Crab Tracker Documentation

User and technical documentation for the Crab Tracker project, including details on system architecture, configuration, and design

Infrared receivers for low background astronomy: Incoherent detectors and coherent devices from one micrometer to one millimeter

The status of incoherent detectors and coherent receivers over the infrared wavelength range from one micrometer to one millimeter is described. General principles of infrared receivers are included, and photon detectors, bolometers, coherent receivers, and important supporting technologies are discussed, with emphasis on their suitability for low background astronomical applications. Broad recommendations are presented and specific opportunities are identified for development of improved devices

OPTIMIZATION OF TIME-RESPONSE AND AMPLIFICATION FEATURES OF EGOTs FOR NEUROPHYSIOLOGICAL APPLICATIONS

In device engineering, basic neuron-to-neuron communication has recently inspired the development of increasingly structured and efficient brain-mimicking setups in which the information flow can be processed with strategies resembling physiological ones. This is possible thanks to the use of organic neuromorphic devices, which can share the same electrolytic medium and adjust reciprocal connection weights according to temporal features of the input signals. In a parallel - although conceptually deeply interconnected - fashion, device engineers are directing their efforts towards novel tools to interface the brain and to decipher its signalling strategies. This led to several technological advances which allow scientists to transduce brain activity and, piece by piece, to create a detailed map of its functions. This effort extends over a wide spectrum of length-scales, zooming out from neuron-to-neuron communication up to global activity of neural populations. Both these scientific endeavours, namely mimicking neural communication and transducing brain activity, can benefit from the technology of Electrolyte-Gated Organic Transistors (EGOTs). Electrolyte-Gated Organic Transistors (EGOTs) are low-power electronic devices that functionally integrate the electrolytic environment through the exploitation of organic mixed ionic-electronic conductors. This enables the conversion of ionic signals into electronic ones, making such architectures ideal building blocks for neuroelectronics. This has driven extensive scientific and technological investigation on EGOTs. Such devices have been successfully demonstrated both as transducers and amplifiers of electrophysiological activity and as neuromorphic units. These promising results arise from the fact that EGOTs are active devices, which widely extend their applicability window over the capabilities of passive electronics (i.e. electrodes) but pose major integration hurdles. Being transistors, EGOTs need two driving voltages to be operated. If, on the one hand, the presence of two voltages becomes an advantage for the modulation of the device response (e.g. for devising EGOT-based neuromorphic circuitry), on the other hand it can become detrimental in brain interfaces, since it may result in a non-null bias directly applied on the brain. If such voltage exceeds the electrochemical stability window of water, undesired faradic reactions may lead to critical tissue and/or device damage. This work addresses EGOTs applications in neuroelectronics from the above-described dual perspective, spanning from neuromorphic device engineering to in vivo brain-device interfaces implementation. The advantages of using three-terminal architectures for neuromorphic devices, achieving reversible fine-tuning of their response plasticity, are highlighted. Jointly, the possibility of obtaining a multilevel memory unit by acting on the gate potential is discussed. Additionally, a novel mode of operation for EGOTs is introduced, enabling full retention of amplification capability while, at the same time, avoiding the application of a bias in the brain. Starting on these premises, a novel set of ultra-conformable active micro-epicortical arrays is presented, which fully integrate in situ fabricated EGOT recording sites onto medical-grade polyimide substrates. Finally, a whole organic circuitry for signal processing is presented, exploiting ad-hoc designed organic passive components coupled with EGOT devices. This unprecedented approach provides the possibility to sort complex signals into their constitutive frequency components in real time, thereby delineating innovative strategies to devise organic-based functional building-blocks for brain-machine interfaces.Nell’ingegneria elettronica, la comunicazione di base tra neuroni ha recentemente ispirato lo sviluppo di configurazioni sempre più articolate ed efficienti che imitano il cervello, in cui il flusso di informazioni può essere elaborato con strategie simili a quelle fisiologiche. Ciò è reso possibile grazie all'uso di dispositivi neuromorfici organici, che possono condividere lo stesso mezzo elettrolitico e regolare i pesi delle connessioni reciproche in base alle caratteristiche temporali dei segnali in ingresso. In modo parallelo, gli ingegneri elettronici stanno dirigendo i loro sforzi verso nuovi strumenti per interfacciare il cervello e decifrare le sue strategie di comunicazione. Si è giunti così a diversi progressi tecnologici che consentono agli scienziati di trasdurre l'attività cerebrale e, pezzo per pezzo, di creare una mappa dettagliata delle sue funzioni. Entrambi questi ambiti scientifici, ovvero imitare la comunicazione neurale e trasdurre l'attività cerebrale, possono trarre vantaggio dalla tecnologia dei transistor organici a base elettrolitica (EGOT). I transistor organici a base elettrolitica (EGOT) sono dispositivi elettronici a bassa potenza che integrano funzionalmente l'ambiente elettrolitico attraverso lo sfruttamento di conduttori organici misti ionici-elettronici, i quali consentono di convertire i segnali ionici in segnali elettronici, rendendo tali dispositivi ideali per la neuroelettronica. Gli EGOT sono stati dimostrati con successo sia come trasduttori e amplificatori dell'attività elettrofisiologica e sia come unità neuromorfiche. Tali risultati derivano dal fatto che gli EGOT sono dispositivi attivi, al contrario dell'elettronica passiva (ad esempio gli elettrodi), ma pongono comunque qualche ostacolo alla loro integrazione in ambiente biologico. In quanto transistor, gli EGOT necessitano l'applicazione di due tensioni tra i suoi terminali. Se, da un lato, la presenza di due tensioni diventa un vantaggio per la modulazione della risposta del dispositivo (ad esempio, per l'ideazione di circuiti neuromorfici basati su EGOT), dall'altro può diventare dannosa quando gli EGOT vengono adoperati come sito di registrazione nelle interfacce cerebrali, poiché una tensione non nulla può essere applicata direttamente al cervello. Se tale tensione supera la finestra di stabilità elettrochimica dell'acqua, reazioni faradiche indesiderate possono manifestarsi, le quali potrebbero danneggiare i tessuti e/o il dispositivo. Questo lavoro affronta le applicazioni degli EGOT nella neuroelettronica dalla duplice prospettiva sopra descritta: ingegnerizzazione neuromorfica ed implementazione come interfacce neurali in applicazioni in vivo. Vengono evidenziati i vantaggi dell'utilizzo di architetture a tre terminali per i dispositivi neuromorfici, ottenendo una regolazione reversibile della loro plasticità di risposta. Si discute inoltre la possibilità di ottenere un'unità di memoria multilivello agendo sul potenziale di gate. Viene introdotta una nuova modalità di funzionamento per gli EGOT, che consente di mantenere la capacità di amplificazione e, allo stesso tempo, di evitare l'applicazione di una tensione all’interfaccia cervello-dispositivo. Partendo da queste premesse, viene presentata una nuova serie di array micro-epicorticali ultra-conformabili, che integrano completamente i siti di registrazione EGOT fabbricati in situ su substrati di poliimmide. Infine, viene proposto un circuito organico per l'elaborazione del segnale, sfruttando componenti passivi organici progettati ad hoc e accoppiati a dispositivi EGOT. Questo approccio senza precedenti offre la possibilità di filtrare e scomporre segnali complessi nelle loro componenti di frequenza costitutive in tempo reale, delineando così strategie innovative per concepire blocchi funzionali a base organica per le interfacce cervello-macchina

Modulation inducing retrodirective optical system technical report, 21 may 1963 - 20 may 1964

Modulation inducing retrodirective optical system for space communication

Printed Organic Photodiodes with Enhanced Performance and Simplified Processing

Zukünftige Technologien in den Bereichen Datenübertragung, Industrieautomatisierung, Verbraucherelektronik und medizinische Diagnostik werden von der Entwicklung optischer Sensortechnologien profitieren, die eine kosteneffiziente Fertigung, mechanische Flexibilität, personalisiertes Design und maßgeschneiderte Funktionalität bieten. Eine vielversprechende Klasse von Sensoren, die diese Eigenschaften gewähren, sind Photodetektoren auf der Basis organischer Halbleiter. Sogenannte organische Photodioden (OPDs) haben sich in den letzten Jahren rasch in ihrer Leistung verbessert und ihr Potenzial als komplementäre Technologie zu anorganischen Bauelementen unter Beweis gestellt. Vor allem aber ermöglicht Prozessierbarkeit aus der Flüssigphase die Bauteilfertigung mit industriellen Drucktechniken. Der große Parameterraum des Druckens in Verbindung mit den morphologischen und energetischen Anforderungen von OPDs führt jedoch zu einer Fülle von Herausforderungen, die den Übergang vom Labormaßstab zu relevanten Produktionsmethoden erschweren. In dieser Arbeit werden drei neue Konzepte für die OPD-Fertigung vorgestellt, die zur Bewältigung dieser Herausforderungen beitragen. Es werden alternative - und in einigen Fällen "unkonventionelle" - photoaktive Materialsysteme eingeführt, die gleichzeitig die Verarbeitung vereinfachen, die Leistung verbessern und zusätzliche Funktionalität bieten. Der erste Ansatz konzentriert sich auf die Verwendung von Isolatoren als Prozessadditive für die Herstellung von photoaktiven Schichten. Entgegen der Intuition behindert dies nicht die Funktionalität der OPDs, sondern verbessert sogar die Detektionsgeschwindigkeit durch eine Erhöhung der molekularen Ordnung der Halbleiterschicht. Ein zweiter Ansatz besteht in der Untersuchung einer neuartigen Materialklasse, nämlich den Nicht-Fulleren Akzeptoren (engl. non-fullerene acceptors, NFA), um die Empfindlichkeit in Richtung des nahen Infrarot-Bereichs zu erweitern und zu erhöhen. Diese Studie führte zur ersten Demonstration von digital gedruckten NFA-OPDs mit einer Rekordempfindlichkeit von über 750 nm und Detektionsgeschwindigkeiten im MHz-Bereich. Schließlich ermöglicht ein drittes Konzept die digitale Herstellung mehrfarbiger OPDs, indem ein innovatives Tintensystem entwickelt wird, das die viskoelastischen und optischen Eigenschaften erfolgreich entkoppelt, um die Fertigung zu vereinfachen und die spektrale Flexibilität von NFAs optimal ausnutzt. Die resultierende farbselektive Detektion ermöglicht die Integration der OPDs in ein Mehrkanal-Kommunikationssystem für sichtbares Licht (engl. visible light communication), das eine der vielversprechendsten aufkommenden Technologien im Bereich der optischen Datenübertragung darstellt. Alle drei Ansätze kombinieren herausragende Funktionalität und Leistung mit vereinfachten Herstellungsverfahren und tragen dazu bei das Potenzial von OPDs für das breite Feld der optischen Sensorik erfolgreich auszuschöpfen

Electron spin resonance studies of impurity ions in rutile

Electron spin resonance techniques were used to study the photo- electronic behaviour of defect centres in rutile, using both single crystal and powdered samples. Single crystals of rutile were grown by a plasma torch method. Analysis of the boules by several techniques established that they contained, in general, fewer impurities than crystals grown by the conventional Verneuil method. Some boules were deliberately doped during growth with specific impurities. Control of the oxygen content of the plasma enabled the growth of some boules in a completely stoichiometric state, requiring no subsequent oxidation. Some crystals were doped after growth with various transition metal ions, using either evaporation and diffusion or vacuum capsule diffusion techniques. E.S.R. analysis indicated the presence of several impurity ions, notably iron and nickel, in most samples. Low temperature ultra-violet irradiation caused significant changes to the intensities of most spectra, together with the appearance of several new spectra. Isochronal annealing then revealed the temperatures at which thermally stimulated charge transfers occurred, as reflected in changes to e.s.r. spectra. At least twelve different trapping centres were detected, with thermal ionization temperatures between 30 and 400K. Where possible, the ionization energies were determined by measuring variations in the rate of charge transfer with temperature and many of the values were in good agreement with those reported using other techniques. In most cases it was also possible to determine the polarity of the traps, by studying their interaction with other centres. It is thought that many of the shallow electron traps consist of complexes of intrinsic defects, such as interstitial ions or vacancies. with nearby Aluminium ions. Iron and chromium appear to form hole trapping centres with energy levels near the valence band. Nickel, Manganese and Copper are recombination centres with levels near the centre of the band gap. The same e.s.r. methods were applied to samples of rutile pigments and a computer simulation technique was used to aid analysis and interpretation of powder spectra. All the pigment samples exhibited the same u.v.-activated e.s.r. spectrum. Isochronal annealing suggested that it represented a trapped hole and also inferred the existence of several shallow electron traps

The SIMPLE Phase II Dark Matter Search

Phase II of SIMPLE (Superheated Instrument for Massive ParticLe Experiments) searched for astroparticle dark matter using superheated liquid C$_{2}$ClF$_{5}$ droplet detectors. Each droplet generally requires an energy deposition with linear energy transfer (LET) $\gtrsim$ 150 keV/$\mu$m for a liquid-to-gas phase transition, providing an intrinsic rejection against minimum ionizing particles of order 10$^{-10}$, and reducing the backgrounds to primarily $\alpha$ and neutron-induced recoil events. The droplet phase transition generates a millimetric-sized gas bubble which is recorded by acoustic means. We describe the SIMPLE detectors, their acoustic instrumentation, and the characterizations, signal analysis and data selection which yield a particle-induced, "true nucleation" event detection efficiency of better than 97% at a 95% C.L. The recoil-$\alpha$ event discrimination, determined using detectors first irradiated with neutrons and then doped with alpha emitters, provides a recoil identification of better than 99%; it differs from those of COUPP and PICASSO primarily as a result of their different liquids with lower critical LETs. The science measurements, comprising two shielded arrays of fifteen detectors each and a total exposure of 27.77 kgd, are detailed. Removal of the 1.94 kgd Stage 1 installation period data, which had previously been mistakenly included in the data, reduces the science exposure from 20.18 to 18.24 kgd and provides new contour minima of $\sigma_{p}$ = 4.3 $\times$ 10$^{-3}$ pb at 35 GeV/c$^{2}$ in the spin-dependent sector of WIMP-proton interactions and $\sigma_{N}$ = 3.6 $\times$ 10$^{-6}$ pb at 35 GeV/c$^{2}$ in the spin-independent sector. These results are examined with respect to the fluorine spin and halo parameters used in the previous data analysis.Comment: 20 pages, 19 figures; accepted Physical Review

Graphene and its derivatives for electronic applications.

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