1,721,144 research outputs found
Time resolution of TileCal and searches for heavy metastable particles
No full textTitle: Time resolution of TileCal and searches for heavy metastable parti- cles Author: Martina Pagáčová Department: Institute of Particle and Nuclear Physics Supervisor: Doc. RNDr. Rupert Leitner, DrSc. Supervisor's e-mail address: [email protected] Abstract: In the present work, the timing of the ATLAS TileCal is stud- ied using the single hadron collision data. The time resolution and also the mean time response depend on the energy deposited in a given cell. The results are compared to the previous analysis with jets and muons. Precise time-of-flight measurement using TileCal can be used to identify the heavy long-lived particles predicted by the models of physics beyond the standard model. Their mass can be reconstructed by combining with the momentum measurement in the ATLAS inner detector. Finally, the mass resolution of an exotic particle with mass M = 600 GeV is estimated. Keywords: ATLAS experiment, TileCal, time resolution, stable massive particle
Odezva kalorimetru Tilecal na miony
Full text linkTitle: Tile Calorimeter response to muons Author: Tomas Javurek Department: Institute of Particle and Nuclear Physics Supervisor: RNDr. Tomas Davidek, Ph.D. Supervisors e-mail address: [email protected] Abstract: The aim of present work is investigation of Tile calorimeter (subde- tector of ATLAS experiment) response to muons. Muons can help to monitor spatial non-linearities in this hadronic detector. Graphs of unifromities are used for these purposes i.e. dependence of dE/dx (deposited energy per unit length) on azimuthal angle φ and polar angle θ which is represented by pseu- dorapidity η. Finally the dependence of dE/dx on energy was also studied. Keywords: TileCal, muon, uniformity, energy los
Going Beyond Counting First Authors in Author Co-citation Analysis
Full text linkThe present study examines one of the fundamental aspects of author co-citation analysis (ACA) - the way co-citation
counts are defined. Co-citation counting provides the data on which all subsequent statistical analyses and mappings
are based, and we compare ACA results based on two different types of co-citation counting - the traditional type that
only counts the first one among a cited work's authors on the one hand and a non-traditional type that takes into
account the first 5 authors of a cited work on the other hand. Results indicate that the picture produced through this non-traditional author co-citation counting contains more coherent author groups and is therefore considerably clearer. However, this picture represents fewer specialties in the research field being studied than that produced through the traditional first-author co-citation counting when the same number of top-ranked authors is selected and analyzed. Reasons for these effects are discussed
Přesné měření parametrů oscilací neutrin
No full textThe Daya Bay Reactor Neutrino Experiment, located in Southeast China, was de- signed to measure short baseline oscillation of electron antineutrinos originating from six 2.9 GWth nuclear reactors. In 2012, it discovered the nonzero value of the θ13 mixing angle and currently provides the world's most precise measurement of this neutrino os- cillation parameter. The goal of this thesis is to check the performance of the detector nonuniformity correction used by the Daya Bay experiment and then design a new im- proved version. For that purpose, the Daya Bay experiment is introduced including the procedure of the event reconstruction. Several types of signals are then studied in detail and later they are used to scrutinize the performance of the nonuniformity correction. Several issues are identified, most significantly an absence of radial dependence in the azimuthal part of the correction and inability to deal with dead photomultipliers. A new improved version of the correction that addresses these issues is then designed with the main goal to improve the precision of Daya Bay neutrino oscillation analyses, especially ongoing one which uses neutron capture on hydrogen. The impact of the new improved correction on said analyses is also assessed. 1Experiment s reaktorovými neutriny Daya Bay (The Daya Bay Reactor Neutrino Experiment) situován v jihovýchodní Číně byl navržen k měření oscilací neutrin pocháze- jících z šesti 2.9 GWth jaderných reaktorů. V roce 2012 jako první naměřil nenulovou hodnotou směšovacího úhlu θ13 a dnes je jeho měření tohoto oscilačního parametru nej- přesnější na světě. Cílem této práce je zhodnotit, jak dobře funguje korekce neuniformity detektorů používaná experimentem Daya Bay, a posléze navrhnout novou vylepšenou verzi této korekce. Za tímto účelem je prvně představen experiment Daya Bay a jeho pro- ces rekonstrukce událostí. Následně je detailně prostudováno několik typů signálů, které by mohly být použity právě ke zhodnocení stávající korekce neuniformity a tvorbě nové verze. Je identifikováno několik problémů stávající korekce, zejména to, že v azimutální části chybí závislost na vzdálenosti od osy detektoru, a dále nemožnost plně korigovat efekt způsobený nefunkčními fotonásobiči. Proto je následně navržena nová vylepšená verze korekce neuniformity, která se s těmito problémy vypořádává, a to s cílem zpřesnit měření oscilací neutrin, především v analýze, která využívá záchytu neutronů na vodíku. V závěru práce je zhodnocen vliv nové verze korekce na toto měření. 1Institute of Particle and Nuclear PhysicsÚstav částicové a jaderné fyzikyFaculty of Mathematics and PhysicsMatematicko-fyzikální fakult
Precision measurement of neutrino oscillations parameters
No full textThe Daya Bay Reactor Neutrino Experiment, located in Southeast China, was de- signed to measure short baseline oscillation of electron antineutrinos originating from six 2.9 GWth nuclear reactors. In 2012, it discovered the nonzero value of the θ13 mixing angle and currently provides the world's most precise measurement of this neutrino os- cillation parameter. The goal of this thesis is to check the performance of the detector nonuniformity correction used by the Daya Bay experiment and then design a new im- proved version. For that purpose, the Daya Bay experiment is introduced including the procedure of the event reconstruction. Several types of signals are then studied in detail and later they are used to scrutinize the performance of the nonuniformity correction. Several issues are identified, most significantly an absence of radial dependence in the azimuthal part of the correction and inability to deal with dead photomultipliers. A new improved version of the correction that addresses these issues is then designed with the main goal to improve the precision of Daya Bay neutrino oscillation analyses, especially ongoing one which uses neutron capture on hydrogen. The impact of the new improved correction on said analyses is also assessed.
Variations on the Author
Full text link“Variations on the Author” discusses two of Eduardo Coutinho’s recent films (Um Dia na Vida, from 2010, and Últimas Conversas, posthumously released in 2015) and their contribution to the general question of documentary authorship. The director’s filmography is characterized by a consistent yet self-effacing form of authorial self-inscription: Coutinho often features as an interviewer that rather than express opinions propels discourses; an interviewer that is good at listening. This mode of self-inscription characterizes him as an author who is not expressive but who is nonetheless markedly present on the screen. In Um Dia na Vida, however, Coutinho is completely absent form the image, while Últimas Conversas, on the contrary, includes a confessional prologue that moves the director from the margins to the center of his films. This article examines the ways in which these works stand out in the filmography of a director who offers new insights into the notion of cinematic authorship
Appropriate Similarity Measures for Author Cocitation Analysis
Full text linkWe provide a number of new insights into the methodological discussion about author cocitation analysis. We first argue that the use of the Pearson correlation for measuring the similarity between authors’ cocitation profiles is not very satisfactory. We then discuss what kind of similarity measures may be used as an alternative to the Pearson correlation. We consider three similarity measures in particular. One is the well-known cosine. The other two similarity measures have not been used before in the bibliometric literature. Finally, we show by means of an example that our findings have a high practical relevance.information science;Pearson correlation;cosine;similarity measure;author cocitation analysis
Časové rozlišení TileCalu a hledání těžkých dlouhožijících částic
No full textNázev práce: Časové rozlíšenie TileCalu a hl'adanie t'ažkých metastabilných častíc Autor: Martina Pagáčová Ústav: Ústav částicové a jaderné fyziky Vedoucí diplomové práce: doc. RNDr. Rupert Leitner, DrSc. E-mail vedoucího: [email protected] Abstrakt: Predložená práca sa zaoberá štúdiom časovania kalorimetru Tile- Cal experimentu ATLAS prostredníctvom dát single hadrónov. Časové rozlíšenie rovnako ako odozva stredného času závisia na deponovanej energii v danej cele. Výsledky sú porovnané s predchádzajúcimi analýzami s jetmi a miónami. Presné meranie doby letu pomocou TileCalu môže identifikovat' t'ažké dlhožijúce častice, ktoré sú predpovedané modelmi za štandardným modelom. Ich hmotu je možné zrekonštruovat' skombinovaním tohto merania s meraním hybnosti vo vnútornom detektore experimentu ATLAS. Nakoniec je vypočítaná chyba určenia hmoty exotickej častice o hmotnosti M = 600 GeV. Klíčová slova: ATLAS experiment, TileCal kalorimeter, časové rozlíšenie, stabilné t'ažké časticeTitle: Time resolution of TileCal and searches for heavy metastable parti- cles Author: Martina Pagáčová Department: Institute of Particle and Nuclear Physics Supervisor: Doc. RNDr. Rupert Leitner, DrSc. Supervisor's e-mail address: [email protected] Abstract: In the present work, the timing of the ATLAS TileCal is stud- ied using the single hadron collision data. The time resolution and also the mean time response depend on the energy deposited in a given cell. The results are compared to the previous analysis with jets and muons. Precise time-of-flight measurement using TileCal can be used to identify the heavy long-lived particles predicted by the models of physics beyond the standard model. Their mass can be reconstructed by combining with the momentum measurement in the ATLAS inner detector. Finally, the mass resolution of an exotic particle with mass M = 600 GeV is estimated. Keywords: ATLAS experiment, TileCal, time resolution, stable massive particlesÚstav částicové a jaderné fyzikyInstitute of Particle and Nuclear PhysicsMatematicko-fyzikální fakultaFaculty of Mathematics and Physic
Metody určení hierarchie hmot neutrin
Full text linkV této práci je zkoumána hierarchie hmot neutrin. Za tímto účelem jsou zmíněny možnosti původu hmot neutrin a jsou představeny oscilace neutrin v modelu tří aktivních vůní. S využitím toho je popsáno, co vlastně hierarchie hmot je a k čemu je její znalost užitečná. Následuje přehled přístupů, jak hierarchii hmot neutrin určit, včetně nástinu experimentu JUNO. Přístup založený na srovnání rozdílů kvadrátů hmot změřených v experimentech s reaktorovými antineutriny a urychlovačovými neutriny je zkoumán detailně. Závěrečnou část práce pak tvoří popis měření RPC detektoru vzhledem k tomu, že použití tohoto typu detektoru bylo zvažováno v experimentu JUNO (nakonec však byl zvolen jiný typ).In this thesis, the question of neutrino mass hierarchy is investigated. For this purpose, possibilities of neutrino mass origin are mentioned and phenomenology of neutrino oscillations within three active neutrino framework is introduced. Using that, it is described what neutrino mass hierarchy is and why it would be good to know it. After that, an overview of approaches to this problem is provided, including outline of the JUNO experiment. The approach based on comparison of mass splitting measured in experiments with reactor antineutrinos and accelerator neutrinos is investigated in great detail. The final part of this thesis is measurement of resistive plate chamber properties, as this type of detector was considered to be used in the JUNO experiment (but eventually other type will be used instead).Institute of Particle and Nuclear PhysicsÚstav částicové a jaderné fyzikyMatematicko-fyzikální fakultaFaculty of Mathematics and Physic
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