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1
Weirich, John R. "Improvements to Argon-Argon Dating of Extraterrestrial Materials". Diss., The University of Arizona, 2011. http://hdl.handle.net/10150/145293.
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The source of potassium and argon in ordinary chondrites is determined by comparing the argon activation energies of feldspar, pyroxene, and olivine with that of the L chondrites Chico and North West Africa (NWA) 091. In addition, shock pressures of 29 to 55.8 GPa are shown to lower the activation energy of feldspar. Comparable shock pressures lowers the activation energy of pyroxene outside of error, but the variability of this value, even among unshocked samples, makes a clear distinction difficult. The effect of shock on olivine has not been investigated, by myself or others. Like many ordinary chondrites, Chico and NWA 091 have two major releases of argon, one at low temperature, and the other at high temperature. The low temperature release of Chico contains two releases, which match the activation energies of shocked and unshocked feldspar. The low temperature release of NWA 091 only contains a single release, which matches shocked feldspar. The high temperature release of both Chico and NWA 091 has an activation energy that is similar to pyroxene, but not olivine. A potassium mass balance of Chico shows that all the potassium in the meteorite is contained in feldspar, and Raman spectroscopy shows this feldspar has not been converted into a high pressure phase, indicating the high temperature release is inclusions in a high temperature mineral. This mineral is probably pyroxene based upon the activation energy, though thin sections provide evidence that feldspar is more closely associated with olivine. NWA 091 exhibits multiple isochrons, showing the presence of two nonprimordial and (probably) non-terrestrial trapped components of argon. The removal of these trapped components reveals a thermal event produced by a collisional impact on the L chondrite parent body at 475 ± 6 Ma (which supports a link between L chondrites and Ordovician fossil meteorites), as well as a similar event at ~800 Ma (which, combined with similar ages on other Solar System objects, suggests an increased impact flux at that time). Chico did not exhibit an isochron, and the age data for Chico is not reported.
2
Harwardt, Heike. "Behandlung von PP- und PET-Substraten im Argon- und Methan/Argon-Plasma". [S.l.] : [s.n.], 2006. http://deposit.ddb.de/cgi-bin/dokserv?idn=983031045.
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3
Edmunds, P. D. "Trapping ultracold argon atoms". Thesis, University College London (University of London), 2015. http://discovery.ucl.ac.uk/1462806/.
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This thesis describes the dipole trapping of both metastable and ground state argon atoms. Metastable argon atoms are first Doppler-cooled down to ∼80 μK in a magneto- optical trap (MOT) on the 4s[3/2]2 to 4p[5/2]3 transitions. These were loaded into dipole traps formed both within the focus of a high-power CO2 laser beam and within an optical build-up cavity. The optical cavity’s well depth could be rapidly modulated: allowing efficient loading of the trap, characterisation of trapped atom temperature, and reduction of intensity noise. Collisional properties of the trapped metastable atoms were studied within the cavity and the Penning and associative losses from the trap calculated. Ground state noble gas atoms were also trapped for the first time. This was achieved by optically quenching metastable atoms to the ground state and then trapping the atoms in the cavity field. Although the ground state atoms could not be directly probed, we detected them by observing the additional collisional loss from co-trapped metastable argon atoms. This trap loss was used to determine an ultra-cold elastic cross section between the ground and metastable states. Using a type of parametric loss spectroscopy we also determined the polarisability of metastable argon at the trapping wavelength of 1064 nm.
4
Grigonis, A., L. Marcinauskas, M. Carnauskas i R. Kaliasas. "Graphite Nanostructures Produce in the Acetylene, Argon-Acetylene and Argon-Hydrogen-Acetylene Plasmas". Thesis, Sumy State University, 2012. http://essuir.sumdu.edu.ua/handle/123456789/35388.
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The amorphous carbon films were deposited on silicon-metal substrates by plasma jet chemical vapor
deposition (PJCVD) and plasma enchanted CVD (PECVD). PJCVD carbon coatings have been prepared at
atmospheric pressure in Ar/ C2H2 and Ar/H2/C2H2 mixtures. The films prepared in Ar/C2H2 plasma are attributed
to graphite-like carbon films. Addition of the hydrogen decreases growth rate and the surface
roughness of the coatings, but coatings have low fraction of oxygen (~5 at.%) The formation of the nanocrystalline
graphite was obtained in Ar/H2/C2H2 plasma. The carbon nanotubes were synthesed by PECVD
using Au/Cr catalyst particles at low (≤ 450 C; p = 40 Pa ) temperature in pure acetylene.
When you are citing the document, use the following link http://essuir.sumdu.edu.ua/handle/123456789/35388
5
Velazquez, Maria Guadalupe Neira. "Argon plasma treatment of polymers". Thesis, University of Sheffield, 2002. http://ethos.bl.uk/OrderDetails.do?uin=uk.bl.ethos.274978.
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6
Chetty, Dashavir. "Strong-field excitation of argon". Thesis, Griffith University, 2021. http://hdl.handle.net/10072/402734.
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The advancement in laser technology in the past few decades have enabled consistent generation of pulses in the femtosecond (fs, x10^-15 s) timescale. The strong electric fields produced by such pulses are comparable to those experienced by bound electrons within atoms and molecules, leading to highly non-linear interactions. One of the most probable such interaction is that of strong-field excitation where the target is left in an excited state. These excited states have been shown to influence other strong-field phenomena and exhibit unique properties that are useful for further applications such as, generation of coherent extreme-ultraviolet radiation, and lasercooling of noble gases. Therefore, a comprehensive understanding of the fundamental excitation process and how excitation rates are affected is necessary in order to tailor conditions for a desired outcome. So far, there have been only a few experimental studies on excitation yields due to the unique experimental arrangements required for observation of these states. In contrast, there have been more theoretical studies which have yet to be experimentally confirmed. The aforementioned experiments have been undertaken with laser pulses with a duration of 30 fs or more centred at a wavelength of 800 nm which contain many optical cycles. But, numerical calculations predict that excitation yields scale differently as the pulse duration reduces such that it contains only a few optical cycles. This has yet to be experimentally confirmed since there has not been any experimental studies on excitation yields from few-cycle pulses. Furthermore, the use of few-cycle pulses enables precise control over the electric field experienced by the atom which may influence the excitation process.
In this dissertation, we experimentally investigate excitation yields of argon interacting with multi- and few-cycle pulses centred at 800 nm and compare them to solutions of the time-dependent Schrodinger equation (TDSE). The first investigation explores the effect of changing the intensity spanning between 50-300 TW/cm2. By directly detecting excited states surviving the flight time to the particle detector, we show that excitation rates exhibit a step-wise increase within the intensity range which correspond to the absorption of 13 and 14 photons with linearly polarized multi-cycle pulses. These were predicted theoretically but were thought to be washed out due to volume-averaging inevitable in the experiment. Analysis of the numerical predictions reveal that these enhancements are mainly due to excitation into low-lying states, specifically the 5g and 6h states for 13- and 14-photon absorption, respectively. These increases are not observed with few-cycle pulses where the offset between the peak of the pulse envelope and the peak of the central electric field cycle, known as the carrier-envelope phase (CEP), was not locked. This is in excellent agreement with TDSE predictions. Population of low-lying states are largely preferred with few-cycle pulses and these enhancements are less pronounced, to the point where they do not persist after volume-averaging.
The second investigation explores excitation with elliptically polarized laser fields of varying ellipticities at select intensities with both multi- and few-cycle pulses. In all cases, excitation rates decrease quicker with increasing ellipticity than that of Ar+ but slower than predicted with the strong-field approximation as well as Ar2+. This indicates a different mechanism than the tunneling-plus-rescattering model proposed for the formation of Ar2+ through non-sequential double ionization. No anomalous peaks at non-zero ellipticity are observed in the experiment for 30 fs and 6 fs pulses at an intensity of 270 TW/cm2 and 200 TW/cm2, respectively, nor were they predicted by TDSE results. At a lower intensity, where previously published results from semi-classical modeling predict anomalous distributions, no obvious deviations from a normal distribution is observed. However, low statistics at this intensity limits any confident conclusions for a peak at very small, non-zero ellipticity values. Lastly, analysis of TDSE results reveals an anomalous distribution for excitation out of the pm= +-1 initial ground state orbitals. Further experiments are required for solid conclusions as well as good agreement between TDSE results and experiments.
The last investigation explores the role of the CEP of a few-cycle pulse. For the first time, we show that excitation rates are highly dependent on both the peak intensity and CEP of the pulse. At a single intensity, TDSE calculations predict up to a 55% variation in excitation rates. Furthermore, the CEP dependent trends can vary significantly with small changes in the intensity, leading to a significant variation in the optimum CEP for maximum excitation yields. In the experiment, volume averaging reduces the maximum observable variation in the CEP dependent yields to 7%. Furthermore, they are still highly dependent on the exact in situ peak intensity of the experimental pulse with many peak intensities resulting in a variation below 5%. This places tight restrictions on conditions which allow successful observation of the variation in yields with varying CEP. Despite the inability to precisely determine the in situ experimental intensity, the agreement with the numerical predictions is very good which serves to validate the theoretical predictions.
The results from these studies reveal that the population of excited states are dependent on the intensity, polarization, and, in the case of few-cycle pulses, the CEP. If the intensity can be precisely controlled, selective excitation to the 5g and 6h states can be achieved with up to a 60% likelihood with the use of multi-cycle pulses. This is reduced with volume-averaging but these states still remain the most populated states. Knowing this, excitation to the metastable state can be increased through direct stimulation via additional radiation. Further studies to determine the precise efficiency of the process is required in order to evaluate it as a suitable replacement for current metastable generation techniques.Thesis (PhD Doctorate)
Doctor of Philosophy (PhD)
School of Environment and Sc
Science, Environment, Engineering and Technology
Full Text
7
Al-Dabbagh, Abdula Nazar. "Charge Mobility in Liquid Argon". Thesis, The University of Arizona, 2014. http://hdl.handle.net/10150/318805.
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8
Harrington, Kathleen M. "Simulated liquid argon interactions with neutrons". Thesis, Massachusetts Institute of Technology, 2012. http://hdl.handle.net/1721.1/78513.
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Thesis (S.B.)--Massachusetts Institute of Technology, Dept. of Physics, 2012.Cataloged from PDF version of thesis.
Includes bibliographical references (p. 77-78).
The GEANT4 physics simulation program is known to have errors in how hadronic interactions are implemented. This has the potential to cause errors in the Monte Carlos used to determine the expected neutron backgrounds in the MiniCLEAN single phase liquid argon WIMP detector. Elastic and inelastic collisions between neutrons and argon nuclei as well as neutron captures were simulated independently in order to characterize the accuracy of the implementation by GEANT4.9.3.pOl and GEANT4.9.5. The effective cross sections, angular distributions, photons, decay schemes, energy conservation, and momentum conservation were determined through analysis of the neutron tracks created by GEANT4. A large proportion of the interactions behave as expected, however energy and momentum are not conserved by varying degrees of severity with some GEANT4.9.3.pOl inelastic collisions resulting in over twice the correct amount of energy.
by Kathleen M. Harrington.
S.B.
9
Taillandier-Loize, Thierry. "Jet lent d’atomes d’argon métastables pour l’étude de l’échange de métastabilité, des interactions de van der Waals et des milieux d’indice négatif". Thesis, Paris 13, 2014. http://www.theses.fr/2014PA132039/document.
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La thématique abordée dans cette thèse relève de la manipulation d’un jet d’atomes d’argon métastables (Ar* ³P2) dans différentes configurations. Premièrement, je présente l’échange de métastabilité entre un atome au fondamental et un atome excité à de faibles énergies de centre de masse (entre 4 et 9 meV). Je propose également l’interprétation théorique par une approche semi-classique (approximation JWKB) qui se révèle validée, dans ce domaine d’énergies, en comparaison avec la résolution exacte de l’équation de Schrödinger radiale mettant en jeu les potentiels concernés par la collision. Les sections efficaces absolues d’échanges, déduites d’une analyse en temps de vol du signal métastable, permettent de réaliser une comparaison sans biais avec les prédictions théoriques. Les caractéristiques d’un jet ralenti par effet Zeeman sont dégradées par le processus de ralentissement et le rende difficilement utilisable en deçà de quelques dizaines de mètres par seconde. C’est pourquoi, dans un deuxième temps, je présente la réalisation d’un jet lent original, issu d’un piège magnéto-optique et présentant des caractéristiques remarquables. La vitesse est accordable entre 10 et 100 m/s, la dispersion de vitesse relative est très faible (6 % à 20 m/s) et le flux est conséquent (10⁹ Ar*/s/sr), pour une ouverture angulaire standard (35 mrad FWHM). Ce nouveau dispositif permet de présenter certaines questions d’interférométrie et d’optique atomique telles que les interactions atome-surface de type van der Waals et l’étude de potentiels comobiles ainsi que leurs applications dans la réalisation de milieux d’indice négatif ou de ralentisseursThe topic of this thesis concerns the manipulation of a metastable argon (Ar* ³p2) atomic beam in different configurations. Firstly, I present the metastability exchange between an atom in fundamental state and an excited atom at low center of mass energy (between 4 and 9 meV). I also propose theoretical interpretation by a semi-classical approach (JWKB approximation) which is validated, in this field of energies, compared to the exact solution of the Schrödinger radial equation with potentials involved in collision. The absolute exchange cross-sections, derived from a time of flight analysis of metastable signal, enable an unbiased comparison with theoretical predictions. The characteristics of a Zeeman slowedbeam are degraded by the process of slowing down and makes it difficult to use below a few tens of meters per second. Secondly, I present the realization of an original slow beam from a magneto-optical trap and having outstanding features. The atomic velocity is tunable between 10 and 100 m/s, the relative velocity dispersion is very low (6 % at 20 m/s) and the flow is substantial, (4.7×108 Ar*/s/sr), for a standard angular aperture (35 mrad FWHM). This new device can present some issues in atomic interferometry and atomic optics such as van der Waals atom-surface interactions or study co-moving potentials and their applications in negative-index media for matter wave or slowers
10
Fladerer, Alexander. "Keimbildung und Tröpfchenwachstum in übersättigtem Argon-Dampf Konstruktion einer kryogenen Nukleationspulskammer /". [S.l. : s.n.], 2002. http://deposit.ddb.de/cgi-bin/dokserv?idn=965487814.
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11
LEFEVRE, JEAN-CLAUDE. "Iphygenie : instrument physique pour la geochronologie d'echantillons naturels et irradies. developpement industriel d'une installation pour la mesure potassium-argon (technique cassignol) et pour la mesure argon 39/argon 40". Paris 11, 1992. http://www.theses.fr/1992PA112452.
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La methode de datation a l'argon profite de differentes techniques; l'une conventionnelle mesure separement le potassium et l'argon, sa plage d'application a ete etendue aux ages tres recents. Elle utilise une comparaison (double pesee): l'argon de l'air permettant une haute resolution sur l'estimation de la teneur en argon radiogenique (technique cassignol). L'autre, mesure simultanement le potassium et l'argon, en spectrometrie de masse, par dosage de l'argon 39 forme a partir du potassium 39 lors de l'irradiation du materiel. Afin de disposer des performances des deux techniques un nouvel appareillage a ete concu. Ce spectrometre de masse 180 offre la possibilite de concentrer dans un petit volume les gaz extraits du mineral. Le pentacollecteur realise, mesure simultanement les masses 36 a 40. L'ensemble de l'appareil a ete etudie et semi automatise pour un emploi routinier et dans l'optique d'une future commercialisation. Les systemes de fusion ont ete assortis au type d'analyse: fusion laser, fusion hf, et fusion lampes. Des tests ont ete effectues sur des mineraux standards, une tentative d'application a la datation de la limite cretace paleogene est proposee
12
Hanna, Gabriel Joseph. "Confocal microscopy of fluid argon under pressure". Pullman, Wash. : Washington State University, 2009. http://www.dissertations.wsu.edu/Dissertations/Fall2009/g_hanna_121109.pdf.
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13
Boulharts, Abderrahmane. "Étude de la synchronisation en phase, par injection, de deux lasers à argon ionisé (Ar⁺)". Paris 11, 1987. http://www.theses.fr/1987PA112408.
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Dans le présent mémoire, nous avons étudié la synchronisation en phase, par injection, de deux lasers à Argon ionisé oscillant en régime monomode longitudinal. Dans le chapitre un, nous avons présenté le fonctionnement et les différentes caractéristiques du Laser à Argon ionisé. Les principales hypothèses, concernant la création de l'inversion de population, sont énumérées. Dans le chapitre deux, après avoir modélisé le gain saturé du milieu amplificateur, nous avons calculé l'intensité émise par le Laser esclave en fonction: du gain non saturé, de l'intensité injectée et du déphasage entre l'onde injectée et l'onde auto-oscillante. Dans le chapitre trois, nous avons analysé les propriétés de la synchronisation en phase, et le transfert de stabilité du maitre oscillateur au Laser esclave, tant que leur décalage en fréquence est à l'intérieur de la plage d'accrochage par injection. Le chapitre quatre est consacré à l'étude d'un asservissement électronique de la cavité de l'esclave, afin de se prémunir des sauts en fréquence qui induisent des oscillations de la phase relative. Le dernier chapitre décrit les différents montages expérimentaux pour mesurer: le gain non saturé du milieu, les pertes par passage, la plage d'injection et l'intensité émise par l'esclave. En dernier lieu, nous avons asservi la cavité de l’esclave lorsque celui-ci est au-dessus du seuil d’oscillation.
14
Arfaoui, Samir. "Système haute-tension du calorimètre à argon liquide du détecteur ATLAS : mise en oeuvre, optimisation, et mesure de luminosité du LHC". Thesis, Aix-Marseille 2, 2011. http://www.theses.fr/2011AIX22081/document.
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Un des principaux objectifs de l'expérience ATLAS auprès du LHC est l'observations ou l'exclusion de nouvelle physique au-delà du Modèle Standard, en passant par les mesures de sections efficaces de production de processus du Modèle Standard. Sachant que le taux de production d'une particule dépends de sa section efficace de production ainsi que de la luminosité, il est necessaire de mesurer cette luminosité avec une grande précision. L'expérience ATLAS possède plusieurs détecteurs capable de mesurer la luminosité, dont les deux principaux: LUCID (Luminosity measurement Using Cerenkov Integrating Detector), et BCM (Beam Condition Monitor). Ces détecteurs sont calibrés absolument pendant des prises de données dédiées appelés van der Meer scans, qui ont permis d'obtenir une erreur systématique sur la détermination de la luminosité de 3.4% en 2010. Afin d'obtenir un maximum de différentes approches à la luminosité, plusieurs autres détecteurs contribuent aux différentes comparaisons. Ce document présente les calorimètres à argon liquide du détecteur ATLAS, et en particulier la mise en route et l'opération de leur système haute-tension. Il est montré qu'en mesurant les courant de ce système haute-tension pendant les prises de données de collisions de protons, il est possible d'obtenir des signaux proportionnels a la luminosité. En calibrant ces courants par rapport a un autre luminomètre, il est montré que cette calibration est stable au niveau de 0.5%The main goals of the ATLAS scientific programme are the observation or exclusion of physics beyond the Standard Model (SM), as well as the measurement of production cross-sections of SM processes. As the rate of events N of a given physics process is linked to the cross-section through the luminosity, it is important to measure the luminosity with great precision. The ATLAS experiment has two major luminosity monitors, LUCID (Luminosity measurement Using Cerenkov Integrating Detector), which consists of Cerenkov tubes located around the beam axis 17m away from the interaction point, and BCM (Beam Condition Monitor) which is a diamond-based detector and has both beam-abort and luminosity capabilities. As these detectors provide a relative luminosity measurement, they were absolutely calibrated in 2010 using the van der Meer procedure, achieving a total systematic uncertainty of 3.4%. The ultimate plan is to provide an absolute calibration using the ALFA detector during a run with special beam optics. In order to provide more cross-checks and a better control on the systematic uncertainties, other luminosity handles are always needed. In particular, an independent measurement using the liquid argon forward calorimeter (FCal), based on the readout current of its high-voltage system, has been developed. This document presents the commissioning and operations of the ATLAS liquid argon calorimeter high-voltage system, as well as its usage to perform a luminosity determination. Analysis of the high-voltage currents during LHC collisions and comparisons with other luminosity detectors have led to a calibration of these currents with a precision better than 0.5%
15
Thompson, C. E. "Thomson scattering measurements in low temperature plasmas". Thesis, Queen's University Belfast, 2002. http://ethos.bl.uk/OrderDetails.do?uin=uk.bl.ethos.269139.
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Izarra, Charles de. "Contribution à l'étude de colonnes de plasma d'argon dans un domaine étendu de températures (2000 k ; 14000 k)". Orléans, 1988. http://www.theses.fr/1988ORLE2023.
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Etude interférométrique et spectroscopique d'un plasma d'argon généré dans un arc Maecker. Les résultats théoriques montrent que les états excités ne donnent qu'une très faible refractivité globale du plasma, ce qui est confirmé par les résultats expérimentaux. Modèle numériques d'écoulement de plasma. On étudie le mélange entre un jet de plasma et un courant annulaire de gaz froids, dans le cadre d'une configuration simple. Le mélange est caracterisé en suivant la vitesse et la température de l'écoulement. Comparaison des résultats numériques et expérimentaux
17
Eberenz, Katharina. "argon daisy edition – DAISY in the commercial book-trade in Germany". Saechsische Landesbibliothek- Staats- und Universitaetsbibliothek Dresden, 2011. http://nbn-resolving.de/urn:nbn:de:bsz:14-qucosa-67974.
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In October 2008 Argon published the first DAISY audio books: 20 bestsellers from the publisher of audio books were “DAISYfied”. At present 10–15 DAISY titles are released per month, which are obtainable at the booksellers. The DAISY books can be classified as type two books; they combine textual headings and audio content. The accompanying booklet is recorded as well and is added as audio content. To distinguish DAISY audio books from audio books on audio CD, the former are packaged in a keep case with a label in Braille. According to Argon’s programme profile the titles of the DAISY edition cover all kinds of genres from literature, entertainment, crime fiction and children‘s books to non-fiction.
18
Dagtekin, Ebru. "Measurement Of Nonuniform Magnetized Argon Plasma Discharge Parameters". Master's thesis, METU, 2006. http://etd.lib.metu.edu.tr/upload/12607934/index.pdf.
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Effects of a magnetic field on the double-probe technique are studied experimentally by means of symmetric floating computer controlled fast double probes in low and intermediate pressure plasmas. In addition, the effects of the magnetic field on the electron temperature, electron density, and electric field have been investigated. As it is expected, when there is no magnetic field, properties of the discharge plasma are best described by Langmuir theory. Whereas, when there&rsquos a magnetic field of sufficient strength Schottky&rsquo
s theory of ambipolar diffusion applies.
19
Bougerolle, Stephen Edward. "Cosmic ray tests of a liquid argon calorimeter". Thesis, University of British Columbia, 1989. http://hdl.handle.net/2429/27397.
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A series of tests have been performed on a liquid argon calorimeter module at the Test Beam Facility at the Stanford Linear Accelerator Centre. We find that the calorimeter performs according to design. Several performance parameters have been measured. The charge-collection efficiency in a tower of the calorimeter was observed to be 87%. This loss is due mainly to recombination; absorption by oxygen impurity seems insignificant. No detectable energy loss has been observed when a particle moves through the crack between adjacent towers. The cross-talk between two adjacent towers was measured and found to be in agreement with a simple model.Science, Faculty of
Physics and Astronomy, Department of
Graduate
20
Nammour, Samir. "Effet du laser à argon sur l'émail dentaire". Doctoral thesis, Universite Libre de Bruxelles, 1988. http://hdl.handle.net/2013/ULB-DIPOT:oai:dipot.ulb.ac.be:2013/241284.
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21
Ingram, S. G. "Investigations of low pressure RF discharges in argon". Thesis, University of Oxford, 1988. http://ethos.bl.uk/OrderDetails.do?uin=uk.bl.ethos.480534.
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22
Lamade, John Dietrick. "Investigation of an argon-filled, thermoacoustic prime mover". Thesis, Monterey, California. Naval Postgraduate School, 1991. http://hdl.handle.net/10945/28308.
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23
Surrey, E. "Fundamental properties of a microwave induced argon plasma". Thesis, London Metropolitan University, 1987. http://ethos.bl.uk/OrderDetails.do?uin=uk.bl.ethos.376458.
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Hamilton, Philip. "A study of neutrino interactions in argon gas". Thesis, Imperial College London, 2015. http://hdl.handle.net/10044/1/26933.
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The T2K (Tokai to Kamioka) experiment uses an intense off-axis muon neutrino beam to study neutrino oscillations through muon neutrino disappearance and electron neutrino appearance. As T2K and other neutrino oscillation experiments move beyond the regime in which they are statistically limited, uncertainties on neutrino-nucleus cross-sections have become increasingly significant as a limiting factor on the precision of these experiments, and on the next generation of detectors. Reducing these uncertainties requires a better understanding of neutrino-nucleus interactions through empirical study. This thesis describes the first ever measurement of neutrino-nucleus interactions on a gaseous target, using the intense T2K beam and the three gaseous argon time-projection chambers in the T2K near detector, ND280. I identify 63 neutrino interaction candidates, and make a comparison of the charged-current muon neutrino differential cross-section with respect to proton multiplicity between data and the simulation packages NEUT and GENIE. This thesis also describes the methods developed to select the gas interactions data sample, which by virtue of the detailed reconstruction available in the ND280 TPCs offers further opportunities to test the predictions of nuclear models than those that are covered by this thesis. Future generations of this analysis are expected to expand both the size of the sample and the range of variables tested.
25
Weldon, Nicholas Cullum. "Argon Diffusion in Rhyolite Melt at 100 MPa". Thesis, University of California, Davis, 2016. http://pqdtopen.proquest.com/#viewpdf?dispub=10165710.
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In this study, we conduct high-pressure (HP) high-temperature (HT) diffusion experiments in anhydrous rhyolite near 1000 °C and 1100 °C at 100 MPa using the cold seal pressure apparatus to diffuse argon into natural obsidian charges. We use electron microprobe measurements of the argon concentration gradients to calculate the argon diffusivity (DAr) as a function of temperature and pressure. The range and mean of DAr calculated from these measurements are in good agreement with previous studies (Carroll 1991, Behrens and Zhang 2001). Even so, we observe significant variability in our DAr results, beyond what is likely due to analytical or experimental uncertainty; nearly as much variability as Carroll (1991) and Behrens and Zhang (2001) reported. In particular, we notice a small systematic geometric bias in the distribution of argon in our samples, which appears to correlate with sample deformation. We attribute this effect to distortion of concentration gradients by viscous advection.
26
Avila, Carlos A. "Laser cooling of a metastable argon atomic beam". FIU Digital Commons, 1996. http://digitalcommons.fiu.edu/etd/1342.
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A production of low velocity and monoenergetic atomic beams would increase the resolution in spectroscopic studies and many other experiments in atomic physics. Laser Cooling uses the radiation pressure to decelerate and cool atoms. The effusing from a glow discharge metastable argon atomic beam is affected by a counterpropagating laser light tuned to the cycling transition in argon. The Zeeman shift caused by a spatially varying magnetic field compensates for the changing Doppler shift that takes the atoms out of resonance as they decelerated. Deceleration and velocity bunching of atoms to a final velocity that depends on the detuning of the laser relative to a frequency of the transition have been observed. Time-of-Flight (TOF) spectroscopy is used to examine the velocity distribution of the cooled atomic beam. These TOF studies of the laser cooled atomic beam demonstrate the utility of laser deceleration for atomic-beam "velocity selection".
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Rosqvist, Emil, i Theodore Vassi. "Characterization of phases in Argon Oxygen Decarburization slag". Thesis, KTH, Materialvetenskap, 2021. http://urn.kb.se/resolve?urn=urn:nbn:se:kth:diva-298409.
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Slag is an important part of steelmaking with the AOD (Argon Oxygen Decarburization) process. In this work the focus was on developing a methodology for characterizing phases in slagsamples obtained after decarburization, reduction and desulphurization. Six samples from two heats, or batches, (heat A and B) were prepared by baking in Bakelite and polishing. These were analysed in SEM (Scanning Electron Microscope), with BSE (Backscattered Electrons) and EDS (Energy Dispersive XraySpectroscopy). Images from BSE were then processed inImageJ with a denoise method for advanced fraction analysis. Average composition for each noticed phase analysed with EDS is presented in element tables. A systematic portraying of the cross section was performed on samples from heat B. This gave a more in-depth composition and fraction analysis. Due to the nature of slag, scratches were often induced during polishing.The negative effect of these scratches could be reduced with the denoise method in the fraction analysis. There are three main phases in each stage of the AOD process with similar composition and structure between the two heats. Results showed the importance of measuring different zones of the slag due to its heterogeneity. More specifically, at least four random images from the cross section were required for accurate fraction analysis of samples after decarburization. Overall, the methodology for characterization was sufficient for samples after decarburization and desulphurization.Slagg är en viktig del av ståltillverkning med AOD-processen (Argon Oxygen Decarburization). Fokus i detta arbete var att utveckla en metod för att karakterisera faser i slaggprover erhållna efter avkolning, reduktion och avsvavling. Sex prover från två batcher (batch A och B) förbereddes genom bakning i bakelit och polering. Dessa prover analyserades i SEM (Svepelektronmikroskop), med BSE (Backscattered Electrons) och EDS (Energy Dispersive Xray Spectroscopy). Bilder från BSE bearbetades sedan i ImageJ med en denoise-metod för avancerad fraktionsanalys. Genomsnittlig sammansättning för varje fas analyserad med EDS presenteras i elementtabeller. En systematisk undersökning av heterogenitet hos slagg utfördes på prover från batch B. Detta gav en mer noggrann komposition och fraktionsanalys. På grund av slaggens karaktär uppkom ofta repor under poleringen. Den negativa effekten av dessa repor kunde minskas med denoise-metoden i fraktionsanalysen. Det finns tre huvudfaser i varje steg i AOD-processen med liknande sammansättning och struktur för de två batcherna. Resultaten visade betydelsen av att mäta slaggprovet i olika zoner på grund av dess heterogenitet. Mer specifikt krävdes minst fyra slumpmässiga bilder från tvärsnittet för noggrann fraktionsanalys av prover efter avkolning. Sammantaget var metoden för karaterisering av slagger tillräcklig för prover efter avkolning och avsvavling.
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McWilliams, Cory K. "The tectonic evolution of the Connecticut Valley Synclinorium constraints from argon/argon thermo chronology, uranium-lead geochronology, thermobarometry and thermal modeling /". [Bloomington, Ind.] : Indiana University, 2008. http://gateway.proquest.com/openurl?url_ver=Z39.88-2004&rft_val_fmt=info:ofi/fmt:kev:mtx:dissertation&res_dat=xri:pqdiss&rft_dat=xri:pqdiss:3350508.
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Thesis (Ph.D.)--Indiana University, Dept. of Geological Sciences, 2008.Title from home page (viewed on Oct. 8, 2009). Source: Dissertation Abstracts International, Volume: 70-03, Section: B, page: 1554. Adviser: Robert P. Wintsch.
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Eberenz, Katharina. "argon daisy edition – DAISY in the commercial book-trade in Germany". Deutsche Zentralbibliothek für Blinde Leipzig (DZB), 2010. https://slub.qucosa.de/id/qucosa%3A1131.
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In October 2008 Argon published the first DAISY audio books: 20 bestsellers from the publisher of audio books were “DAISYfied”. At present 10–15 DAISY titles are released per month, which are obtainable at the booksellers. The DAISY books can be classified as type two books; they combine textual headings and audio content. The accompanying booklet is recorded as well and is added as audio content. To distinguish DAISY audio books from audio books on audio CD, the former are packaged in a keep case with a label in Braille. According to Argon’s programme profile the titles of the DAISY edition cover all kinds of genres from literature, entertainment, crime fiction and children‘s books to non-fiction.
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Mouele, Flore. "Evolution des latérites manganesifères de Serra Do Navio (Brésil). Pétrologie et datation 40Ar/39Ar des cryptomélanes". Aix-Marseille 3, 2004. http://www.theses.fr/2004AIX30004.
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La datation 40Ar/39Ar des cryptomelanes (K1-2Mn8O16 nH2O) est appliquée aux minerais supergènes manganésifères de Serra do Navio (Brésil). Les études pétrologiques montrent que les cryptomélanes présentent divers caractères. La datation de ces minéraux indique que l'enfoncement du front d'oxydation (vitesses moyennes autour de 2,5 m/Ma) n'est pas toujours continue. Elle confirme par ailleurs, l'existence de différentes générations de cryptomélane associées à des périodes d'altération successives (pré-Oligocène ; 25-18 Ma et 15-13 Ma ; 6,2-4,6 Ma ; 2,6-2,3 Ma ; 0,5-0,2 Ma). L'Oligocène et le Miocène supérieur apparaissent comme des périodes d'érosion. Ainsi, la datation 40Ar/39Ar des cryptomélanes est un outil efficace pour l'étude morpho-climatique des paysages latéritiques. Deux hypothèses sont proposées : 1) la surface supérieure serait d'age Crétacé-Eocène et la surface inférieure d'âge Oligo-Miocène, 2) ces surfaces seraient respectivement d'âge Oligocène et Miocène supérieurThe 40Ar/39Ar dating of the cryptomelanes (K1-2Mn8O16 nH2O) has been applied to the supergene ores of the Serra do Navio manganese deposit from North Brazil. The petrological studies show that the cryptomelanes present varied characters. The dating of these minerals suggests that the oxidation front (rates of the weathering front are about 2. 5 m/Ma) didn't always continuously propagate with time. These results confirm the existence of distinct generations of cryptomelane associated to successive weathering periods (pre-Oligocene; 25-18 Ma and 15-13 Ma; 6. 2-4. 6 Ma; 2. 6-2. 3 Ma; 0. 5-0. 2 Ma). The Oligocene and the late Miocene seem erosion periods. Then, we conclude that the 40Ar/39Ar dating of the cryptomelanes is an effective tool to study morphoclimatic events of the laterite landscapes. Two hypotheses are proposed : 1) the upper surface would be the Cretaceous-Eocene age and the lower surface to Miocene period, 2) this surfaces would be respectively from Oligocene and late Miocene periods
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Catala, Juan Carlos. "Laser cooling and trapping of argon metastable atomic beam". FIU Digital Commons, 1998. http://digitalcommons.fiu.edu/etd/2083.
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The high velocity of free atoms associated with the thermal motion, together with the velocity distribution of atoms has imposed the ultimate limitation on the precision of ultrahigh resolution spectroscopy. A sample consisting of low velocity atoms would provide a substantial improvement in spectroscopy resolution.
To overcome the problem of thermal motion, atomic physicists have pursued two goals; first, the reduction of the thermal motion (cooling); and second, the confinement of the atoms by means of electromagnetic fields (trapping). Cooling carried sufficiently far, eliminates the motional problems, whereas trapping allows for long observation times.
In this work the laser cooling and trapping of an argon atomic beam will be discussed. The experiments involve a time-of-flight spectroscopy on metastable argon atoms. Laser deceleration or cooling of atoms is achieved by counter propagating a photon against an atomic beam of metastable atoms. The solution to the Doppler shift problem is achieved using spatially varying magnetic field along the beam path to Zeeman shift the atomic resonance frequency so as to keep the atoms in resonance with a fixed frequency cooling laser.
For trapping experiments a Magnetooptical trap (MOT) will be used. The MOT is formed by three pairs of counter-propagating laser beams with mutual opposite circular polarization and a frequency tuned slightly below the center of the atomic resonance and superimposed on a magnetic quadrupole field.
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Lamarche, François. "Étude de collisions relativistes Argon sur Argent dans l'émulsion". Thesis, University of Ottawa (Canada), 1985. http://hdl.handle.net/10393/4988.
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Dudley, John Michael. "Coherent transient phenomena in the mode-locked argon laser". Thesis, University of Auckland, 1992. http://hdl.handle.net/2292/2005.
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An investigation has been carried out into the operation of a mode-locked argon laser at a wavelength of 514.5 nm and a repetition rate of 76.8 MHz. The characteristics of the pulses from the laser have been found to depend on the intra-cavity power level in the laser, and at average intra-cavity power levels exceeding 4 W, the pulses from the laser have a duration of typically 35 psec accompanied by a characteristic double-peaked spectrum with a spectral width of 13 GHz These pulse durations are approximately three times shorter than expected based on the inhomogeneously broadened transition bandwidth of 4 GHz. The dependence of the pulse characteristics on the intra-cavity power level has been explained by a model of pulse propagation where the coherent coupling between the pulse and the atomic polarisation in the laser gain medium is included. Detailed examination of the pulse structure reveals the presence of afterpulses that have a typical intensity two orders of magnitude lower than the main pulse. These afterpulses are interpreted as ringing arising from coherent Rabi-type oscillation of the atomic polarisation associated with the circulating pulse in the laser. Numerical simulations of the mode-locked laser have also been developed based on the fully coherent Maxwell-Bloch equations, and the results from the simulations reproduce well the experimentally observed variation in pulse characteristics. Based on results from the simulations, the short pulses observed at high intra-cavity powers are interpreted as the superfluorescent π –pulse solutions predicted in the long distant limit of pulse propagation in a swept-gain amplifying medium. The laser operation has also been studied in a mode-locked cavity dumped configuration. In this case the combination of the coherent mode-locking processes described above with the cavity dumped operation at a repetition rate of 3.8 MHz results in the observation of stable pulses with peak power of 1.6 kW.
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Stevenson, Mark. "Correlation studies of the ionization of argon and calcium". Thesis, University of Newcastle Upon Tyne, 2003. http://ethos.bl.uk/OrderDetails.do?uin=uk.bl.ethos.397363.
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McConville, Paul. "Development of a laser probe for argon isotope studies". Thesis, University of Sheffield, 1985. http://ethos.bl.uk/OrderDetails.do?uin=uk.bl.ethos.293264.
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Maher-McWilliams, C. "Creation, trapping and manipulation of a cold argon gas". Thesis, University College London (University of London), 2013. http://discovery.ucl.ac.uk/1380709/.
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This thesis describes the construction and characterisation of a unique cold argon atom source for sympathetic cooling of molecules. Argon atoms were laser cooled from their lowest lying metastable state using the 4s[3/2]2 → 4p[5/2]3 transition at 811.5 nm. A magneto-optical trap (MOT) was used to cool the metastable argon (Ar*) atoms to 73.2 ± 0.4 μK and trap them at a density of 3.93 × 10^9 cm-3. Cooling was facilitated using an external-cavity diode laser which was frequency-stabilised to the cooling transition using a magnetic dichroism technique. This was the first application of this technique to a plasma operated at our pressures where the applied magnetic field affected the gas behaviour. The Ar* atoms in the MOT were used to demonstrate chirped optical Stark acceleration for the first time. Atoms were accelerated up to velocities of 191 ± 1 ms-1 while maintaining narrow energy spreads in the accelerated ensemble (30-100 mK). The acceleration occurred over tens of nanoseconds and on micrometre length scales. Control over the number of particles accelerated was achieved by tailoring the depth of the optical lattice potential. Monte Carlo numerical simulations of acceleration were used to fit experimental results and study the dynamics of particles over the acceleration duration. Trapping of Ar* atoms in a quasi-electrostatic trap (QUEST) has also been demonstrated. The QUEST was formed at the focus of a 100 W laser beam with a wavelength of 10.6 μm. A trap lifetime of 18.3 ± 0.3 ms was measured.
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Sode, Maik [Verfasser]. "Quantitative Beschreibung von Wasserstoff-Stickstoff-Argon-Mischplasmen / Maik Sode". Kiel : Universitätsbibliothek Kiel, 2014. http://d-nb.info/1048558398/34.
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Kong, Yung 1967. "Particle contamination in sulfur-hexafluoride/argon plasma etching process". Thesis, The University of Arizona, 1991. http://hdl.handle.net/10150/277919.
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Process generated particle contamination on unpatterned silicon wafers etched in an SF6/argon plasma using a Tegal MCR-1 etcher in the plasma triode-1 mode was characterized using response surface methodology. Particle deposition was observed to be a predictable function of plasma parameter space, which can be determined by relatively few statistically designed experiments. A model of particle deposition as a function of 13.56 MHz chamber electrode rf power, chamber pressure, gas flow rate, etch time and 100 kHz wafer electrode power was constructed. It is found that particle deposition depends linearly on etch time and both 13.56 MHz and 100 kHz power. In addition, particle deposition increased with gas flow rate at low flow rate, reaches a maximum, then decreased as flow rate increased further. Moreover, there was no observable effect on particle deposition due to pressure variation in the pressure range explored. Auger chemical analysis showed that the particles contained elemental sulfur, fluorine, silicon, aluminum, carbon and oxygen. Most particles were typically less than 2 μm in diameter.
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Pazzona, Federico G., Marco Sant, Evangelia Pantatosaki, George K. Papadopoulos i Doros N. Theodorou. "Analysis of argon diffusion in zeolite imidazolate framework-8". Universitätsbibliothek Leipzig, 2015. http://nbn-resolving.de/urn:nbn:de:bsz:15-qucosa-191467.
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Cupido, Ian Patrick. "Nitrogen and argon treatment of titanium dioxide nanowire arrays". University of Western Cape, 2021. http://hdl.handle.net/11394/8040.
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>Magister Scientiae - MScTiO2 nanoparticle films are important electron transport layers (ETLs) in photovoltaics such as dye-sensitised, perovskite and polymer hetero-junction solar cells. These films, however, have significant electron trap-sites as a result of the large density of oxygen vacancies present in nano-sized TiO2. These trap-sites cause electron-hole recombination and ultimately lower photon-to-current conversion efficiency of the underlying cell during operation. Doping the TiO2 lattice with low atomic number elements such as nitrogen is a proven method to overcoming the charge transport inefficiency of TiO2 ETLs; another is the use of one-dimensional (1D) nanowires (NWs), instead of nanoparticles.
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Parneix, Pascal. "Dynamique des microsolutions aniline-(argon)#n par simulation numerique". Paris 11, 1993. http://www.theses.fr/1993PA112238.
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Ce travail de these porte sur l'etude de la dynamique vibrationnelle des agregats de van der waals aniline-(argon)#n. A partir des structures calculees d'energie minimum de ces agregats, on a pu etablir un modele de deplacement electronique specifique en fonction du site d'adsorption occupe par l'atome d'argon. On a etudie les phenomenes d'isomerisation et d'evaporation unimoleculaire au moyen de simulations de dynamique moleculaire. On a en particulier analyse l'influence de la taille et de la structure isomerique sur l'ensemble des processus dynamiques. On a effectue egalement des calculs quantiques des etats lies sur les agregats aniline-argon, aniline-helium, aniline-neon et aniline-deuterium. Dans le premier cas, on a teste l'influence de l'addition d'un terme empirique dans le premier etat electronique excite singulet s#1. Ce terme tend a reproduire l'interaction specifique entre les atomes d'azote et d'argon. Enfin, on a utilise une methode semi-classique pour simuler les spectres electroniques des microsolutions aniline-(argon)#n (n=1-14). Ces simulations rendent compte parfaitement des deplacements electroniques de la transition s#1s#0 pour les petits agregats. On a mis egalement en evidence l'influence de la temperature et de la structure des isomeres sur la largeur du profil spectral. Pour les plus gros agregats (n=7 et n=14), on a montre l'importance des contributions inhomogenes a l'elargissement spectral pour une taille donnee
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Armijo, Michael Charles. "The vacuum ultraviolet emission of the argon fluoride molecule /". The Ohio State University, 1988. http://rave.ohiolink.edu/etdc/view?acc_num=osu1487588249823041.
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Chang, Bor-Chen. "Electronic spectroscopy of argon-hydroxyl and neon-hydroxyl complexes /". The Ohio State University, 1993. http://rave.ohiolink.edu/etdc/view?acc_num=osu1487844948074256.
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Cole, Eric D. "Electrical analysis of low energy argon ion bombarded GaAs". Diss., Virginia Polytechnic Institute and State University, 1988. http://hdl.handle.net/10919/53676.
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An electrical analysis was done on A1 and Au Schottky diodes fabricated on n-type (100) GaAs which had been bombarded with low energy Ar ions. The purpose of this study was to quantify electrically damage caused by the Ion Beam Etching (IBE) as functions of energy and fluence.
Electrical studies included Deep Level Transient Spectroscopy (DLTS), Current-Voltage (I-V), Capacitance-Voltage (C-V), ConductanceVoltage (G-V), Capacitance-Temperature (C-T), and Activation Energy Analysis. These electrical measurements were carried out on GaAs which had been exposed to a variety of treatments after IBE (such as chemical etch removal) to determine damage depth.
At the lowest energy studied, 0.5keV, Schottky reverse saturation currents (Isat) increased by over 4 orders of magnitude from the virgin case. The ideality factor, n, increased slightly while the breakdown voltage decreased. The most prominent changes occurred in the DLTS spectrum where it was observed that the native arsenic defect EL2 peak disappeared completely after ion etching. Concurrently a sharp increase in the diode conductivity with temperature was seen. It was found that chemical removal of 100Å of GaAs by chemical means could restore most of the diode parameters and the EL2 peak. It is proposed that the loss of EL2 is not related to a true physical reduction (i.e. an arsenic depletion) since calculations showed that the As loss would have extended beyond 3000Å for detectable DLTS changes. Also, the EL2 peak could be made to artificially disappear on a virgin sample with an external diode shunting resistor. The loss of the EL2 peak is, rather, attributed to a thin low resistivity surface layer having a partly amorphous nonstoichiometric crystal structure which can desensitize or mask the DLTS measurement. Surface chemical etch studies over the top of the Schottky diodes recovered 25% of the EL2 peak supporting this conclusion. Lower fluences had no effect at 0.5keV.
Increasing ion bombardment energy showed a steady degradation in diode ideality factors. The reverse breakdown voltage increased past the unetched value and the DLTS spectrum began to show a very slight return of EL2. At 3keV the ideality factor was large, indicating the presence of a somewhat thicker high resistance layer. In fact recovery of diode parameters and EL2 did not occur until after 100Å removal. This was much deeper than expected at this energy, according to theory.
Physical and lumped R-C electrical models are reported with an accompanying computer simulation of experimental DLTS results. The simulation used both thin low resistance and thick high resistance top layers to show that EL2 could be removed artificially. The models were also somewhat successful in explaining previously reported capacitance dispersion found in IBE GaAs.Ph. D.
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Žáková, Marie. "Optická emisní spektroskopie dohasínajícího plazmatu ve směsi dusík-argon". Master's thesis, Vysoké učení technické v Brně. Fakulta chemická, 2009. http://www.nusl.cz/ntk/nusl-216566.
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The study of plasmas generated in pure nitrogen and their afterglows are a subject of many hundreds works bringing a lot of information about the kinetic processes and energy transfer reactions. The effect of nitrogen pink afterglow has a specific position among the other kinds of discharges and post-discharges. The post-discharge, and especially the pink afterglow, is extremely sensitive to the presence of various impurities and experimental conditions (total gas pressure in a discharge tube, temperature, etc.) because of their significant influence on all kinetic processes. That is the reason, why it is so important to study this processes. The DC flowing afterglow (generated using the hollow molybdenum electrodes in the distance of 12 cm, power ± 290 W) was used for the experimental part of this work. The discharge was created in Pyrex discharge tube at different concentration ratio of nitrogen and argon. The total gas presure was in range from 500 Pa to 5000 Pa. The emission spectra of post-discharge were recorded by TRIAX 550 spectrometer with CCD detector in the range of 320-780 nm. The vibrational populations at individual vibrational levels were calculated using the emission bands of the first (N2 (B 3g) N2 (A 3u+)) and the second (N2 (C 3u) N2 (B 3g)) positive and the first negative (N2+ (B 2u+) N2+ (X 2g+) nitrogen spectral systems. The dependencies of intensity on decay time and relative vibrational populations on argon concentration and pressure were obtained. The pink afterglow was very sharp in pure nitrogen at low pressure. With the increasing total pressure it was shifted to the later decay times and it was visible for longer time, too. The same effect was observed with the increase of argon concentration in the gas mixture. At the highest argon concentrations, especially at lower pressure, the effect of pink afterglow dissapeared. The knowledge of these processes can give the solution of all kinetic reactions in plasma and this can be used in plasma chemistry and for development of new technologies. This will be a subject of further intensive studies.
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LAI, MICHELA. "Dark matter search and neutrino physics in Liquid Argon". Doctoral thesis, Università degli Studi di Cagliari, 2021. http://hdl.handle.net/11584/308084.
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Several astrophysical observations, both on a galactic and cosmological scales, showing that there’s a “missing mass” in the observable Universe, can be explained assuming a non-luminous kind of matter, hence called “dark matter”. One of the most promising candidates is the Weakly Interacting Massive Particle (WIMP), a non-relativistic massive particle, gravitationally and weakly interacting with baryonic matter. The present work is specifically focused on the physics potential besides WIMP search of dark matter detectors filled with Liquid argon, like DarkSide and DEAP-3600. Liquid argon is an optimal target thanks to its high scintillation and ionization yields. DEAP-3600 is a single-phase detector, exploiting the scintillation channel only, while DarkSide-20k and Argo, future tonne scale experiments from the DarkSide program, are dual-phase Time Projection Chambers (TPCs), looking at both scintillation and ionization signals. The large mass (3.3 tons)
of the DEAP-3600 target has allowed me to perform an analysis to search for Multi Interacting Massive Particles (MIMPs), a dark matter candidate alternative to WIMPs, at masses above 10^{ 16} GeV and with argon-dark matter spin-independent cross-section of about 10^{ −22 }cm^{ 2} , fully setting up the upcoming unblinding of three years of data taking. Going from the present to the future dark matter detectors, DarkSide-20k and Argo will be characterized by an extraordinary sensitivity at low energy recoils. This is mainly consequence of the high energy resolution of the chosen photodetectors, Silicon Photomultipliers (SiPMs). Custom SiPMs have been designed for the dark matter search in DarkSide-20k; hence, SiPMs have been here characterized, with a focus on their correlated noises, namely afterpulses and optical crosstalks. The same sensitivity at low energy brings also to a strong potential in detecting supernova neutrinos via coherent elastic neutrino-nucleus scattering (CEvNS) in argon by exploiting the ionization signal. The related sensitivity study is here performed showing that the neutrino emission will be detected for any galactic supernova, with a good accuracy in reconstructing the main parameters of the burst, namely the total energy of neutrinos and
their average energy.
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Karderinis, Sideris. "Spectroscopic studies of radio-frequency plasmas". Thesis, University of Oxford, 2000. http://ethos.bl.uk/OrderDetails.do?uin=uk.bl.ethos.325952.
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Tshoso, Gomotsang. "Structure, chronologie et mode de mise en place du système géant de dykes de l'Okavango, Nord-Botswana : Une approche multidisciplinaire". Brest, 2003. http://www.theses.fr/2003BRES2029.
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Les complexes de laves et dykes basaltiques formant la Grande Province Magmatique Karoo d'Afrique Australe (140 000 km2) se prolongent vers l'Est au niveau de la ceinture ignée de Ferrar, en Antarctique. L'origine de ces provinces magmatiques est généralement attribuée, soit à la mise en place d'un panache mantellique dont l'expression de surface se marquerait par la convergence de plusieurs systèmes de dykes géants dans la région de Nuanetsi (SO Zimbabwe), soit au poinçonnement d'une zone de subduction par un panache. Parmi les systèmes de dykes Karoo, le complexe géant de l'Okavango (ODS), situé au NE du Botswana, apparait sur les cartes aéromagnétiques comme une structure magmatique linéaire (N110°E) de dimensions exceptionnelles (2000 x 100 km), recoupant le socle Précambrien et sa couverture Karoo (sédiments et laves). L'ODS constitue donc un indicateur de premier ordre pour mieux contraindre les modèles géodynamiques appliqués à la Grande Province Magmatique Karoo, et les buts principaux de cette thèse ont donc consisté, sur la base d'une approche multidisciplinaire, à préciser : 1) la chronologie de sa mise en place, 2) sa signature géochimique, 3) sa structure, et 4) son mode de mise en place. La chronologie Ar-Ar obtenue sur les dykes et les coulées basaltiques montre leur contemporanéité dans l'intervalle 178-180 Ma. Ces ages sont légèrement plus jeunes que ceux obtenus sur le magmatisme Karoo du NO Zimbabwe, de Namibie et d'Afrique du Sud. Ces datations ont également révélé la présence de dykes d'âge protérozoique au sein de l'ODS, suggérant la mise en place du complexe de dykes Karoo le long d'une structure linéaire pré-existante. L'analyse géochimique des basaltes de Shadi-Shadi montre que les 2 sous-provinces 'Low-Ti et High-Ti', précédemment supposées marquer une zonation spatiale majeure, indiquent plutot une zonation temporelle à l'intérieur des provinces Karro et Ferrar. Les signatures géochimiques des roches mafiques 'Low-Ti et High-Ti' du NE Botswana sont typiques d'une origine à partir d'un manteau enrichi lors d'un processus de subduction situé plus au sud. Les mécanismes de mise en place de l'ODS ont été abordés sur la base de l'analyse de 1) données aéromagnétiques, 2) relevés magnétiques au sol, mesures de l'Anisotropie de Susceptibilité Magnétique, et 3) observations structurales. L'ODS est interprété comme un complexe filonien alimenté par du magma se propageant latéralement d'E en W. L'existence éventuelle d'une chambre magmatique intermédiaire dans la région de Tuli est suggérée par des directions d'écoulement vertical dans les dykes. Cette chambre magmatique se serait comportée comme un réservoir de stockage, contribuant à maintenir l'écoulement du faisceau sur une distance de plus de 2000 km. Les mesures structurales indiquent que, durant la phase de magmatisme Karoo, la dilatation crustale a été accomodée pour l'essentiel, par l'intrusion des dykes, sans l'intervention de failles extensives. Les faisceaux de dykes Karoo N110° et N70° se sont injectés le long de discontinuités pré-éxistantes intra-socle, réactivées comme des fractures obliques (N110°) ou en extension pure (N70°) en réponse à une extension régionale orientée au N160°. A l'échelle régionale, le système radial de dykes/fractures Karoo convergeant au point triple de Nuanetsi est donc interprétée comme une structure héritée, superposée aux bordures des cratons du Kaapvaal et du Zimbabwe, et il ne peut donc plus être considéré comme l'expression spécifique d'un panache mantellique.
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Lo, Bello Philippe. "Géochronologie par la méthode 39Ar/40Ar de ponces quaternaires contaminées : exemple des ponces du Mont-Doré (Massif Central français) : utilisation d'un laser continu pour la datation de minéraux individuels". Nice, 1988. http://www.theses.fr/1988NICE4184.
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Méthodologie de la méthode de datation 39Ar/40Ar qui permet de dater des formations pyroclastiques quaternaires, même si celles-ci sont contaminées par des minéraux hercyniens du Sale, elle est plus fiable que la méthode K-Ar conventionnelle. La datation d'outils à 2,5 Ma a été confirmée, si bien qu'on repousse l'arrivée des premiers hominidés en Europe. L'étude de la diffusion de l'argon dans des xénolites emballés dans les coulées de ponces peut permettre d'apprécier les temps de résidence de ces minéraux dans une chambre magmatique ou dans une coulée de ponce
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TORTI, MARTA. "Effects of electric and magnetic fields on the event reconstruction in the ICARUS T600 detector". Doctoral thesis, Università degli studi di Pavia, 2017. http://hdl.handle.net/11571/1203315.
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In recent years, a number of anomalies in neutrino oscillation scenario were observed, that point out to possible non-standard oscillations which could imply the existence of a fourth (or more) sterile neutrino. Its existence, or absence, calls for a definitive clarification with new data.
In particular, the Short Baseline Neutrino program at FNAL, will exploit three Liquid Argon Time Projection Chamber (LAr TPC) detectors along the Booster Neutrino Beamline. Each detector has different mass and a different position: the near detector SBND is the smallest, the intermediate detector MicroBooNE is the medium sized while the biggest one is the far detector, the ICARUS T600.
This Ph.D. thesis is focused on the ICARUS T600 detector, the largest LAr TPC ever built, which concluded successfully the operation at LNGS in Italy. Here it was exposed at underground conditions to the CNGS beam to study oscillations.
After the CNGS shut down, the detector continued taking data with cosmic rays until it was de-commissioned and transported to CERN, where it is now under refurbishment, before moving to FNAL.
In a LAr TPC, when a charged particle crosses the detector, ionizing electrons are drifted towards the wire anode planes, where they are collected providing two spatial coordinates of the track; arrays of PMTs detect scintillation light, providing the measurement of the absolute time of occurrence that, combined with the knowledge of the drift velocity, permits the determination of the third coordinate of the track, that along the drift direction.
The goal of the ICARUS reconstruction procedure is to extract, in an accurate way, all the physical information contained in the wire and PMT output signals, to build a complete 3D spatial and calorimetric picture of the event.
To have this faithful event reconstruction, it is mandatory to determine wire and drift coordinates accurately and so it is essential to understand everything that could distort the information.
The uniformity of electric field is essential in order to ensure a uniform drift velocity and thus the proportionality between drift time and drift coordinate.
Electric field distortions may arise by a local accumulation, along the drift path, of positive ions, which are drifted towards the cathode more slowly than the electrons.
This accumulation is emphasised by high interaction rate, given for example by high cosmic ray flux. This problem, called space charge, could be present at FNAL, where the ICARUS detector will be placed at shallow depths.
In order to understand the influence of this effect in track reconstruction, a data sample is analysed, collected when the detector was at surface condition for a test run in Pavia. In the thesis are described the parameters used to study space charge effects in the ICARUS detector and the obtained results are illustrated.
As stated before, the drift coordinate precision is derived by the electrons drifted towards the wire planes and it is affected by several factors, such as the diffusion. To evaluate the diffusion parameter, a dedicated run with different electric field values was performed collecting cosmic rays at the end of LNGS run. The analysis of these data samples is pointed out, considering the dependence of the width of the signal registered by the TPC.
The ICARUS Collaboration is also involved in a long time project, called DUNE (Deep Underground Neutrino Experiment): it will be a long baseline experiment, with modular kiloton LAr-TPCs, to be built in the next 20 years. The T600 could be used as Near Detector, once provided with a magnetic field for particle momentum measurements and charged particle identification.
The presence of a magnetic field introduces new parameters and possibilities for the reconstruction procedure. In this framework, an algorithm is developed, in order to discriminate between electron neutrino and electron antineutrino, considering their interaction products.In recent years, a number of anomalies in neutrino oscillation scenario were observed, that point out to possible non-standard oscillations which could imply the existence of a fourth (or more) sterile neutrino. Its existence, or absence, calls for a definitive clarification with new data. In particular, the Short Baseline Neutrino program at FNAL, will exploit three Liquid Argon Time Projection Chamber (LAr TPC) detectors along the Booster Neutrino Beamline. Each detector has different mass and a different position: the near detector SBND is the smallest, the intermediate detector MicroBooNE is the medium sized while the biggest one is the far detector, the ICARUS T600. This Ph.D. thesis is focused on the ICARUS T600 detector, the largest LAr TPC ever built, which concluded successfully the operation at LNGS in Italy. Here it was exposed at underground conditions to the CNGS beam to study oscillations. After the CNGS shut down, the detector continued taking data with cosmic rays until it was de-commissioned and transported to CERN, where it is now under refurbishment, before moving to FNAL. In a LAr TPC, when a charged particle crosses the detector, ionizing electrons are drifted towards the wire anode planes, where they are collected providing two spatial coordinates of the track; arrays of PMTs detect scintillation light, providing the measurement of the absolute time of occurrence that, combined with the knowledge of the drift velocity, permits the determination of the third coordinate of the track, that along the drift direction. The goal of the ICARUS reconstruction procedure is to extract, in an accurate way, all the physical information contained in the wire and PMT output signals, to build a complete 3D spatial and calorimetric picture of the event. To have this faithful event reconstruction, it is mandatory to determine wire and drift coordinates accurately and so it is essential to understand everything that could distort the information. The uniformity of electric field is essential in order to ensure a uniform drift velocity and thus the proportionality between drift time and drift coordinate. Electric field distortions may arise by a local accumulation, along the drift path, of positive ions, which are drifted towards the cathode more slowly than the electrons. This accumulation is emphasised by high interaction rate, given for example by high cosmic ray flux. This problem, called space charge, could be present at FNAL, where the ICARUS detector will be placed at shallow depths. In order to understand the influence of this effect in track reconstruction, a data sample is analysed, collected when the detector was at surface condition for a test run in Pavia. In the thesis are described the parameters used to study space charge effects in the ICARUS detector and the obtained results are illustrated. As stated before, the drift coordinate precision is derived by the electrons drifted towards the wire planes and it is affected by several factors, such as the diffusion. To evaluate the diffusion parameter, a dedicated run with different electric field values was performed collecting cosmic rays at the end of LNGS run. The analysis of these data samples is pointed out, considering the dependence of the width of the signal registered by the TPC. The ICARUS Collaboration is also involved in a long time project, called DUNE (Deep Underground Neutrino Experiment): it will be a long baseline experiment, with modular kiloton LAr-TPCs, to be built in the next 20 years. The T600 could be used as Near Detector, once provided with a magnetic field for particle momentum measurements and charged particle identification. The presence of a magnetic field introduces new parameters and possibilities for the reconstruction procedure. In this framework, an algorithm is developed, in order to discriminate between electron neutrino and electron antineutrino, considering their interaction products.