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  • About
  • The Global ETD Search service is a free service for researchers to find electronic theses and dissertations. This service is provided by the Networked Digital Library of Theses and Dissertations.
    Our metadata is collected from universities around the world. If you manage a university/consortium/country archive and want to be added, details can be found on the NDLTD website.
1

Lifetime measurements of excited nuclei through modern nuclear spectroscopy

January 2021 (has links)
Philosophiae Doctor - PhD / The progressive development of scintillator detectors has made it possible to perform direct electronic lifetime determination up to a few hundred nanoseconds. The 2" by 2" LaBr3:Ce detectors provide a combination of excellent time resolution and good energy resolution. Recently a fast timing array has been commissioned at iThemba LABS, Cape Town consisting of eight 2" by 2" LaBr3:Ce detectors. Test measurements using radioactive sources produced at the laboratory were conducted. Six 2" by 2" LaBr3:Ce detectors were coupled to the AFRODITE array as their rst in-beam experiment. AFRODITE consisted of eight HPGe clover detectors as well as two 3.5" x 8" LaBr3:Ce detectors. A particle telescope was used to select the desired reaction channels. The reactions of interest 45Sc(p,d)44Sc and 45Sc(p, )42Ca were carried out at a beam energy of 27 MeV. The current analysis also investigates the rare earth nucleus 150Gd which was populated through 150Sm( ,4n)150Gd at a beam energy of 48 MeV.
2

Developing a sorting code for Coulomb excitation data analysis

Mehl, Craig January 2015 (has links)
>Magister Scientiae - MSc / This thesis aims at developing a sorting code for Coulomb excitation studies at iThemba LABS. In Coulomb excitation reactions, the inelastic scattering of the projectile transfers energy to the partner nucleus (and vice-versa) through a time-dependent electromagnetic field. At energies well below the Coulomb barrier, the particles interact solely through the well known electromagnetic interaction, thereby excluding nuclear excitations from the process . The data can therefore be analyzed using a semiclassical approximation. The sorting code was used to process and analyze data acquired from the Coulomb excitation of 20Ne beams at 73 and 96 MeV, onto a 194Pt target. The detection of gamma rays was done using the AFRODITE HPGe clover detector array, which consists of nine clover detectors, in coincidence with the 20Ne particles detected with an S3 double-sided silicon detector. The new sorting code includes Doppler-correction effects, charge-sharing, energy and time conditions, kinematics and stopping powers, among others, and can be used for any particle-γ coincidence measurements at iThemba LABS. Results from other Coulomb excitation measurements at iThemba LABS will also be presented.
3

New collective structures in the Z=76 stable odd neutron nucleus, 187Os

Sithole, Makuhane Abel January 2021 (has links)
Philosophiae Doctor - PhD / Low- and medium-spin bands of 187Os have been studied using the AFRODITE array, following the 186W(4He,3n)187Os reaction at a beam energy of 37 MeV. The measurements of 􀀀 coincidences, angular distribution ratios (RAD), polarization and -intensities were performed using eleven High Purity Germanium (HPGe) clover detectors. In the current work, all the previously known bands have been signi cantly extended and ve new bands have been added to the level scheme. The observed bands are interpreted within the cranked shell model (CSM), cranked Nilsson-Strutinsky- Bogoliubov (CNSB) formalism and Quasiparticle-plus-Triaxial-Rotor (QTR) model. Systematic comparison of bands with the neighbouring isotopes has also been made. Comparison of the models with experimental data shows good agreement.
4

Determination of the Spectroscopic Quadrupole moment of the first 2+ excited state in 32S

Mavela, Lihleli January 2019 (has links)
>Magister Scientiae - MSc / In this work we have determined the spectroscopic or static quadrupole moment of the rst excited state (QS (2+1) lying at 2230.6 keV in 32S using the reorientation e ect. The Coulomb-excitation experiment at safe bombarding energies was performed at iThemba LABS's AFRODITE vault, where 32S beams at 120.3 MeV were bombarded onto a 194Pt target of 1 mg/cm2 thickness. The beam energy has been chosen such that the separation between nuclear surfaces is greater than 6.5 fm at all scattering angles, in order to avoid nuclear interactions. A double-sided CD-type S3 silicon detector, with 24 rings and 32 sectors, has been placed upstream (at backward angles) to detect the scattered particles. Gamma rays have been detected with the AFRODITE clover array. This particle-gamma coincidence experiment allows for an angular distribution and Doppler correction of the gamma rays emitted at 9% the speed of light. The cross sections (or gamma-ray integrated yields) measured as a function of scattering angle at backward angles are sensitive to second-order perturbation e ects in Coulomb excitation, i.e., diagonal matrix elements which are directly related to the spectroscopic quadrupole moment. The gamma-ray integrated yields obtained from this experiment are compared with the GOSIA simulations, yielding a new measurement of QS (2+1) = 􀀀0:10 0:7 eb, which corresponds to a prolate shape in the intrinsic frame of the nucleus. The uncertainty of this measurement is limited by statistics. This result agrees with previous measurements and con rms the zig zag of shapes at the end of the sd shell when approaching the doubly-magic nucleus 40Ca. Nonetheless, the mystery continues as a prolate shape for the rst 2+ disagrees with modern theoretical mean- eld calculations and the pairing coupling model.
5

Imagens de Afrodite: variações sobre a deusa na mélica grega arcaica / Aphrodit´s images: changes on the goddess in greek melic archaic

Faria, Giuliana Ragusa de 04 December 2008 (has links)
Centrado em dezessete fragmentos da mélica grega arcaica (final do século VII a meados do VI a.C.), este trabalho consiste no estudo da representação de Afrodite nos poetas Álcman, Alceu, Estesícoro, Íbico e Anacreonte. Desse modo, esta tese de doutoramento dá continuidade à dissertação de mestrado já publicada em livro, na qual realizei o mesmo estudo em catorze fragmentos mélicos de Safo (c. 630 - 580 a.C.). Com o recorte agora realizado, o retrato da deusa torna-se ainda mais multifacetado neste que é um dos gêneros poéticos mais importantes da literatura grega antiga, a mélica. Na busca de apreender os movimentos executados nos desenhos de Afrodite pelos cinco poetas mélicos do corpus desta tese, privilegiei a análise interpretativa dos fragmentos sem perder de vista elementos provenientes de outros gêneros poéticos, da iconografia e de registros extraliterários. Procurei, assim, superar, na medida do possível, a precariedade material mais ou menos acentuada das canções fragmentárias e dar conta de uma personagem que não pertence exclusivamente à poesia, mas também a outros gêneros artísticos, à história e à religião gregas. / Concentrated on seventeen fragments of the archaic Greek melic poetry (end of 7th to the middle of 6th centuries B.C.), this work consists in the study of Aphrodites representation in the songs of Alcman, Alcaeus, Stesichorus, Ibycus and Anacreon. Thus, the present graduation thesis gives sequence to the Masters dissertation that has already been published as a book, and in which fourteen melic fragments of Sappho (c. 630 - 580 B.C.) are studied according to the same approach. Now, in this work, the goddesss portrait is even more enhanced in its multiple aspects, despite being fragmented, and inserted in one of the most important genres of ancient Greek literature set within a specific historic period. In the effort to apprehend the movements executed in the drawings of Aphrodite by the five poets in the corpus of this thesis, I have favored the interpretative analysis of the fragments without overlooking the elements originated from other poetic genres, iconographic tradition and extra-literary records. By doing so, I have attempted to overcome, as much as possible, the precariousness of the material, somewhat more or less evident in the fragmented songs, and to understand in-depth a divine character that is not confined to poetry, but pertains to other artistic genres, as well as to Greek history and religion.
6

Imagens de Afrodite: variações sobre a deusa na mélica grega arcaica / Aphrodit´s images: changes on the goddess in greek melic archaic

Giuliana Ragusa de Faria 04 December 2008 (has links)
Centrado em dezessete fragmentos da mélica grega arcaica (final do século VII a meados do VI a.C.), este trabalho consiste no estudo da representação de Afrodite nos poetas Álcman, Alceu, Estesícoro, Íbico e Anacreonte. Desse modo, esta tese de doutoramento dá continuidade à dissertação de mestrado já publicada em livro, na qual realizei o mesmo estudo em catorze fragmentos mélicos de Safo (c. 630 - 580 a.C.). Com o recorte agora realizado, o retrato da deusa torna-se ainda mais multifacetado neste que é um dos gêneros poéticos mais importantes da literatura grega antiga, a mélica. Na busca de apreender os movimentos executados nos desenhos de Afrodite pelos cinco poetas mélicos do corpus desta tese, privilegiei a análise interpretativa dos fragmentos sem perder de vista elementos provenientes de outros gêneros poéticos, da iconografia e de registros extraliterários. Procurei, assim, superar, na medida do possível, a precariedade material mais ou menos acentuada das canções fragmentárias e dar conta de uma personagem que não pertence exclusivamente à poesia, mas também a outros gêneros artísticos, à história e à religião gregas. / Concentrated on seventeen fragments of the archaic Greek melic poetry (end of 7th to the middle of 6th centuries B.C.), this work consists in the study of Aphrodites representation in the songs of Alcman, Alcaeus, Stesichorus, Ibycus and Anacreon. Thus, the present graduation thesis gives sequence to the Masters dissertation that has already been published as a book, and in which fourteen melic fragments of Sappho (c. 630 - 580 B.C.) are studied according to the same approach. Now, in this work, the goddesss portrait is even more enhanced in its multiple aspects, despite being fragmented, and inserted in one of the most important genres of ancient Greek literature set within a specific historic period. In the effort to apprehend the movements executed in the drawings of Aphrodite by the five poets in the corpus of this thesis, I have favored the interpretative analysis of the fragments without overlooking the elements originated from other poetic genres, iconographic tradition and extra-literary records. By doing so, I have attempted to overcome, as much as possible, the precariousness of the material, somewhat more or less evident in the fragmented songs, and to understand in-depth a divine character that is not confined to poetry, but pertains to other artistic genres, as well as to Greek history and religion.
7

Search for low spin collective structures in 158Er and 159Er

Dinoko, Tshepo Samuel January 2013 (has links)
Philosophiae Doctor - PhD / Lying in a rapidly-changing transitional region between nuclei that may behave as spherical vibrators (N ≤ 88) or good rotors (N ≥ 92), the N = 90 isotones present a unique testing ground where new nuclear collective phenomena may be uncovered. As part of a general investigation of collective structures and the coupling of single-particle states to these structures, the 150Sm(12C,4nγγ) and 150Sm(13C,4nγγ) reactions at a beam energy of Elab = 65 MeV were used to study the low and medium spin structure of 158,159Er nuclei below spin 20~. The γ-γ coincidence events were detected in the nine escape-suppressed HPGe Clover detectors using the AFRODITE γ-ray spectrometer at the iThemba Laboratory for Accelerator Based Sciences. DCO ratios and γ-ray polarization measurements were used to establish the spins and parities of newly observed and confirm previously established rotational bands. The observed bands will be discussed in terms of both traditional quadrupole rotational-vibration models and recent predictions of octupole correlations in the N = 90 isotones and neighbouring nuclei. The data obtained will be compared with the spectroscopic systematics of neighbouring nuclei.
8

New Collective structures in the Z=76 stable odd neutron nucleus, 187Os

Sithole, Makuhane Abel January 2021 (has links)
Philosophiae Doctor - PhD / Low- and medium-spin bands of 187Os have been studied using the AFRODITE array, following the 186W(4He,3n)187Os reaction at a beam energy of 37 MeV. The measurements of γ − γ coincidences, angular distribution ratios (RAD), polarization and γ-intensities were performed using eleven High Purity Germanium (HPGe) clover detectors. In the current work, all the previously known bands have been significantly extended and five new bands have been added to the level scheme. The observed bands are interpreted within the cranked shell model (CSM), cranked Nilsson-StrutinskyBogoliubov (CNSB) formalism and Quasiparticle-plus-Triaxial-Rotor (QTR) model. Systematic comparison of bands with the neighbouring isotopes has also been made. Comparison of the models with experimental data shows good agreement. The configurations of some of the previously observed bands have been modified. Most importantly, the coupling of 2+ γ band to the 11/2+[615] neutron configuration is observed for the first time.
9

As deusas gregas virgens face ao poder de Afrodite / The virgin Greek goddesses vis-a-vis Aphrodite's power

Pereira, Vera Lucia Crepaldi, 1945- 14 August 2018 (has links)
Orientador: Joaquim Brasil Fontes Junior / Dissertação (mestrado) - Universidade Estadual de Campinas, Faculdade de Educação / Made available in DSpace on 2018-08-14T19:56:09Z (GMT). No. of bitstreams: 1 Pereira_VeraLuciaCrepaldi_M.pdf: 1014426 bytes, checksum: 4bf613cfdbab6c42a9ff6682500f548c (MD5) Previous issue date: 2009 / Resumo: O objetivo deste estudo, as deusas gregas virgens, Ártemis, Atena e Héstia, é demarcar a existência e a significação especial dessas deusas no mundo arcaico grego frente à posição ocupada por Afrodite, como representação do desejo. O sistema mítico prevê a questão do desejo articulada ao 'poder', conforme evidenciam as reflexões feitas a partir do corpus selecionado: as obras de Homero, de Hesíodo e os Hinos Homéricos referentes às deusas virgens e a Afrodite. A metodologia que orienta esta pesquisa segue uma linha antropológica comparativa, incluindo autores como Geertz e Detienne, com enfoque no uso e na significação da linguagem da produção escrita dos rapsodos gregos. O conceito de virgindade é direcionado pelo conceito de desejo e parece necessário que se considerem as propriedades e os atributos de Afrodite para definir as deusas gregas virgens, que fruem "de um outro modo de desejo e de poder". Esse aspecto nos faz refletir sobre uma sociedade patriarcal e as formas de independência feminina como instância de compromisso sócio-político, bem como sobre a manutenção de uma tradição herdada da grande mãe (Magna Mater) e das Amazonas. Uma possível indicação, a partir desses dados, é que o Cristianismo procurou dar continuidade a esse aspecto de gênero que promove a civilização e a organização da sociedade, através da figura da 'madre', como elemento de significação cultural. / Abstract: The aim of this study which focuses on the Virgin Greek goddesses, Artemis, Athene and Hestia, is to stress the existence and the special meaning of those goddesses in the archaic Greek world, compared with Aphrodite's position as a representative of 'desire'. The mythical system comprises the matter of desire linked to the meaning of "power", according to the evidence of reflections made from the corpus selected, Homer's and Hesiod's works and the Homeric Hymns referring to the virgin goddesses and Aphrodite. The methodology that orients this paper follows authors such as Geertz and Detienne, focusing on the use and meaning of the language in the written production of the Greek rapsodes. The concept of virginity is directed by the concept of desire, and it is necessary to consider Aphrodite's properties and attributes to define the virgin Greek goddesses who have another form of desire and power. That aspect brings up considerations on a patriarchal society and ways of feminine independence as a means of socialpolitical commitment, as well as on the maintenance of a tradition inherited from the Great Mother and the Amazons. One possible direction arising from the above facts is that Christianity tried to give sequence to this aspect of gender which promotes civilization and the organization of society, by way of the 'mater figure', as an element of cultural significance. / Mestrado / Educação, Conhecimento, Linguagem e Arte / Mestre em Educação
10

Afrodite : en kvinna av idag

Nyberg, Siv January 2005 (has links)
<p>Syftet med uppsatsen har varit att få en uppfattning om hur andra ser på Afrodite, om de beskriver henne som i myterna eller om det finns en annan bild av henne, men också att få en beskrivning av Afrodite som en kvinna av idag och vilka egenskaper hon i sådana fall har.</p><p>Empiriska data har samlats in med hjälp av kvalitativ intervju med öppna frågeställningar. Utgångspunkten har varit en bild av en staty med Afrodite, Pan och Eros och informanterna fick beskriva vad de såg och kände inför bilden. Därefter följde en frågeställning om vem Afrodite-kvinnan av idag är. Förutom bilden av statyn diskuterade informanterna Afrodite som barn och tonåring, kvinnan Afrodite, kärlek och sexualitet, yrke och makt, man och barn, utseende och skönhet.</p>

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