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The vastness of the universe (i.e., cosmic vastness) can evoke polarizing existential experiences. Some people report elevating experience, such as awe, elevation, and self-transcendence, whereas others experience existential distress, such as feeling insignificant, powerless, and vulnerable. The purpose of this thesis was to examine three main research questions: 1) How do people react to the vastness of the universe? 2) What is it about witnessing cosmic vastness (i.e., mediators) that elicits polarizing experiences? 3) What is it about a person and their individual traits (i.e., moderators) that causes people to react differently? Two studies were conducted to investigate these questions. Study 1 was a primarily qualitative in-lab study where participants watched one of two videos depicting the vastness of the universe. Participants answered open-ended questions about their experiences, along with some preliminary quantitative questions, and these responses were used to inform what experiences were measured in Study 2. Study 2 was an online quantitative experiment in which a cosmic vastness video was compared to two other videos (Earth nature vastness and neutral control). Study 2 also examined mediators and moderators that explain the relationship between witnessing cosmic vastness and both elevating experience and existential distress. Both studies found that facing cosmic vastness can elicit positive and negative experiences. Study 1 found that most participants reported positive (93%) and negative experiences (68%), including a substantial degree of elevating experience (58%) and existential distress (46%). Study 1 also found several cognitive responses that were good candidates to be mediators in Study 2, including small self, need for accommodation, experience of the unknown, and existential contemplation. Study 2 showed that a cosmic vastness condition elicited greater levels of elevating experience than the neutral control condition and greater levels of existential distress than both the neutral control and Earth nature vastness conditions. Results from both studies also found significant polarization in participants responses, such that half of the participants reported more elevating experience, and half of participants reported more existential distress. Mediation analyses in Study 2 demonstrated that the four cognitive responses each mediated the positive relationship between witnessing cosmic vastness and both elevating experience and existential distress. Furthermore, moderation analyses revealed that self-esteem moderated the relationship between witnessing cosmic vastness and elevating experience, whereas both self-esteem and meaning in life moderated the relationship between cosmic vastness and existential distress. This research provided unique contributions to literature on how people react to vast stimuli that has the capacity to be existentially threatening. Further implications of these results are discussed, as well as how these results may generalize to other areas of research.

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京都大学 / 新制・課程博士 / 博士(理学) / 甲第23706号 / 理博第4796号 / 新制||理||1686(附属図書館) / 京都大学大学院理学研究科物理学・宇宙物理学専攻 / (主査)講師 LEE Shiu Hang, 教授 嶺重 慎, 准教授 前田 啓一 / 学位規則第4条第1項該当 / Doctor of Science / Kyoto University / DFAM

Cette thèse est dédiée à la création d'un nouvel outil pour la mesure directionnelle du flux muonique basé sur une chambre de projection temporelle fine avec un plan de lecture Micromegas, afin d’obtenir un détecteur compact avec une résolution angulaire compatible avec les applications d’imagerie ou de monitoring en génie civil et géophysique. La principale motivation est de développer un détecteur capable de combler le vide technologique pour les applications ayant des contraintes d’encombrement et de transportabilité. Cette thèse fournit une revue des différentes technologies de détection de muons existantes et de leurs divers domaines d’application. Deux techniques de mesure de muons sont présentées : la muographie par transmission ou par diffusion. La muographie par transmission, mieux adaptée aux grandes cibles, est basée sur l'atténuation du flux naturel de muons cosmiques due à l'opacité des matériaux traversés. Cette technique passive et non-destructive fournit des informations originales qui pourront être intégrées dans une démarche d’imagerie. Le manuscrit présente la méthodologie utilisée pour la caractérisation du flux incident de muons à la fois en surface et dans des conditions souterraines. Une description détaillée des processus physiques déclenchés par le passage d'un muon à travers le détecteur est fournie. Les résultats des simulations des processus de formation du signal sont présentés et commentés pour justifier les choix du design des composants clés afin de répondre aux exigences de performance quant à résolutions temporelle, spatiale et angulaire. L'influence des paramètres opérationnels ou externes tels que le gain, la température ou la présence de contaminants est également traitée. La thèse étudie en détail les principales phases de conception et d'assemblage du détecteur MUST2, incluant (i) le design du plan de lecture Micromegas, (ii) le choix du gaz, (iii) le design d'un élément homogénéisateur de champ électrique (iv) le choix de l'instrumentation électronique et du signal de déclenchement associé au passage du muon, et (v) la création d'un système auxiliaire de gestion du gaz. La polyvalence du détecteur MUST2 a été prouvée avec l'utilisation réussie de différentes options de déclenchement et d’acquisition. Les données sont obtenues au travers d’un logiciel développé pour le système d’acquisition modulaire du CERN SRS, puis analysées avec un algorithme de reconstruction de la trajectoire, qui récupère le temps de passage, la position 2D, les angles zénith et azimut des muons qui traversent le détecteur. Les caractéristiques, les performances et les limites de la chaîne d'acquisition de données sont présentées et évaluées. Une série de directives visant à améliorer l’efficacité de la chaîne d'acquisition est proposée. Une série de tests de caractérisation a été effectuée dans différents environnements : faisceau contrôlé de muons, ciel ouvert, au fond d'une vallée et dans des conditions souterraines. Ces tests ont contribué à une meilleure compréhension des performances du détecteur et ont permis de régler ses paramètres opérationnels. Malgré les faibles statistiques des tests, les flux mesurés montrent une bonne corrélation avec les environnements ciblés. Une campagne de mesures en conditions réelles a été menée sur le barrage de Saint-Saturnin-les-Apt (Vaucluse). Les résultats expérimentaux obtenus, sont conformes aux valeurs anticipées par le modèle numérique, la transportabilité sur le terrain et la capacité à effectuer des mesures hors laboratoire à long terme ont été démontrées. En revanche, l’impact de la température externe sur l’acquisition des données devra être compensée pour obtenir une acquisition stable permettant de surveiller l’évolution temporelle du flux de muons. En conclusion, les bons résultats obtenus lors de ces tests permettent de valider la caméra MUST2 à des fins de muographie en transmission. / This thesis is dedicated towards the creation of a new direction-sensitive tool for muon flux measurement based on a thin time projection chamber with a Micromegas readout, to achieve a compact detector with an angular resolution compatible with civil engineering and geophysics imagery and monitoring applications. The main motivation is to develop a detector capable to fill the technological gap for applications with compactness and transportability constraints. The dissertation provides a review of the different existing muon detection technologies and their diverse fields of application. Two muon imaging techniques are introduced: transmission and scattering muography. Transmission muography, more suitable for big targets, is based on the attenuation of the natural-occurring cosmic-muon flux due to the opacity of the material they traverse. This non-destructive, passive technique provides original information that can be used for imaging purposes. The work covers the methodology used towards the characterization of the incidental muon flux both on the surface and in underground conditions. A detailed description of the physical processes triggered by the passage of a muon through the detector is provided. Results of the simulations of the signal formation processes are presented and discussed to justify the design choices of the key components so as to meet performance requirements in term of temporal, spatial and angular resolution. The influence of operational or external parameters such as the gain, temperature or presence of contaminants is covered as well. The thesis describes in detail the principal phases of design and assembly of the MUST2 detector, including: (i) the design of the Micromegas readout layout, (ii) the choice of gas, (iii) the conception of an electric field homogenizer, (iv) the choice of the electronics instrumentation and its trigger signal, and (v) the creation of an auxiliary system to manage the gas. The versatility of MUST2 has been proved with the successful use of different trigger options and electronics. The data is acquired by means of software developed for the CERN’s Scalable Readout System electronics and subsequently analyzed with a muon trajectory reconstruction algorithm, which retrieves the: time of passage, 2D position, zenith and azimuth angles of the muons traversing the detector. The characteristics, performance and limitations of the data acquisition chain are presented and evaluated, a series of guidelines towards the improvement of its efficiency of are provided. A series of characterization tests has been carried out in different environments: controlled muon beam, open sky, at the bottom of a valley and in underground conditions. These tests have enabled a better understanding of the performance of the detector and allowed to tune up its operational parameters. Despite the weak statistics of the test runs, the measured muon flux has shown a good correlation with the surrounding target volumes. A campaign of measurements in real field conditions has been carried out at the Saint-Saturnin-les-Apt (Vaucluse, France) dam. The experimental results obtained are in consonance with the values anticipated by the digital model, the field transportability and the capability to perform long-term out-of-lab measurements have been demonstrated. On the downside, the impact of the external temperature on the data acquisition should be balanced out to get a steady acquisition and monitor the temporal evolution of the muon flux. In conclusion, the successful proof-of-concept trial allows to validate the MUST2 camera for transmission muography purposes.

Orientador: José Augusto Chinellato / Dissertação (mestrado) - Universidade Estadual de Campinas, Instituto de Física Gleb Wataghin / Made available in DSpace on 2018-09-02T17:59:22Z (GMT). No. of bitstreams: 1 Kuno_YugoMafra_M.pdf: 3634635 bytes, checksum: afd1f210608c9cb926532d441cade068 (MD5) Previous issue date: 2017 / Resumo: O fluxo de raios cósmicos de ultra-alta energia (superiores a 10^18 eV) que chega ao topo da atmosfera é baixo, tal que torna-se necessário estudar em detalhes os chuveiros atmosféricos extensos de modo a se determinar a composição e a energia da partícula primária. Dispõe-se de algoritmos que simulam processos de QED e QCD, e descrevem a difusão das partículas na atmosfera, fornecendo o estado (x, p, id, t) de cada uma. Entretanto, é também necessário parametrizar as funções que descrevem sua distribuição ao longo da cascata atmosférica. O método da entropia máxima (MEM) permite que se parametrize a distribuição de partículas em função dos momentos estatísticos esses perfis, que são menos afetados pelo ruído. A maximização da entropia também permite que a distribuição seja inferida minimizando o enviesamento que ocorre, por exemplo, no ajuste de curvas tradicionalmente realizado. No presente trabalho foi estudada aplicação do MEM na análise do perfil longitudinal das componentes eletrônica e muônica geradas por simulação no CORSIKA, já conhecendo as características da partícula primária, de forma a avaliar os benefícios dessa metodologia no estudo de chuveiros atmosféricos / Abstract: The flux of ultra-high energy cosmic rays (above 10^18 eV) that reach the upper atmosphere is low, so that it is necessary to thoroughly study air showers in order to determine the composition and energy of the primary particle. There are algorithms that simulate QED and QCD processes, and track the particle diffusion in the atmosphere, providing the state (x, p, id, t) of each one. Still, it is also necessary to parameterize the functions that describe its distribution throughout the atmospheric cascade. The maximum entropy method (MEM) allows the parameterization of the particle distribution with the statistical moments as variables, which are less affected by noise. The maximum entropy also allows the inference of the distribution minimizing the bias, which is high in inference processes such as the traditional curve fitting. The application of MEM in the analysis of the longitudinal profile of the electronic and muonic components generated by simulation with CORSIKA was the object of study in this research work, having as a prior the characteristics of the primary particle, in order to evaluate the benefits of the method in the study of air showers / Mestrado / Física / Mestre em Física / CAPES