Extensive air showers’ (EAS) observables sensible to primary cosmic ray mass are a valuable asset in constraining competing astrophysical and particle physics scenarios proposed both to explaining cosmic rays features, such as their all-particle spectra, as well as their origin. These observables, however, need to be interpreted by comparison to EAS simulations, which are a source of great uncertainty. Shower simulations need to rely on a technique called thinning, an algorithm created to reduce computing time and storage requirement. In this work, we evaluate the effects of thinning over the muon production profile of an EAS simulation. For heavier particles it appears that thinned showers generate profiles with a deeper maximum, while results were not conclusive for protons and photon primaries. We investigate the thinning technique by constructing a toy model for shower simulations in which we have full control of the thinning implementation. To that end, we parameterized the energy distribution and particle production multiplicity from proton-air interactions and proton-pion interactions. However, we find that thinning effects over our model were too severe, rendering it impossible to draw further conclusions about its effects on full air showers simulations. / Observáveis sensíveis à composição de raios cósmicos primários em chuveiros atmosféricos extensos são um recurso valioso na constrição de cenários competidores em astrofísica e física de partículas, propostos tanto para explicar características dos raios cósmicos, como o espectro de energia de todas as partículas, quanto sua origem. Estes observáveis, no entanto, precisam ser interpretados por comparação a simulações de chuveiros atmosféricos, que constituem fonte de grandes incertezas. Simulações de chuveiros são dependentes de uma técnica chamada thinning, um algoritmo criado para reduzir o tempo de computação e exigências de armazenamento. Neste trabalho, nós avaliamos os efeitos do thinning sobre o perfil de produção de múons em uma simulação de chuveiro atmosférico. Para partículas mais pesadas, aparentemente, chuveiros sujeitos ao thinning geram perfis com máximos mais profundos, e para prótons e fótons nossas análises foram inconclusivas. Nós investigamos a técnica do thinning construindo um simulador de chuveiros simplificado, em que o total controle sobre a implementação do thinning é garantido. Para este fim, parametrizamos a distribuição de energia e a multiplicidade de partículas em interações de próton com o ar e de píons com o ar. Entretanto, descobrimos que o efeito do thinning sobre o nosso modelo era muito severo, tornando impossível concluir seus efeitos sobre simulações completas.

Extensive air showers’ (EAS) observables sensible to primary cosmic ray mass are a valuable asset in constraining competing astrophysical and particle physics scenarios proposed both to explaining cosmic rays features, such as their all-particle spectra, as well as their origin. These observables, however, need to be interpreted by comparison to EAS simulations, which are a source of great uncertainty. Shower simulations need to rely on a technique called thinning, an algorithm created to reduce computing time and storage requirement. In this work, we evaluate the effects of thinning over the muon production profile of an EAS simulation. For heavier particles it appears that thinned showers generate profiles with a deeper maximum, while results were not conclusive for protons and photon primaries. We investigate the thinning technique by constructing a toy model for shower simulations in which we have full control of the thinning implementation. To that end, we parameterized the energy distribution and particle production multiplicity from proton-air interactions and proton-pion interactions. However, we find that thinning effects over our model were too severe, rendering it impossible to draw further conclusions about its effects on full air showers simulations. / Observáveis sensíveis à composição de raios cósmicos primários em chuveiros atmosféricos extensos são um recurso valioso na constrição de cenários competidores em astrofísica e física de partículas, propostos tanto para explicar características dos raios cósmicos, como o espectro de energia de todas as partículas, quanto sua origem. Estes observáveis, no entanto, precisam ser interpretados por comparação a simulações de chuveiros atmosféricos, que constituem fonte de grandes incertezas. Simulações de chuveiros são dependentes de uma técnica chamada thinning, um algoritmo criado para reduzir o tempo de computação e exigências de armazenamento. Neste trabalho, nós avaliamos os efeitos do thinning sobre o perfil de produção de múons em uma simulação de chuveiro atmosférico. Para partículas mais pesadas, aparentemente, chuveiros sujeitos ao thinning geram perfis com máximos mais profundos, e para prótons e fótons nossas análises foram inconclusivas. Nós investigamos a técnica do thinning construindo um simulador de chuveiros simplificado, em que o total controle sobre a implementação do thinning é garantido. Para este fim, parametrizamos a distribuição de energia e a multiplicidade de partículas em interações de próton com o ar e de píons com o ar. Entretanto, descobrimos que o efeito do thinning sobre o nosso modelo era muito severo, tornando impossível concluir seus efeitos sobre simulações completas.

This study lays a foundation for the empirical mapping of the material production of Afrikaans fiction from 1990 to 2005. The primary research question, namely, how to map Afrikaans fiction production during this period, has been answered through both descriptive-qualitative and statistical-quantitative empirical research. In the first, contextual descriptive component, qualitative research is used to describe the context within which Afrikaans fiction production takes place. The impact of transformation shifts on the production and producer landscapes are mapped through a description of the publishing system. Within this system, book production is regarded as an institution that has inter-systemic relationships with other sub-systems, including institutional contexts (such as media, cultural, literary, educational and library sub-systems), as well as broader societal contexts (such as political, economic and technological contexts). Transformation shifts in the producer landscape (including the establishment, conglomeration, mergers, take-overs and closures of publishing houses) are described through profiling the relevant producers (including publishing houses and other kinds of producers) who contribute to this landscape. In the second, statistical empirical component, quantitative research is used to sketch the contours of Afrikaans fiction production through the construction of production and producer profiles. On a theoretical level, the study follows a sociological and institutional approach to empirical literary studies. This study has been positioned within the developing field of book and publishing studies, specifically within the parameters of the epistemology of production statistics. Itamar Even-Zohar’s poly-system theory and Pierre Bourdieu’s theory of the field of cultural production form the theoretical framework. Several methodological instruments were developed for the purpose of this study, including a new model of the publishing system, a database of production statistics (the Production Database of Afrikaans Fiction – PDAF), and two typologies of kinds of producers and fiction publications according to which both producer and production categories can be distinguished. The publishing system, the PDAF and the two typologies have been proven useful instruments for the mapping of book production. These instruments will contribute to the fields of book and publishing studies through their application to research on other production categories. The PDAF is a useful resource for measuring the growth and diversity of Afrikaans fiction production. The study concludes that Afrikaans fiction production between 1990 and 2005 was incisively influenced by transformation shifts. Publishing in this field became more challenging in that Afrikaans fiction production had to wean itself from the artificial institutional privilege and substantial state support it had enjoyed and was forced to become economically independent. By 2005, there were far fewer significant producers of Afrikaans fiction in the producer landscape than in 1990. In some production categories, fiction production has shrunk, while, in others, it has grown. Overall, the production profile of Afrikaans fiction has greatly diversified, with Afrikaans fiction appearing in a wide variety of production categories. Afrikaans fiction remains the most diverse and best-developed indigenous tradition of fiction production. The challenge for future case studies is to investigate the relationships between production patterns and specific transformation shifts in the publishing system in terms of specific production categories. / Thesis (PhD)--University of Pretoria, 2008. / Information Science / unrestricted