Najafi, Faraz. "Timing performance of superconducting nanowire single-photon detectors". Thesis, Massachusetts Institute of Technology, 2015. http://hdl.handle.net/1721.1/97816.

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Thesis: S.M., Massachusetts Institute of Technology, Department of Electrical Engineering and Computer Science, 2015.
Cataloged from PDF version of thesis.
Includes bibliographical references (pages 83-89).
Superconducting nanowire single-photon detectors (SNSPDs) are becoming increasingly popular for applications in quantum information and long-distance communication. While the detection efficiency of SNSPDs has significantly improved over time, their timing performance has largely remained unchanged. Furthermore, the photodetection process in superconducting nanowires is still not fully understood and subject to ongoing research. In this thesis, I will present a systematic study of the timing performance of different types of nanowire single-photon detectors. I will analyze the photodetection delay histogram (also called instrument response function IRF) of these detectors as a function of bias current, nanowire width and wavelength. The study of the IRF yielded several unexpected results, among them a wavelength-dependent exponential tail of the IRF and a discrepancy between experimental photodetection delay results and the predicted value based on the electrothermal model. These results reveal some shortcomings of the basic models used for SNSPDs, and may include a signature of the initial process by which photons are detected in superconducting nanowires. I will conclude this thesis by presenting a brief introduction into vortices, which have recently become a popular starting point for photodetection models for SNSPDs. Building on prior work, I will show that a simple image method can be used to calculate the current flow in presence of a vortex, and discuss possible implications of recent vortex-based models for timing jitter.
by Faraz Najafi.
S.M.

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9

Kirkwood, Robert A. "Superconducting single photon detectors for quantum information processing". Thesis, University of Glasgow, 2017. http://theses.gla.ac.uk/8136/.

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Single photon detectors are a vital part of many emerging technologies which harness the quantum properties of light to benefit the fields of communication, computation and sensing. Superconducting nanowire single photon detectors (SNSPDs) offer high detection efficiency, low dark count rates, low timing jitter, and infrared sensitivity that are required by the most demanding single photon counting applications. This thesis presents SNSPDs fabricated and tested at the University of Glasgow that are integrated with optical structures which enable enhanced detection efficiency and integration with waveguide circuit technology. The monolithic integration of waveguide circuit components presents a route towards realisation of an optical quantum information processor that has the stability and scalability to perform the demanding tasks of quantum computation. A novel process is introduced for incorporating superconducting detectors with single mode gallium arsenide waveguides and quantum dot single photon sources. Together these elements would enable the generation of quantum states of light which could be manipulated and detected on a single chip. Detectors are patterned in NbTiN thin superconducting films on to suspended nanobeam waveguides with better than 50 nm alignment accuracy. Low temperature electrical and optical testing confirms the detectors’ single photon sensitivity under direct illumination as well as to waveguide coupled light. Measured detectors were found to have internal registering efficiencies of 6.8 ± 2.4%. Enhancing absorption of photons into thin superconducting films is vital to the creation of high efficiency superconducting single photon detectors. Fabricating an SNSPD on a dielectric mirror creates a partial cavity that can be tailored to enhance detection of light at specific wavelengths. Devices have been fabricated and tested in this thesis with enhanced detection efficiency at infrared and visible wavelengths for quantum cryptography, remote sensing and life science applications. Detectors fabricated in NbTiN on GaAs/AlGaAs Bragg mirrors exhibited a system detection efficiency of 1.5% at 1500 nm wavelength for the best device measured. SNSPDs were also fabricated in NbN on aperiodic dielectric mirrors with a range of different bandwidths. A peak system detection efficiency of 82.7% at 808 nm wavelength was recorded.

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10

BALOSSINO, Ilaria. "Studies of innovative photon detectors working in the single-photon regime for the RICH detector of the CLAS12 experiment". Doctoral thesis, Università degli studi di Ferrara, 2018. http://hdl.handle.net/11392/2488231.

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Subatomic particles interaction have been the main goal of high energy physics. Worldwide experimental facilities use different techniques to improve the knowledge of the elementary components of the nature around us. Many experiments have been built during the years with a continuously improving technology to boost the precision with which detect new particles and structures. This work is focused on the photon detectors for a newer and innovative Ring Imaging CHerenkov detector (RICH). It is the most recent development of the so-called CLAS12 experiment. CLAS12 it is the acronym for CEBAF (Continuous Electron Beam Accelerator Facility) Large Acceptance Spectrometer at 12 GeV and it is an experiment hosted by the Thomas Jefferson National Accelerator Facility (JLAB). It is the follower of the old CLAS experiment built for the 6 GeV electron beam energy. The JLAB facility has recently been upgraded together with all the experiments involved in it, to double the beam energy and increase by orders of magnitude the luminosity. For this upgrade the CLAS12 collaboration decided to replace one of the already existing gas Cherenkov detector with the RICH in order to improve detection capabilities over the wider range of momentum achievable with the new beam. The RICH detector will be composed of two modules having similar geometry. They will both have an hybrid optic design to satisfy performance requirements and geometrical constraints: small dead space, low dead time, high spatial and time resolutions. For the active part, two different photon detector have been chosen: the first module, already installed, is based on Multi-Anode PhotoMultiplier Tubes (MAPMTs) while the second one, to be ready in few years, will be build with Silicon PhotoMultiplier (SiPM). The CLAS12 RICH is the first to use flat panel MAPMTs of large area. A dedicated front-end electronics has been developed for the readout of this kind of sensors, to enable single photon detection. In this thesis, the author's contribution to the study step that preceded the active component's installation on the first sector of the detector are presented: preparation of the laser setup for the characterization of all the final components (sensors and electronics), analysis of the collected data to extract a set of parameters that optimizes the performance of the MAPMTs during the physics runs and definition of a set of performance indicators to be used as a reference during calibration run. The author's work continues with the photon sensor studies for the second sector that will be installed in the next future. Although SiPMs have never been used in Cherenkov application, the rapid evolution in their production technology has lately opened interesting opportunities. The test to validate the SiPM use in the CLAS12 environment are described starting from the irradiation test, introducing a detailed study of the dark counts, dedicated to the characterization of the non trivial detector background. A preliminary test of the single photon detection capability of novel SiPM matrices in conjunction with the RICH readout electronics is also shown to validate their use togheter. As a completion of the author's work, the photon detector assembling and commissioning is described. A dedicated setup was developed to test the photon detector with cosmic muons, in a configuration mimicking the one in the experimental hall. This allowed to test the correct mapping of the detector and the timing precision. This work concentrates on the validation, characterization and commissioning of novel photon sensors for the challenging Cherenkov application, that requires single photon capability. It has lead to the installation of the first RICH sector that is now installed and running in the CLAS12 experiment and the validation of SiPM use in the single photon regime for the second RICH module at the moderate radiation levels foreseen in the experimental Hall B at JLAB.
Lo scopo principale della fisica delle alte energie è investigare la struttura subatomica della natura che ci circonda. Per farlo, molti laboratori ed esperimenti usano diverse tecniche di rivelazione, sfruttando il continuo sviluppo tecnologico, per raggiungere sempre nuovi livelli di precisione per rivelare nuove particelle. Il lavoro presentato si interessa dei rivelatori di fotoni per un innovativo rivelatore Ring Imaging CHerenkov che fa parte del potenziamento dell'esperimento CLAS12: CEBAF (Continuous Electron Beam Accelerator) Large Acceptance Spectrometer at 12 GeV. Questo esperimento si trova presso il laboratorio nazionale Thomas Jefferson ed è il proseguimento del precedente esperimento, CLAS, che usufruiva del fascio di elettroni a 6 GeV. Il laboratorio ha recentemente completato il potenziamento della strumentazione per raddoppiare l'energia del fascio e aumentare la luminosità. La collaborazione in questa fase ha deciso di sostituire una parte del rivelatore Cherenkov a gas con il RICH per poter migliorare le capacità di rivelazione in un intervallo più ampio di energie. Il rivelatore sarà composto da due moduli progettati con un disegno ottico ibrido per poter soddisfare le specifiche di prestazione e i vincoli geometrici dell'esperimento: massimizzazione dell'area attiva di rivelazione, minimizzazione di tempi morti dell'elettronica, alte risoluzioni spaziali e temporali. Sono però stati scelti due rivelatori di fotoni diversi, seguendone principalmente lo sviluppo tecnologico: il primo modulo, già installato, è basato sulla tecnologia matura dei tubi fotomoltiplicatori a multi anodo (MAPMT), mentre il secondo, pronto tra pochi anni, utilizzerà una soluzione innovativa e monterà fotomoltiplicatori al silicio (SiPM). Il RICH di CLAS12 è il primo rivelatore ad utilizzare fotomoltiplicatori a multi anodo di grande area per coprire un’ampia superficie. Per poter lavorare in condizioni di singolo fotone è stata sviluppata un specifica elettronica di front-end. In questo lavoro verranno presentate le diverse fasi che hanno anticipato l'istallazione nella sala sperimentale: preparazione di tutte le componenti (sensori e schede di elettronica) per la caratterizzazione, l'analisi dei dati collezionati in questa fase per definire i parametri di lavoro ottimali durante i run di fisica e preparazione di un set di indicatori di rifermento da confrontare con i futuri dati estratti dai run di calibrazione dell'esperimento. La seconda parte del lavoro riguarda il settore del RICH che verrà installato nel prossimo futuro e che, sfruttando la loro rapida evoluzione tecnologica, prevede l'utilizzo dei SiPM. Gli studi per validare il loro uso in condizioni di singolo fotone sono stati fatti, e presentati in questo documento, a partire da un test di irraggiamento con lo sviluppo di un'analisi ad-hoc per lo studio approfondito del rumore di fondo. Inoltre sono presentati anche i test preliminari fatti per studiare il comportamento delle matrici di SiPM connesse con l'attuale elettronica di lettura del segnale sviluppata appositamente per il RICH. Infine viene descritto il processo di assemblaggio e di messa in opera del rivelatore finale. Un test per lavorare con i raggi cosmici e simulare le condizioni finali di lavoro del foto-rivelatore è stato realizzato prima dell’installazione all’interno del modulo RICH. Questo ha permesso di fare una verifica della mappatura del rivelatore e della risoluzione temporale. Questo lavoro si è concentrato su validazione, caratterizzazione e messa in opera di rivelatori di fotoni innovativi per applicazioni Cherenkov in condizioni di singolo fotone. I risultati ottenuti hanno portato ad installare con successo il primo settore del RICH che ora sta già prendendo dati nell'esperimento e a validare l'utilizzo dei SiPM per il secondo settore ai livelli di radiazione attesi nella sala sperimentale del laboratorio.

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11

Sidorova, Mariia. "Timing Jitter and Electron-Phonon Interaction in Superconducting Nanowire Single-Photon Detectors (SNSPDs)". Doctoral thesis, Humboldt-Universität zu Berlin, 2021. http://dx.doi.org/10.18452/22296.

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Die vorliegende Doktorarbeit beschäftigt sich mit der experimentellen Studie zweier miteinander verbundener Phänomene: Dem intrinsischen Timing-Jitter in einem supraleitendenden Nanodraht-Einzelphotonen-Detektor (SNSPD) und der Relaxation der Elektronenenergie in supraleitenden Filmen. Supraleitende Nanodrähte auf einem dielektrischen Substrat als mikroskopische Grundbausteine jeglicher SNSPDs stellen sowohl für theoretische als auch für experimentelle Studien komplexe Objekte dar. Die Komplexität ergibt sich aus der Tatsache, dass SNSPDs in der Praxis stark ungeordnete und ultradünne supraleitende Filme verwenden, die eine akustische Fehlanpassung zu dem zugrundeliegenden Substrat aufweisen und einen Nichtgleichgewichts-Zustand implizieren. Die Arbeit untersucht die Komplexität des am weitesten in der SNSPD Technologie verbreiteten Materials, Niobnitrid (NbN), indem verschiedene experimentelle Methoden angewandt werden. Als eine mögliche Anwendung der SNSPD-Technologie wird ein Prototyp eines dispersiven Raman-Spektrometers mit Einzelphotonen-Sensitivität demonstriert.
This Ph.D. thesis is based on the experimental study of two mutually interconnected phenomena: intrinsic timing jitter in superconducting nanowire single-photon detectors (SNSPDs) and relaxation of the electron energy in superconducting films. Microscopically, a building element of any SNSPD device, a superconducting nanowire on top of a dielectric substrate, represents a complex object for both experimental and theoretical studies. The complexity arises because, in practice, the SNSPD utilizes strongly disordered and ultrathin superconducting films, which acoustically mismatch with the underlying substrate, and implies a non-equilibrium state. This thesis addresses the complexity of the most conventional superconducting material used in SNSPD technology, niobium nitride (NbN), by applying several distinct experimental techniques. As an emerging application of the SNSPD technology, we demonstrate a prototype of the dispersive Raman spectrometer with single-photon sensitivity.

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12

Jerjen, Iwan. "Superconducting tunnel junctions as energy resolving single photon detectors /". Zürich : ETH, 2007. http://e-collection.ethbib.ethz.ch/show?type=diss&nr=17113.

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13

O'Connor, John Alexander. "Nano-optical studies of superconducting nanowire single-photon detectors". Thesis, Heriot-Watt University, 2011. http://hdl.handle.net/10399/2515.

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uperconducting single-photon detectors based on superconducting nanowires offer broadband single-photon sensitivity, from visible to mid-infrared wavelengths. They have attracted particular attention due to their promising performance at telecommunications wavelengths. The additional benefits of superconducting nanowire single-photon detectors (SNSPDs) include low dark count rates (Hz) and low timing jitter (sub 100 ps). SNSPDs have been employed in practical photon-counting applications such as quantum key distribution (QKD), operation of quantum waveguide circuits and quantum emitter characterisation. Major challenges in the development of SNSPDs are the improvement of device uniformity and achieving efficient optical coupling. Nano-optical techniques such as confocal microscopy can be used to image localised areas of SNSPDs providing a direct measurement of the device uniformity. The work in this thesis describes both initial nano-optical testing at visible wavelengths in liquid helium and the construction of a fibre based miniature confocal microscope configuration operating at telecommunications wavelengths for use in a closed cycle refrigerator. In both cases localised areas of SNSPDs can be studied whilst maintaining efficient optical coupling. The miniature confocal microscope configuration has sub-nanometre position resolution over a 30 μm x 30 μm area by way of a piezoelectric X-Y scanner. A full width at half maximum (FWHM) optical resolution of 1305 nm at a wavelength of 1550 nm is achieved. SNSPDs based upon niobium nitride (NbN) nanowires fabricated on magnesium oxide (MgO) have been studied. The microscope system has allowed us to map the temporal response (timing jitter and output pulse timing delay) of constricted (non-uniform) SNSPDs. By fitting to a theoretical model, the variations in output pulse timing delay have been shown to be caused by variations in hotspot resistances across the device. This observation has provided insights into the underlying physics of SNSPDs and especially the origins of timing jitter in SNSPDs. This provides a pathway to exploitation of this effect in next-generation device designs for applications such as imaging.

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14

Rafferty, Helen Marie. "Electronic transport properties of silicon-germanium single photon avalanche detectors". Thesis, University of Leeds, 2017. http://etheses.whiterose.ac.uk/20373/.

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Single photon avalanche detectors (SPADs) have uses in a number of applications, including time-of-flight ranging, quantum key distribution and low-light sensing. Germanium has an absorption edge at the key communications wavelengths of 1.3-1.55um, and can be grown epitaxially on silicon, however, SiGe SPADs exhibit a number of performance limitations, including low detection efficiencies, high dark counts and afterpulsing. Unintentional doping may affect electronic performance, and band-to-band tunnelling at high operational voltages SPADs may lead to noise currents. Additionally, defects in the Si/Ge interface lead to trap states within the bandgap and contribute to afterpulsing. This work investigates a range of critical performance parameters in SiGe SPADs. The effect of intentional and unintentional doping in SPADs on electric fields, potential profiles and carrier transport in the device is investigated, and optimal dopant profiles for a SiGe SPAD discussed. The dependence of band-to-band tunnelling currents in Ge on bias voltage, Ge thickness and temperature is investigated, and these currents are compared to other sources of noise currents in SPADs. DFT calculations of misfit dislocation structures in Ge are undertaken, to establish electronic bandstructures and optimised geometries for these defects, and identify trap states in the bandgap, which may contribute to afterpulsing and dark counts in SPADs. A number of directions for continuing work are identified, to progress understanding of noise currents and afterpulsing in SPADs.

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15

Yang, Joel K. (Joel Kwang wei). "Superconducting nanowire single-photon detectors and sub-10-nm lithography". Thesis, Massachusetts Institute of Technology, 2009. http://hdl.handle.net/1721.1/53307.

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Thesis (Ph. D.)--Massachusetts Institute of Technology, Dept. of Electrical Engineering and Computer Science, 2009.
Cataloged from PDF version of thesis.
Includes bibliographical references (p. 155-169).
Superconducting nanowire single-photon detectors (SNSPDs) are useful in applications such as free-space optical communications to achieve high-speed data transfer across vast distances with minimum transmission power. In this and other applications, SNSPDs with high detection efficiencies are required. To this end, we designed and fabricated an integrated optical cavity and anti-reflection coating that enhanced the detection efficiency of SNSPDs by almost threefold to current record values of 57% at 1550 nm wavelength. We also improved our understanding of SNSPDs by modeling the electro-thermal response of the detector. This model showed that, beyond the initial formation of a photon-induced resistance across the nanowire, Joule heating results in the growth of the resistive segment. While simple, this model was useful in designing SNSPDs that reset more quickly, and also in explaining an undesirable behavior of the SNSPDs where the devices latch into a resistive state and fail to reset. Like many other devices, such as transistors, SNSPDs would benefit from device miniaturization: SNSPDs with narrower nanowires have higher detection efficiencies and increased sensitivity to low-energy photons. In this thesis, we investigated the resolution performance of electron-beam lithography (EBL) by first improving the contrast performance of hydrogen silsesquioxane (HSQ) negative-tone resist. The contrast of HSQ was improved by adding NaCl salt to an aqueous NaOH developer solution. With this improvement, we achieved a high-resolution electron-beam lithography process capable of patterning structures at 9-nm-pitch dimensions.
(cont.) The ability to pattern sub-10-nm structures is useful for fabricating future high-performance SNSPDs, nanoimprint lithography molds, prototypes of next generation transistors and storage media, and templates for controlling the self-assembly of block copolymers (BCPs). While this EBL process affords high-resolution, it is inherently a low-throughput process due to the serial nature of the pattern exposure. As a result, EBL is not cost effective in fabricating densely-patterned devices in large volumes. However, coin-bining this top-down EBL process with bottom-up BCP self-assembly techniques, we can simultaneously achieve high resolution without sacrificing throughput or pattern registration. We demonstrated that high-throughput fabrication of a hexagonally-ordered array of posts could be achieved by patterning only a sparse array of posts with EBL and using block copolymers to complete the missing structures.
by Joel K. Yang.
Ph.D.

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16

Sidorova, Mariia [Verfasser]. "Timing Jitter and Electron-Phonon Interaction in Superconducting Nanowire Single-Photon Detectors (SNSPDs) / Mariia Sidorova". Berlin : Humboldt-Universität zu Berlin, 2021. http://d-nb.info/1226153380/34.

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17

Herder, Charles H. (Charles Henry) III. "Designing and implementing a readout strategy for superconducting single photon detectors". Thesis, Massachusetts Institute of Technology, 2010. http://hdl.handle.net/1721.1/63024.

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Thesis (M. Eng.)--Massachusetts Institute of Technology, Dept. of Electrical Engineering and Computer Science, 2010.
Cataloged from PDF version of thesis.
Includes bibliographical references (p. 109-112).
Introduction: Photon detection is an integral part of experimental physics, high-speed communication, as well as many other high-tech disciplines. In the realm of communication, unmanned spacecraft are travelling extreme distances, and ground stations need more and more sensitive and selective detectors to maintain a reasonable data rate.[10] In the realm of computing, some of the most promising new forms of quantum computing require consistent and efficient optical detection of single entangled photons.[27] Due to projects like these, demands are increasing for ever more efficient detectors with higher count rates. The Superconducting Nanowire Single-Photon Detector (SNSPD) is one of the most promising new technologies in this field, being capable of counting photons as faster than 100MHz and with efficiencies around 50%. Currently, the leading competition is from the geiger-mode avalanche photodiode, which is capable of ~20- 70% efficiency at a ~5MHz count rate depending on photon energy. In spite of these advantages, the SNSPD is still a brand-new technology and as a result they do not have the same support hardware support as other detectors. As such, SNSPD's are much more difficult to integrate into an existing an experiment. Because of this difficulty, SNSPD's have not been deployed extensively for research or industrial applications. The signal analysis chain that is connected to this detector is one of the key choke points. Each detector count produces a 0.1 mV, 10 nS wide pulse with a maximum count frequency on the order of 100MHz. Currently, this signal is processed outside of the cryostat with a series of RF amplifiers and a high-speed counter. This design works for detector prototyping, but poses a series of problems with actual design implementation. Most importantly, it prevents our design from being scalable. Even though we can fabricate thousands of detectors on a single wafer, it would be extremely difficult to place that many RF lines without crosstalk or other interference. The purpose of this thesis is to build a more robust and scalable readout technology for SNSPDs. First, we will develop intermediate technologies that improve upon current readout technology and will be necessary to develop the final goal. Ultimately, we plan to build circuitry on-chip that will first convert each detector's analog signal to a digital signal and then condense the data from each detector into an externally clocked, single-bit output indicating the presence or absence of a photon at any detector. This will allow simultaneous readout of a large number of detectors on a single wafer. Additionally, our cryogenic will decrease the noise observed by the detector, as the amplifier is no longer operating at room temperature. Finally, our readout will provide a simple hardware API to be interfaced to a computer or embedded processing unit. The catch to this development process is that the entire system must operate at 4.2K or below. As such, one must either use HEMT CMOS or Rapid Single-Flux- Quantum (RSFQ) logic. HEMT CMOS is better suited to analog amplification of the output signal, while RSFQ circuitry is better suited to the construction of the SNSPD interface and digital logic. RSFQ circuitry is better suited as an input stage because input amplification with CMOS is difficult, as one must operate in the linear regime of a HEMT. This requires on the order of 1 mA at 1.8 V minimum, which results in approximately 2 mW per stage. This is to be compared against RSFQ comparators which utilize approximately 0.5 mA at almost no voltage, resulting in muW of dissipation per stage. Given that we are hoping to produce a large number of SNSPD input stages, RSFQ is clearly a better choice. However, we only have a small number of output signals from the cryostat, so it is much more reasonable to use CMOS, as we can attain larger signal amplitudes.
by Charles Henry Herder III.
M.Eng.

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18

Fancey, Stuart James. "Single-photon avalanche diodes for time-resolved photoluminescence measurements in the near infra-red". Thesis, Heriot-Watt University, 1996. http://hdl.handle.net/10399/1309.

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19

Hu, Xiaolong Ph D. Massachusetts Institute of Technology. "Efficient superconducting-nanowire single-photon detectors and their applications in quantum optics". Thesis, Massachusetts Institute of Technology, 2011. http://hdl.handle.net/1721.1/63073.

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Thesis (Ph. D.)--Massachusetts Institute of Technology, Dept. of Electrical Engineering and Computer Science, 2011.
Cataloged from PDF version of thesis.
Includes bibliographical references (p. 123-131).
Superconducting-nanowire single-photon detectors (SNSPDs) are an emerging technology for infrared photon counting and detection. Their advantages include good device efficiency, fast operating speed, low dark-count rate, low timing jitter, free running mode, and no afterpulsing. The challenges to be addressed prior to real applications are cryogenic operations, small active areas, and efficiency-speed tradeoffs. This thesis presents the effort to address these challenges. A fiber-coupled SNSPD system with a large-area detector in a closed-cycle cryocooler has been built, demonstrating 24% system detection efficiency with a darkcount rate of -1000 counts/sec. As a result, the SNSPD system becomes a convenient tool with a single-mode fiber as the input channel and an SMA cable as the output channel. This system has enabled high-quality polarization-entanglement distribution at the wavelength of 1.3 tm. The 99.2% visibility in Hong-Ou-Mandel (HOM) interference measured in this experiment is the highest HOM visibility that has ever been reported for waveguide-based photon-pair sources. After entanglement is distributed, a pair rate of 5.8 pairs/sec at a pump power of 25 iW and two-photon quantum interference visibility of 97.7% have been measured. On the other hand, increasing the active area of the detector does decrease its speed. To address the issue of efficiency-speed tradeoff, SNSPDs have been integrated with optical nano-antennae. A 9- im-by-9- tm detector with 47% device efficiency and 5-ns reset time has been demonstrated. In terms of active area, device efficiency and speed, this SNSPD has the record performance among single-element SNSPDs. Finally, waveguide-integrated SNSPDs have been proposed and designed. The device structure permits efficient coupling of photons into a short nanowire, and thus, efficient and fast SNSPDs. This structure is compatible with on-chip photonic technologies, including inverse-taper couplers and ring resonators, that have been developed in recent years.
by Xiaolong Hu.
Ph.D.

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20

Archer, Lucy Elizabeth. "Optical properties of ultra-thin niobium nitride films for single photon detectors". Thesis, Massachusetts Institute of Technology, 2017. http://hdl.handle.net/1721.1/112044.

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Thesis: S.M., Massachusetts Institute of Technology, Department of Physics, 2017.
Cataloged from PDF version of thesis.
Includes bibliographical references (pages 75-78).
In this thesis I made a study of the properties of reactively sputtered ultra-thin films of niobium nitride (NbN) and niobium titanium nitride (NbTiN). Using Variable Angle Spectral Ellipsometry (VASE), I found that the optical properties of NbN films appear to have a critical thickness above which the optical parameters stabilize. I also found that the deposition process has better stability over time for thicker films than for thinner ones; that is, when films are deposited weeks apart, the thinner films show more variation in thickness and optical properties than do the thicker films. The data also suggest that the crystallinity of the substrate upon which the NbN is deposited has a significant effect on the optical parameters. The set of films deposited for the optical study was also tested against a universal scaling law for thin film superconductors, which seems to support the existence of the critical thickness, below which the properties change significantly and do not conform to the power law scaling that holds for thicker films. Finally, I explored recipes for depositing NbTiN with our sputtering system, in the hope of creating films that have better properties than NbN to be used in device manufacturing. I was able to create films with the same properties as our current NbN films with minimal optimization, and further work in this area should result in NbTiN films that are better than our NbN films.
by Lucy Elizabeth Archer.
S.M.

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21

Schmidt, Wolfgang-Gustav Ekkehart [Verfasser]. "Superconducting Nanowire Single-Photon Detectors for Quantum Photonic Integrated Circuits on GaAs / Wolfgang-Gustav Ekkehart Schmidt". Karlsruhe : KIT Scientific Publishing, 2020. http://d-nb.info/1213447836/34.

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22

Richardson, Justin Andrew. "Time resolved single photon imaging in nanometer scale CMOS technology". Thesis, University of Edinburgh, 2010. http://hdl.handle.net/1842/7588.

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Time resolved imaging is concerned with the measurement of photon arrival time. It has a wealth of emerging applications including biomedical uses such as fluorescence lifetime microscopy and positron emission tomography, as well as laser ranging and imaging in three dimensions. The impact of time resolved imaging on human life is significant: it can be used to identify cancerous cells in-vivo, how well new drugs may perform, or to guide a robot around a factory or hospital. Two essential building blocks of a time resolved imaging system are a photon detector capable of sensing single photons, and fast time resolvers that can measure the time of flight of light to picosecond resolution. In order to address these emerging applications, miniaturised, single-chip, integrated arrays of photon detectors and time resolvers must be developed with state of the art performance and low cost. The goal of this research is therefore the design, layout and verification of arrays of low noise Single Photon Avalanche Diodes (SPADs) together with high resolution Time-Digital Converters (TDCs) using an advanced silicon fabrication process. The research reported in this Thesis was carried out as part of the E.U. funded Megaframe FP6 Project. A 32x32 pixel, one million frames per second, time correlated imaging device has been designed, simulated and fabricated using a 130nm CMOS Imaging process from ST Microelectronics. The imager array has been implemented together with required support cells in order to transmit data off chip at high speed as well as providing a means of device control, test and calibration. The fabricated imaging device successfully demonstrates the research objectives. The Thesis presents details of design, simulation and characterisation results of the elements of the Megaframe device which were the author’s own work. Highlights of the results include the smallest and lowest noise SPAD devices yet published for this class of fabrication process and an imaging array capable of recording single photon arrivals every microsecond, with a minimum time resolution of fifty picoseconds and single bit linearity.

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23

Kahl, Oliver [Verfasser] y M. [Akademischer Betreuer] Wegener. "Superconducting Single-Photon Detectors for Integrated Quantum Optics / Oliver Kahl. Betreuer: M. Wegener". Karlsruhe : KIT-Bibliothek, 2016. http://d-nb.info/1093559098/34.

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24

Charaev, Ilya [Verfasser]. "Improving the Spectral Bandwidth of Superconducting Nanowire Single-Photon Detectors (SNSPDs) / Ilya Charaev". Karlsruhe : KIT Scientific Publishing, 2018. http://www.ksp.kit.edu.

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25

Carramate, Lara Filipa das Neves Dias. "Development of a single photon counting computed tomography system using MPGDs". Doctoral thesis, Universidade de Aveiro, 2014. http://hdl.handle.net/10773/14003.

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Desenvolvimento de um sistema de tomografia computorizada de contagem de fotão único usando MPGDs
The development of computed tomography systems with energy resolving detectors is a current challenge in medical physics and biomedical engineering. A computed tomography system of this kind allows getting complementary informations relatively to conventional systems, that can help the medical diagnosis, being of great interest in medicine. The work described in this thesis is related to the development of a computed tomography system using micropattern gaseous detectors, which allow storing, simultaneously, information about the interaction position and the energy of each single photon that interacts with the detector. This kind of detectors has other advantages concerning the cost and characteristics of operation when compared with solid state detectors. Tomographic acquisitions were performed using a MicroHole & Strip Plate based detector, which allowed reconstructing cross-sectional images using energy windows, applying the energy weighting technique and performing multi-slice and tri-dimensional reconstructions. The contrast-to-noise ratio was improved by 31% by applying the energy weighting technique, comparing with the corresponding image obtained with the current medical systems. A prototype of a computed tomography with flexibility to change the detector was developed, making it possible to apply different detectors based on Thick-COBRA. Several images acquired with these detectors are presented and demonstrate their applicability in X-ray imaging. When operating in NeCH4, the detector allowed a charge gain of 8 104, an energy resolution of 20% (full width at half maximum at 8 keV), a count rate of 1 106 Hz/mm2, a very stable operation (gain fluctuations below 5%) and a spacial resolution of 1.2 mm for an energy photon of 3.6 keV. Operating the detector in pure Kr allowed increasing the detection efficiency and achieving a charge gain of 2 104, an energy resolution of 32% (full width at half maximum at 22 keV), a count rate of 1 105 Hz/mm2, very stable operation and a spatial resolution of 500 m. The software already existing in the group was improved and tools to correct geometric misalignments of the system were also developed. The reconstructions obtained after geometrical correction are free of artefacts due to the referred misalignments.
O desenvolvimento de sistemas de tomografia computorizada que incorporem detetores com resolução em energia é um desafio atual em física médica e engenharia biomédica. Um sistema de tomografia computorizada espetral permite obter informações complementares comparativamente a um sistema convencional, que podem auxiliar no diagnóstico médico, sendo por isso de grande interesse em medicina. O trabalho exposto nesta tese prende-se com o desenvolvimento de um sistema de tomografia usando detetores gasosos microestruturados que permitem, simultaneamente, ter informação da posição de interacção e da energia de cada fotão que interage com o detetor. Este tipo de detetores possui ainda outras vantagens relativamente a custo ou características de funcionamento quando comparados com detetores de estado sólido. Foram realizadas aquisições tomográficas usando um detetor baseado numa MicroHole & Srip Plate que permitiu reconstruir imagens utilizando diferentes gamas de energia, aplicar técnicas de ponderação em energia e fazer pela primeira vez reconstrução multi-corte e obter imagens tri-dimensionais. Aplicando a técnica de ponderação em energia foi possível melhorar a relação contraste-ruído em 31% comparativamente à imagem correspondente aquela obtida nos actuais sistemas médicos. Posteriormente, foi desenvolvido um protótipo de um sistema de tomografia computorizada com flexibilidade para alterar o detetor, tornando possível utilizar vários detetores baseados na microestrutura Thick-COBRA. São apresentadas várias imagens adquiridas com estes detetores que evidenciam a sua aplicabilidade em imagiologia por raio-X. A operar no meio gasoso NeCH4 o detetor permitiu um ganho de 8 104, uma resolução em energia de 20% (largura a meia altura a 8 keV), uma taxa de contagem de 1 106 Hz/mm2, um funcionamento muito estável (variações de ganho inferiores a 5%) e uma resolução espacial de 1.2 mm para fotões de 3.6 keV. A operar em Kr puro foi possível aumentar a eficiência de deteção e alcançar um ganho de 2 104, uma resolução em energia de 32% (largura a meia altura a 22 keV), uma taxa de contagem de 1 105 Hz/mm2, um funcionamento também bastante estável e uma resolução espacial de 500 m. O software já existente no grupo para reconstrução de imagem foi melhorado e foram ainda desenvolvidas ferramentas para correcção de desalinhamentos geométricos do sistema. As reconstruções obtidas após correção geométrica surgem livres de artefactos originados pelos referidos desalinhamentos.

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26

Daibes, Figueroa Said. "Discrete NaI(TI) crystal detector optimization for small animal SPECT molecular imaging". Diss., Columbia, Mo. : University of Missouri-Columbia, 2005. http://hdl.handle.net/10355/5821.

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Thesis (Ph.D.)--University of Missouri-Columbia, 2005.
The entire dissertation/thesis text is included in the research.pdf file; the official abstract appears in the short.pdf file (which also appears in the research.pdf); a non-technical general description, or public abstract, appears in the public.pdf file. Title from title screen of research.pdf file viewed on (November 15, 2006) Vita. Includes bibliographical references.

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27

Xu, Hesong. "Solid-state single-photon Detectors and CMOS Readaout Circuits for Positron Emission Tomography Applications". Doctoral thesis, Università degli studi di Trento, 2016. https://hdl.handle.net/11572/368477.

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In recent years, Silicon Photomultipliers (SiPMs) have been increasingly used as photo-detectors in Positron Emission Tomography (PET) application, which is a nuclear imaging tech-nique that is used to accurately image biochemical processes inside the human body. A SiPM is composed by an array of parallel connected micro-cells of Single Photon Avalanche Diodes (SPADs), and can be classified mainly into two categories Digital-SiPMs (D-SiPMs) and Analog-SiPMs (A-SiPMs). In A-SiPMs, all the microcells share the same bias voltage and have a common readout line. Through custom manufacturing process, the performance of A-SiPMs can be exten-sively optimized. With respect to A-SiPMs, D-SiPMs are composed by many SPAD pixels, each one containing one SPAD and local front-end circuitry. The digital SiPM takes advantage of CMOS technology to perform a 1-b direct A/D conversion per SPAD thus providing a fully digi-tal implementation. On the other hand, SPADs fabricated in CMOS process typically suffer high noise since the critical SPAD implants can hardly be optimized by using the standard CMOS process flow. The main activities carried out within this PhD thesis have been focused on two critical as-pects relevant for the optimization of PET systems performance: (I) the improvement of the per-formance of SPAD in D-SiPMs and (II) the development of high-performance A-SiPM readout application specific integrated circuit (ASIC). Concerning the first point, novel SPADs have been fabricated in CMOS 150-nm technology targeting at low noise, high sensitivity and excellent timing jitter. Three structures with different shapes, geometries and diameters, have been implemented in three test chips. Measurement re-sults of one p+/n-well SPAD array show a 0.4Hz/Âµm2 dark count noise, 0.85% afterpulsing for a dead time of 150ns at 3V excess bias. The photon detection probability is about 31% at 450nm wavelength at 5V excess bias. The SPAD exhibits a timing jitter of 82ps (FWHM) under a blue laser, which is potentially suitable for D-SiPMs in PET application. The second objective of this PhD work was to develop A-SiPM readout ASIC for PET appli-cation. To utilize the high intrinsic time resolution of A-SiPMs, the development of specialized, highly integrated readout electronics is required. Therefore, two ASICs, first chip with test struc-tures and 16 channels and the second chip with 32 channels, have been developed in 150-nm CMOS technology, with the aim of developing a compact A-SiPM module. The performance of the second chip has been validated by using 3 Ã— 3 Ã— 5 mm3 LYSO crystals coupled to 4 Ã— 4 mm2 SiPMs (FBK-NUV-HD). The measurements show an energy resolution of 14.7% FWHM for the detection of 511 keV photons and the coincidence time resolution is 433ps (FWHM). To improve the timing resolution, part of the PhD work was carried on Stanford University, focused on char-acterization of A-SiPMs and analysis of noise contribution.

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28

Shastri, Vasant. "Single-photon-counting technique for luminescence spectra and decay measurements". Ohio : Ohio University, 1987. http://www.ohiolink.edu/etd/view.cgi?ohiou1183060409.

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29

ThÃ, George AndrÃ Pereira. "Teoria e implementaÃÃo de detectores de fÃtons isolados para comunicaÃÃes quÃnticas em redes Ãpticas". Universidade Federal do CearÃ, 2006. http://www.teses.ufc.br/tde_busca/arquivo.php?codArquivo=2111.

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nÃo hÃ
Tecnologia da InformaÃÃo QuÃntica Ã uma Ãrea multidisciplinar nova que tem recebido muita atenÃÃo por ser promissora e devido a seu alto potencial em resolver problemas ainda nÃo solucionados. Dentro desta grande Ãrea, as ComunicaÃÃes QuÃnticas estÃo bastante desenvolvidas. Nesta sub-Ãrea, distribuiÃÃo QuÃntica de Chaves Ã o campo mais avanÃado. Ela permite que duas partes, chamadas Alice e Bob, compartilhem uma chave criptogrÃfica atravÃs de um canal seguro (seguranÃa garantida por leis da mecÃnica quÃntica). A maior parte dos Sistemas de DistribuiÃÃo QuÃntica de Chaves Ã executada em enlaces de fibras Ãpticas e, nestes sistemas, a mais importante parte Ã o Detector de FÃtons Isolados. Detector de FÃtons Isolados Ã um equipamento capaz de absorver um fÃton e gerar um sinal TTL. Assim, em um Detector de FÃtons Isolados ideal, cada fÃton que chega deve disparar um pulso TTL na saÃda. Dado que a energia de um fÃton isolado Ã muito baixa, um fotodiodo de avalanche Ã usado para realizar o processo absorÃÃo do fÃtongeraÃÃo de portador, uma vez que este fotodiodo, se corretamente polarizado, pode disparar uma avalanche de portadores detectÃvel. ApÃs a avalanche ter se iniciado, ela deve ser extinta para evitar qualquer dano ao fotodiodo, o que Ã feito por um circuito de extinÃÃo de avalanche. O fotodiodo de avalanche Ã o elemento mais importante de um Detector de FÃtons Isolados e sua caracterizaÃÃo requer muita atenÃÃo. Neste contexto, esta dissertaÃÃo lida com aspectos teÃricos e prÃticos de Detectores de FÃtons Isolados para ComunicaÃÃes QuÃnticas. Inicia com a teoria de fotodiodos de avalanche e circuitos de extinÃÃo (resultados numÃricos de circuitos de extinÃÃo tambÃm sÃo mostrados), e segue atÃ a caracterizaÃÃo de um Detector de FÃtons Isolados construÃdo em laboratÃrio e suas aplicaÃÃes em metrologia de dispositivos Ãpticos, bem como em resoluÃÃo de nÃmero de fÃtons.
Quantum Information Technology is a new multi-disciplinary area which has received a lot of attention due to its promises and its high potential in solving problems still unsolved. In this big area, Quantum Communication is too much developed. In this subarea, Quantum Key Distribution is the most advanced field. It permits two parties, named Alice and Bob, sharing a cryptography key through a secure channel (guaranteed by laws of quantum mechanics). The most of Quantum Key Distribution Systems run over optical fiber links and, in these systems, the most important part is the Single-Photon Detector. Single-Photon Detector is an equipment able to absorb a photon and generate a TTL pulse. Thus, in an ideal Single-Photon Detector, each photon incoming must trigger a TTL pulse at the output. Since the energy level of a single-photon is too much low, an avalanche photodiode is used to perform the photon absorption-carrier generation process, once this photodiode if correctly biased can trigger a detectable avalanche of carriers. After the avalanche has been started, it must be quenched in order to avoid any damage to the photodiode, which is made by an avalanche quenching circuit. The avalanche photodiode is the most important element of a Single-Photon Detector and its characterization requires much attention. In this context, this dissertation deals with theoretical and practical aspects of Single-Photon Detectors for Quantum Communication. It starts from the theory of avalanche photodiodes and quenching circuits (numerical results of quenching circuits are also shown) and follows until the characterization of a home-made Single-Photon Detector and its applications in Metrology of optical devices and in Photon-Number Resolution as well.

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30

Schmidt, Wolfgang-Gustav Ekkehart [Verfasser] y M. [Akademischer Betreuer] Siegel. "Superconducting Nanowire Single-Photon Detectors for Quantum Photonic Integrated Circuits on GaAs / Wolfgang-Gustav Ekkehart Schmidt ; Betreuer: M. Siegel". Karlsruhe : KIT-Bibliothek, 2019. http://d-nb.info/119312672X/34.

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31

Benetti, Michele. "Simulation and Characterization of Single Photon Detectors for Fluorescence Lifetime Spectroscopy and Gamma-ray Applications". Doctoral thesis, Università degli studi di Trento, 2012. https://hdl.handle.net/11572/367882.

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Gamma-ray and Fluorescence Lifetime Spectroscopies are driving the development of non-imaging silicon photon sensors and, in this context, Silicon Photo-Multipliers (SiPM)s are leading the starring role. They are 2D array of optical diodes called Single Photon Avalanche Diodes (SPAD)s, and are normally fabricated with a dedicated silicon process. SPADs amplify the charge produced by the single absorbed photon in a way that recalls the avalanche amplification exploited in Photo-Multiplier Tubes (PMT)s. Recently 2D arrays of SPADs have been realized also in standard CMOS technology, paving the way to the realization of completely custom sensors that can host ancillary electronic and digital logic on-chip. The designs of scientific apparatus have been influenced for years by the bulky PMT-based detectors. An overwhelming interest in both SiPMs and CMOS SPADs lies in the possibility of displacing these small sensors realizing new detectors geometries. This thesis examines the potential deployment of SiPM-based detector in an apparatus built for the study of the Time-Of-Flight (TOF) of Positronium (Ps) and the displacement of 2D array of CMOS SPADs in a lab-on-chip apparatus for Fluorescence Lifetime Spectroscopy. The two design procedures are performed using Monte-Carlo simulations. Characterizations of the two sensor have been carried out, allowing for a performance evaluation and a validation of the two design procedures.

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32

Henrich, Dagmar [Verfasser]. "Influence of Material and Geometry on the Performance of Superconducting Nanowire Single-Photon Detectors / Dagmar Henrich". Karlsruhe : KIT Scientific Publishing, 2013. http://www.ksp.kit.edu.

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33

Müller, Ingmar. "Linking detector radiometry from milliwatts radiant power to single photons". Doctoral thesis, Humboldt-Universität zu Berlin, Mathematisch-Naturwissenschaftliche Fakultät I, 2014. http://dx.doi.org/10.18452/16883.

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Das Ziel dieser Dissertation ist das Schließen der radiometrischen Lücke zwischen der klassischen Radiometrie und der Radiometrie im Bereich weniger und einzelner Photonen. In dieser Arbeit wurden dazu zwei wesentliche Themen bearbeitet. Erstens, die Charakterisierung und Validierung eines neuen radiometrischen Detektorprimärnormals für den Wellenlängenbereich von 400 nm bis 800 nm basierend auf Silizium-Photodioden. Dieses neuartige Primärnormal kann sowohl in der Radiometrie im Bereich weniger Photonen als auch in der klassischen Radiometrie eingesetzt werden, der sogenannte “Predictable Quantum Efficient Detector” (PQED). Der PQED wurde im Rahmen dieser Arbeit charakterisiert und experimentell validiert. Für die Validierung war es nötig, die relativen Unsicherheiten der klassischen Radiometrie und insbesondere der Kryoradiometrie, deutlich zu verringern. Mit der Inbetriebnahme eines neuen Kryoradiometers wurde das Ziel, in den Unsicherheitsbereich von ca. 10E−5 vorzudringen, erreicht. Zweitens, es wurde eine Kalibriermethode für Einzelphotonendetektoren eingesetzt, rückgeführt auf das internationale Einheitensystem, die auf den einzigartigen Eigenschaften von Synchrotronstrahlung basiert. Diese Methode kann benutzt werden um sowohl Freistrahl- als auch fasergekoppelte Einzelphotonendetektoren bei praktisch jeder gewünschten Wellenlänge zu kalibrieren und erreicht im Moment die weltweit geringsten Messunsicherheiten. Mit dem neuen Kryoradiometer, dem PQED und dem auf Synchrotronstrahlung basierenden Kalibrierverfahren sind die erreichbaren Messunsicherheiten in der Radiometrie im Bereich von wenigen Photonen bis zu Strahlungsleistungen im Milliwattbereich deutlich reduziert worden.
This thesis addresses the bridging of the radiometric gap in the transition from classical radiometry to the few and single photon radiometry. In this context, two main tasks were emphasised. First: A new radiometric primary detector standard for wavelengths between 400 nm and 800 nm, suitable for classical and few photon radiometry, the so-called “Predictable Quantum Efficient Detector” (PQED) was characterised and validated. For the validation of the PQED, the relative uncertainties achievable in classical radiometry and, in particular, with cryogenic radiometers had to be reduced to a level of 10E−5 with the commissioning of a new cryogenic radiometer facility. Second: A calibration method for single photon detectors in the visible and NIR has been used which is based on the unique properties of synchrotron radiation. This calibration method allows radiometric single photon detector calibrations with the lowest uncertainties reported so far. This method can be used to calibrate free space and fibre-coupled single photon detectors traceable to the international system of units at practically every desired optical wavelength. With the new cryogenic radiometer, the PQED, and the calibration method based on synchrotron radiation, the uncertainties in radiometry have been signiﬁcantly reduced in the range from milliwatts of radiant power down to attowatts corresponding to a few photons per second.

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34

McWhirter, Ian. "Imaging photon detectors and their use with single and multiple Fabry-Perot etalon systems for atmospheric wind measurements". Thesis, University College London (University of London), 1993. http://ethos.bl.uk/OrderDetails.do?uin=uk.bl.ethos.360191.

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35

Meng, Xiao. "InGaAs/InAlAs single photon avalanche diodes at 1550 nm and X-ray detectors using III-V semiconductor materials". Thesis, University of Sheffield, 2015. http://etheses.whiterose.ac.uk/11405/.

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36

Hsu, Mark J. "Development of shallow trench isolation bounded single-photon avalanche detectors for acousto-optic signal enhancement and frequency up-conversion". Diss., [La Jolla] : University of California, San Diego, 2010. http://wwwlib.umi.com/cr/ucsd/fullcit?p3407959.

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Thesis (Ph. D.)--University of California, San Diego, 2010.
Title from first page of PDF file (viewed June 17, 2010). Available via ProQuest Digital Dissertations. Vita. Includes bibliographical references (leaves 172-191).

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37

Rae, Bruce R. "Micro-systems for time-resolved fluorescence analysis using CMOS single-photon avalanche diodes and micro-LEDs". Thesis, University of Edinburgh, 2009. http://hdl.handle.net/1842/4219.

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Fluorescence based analysis is a fundamental research technique used in the life sciences. However, conventional fluorescence intensity measurements are prone to misinterpretation due to illumination and fluorophore concentration non-uniformities. Thus, there is a growing interest in time-resolved fluorescence detection, whereby the characteristic fluorescence decay time-constant (or lifetime) in response to an impulse excitation source is measured. The sensitivity of a sample’s lifetime properties to the micro-environment provides an extremely powerful analysis tool. However, current fluorescence lifetime analysis equipment tends to be bulky, delicate and expensive, thereby restricting its use to research laboratories. Progress in miniaturisation of biological and chemical analysis instrumentation is creating low-cost, robust and portable diagnostic tools capable of high-throughput, with reduced reagent quantities and analysis times. Such devices will enable point-of-care or in-the-field diagnostics. It was the ultimate aim of this project to produce an integrated fluorescence lifetime analysis system capable of sub-nano second precision with an instrument measuring less than 1cm3, something hitherto impossible with existing approaches. To accomplish this, advances in the development of AlInGaN micro-LEDs and high sensitivity CMOS detectors have been exploited. CMOS allows electronic circuitry to be integrated alongside the photodetectors and LED drivers to produce a highly integrated system capable of processing detector data directly without the need for additional external hardware. In this work, a 16x4 array of single-photon avalanche diodes (SPADs) integrated in a 0.35μm high-voltage CMOS technology has been implemented which incorporates two 9-bit, in-pixel time-gated counter circuits, with a resolution of 400ps and on-chip timing generation, in order to directly process fluorescence decay data. The SPAD detector can accurately capture fluorescence lifetime data for samples with concentrations down to 10nM, demonstrated using colloidal quantum dot and conventional fluorophores. The lifetimes captured using the on-chip time gated counters are shown to be equivalent to those processed using commercially available external time-correlated single-photon counting (TCSPC) hardware. A compact excitation source, capable of producing sub-nano second optical pulses, was designed using AlInGaN micro-LEDs bump-bonded to a CMOS driver backplane. A series of driver array designs are presented which are electrically contacted to an equivalent array of micro-LEDs emitting at a wavelength of 370nm. The final micro-LED driver design is capable of producing optical pulses of 300ps in width (full width half maximum, FWHM) and a maximum DC optical output power of 550μW, this is, to the best of our knowledge, the shortest reported optical pulse from a CMOS driven micro-LED device. By integrating an array of CMOS SPAD detectors and an array of CMOS driven AlInGaN micro-LEDs, a complete micro-system for time-resolved fluorescence analysis has been realised. Two different system configurations are evaluated and the ability of both topologies to accurately capture lifetime data is demonstrated. By making use of standard CMOS foundry technologies, this work opens up the possibility of a low-cost, portable chemical/bio-diagnostic device. These first-generation prototypes described herein demonstrate the first time-resolved fluorescence lifetime analysis using an integrated micro-system approach. A number of possible design improvements have been identified which could significantly enhance future device performance resulting in increased detector and micro-LED array density, improved time-gate resolution, shorter excitation pulse widths with increased optical output power and improved excitation light filtering. The integration of sample handling elements has also been proposed, allowing the sample of interest to be accurately manipulated within the micro-environment during investigation.

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38

Melbourne, Thomas. "Magnesium Diboride Devices and Applications". Thesis, Temple University, 2018. http://pqdtopen.proquest.com/#viewpdf?dispub=10689307.

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Magnesium diboride MgB₂ is an interesting material that was discovered to be a superconductor in 2001. It has a remarkably high critical temperature of 39 K which is much greater than was previously thought possible for a phonon-mediated superconductor. MgB₂ was also the first material found to exhibit multiple gap superconductivity. It has two energy gaps, the pi gap with a value of 2.3 meV, and the sigma gap with a value of 7.1 meV. Both the high critical temperature and the multiple large energy gaps make MgB₂ an attractive candidate for superconducting devices. While the initial discovery of MgB₂ was accompanied by much excitement, the enthusiasm has mostly disappeared due to the lack of progress made in implementing MgB₂ in practical devices. The aim of this thesis is to attempt to reinvigorate interest in this remarkable material through a study of a variety of practical superconducting devices made with MgB₂ thin films grown by hybrid physical-chemical vapor deposition (HPCVD).

Two different methods of fabricating MgB₂ Josephson junctions are explored. The first is a sandwich type trilayer configuration with a barrier made by magnetron sputtered MgO. Junctions of this sort have been previously studied and implemented in a variety of devices. While they do show some attractive properties, the on-chip spread in critical current due to barrier non-uniformity was too high to be considered a viable option for use in many-junction devices. By developing a fabrication scheme which utilizes electron beam lithography, modest improvements were made in the on-chip parameter spread, and miniaturization of junction size yielded some insight into the non-uniform barriers.

The second approach of creating MgB₂ Josephson junctions utilized a planar geometry with a normal metal barrier created by irradiating nano-sized strips of the material with a focused helium ion beam. The properties of these junctions are investigated for different irradiation doses. This new technique is capable of producing high quality junctions and furthermore the parameter spread is greatly reduced as compared to the sandwich type junctions. While more research is necessary in order to increase the I_cR_n products, these junctions show promise for use in many-junction devices such as RSFQ circuits.

Prior to this work, the largest substrates that could be coated with HPCVD grown MgB₂ were 2" in diameter. A new chamber was designed and constructed which demonstrated the ability to coat substrates as large as 4". This scaled-up system was used to grow MgB₂ films on 1 x 10 cm flexible substrates. A method of fabrication was developed which could pattern these 10 cm long samples into ribbon cables consisting of many high frequency transmission lines. This technology can be utilized to increase the cooling efficiency of cryogenic systems used for RSFQ systems which require many connections between low temperature and room temperature electronics.

Finally, a method of producing MgB₂ films with thicknesses as low as 8 nm was developed. This is achieved by first growing thicker films and using a low angle ion milling step to gradually reduce the film thickness while still maintaining well connected high quality films. A procedure was developed for fabricating meandering nanowires in these films with widths as low as 100 nm for use as superconducting nanowire single photon detectors (SNSPDs). A study of the transport properties of these devices is first presented. Measurements show low values of kinetic inductance which is ideal for high count rates in SNSPDs. The kinetic inductance measurements also yielded the first measurements of the penetration depth of MgB₂ films in the ultra-thin regime. Devices made from these ultra-thin films were found to be photon sensitive by measurements made by our collaborators.

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39

Merzi, Stefano. "Novel applications of FBK SiPMs in the detection of low energy ionizing radiation". Doctoral thesis, Università degli studi di Trento, 2020. http://hdl.handle.net/11572/276309.

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Silicon photon multipliers, or SiPMs, are single photon detectors that have grown increasing interest in the last decade as an alternative to photomultiplier tubes in many field of physics, engineering and medicine. Compared to PMTs, SiPMs are more compact, rugged and operate at much lower bias voltage, in the order of tens of volts. Moreover they are insensitive to magnetic field and can achieve a very high radiopurity SiPM detectors work on the principle of a diode operated above the breakdown voltage, in Geiger mode. In this condition, the electric field in the depletion region is high enough that the electron-hole pairs, generated by a single photon absorption through photoelectric effect, create secondary charges by impact ionization in a potentially diverging avalanche effect that can be exploited to generate a macroscopical current at the output of the diode. Thanks to this effect, the SiPM is capable of counting the number of impinging photons down to single photon level. Noise sources in the SiPM include dark counts and correlated noise. Dark counts are counts happening when an electron-hole pair is generated in the active volume of the device in absence of photon absorptions. These events are caused either by thermal generation, diffusion from the neutral region or by tunnel effect. Correlated noise events, or counts, on the other hand, are generated when a primary firing cell retriggers after a certain time or cause the triggering of another cell. All these noise sources introduce errors in the photon count by adding fake events to the output signal of the detector.Traditional SiPM application is 511 keV gamma-ray detection in PET machines, using scintillator LYSO crystals to convert a single gamma ray into a flash of visible photons. An application based on the same principle was studied in this thesis by coupling FBK RGB-HD SiPMs with CsI:Tl crystals in order to detect lower energy X and gamma-rays. This setup has proven to be effective in the detection of radiation with energy as low as 5.9 keV with a resolution of 38.3%, which is the minimum value of energy resolution measured with SiPMs coupled to scintillator crystals at such low energy. At the same time it was observed that large area detectors provided a dynamic range wide enough to simultaneously detect radiation ranging from 6.4 keV to 122 keV with minimal saturation. In another activity of this thesis it was developed a simulation software that reproduces the behaviour of a SiPM under different light conditions by taking into account the detector efficiency, the dead time and the recharge behaviour of its cells and theoretical modelizations of the noise parameters that affect the measurement. From a given light profile the simulation generates a waveform that reproduces the one measured during the operation of real SiPMs. This waveform was then analysed using FBK software developed for SiPM characterization and the results showed an excellent agreement between the simulated detector and a reference SiPM. This software will become a useful tool for the design of SiPMs for future experiments because it will allow to tune the properties of the detectors to specific applications and it will reduce the need of layout and process split to find the optimal configuration of the detector parameters.Among all FBK technologies, this work was focused on the position-sensitive LG-SiPM. Unlike standard SiPMs, which have a single output, the LG-SiPM employs a more complex structure that splits the current signal into four output channels with ratios depending on the position of the impinging light on its surface. Center of mass calculations are used to reconstruct the position of the firing cell with precision down to some tens of microns while maintaining the fast time response of SiPMs. An application of the LG-SiPM was studied in the framework of the ARIADNE experiment in collaboration with the university of Liverpool. In this work the LG-SiPM was used to detect scintillation light coming from ionization tracks generated by alpha particles inside a CF4 TPC chamber. The ionized electrons where drifted through the action of a high electric field in the TPC towards a THGEM where they created light with timing depending on the distance of each track segment from the scintillator. The LG detector was able to reconstruct the 3D track particle inside the chamber with an error below 8 mm RMS inside the 40 l chamber and, at the same time, to reconstruct the energy released by the particle as function of time and calculate the total energy of the interacting particle and its linear energy transfer. These results open a novel approach for the TPC position reconstruction that combines the low number of readout channels needed for the LG detector to its time-continuous response which allows to reconstruct the tree-dimensional track of a particle inside the chamber.During the experiment it emerged the presence of an artifact that drifted all the reconstructed tracks towards the centre of the detection area, at the end of the signal. This effect was studied by creating a second simulation software that recreates the electrical behaviour of the LG-SiPM equivalent circuit when one or more cells trigger. It was simulated the output of the circuit with different light conditions and different values of the circuit elements and it was observed that the presence of the artifact was related to low intensity currents flowing through the net of the LG-SiPM metal tracks and quenching resistors. Several simulations were run in order to identify the optimal configuration of parameters for the reduction of this unwanted effect and to implement improvements in future LG-SiPM productions.Another application of the LG-SiPM in the field of radiation detection is the position reconstruction of the scintillation light emitted by gamma-rays in a monolithic crystal. Using a thin CsI:Tl crystal and lowering the detector temperature it was possible to distinguish different positions of interaction on the surface of the detector with an error below 1 mm FWHM. This technology can be effective for the creation of monolithic, position sensitive X and gamma-ray detector with good energy resolution for low energy spectroscopy or medical imaging devices.

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40

Merzi, Stefano. "Novel applications of FBK SiPMs in the detection of low energy ionizing radiation". Doctoral thesis, Università degli studi di Trento, 2020. http://hdl.handle.net/11572/276309.

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Silicon photon multipliers, or SiPMs, are single photon detectors that have grown increasing interest in the last decade as an alternative to photomultiplier tubes in many field of physics, engineering and medicine. Compared to PMTs, SiPMs are more compact, rugged and operate at much lower bias voltage, in the order of tens of volts. Moreover they are insensitive to magnetic field and can achieve a very high radiopurity SiPM detectors work on the principle of a diode operated above the breakdown voltage, in Geiger mode. In this condition, the electric field in the depletion region is high enough that the electron-hole pairs, generated by a single photon absorption through photoelectric effect, create secondary charges by impact ionization in a potentially diverging avalanche effect that can be exploited to generate a macroscopical current at the output of the diode. Thanks to this effect, the SiPM is capable of counting the number of impinging photons down to single photon level. Noise sources in the SiPM include dark counts and correlated noise. Dark counts are counts happening when an electron-hole pair is generated in the active volume of the device in absence of photon absorptions. These events are caused either by thermal generation, diffusion from the neutral region or by tunnel effect. Correlated noise events, or counts, on the other hand, are generated when a primary firing cell retriggers after a certain time or cause the triggering of another cell. All these noise sources introduce errors in the photon count by adding fake events to the output signal of the detector.Traditional SiPM application is 511 keV gamma-ray detection in PET machines, using scintillator LYSO crystals to convert a single gamma ray into a flash of visible photons. An application based on the same principle was studied in this thesis by coupling FBK RGB-HD SiPMs with CsI:Tl crystals in order to detect lower energy X and gamma-rays. This setup has proven to be effective in the detection of radiation with energy as low as 5.9 keV with a resolution of 38.3%, which is the minimum value of energy resolution measured with SiPMs coupled to scintillator crystals at such low energy. At the same time it was observed that large area detectors provided a dynamic range wide enough to simultaneously detect radiation ranging from 6.4 keV to 122 keV with minimal saturation. In another activity of this thesis it was developed a simulation software that reproduces the behaviour of a SiPM under different light conditions by taking into account the detector efficiency, the dead time and the recharge behaviour of its cells and theoretical modelizations of the noise parameters that affect the measurement. From a given light profile the simulation generates a waveform that reproduces the one measured during the operation of real SiPMs. This waveform was then analysed using FBK software developed for SiPM characterization and the results showed an excellent agreement between the simulated detector and a reference SiPM. This software will become a useful tool for the design of SiPMs for future experiments because it will allow to tune the properties of the detectors to specific applications and it will reduce the need of layout and process split to find the optimal configuration of the detector parameters.Among all FBK technologies, this work was focused on the position-sensitive LG-SiPM. Unlike standard SiPMs, which have a single output, the LG-SiPM employs a more complex structure that splits the current signal into four output channels with ratios depending on the position of the impinging light on its surface. Center of mass calculations are used to reconstruct the position of the firing cell with precision down to some tens of microns while maintaining the fast time response of SiPMs. An application of the LG-SiPM was studied in the framework of the ARIADNE experiment in collaboration with the university of Liverpool. In this work the LG-SiPM was used to detect scintillation light coming from ionization tracks generated by alpha particles inside a CF4 TPC chamber. The ionized electrons where drifted through the action of a high electric field in the TPC towards a THGEM where they created light with timing depending on the distance of each track segment from the scintillator. The LG detector was able to reconstruct the 3D track particle inside the chamber with an error below 8 mm RMS inside the 40 l chamber and, at the same time, to reconstruct the energy released by the particle as function of time and calculate the total energy of the interacting particle and its linear energy transfer. These results open a novel approach for the TPC position reconstruction that combines the low number of readout channels needed for the LG detector to its time-continuous response which allows to reconstruct the tree-dimensional track of a particle inside the chamber.During the experiment it emerged the presence of an artifact that drifted all the reconstructed tracks towards the centre of the detection area, at the end of the signal. This effect was studied by creating a second simulation software that recreates the electrical behaviour of the LG-SiPM equivalent circuit when one or more cells trigger. It was simulated the output of the circuit with different light conditions and different values of the circuit elements and it was observed that the presence of the artifact was related to low intensity currents flowing through the net of the LG-SiPM metal tracks and quenching resistors. Several simulations were run in order to identify the optimal configuration of parameters for the reduction of this unwanted effect and to implement improvements in future LG-SiPM productions.Another application of the LG-SiPM in the field of radiation detection is the position reconstruction of the scintillation light emitted by gamma-rays in a monolithic crystal. Using a thin CsI:Tl crystal and lowering the detector temperature it was possible to distinguish different positions of interaction on the surface of the detector with an error below 1 mm FWHM. This technology can be effective for the creation of monolithic, position sensitive X and gamma-ray detector with good energy resolution for low energy spectroscopy or medical imaging devices.

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41

Corbeil, Therrien Audrey. "Conception et modélisation de détecteurs de radiation basés sur des matrices de photodiodes à avalanche monophotoniques pour la tomographie d'émission par positrons". Thèse, Université de Sherbrooke, 2018. http://hdl.handle.net/11143/11909.

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La tomographie d'émission par positrons (TEP) se distingue des autres modalités d'imagerie par sa capacité à localiser et quantifier la présence de molécules marquées, appelées radiotraceurs, au sein d'un organisme. Cette capacité à mesurer l'activité biologique des différents tissus d'un sujet apporte des informations uniques et essentielles à l'étude de tumeurs cancéreuses, au fonctionnement du cerveau et de ses maladies neurodégénératives et de la pharmacodynamique de nouveaux médicaments. Depuis les tout débuts de la TEP, les scientifiques rêvent de pouvoir utiliser l'information de temps de vol des photons pour améliorer la qualité de l'image TEP. L'arrivée des photodiodes avalanche monophotoniques (PAMP), rend maintenant ce rêve possible. Ces dispositifs détectent la faible émission de lumière des scintillateurs et présentent une réponse grandement amplifiée avec une faible incertitude temporelle. Mais le potentiel des PAMP n'est pas encore entièrement exploré. Plutôt que de faire la somme des courants d'une matrice de PAMP, il est possible d'utiliser leur nature intrinsèquement binaire afin de réaliser un photodétecteur numérique capable de déterminer avec précision le temps d'arrivée de chaque photon de scintillation. Toutefois, la conception de matrices de PAMP numériques en est encore à ses débuts, et les outils de conception se font rares. Ce projet de doctorat propose un simulateur facilitant la conception de matrices de PAMP, que celles-ci soient analogiques ou numériques. Avec cet outil, l'optimisation d'une matrice de PAMP numérique basée dans une technologie Teledyne DALSA HV CMOS \SI{0,8}{\micro\metre} est proposée. En plus de guider les choix de conception de l'équipe, cette optimisation permet de mieux comprendre quels paramètres influencent les performances du détecteur. De plus, puisque le photodétecteur n'est pas l'unique acteur des performances d'un détecteur TEP, une étude sur l'impact des scintillateurs est aussi présentée. Cette étude vérifie l'amélioration apportée par l'intégration de photons prompts dans des scintillateurs LYSO. Enfin, une approche novatrice pour discriminer l'énergie des évènements TEP basée sur l'information temporelle des photons de scintillation a été développée et vérifiée à l'aide du simulateur. Bien que ce simulateur et les études réalisées dans le cadre de cette thèse soient concentrés sur des détecteurs TEP, l'utilité des PAMP et du simulateur ne se limite pas à cette application. Les matrices de PAMP sont prisées pour le développement de détecteur en physique des particules, physique nucléaire, informatique quantique, LIDAR et bien d'autres.
Abstract : Positron emission tomography (PET) stands out among other imaging modalities by its ability to locate and quantify the presence of marked molecules, called radiotracers, within an organism. The capacity to measure biological activity of various organic tissues provides unique information, essential to the study of cancerous tumors, brain functions and the pharmacodynamics of new medications. Since the very beginings of PET, scientists dreamed of using the photon's time-of-flight information to improve PET images. With the recent progress of Single Photon Avalanche Diodes (SPAD), this dream is now possible. These photodetectors detect the scintillators' low light emission and offers a greatly amplified response with only a small time uncertainty. However the potential of SPAD has not yet been entirely explored. Instead of summing the currents of a SPAD array, it is possible to use their intrinsically binary operation to build a digital photodetector, able to establish with precision the time of arrival of each scintillation photon. With this information, the time-of-flight measurements will be much more precise. Yet the design of digital SPAD arrays is in its infancy and design tools for this purpose are rare. This project proposes a simulator to aid the design of SPAD arrays, both analog and digital. With this tool, we propose an optimised design for a digital SPAD array fabricated in Teledyne Dalsa HV CMOS \SI{0.8}{\micro\metre} technology. In addition to guiding the design choices of our team, this optimisation led to a better understanding which parameters influence the performance of a PET detector. In addition, since the photodetector is not the sole actor in the performance of a PET detector, a study on the effect of scintillators is also presented. This study evaluates the improvement brought by incorporating a prompt photon emission mechanism in LYSO crystals. Finally, we describe a novel approach to energy discrimination based on the timing information of scintillation photons was developped and tested using the simulator. While this simulator and the studies presented in this thesis focus on PET detectors, SPAD are not limited to this sole application. SPAD arrays are promising for a wide variety of fields, including particle physics, high energy physics, quantum computing, LIDAR and many more.

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42

Zhao, Kai. "III-V single photon avalanche detector with built-in negative feedback for NIR photon detection". Diss., Connect to a 24 p. preview or request complete full text in PDF format. Access restricted to UC campuses, 2008. http://wwwlib.umi.com/cr/ucsd/fullcit?p3320151.

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Thesis (Ph. D.)--University of California, San Diego, 2008.
Title from first page of PDF file (viewed September 22, 2008). Available via ProQuest Digital Dissertations. Vita. Includes bibliographical references.

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43

Cajgfinger, Thomas. "Etudes théorique et expérimentale du suivi de particules uniques en conditions extrêmes : imagerie aux photons uniques". Phd thesis, Université Claude Bernard - Lyon I, 2012. http://tel.archives-ouvertes.fr/tel-00999629.

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Ce manuscrit présente mon travail de thèse portant sur le détecteur de photons niques electron-bpmbarded CMOS (ebCMOS) à haute cadence de lecture (500 images/seconde). La première partie compare trois détecteurs ultra-sensibles et leurs méthodes d'amélioration de la sensibilité au photon : le CMOS bas bruit sCMOS), l'électron-multiplying CCD (emCCD) à multiplication du signal apr pixel et l'ebCMOS à amplification par application d'un champ électrique. La méthode de mesure de l'impact intra-pixel des photons sur le détecteur ebCMOS est présentée. La seconde partie compare la précision de localisation de ces trois détecteurs dans des conditions extrêmes de très bas flux de phtons (<10 photons/image). La limite théoriques est d'abord calculée à l'aide de la limite inférieure de Cramér-Rao pour ces jeux de paramètres significatifs. Une comparaison expérimentale des trois détecteurs est ensuite décrite. Le montage permet la création d'un ou plusieurs points d'accès contrôlés en position, nombre de photons et bruit de fond. Les résultats obtenus permettent une comparaison de l'efficacité, de la pureté et de la précision de localisation des sources. La dernière partie décrit deux expériences réalisées avec la caméra ebCMOS. La première consiste au suivi des nano-cristaux libres (D>10 µm2/s) au centre Nanoptec avec l''équipe de Christophe Dujardin. La seconde s'intéresse à la nage de bactéries en surface à l'Institu Joliot curie avec l'équipe de Laurence Lemelle. L'algorithme de suivi de sources ponctuelles au photon unique avec l'implémentation d'un filtre de Kalman est aussi décrit.

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44

Meunier, Nathalie. "Caractérisations de détecteurs à base de tellurure de cadmium pour l'imagerie radiologique". Université Joseph Fourier (Grenoble), 1994. http://www.theses.fr/1994GRE10123.

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Les travaux de recherche ont eu pour objet l'etude preliminaire a la faisabilite d'un imageur radiologique a base de tellurure de cadmium (cdte) alliant une haute resolution spatiale (100 m) a une grande sensibilite (detection du photon unique). Le point a ete fait sur les imageurs bidimensionnels actuellement disponibles ou en cours de developpement. Le cahier des charges d'un imageur travaillant dans la gamme d'energie 10-100 kev a egalement ete fixe. Des detecteurs elementaires comportant un seul pixel (10/0 mm#2) ont tout d'abord ete testes. Des valeurs de rendements de collection et d'efficacite quantique de detection ont ete determinees et ont valide l'utilisation du materiau cdte pour la detection de rayonnement x ( 60 kev). Ensuite differentes structures metal-semiconducteur-metal comprenant un grand nombre de pixels au pas de 1 mm, ont ete caracterisees. La mise en place d'un anneau de garde autour des pixels a permis la limitation du volume de detection. Les differents motifs d'electrodes de la structure ont permis de juger la reproductibilite, l'influence de la taille et de la geometrie de l'electrode, l'influence de la garde et l'influence de la presence d'un joint de grain traversant un pixel. Un premier detecteur prototype comprenant 64+4 pixels au pas de 100 m a ete construit. Des tests de linearite, de dispersion des pixels ainsi qu'une mesure de la fonction de transfert de modulation montrent que ce detecteur repond tout a fait aux objectifs decrits dans le cahier des charges

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45

Lopes, Tiago Neves. "VUV single photon gaseous photomultiplier with position capability". Master's thesis, Universidade de Aveiro, 2013. http://hdl.handle.net/10773/11780.

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Mestrado em Engenharia Física
A new position sensitive gas photomultiplier for the Vacuum Ultraviolet (VUV) region is presented in this work. The detector is composed by two THGEMs, followed by a 2D-THCOBRA being operated in Ne/CH4(5%), at 1 bar pressure in single photon mode. The 2D-THCOBRA is an hybrid microstructure which combines the robustness and the resistance to discharges of a THGEM with the two independent charge multiplication stages and the position discrimination of the 2D-MHSP. In this work the 2D-THCOBRA influence in the charge gain and IBF values was studied. The position resolution of the entire system was also studied. The achieved results shown a charge gain of 106 and, for this gain values, an IBF value of about 20%. Position resolutions below 300 μm were also obtained.
O presente trabalho baseia-se no desenvolvimento e estudo de um fotomultiplicador gasoso na região do Utra-Violeta de Vazio (UVV) e com capacidade de discriminação de posição. O detector é constituído por duas THGEM seguidas de uma 2D-THCOBRA, a operar em Ne/CH4(5%) à pressão de 1 bar e em modo de fotão único. A 2D-THCOBRA é uma estrutura híbrida, que resulta da combinação entre uma THGEM e uma 2D-MHSP, beneficiando da robustez e resistência às descargas da primeira e dos dois estágios de multiplicação e da capacidade de discriminação da posição da 2D-MHSP. Neste trabalho foi estudada a influência dos potenciais aplicados aos eléctrodos da 2D-THCOBRA no ganho e no refluxo de iões (IBF) do detector. Foi ainda avaliada a resolução em posição deste detector. Foram medidos ganhos da ordem de 106 e, para estes valores de ganho, IBF na ordem dos 20%. Obteve-se ainda resoluções em posição inferiores a 300 μm.

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46

Wu, Mengqing. "Search for Dark Matter and Supersymmetry in the single photon events with the ATLAS detector". Thesis, Université Grenoble Alpes (ComUE), 2015. http://www.theses.fr/2015GREAY046/document.

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Cette thèse présente la recherche de nouvelle physique avec un état final contenant un seul photon et de l'énergie transverse manquante. On recherche la matière sombre (ou noire) et la signature de particules supersymétriques. L'analyse des données collectées par le détecteur ATLAS au LHC, issues de collisions proton-proton dont l'énergie dans le centre de masse est de 8 TeV, est faite avec une luminosité intégrée de 20.3fb−1. L'accord entre les données mesurées et les prédictions du modèle standard permet d'établir une limite sur la section effi- cace de production mesurable. Cette limite est observée à la valeur de 3.64 fb à 95% de niveau de confiance.Dans cette thèse, la limite expérimentale obtenue est également interprétée comme une limite dans l'espace des paramètres de deux nouveaux modèles.Le premier est basé sur une théorie des champs effective qui s'inspire des résultats du satellite Fermi-LAT. Dans ce modèle, les particules de matière sombre se couplent aux pho- tons par une interaction de contact. Les limites sur l'échelle de masse effective sont établies et dépendent d'un postulat sur les constantes de couplage. Elles contraignent l'espace des paramètres qui est compatible avec les résultats de Fermi-LAT.Le second est un modèle supersymétrique simplifié décrivant la production de paires de squarks se désintégrant en un quark et un neutralino. Dans ce cas, le photon est émis soit dans l'état initial soit dans l'état final. De plus, le spectre en masse est compressé, i.e. que la différence de masse entre les squarks et les neutralinos est supposée petite. Les limites sont établies sur la section efficace de production. Ces limites montrent une exclusion sur la masse des squarks jusqu'à 250 GeV dans la région la plus compressée de l'espace des paramètres. Le photon pouvant être émis par le squark intermédiaire, cet état final pourrait permettre de déterminer la charge du squark.Enfin, une étude préliminaire prospective à l'énergie de collision de 13 TeV a égale- ment été menée. Elle montre qu'avec 5fb−1 de données seulement, les limites peuvent être améliorées de 10%
This thesis presents the search for new physics in the final state containing a single photon and missing transverse momentum. The analysis is performed on 20.3fb−1 of proton-proton collisions data at a center-of-mass energy of 8 TeV collected by the ATLAS detector at the Large Hadron Collider. Given the good agreement of the data with the Standard Model pre- diction of such events, an upper limit to the visible cross section produced by new physics is derived. The observed limit at 95% confidence level is 3.64 fb.In this thesis, the results are also interpreted as limits in the parameter space of two new physics models. The first model is an effective field theory, inspired by Fermi-LAT results, in which dark matter particles couple to photons via a contact interaction vertex. Limits are set on the effective mass scale and depend on the postulated coupling constants. The limits set in this dark matter model provide an effective constraint in the parameter space of the theory compatible with the Fermi-LAT results. The second one is a simplified supersymmetric model describing squark pair production with their subsequent decay into a quark and a neutralino. The photon is emitted as initial or final state radiation and the spectrum is compressed, i.e. the mass difference between the squark and the neutralino is assumed to be small. Limits are set on the production cross-section; squark masses are excluded up to 250 GeV in the very compressed region. As the photon can be irradiated from the intermediate squark, this final state would eventually provide the possibility to probe the charge of the squark.A preliminary study has also been carried out to show the search sensitivity with 13 TeV data, which indicate that the limits presented in this thesis can already be improved by 10% with 5fb−1

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Marchiori, Giovanni. "Prompt photons at the LHC : selection, measurements of single- and di-photon production cross sections, and Higgs boson searches with the ATLAS detector". Habilitation à diriger des recherches, Université Pierre et Marie Curie - Paris VI, 2013. http://tel.archives-ouvertes.fr/tel-00919608.

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This document, prepared to obtain the "Habilitation à Diriger des Recherches", is a compendium of the photon-related analysis activities I carried on within ATLAS in the past four years and a half. The activities I will describe can be broadly classified into three categories: optimization and/or in situ measurement of photon-related performance, measurements of the cross sections of Standard Model processes producing prompt photons, and searches (leading to discovery!) of a Standard Model Higgs boson decaying to final states containing photons.

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Hofherr, Matthias [Verfasser]. "Real-time imaging systems for superconducting nanowire single-photon detector arrays / Matthias Hofherr". Karlsruhe : KIT Scientific Publishing, 2014. http://www.ksp.kit.edu.

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Vedin, Robert. "Simulations of an Effective Model of a Superconducting Nano-Wire Single Photon Detector". Thesis, KTH, Fysik, 2018. http://urn.kb.se/resolve?urn=urn:nbn:se:kth:diva-235401.

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Hebecker, Dustin. "Development of a single photon detector using wavelength-shifting and light-guiding technology". Doctoral thesis, Humboldt-Universität zu Berlin, 2021. http://dx.doi.org/10.18452/23231.

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Das IceCube Neutrino-Observatorium ist ein am geografischen Südpol im Eis installierter Neutrinodetektor. In IceCube werden Neutrinos mit Tscherenkow-Strahlung von Sekundärteilchen aus Neutrino Interaktionen detektiert. Für den Nachfolgedetektor IceCube-Gen2, werden neue und verbesserte Lichtdetektoren gesucht. Die vorliegende Arbeit beschreibt die Entwicklung eines dieser Lichtdetektoren. Dieser basiert auf Wellenlängen schiebenden und Licht leitenden Technologien. Der Detektor mit dem Namen "Wavelength-shifting Optical Module" (WOM) verwendet eine transparente Röhre, mit wellenlängenschiebender Farbe, als passiver Photonendetektor. Das in der Wellenlänge verschobene Licht wird durch Totalreflexion, zu kleinen PMTs an beiden Enden geleitet. Die Auswahl dieses Designs reduziert die Kosten und verbessert das Signal-Rausch-Verhältnis wesentlich, möglicherweise können mit dieser Lösung extragalaktische Supernova in zukünftigen Detektoren beobachtet werden. Als eine Kernkomponente wird die wellenlängenschiebende Röhre ausführlich untersucht. Verschiedene Messaufbauten und Auswertungsmethoden werden entwickelt, um diese im Anschluss zu untersuchen und zu bewerten. Iterative Verbesserungen der Materialien und des Farbauftrageverfahren als auch Messmethoden, resultieren in einer kombinierten Einfang-, Wellenlängenschiebe- und Transporteffizienz von 28,1 +/- 5,4 % der Röhre. Ein Model zur Beschreibung des Lichtverhaltens in der Röhre wird entwickelt um eine Diskrepanz zwischen Theorie und Messung zu untersuchen. Die Kombination zwischen Messung und Model, bestätigt die Aussagekraft des Models und zeigt, dass ein Großteil der Verluste beim Lichttransport zustande kommen. Darüber hinaus werden die physikalischen Eigenschaften des WOM in die IceCube Simulationsumgebung eingebaut. Der Vergleich zu einem Konkurrenzmodul zeigt eine Überlegenheit des WOM um den Faktor 1,05 +/- 0,07. Es werden Vorschläge und Ausblicke für Verbesserungen der Leistungsfähigkeit des WOMs gegeben.
The IceCube Neutrino Observatory is an in ice neutrino detector located at the geographic South Pole. In IceCube neutrinos are detected via Cherenkov light produced by secondary particles in neutrino interactions. For the upgraded detector IceCube-Gen2, new and improved light detectors are sought-after. This work describes the development of one of those light detectors based on a novel combination of wavelength-shifting and light-guiding technology. The detector named the Wavelength-shifting Optical Module (WOM) utilizes a large transparent tube, coated with wavelength-shifting paint as a passive photon detector. The wavelength-shifted light is guided via total internal reflection towards small active light detectors, at each end of the tube. This design reduces costs and improves the signal to noise ratio significantly, thereby potentially enabling extragalactic supernova detections in future detectors. As a core component, the wavelength-shifting tube is extensively investigated. Different measurement setups and evaluation techniques are developed and investigated. Iterative improvement of materials and coating techniques as well as measurement methods currently result in a combined photon capture, shift and transport efficiency of 28.1 +/- 5.4 % for the tube. Those results contrast the theoretical maximum of 74.5 %. A model is developed to describe the light propagation and loss processes in the tube and to understand the discrepancies between theory and measurement. The combination of the measurements with the model, validate the descriptive qualities of the model and show that most of the light is lost during the light propagation in the tube. Additionally, the physical properties of the WOM are included in the IceCube simulation framework. A comparison to a competing module showed that the WOM outperforms by a factor of 1.05 +/- 0.07 in photon detection numbers. Where applicable, suggestions and outlooks are given to enhance the performance of the WOM.

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