QC 20100420

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The Alpha Magnetic Spectrometer (AMS-02) is a cosmic ray detector operating aboard the International Space Station (ISS) since May 2011. The identification of cosmic ray deuterium and hydrogen particles is the main goal of this work. Using the data collected by the AMS-02 experiment between May 2011 and May 2014 we provide the measurement of the 2H to the 1H ratio between 0.7 and 7 GeV/n. Cosmic rays are mainly composed of hydrogen nuclei. No significant amount of deuterium nuclei is expected to be released from galactic sources since they are destroyed rather than formed in thermonuclear reactions inside stars. As a consequence of their production history, they are part of a class of secondary stable nuclei that provide information on the propagation of cosmic rays in the galaxy. Despite their relevance for propagation studies, very few measurements of deuterium exist above 1 GeV/n, due to the poor isotopic separation capacity of previous experiments. For this reason, the deuterium to hydrogen flux ratio is a very important measurement to be carried out using the data collected by the AMS-02 experiment. The mass and the isotopic composition of cosmic-rays nuclei can be measured by the AMS-02 experiment using measurements of the momentum (provided by the tracker) and velocity of the particles (provided by the Time-of-Flight and the RICH). This analysis is one of the first to be focused on hydrogen isotopic composition with AMS-02 data, and our results are in fair agreement with a similar and independent analysis that has been carried out within the Collaboration. / O Espectômetro Magnético Alpha (AMS-02) é um detetor de raios cósmicos operando na Estação Espacial Internacional (ISS) desde maio de 2011. O principal objetivo deste trabalho é a identificação de deutério e hidrogênio nos raios cósmicos. Usando dados coletados pelo experimento AMS-02 entre maio de 2011 e maio de 2014 foi medida a razão entre os fluxos de 2H e 1H entre 0.7 e 7 GeV/n. Raios cósmicos são compostos, principalmente, por núcleos de hidrogênio. Não é esperado que fontes galácticas de raios cósmicos liberem uma quantidade significativa de núcleos de deutério, já que eles são destruidos, em vez de formados, nas reações termonucleares no interior de estrelas. Assim, eles fazem parte de uma classe de partículas secundárias estáveis que fornecem informações acerca da propagação de raios cósmicos na galáxia. Apesar da relevância para o estudo da propagação de raios cósmicos, poucas medidas da sua quantidade acima de 1 GeV/n existem, devido à baixa capacidade de separação de isótopos de prévios experimentos. Por isso a razão entre os fluxos de deutério e hidrogênio é uma importante medida a ser feita com os dados do AMS-02. A massa, e portanto a composição isotópica dos raios cósmicos, pode ser medida pelo AMS-02 a partir das medições de momento (realizada pelo tracker) e velocidade (realizadas pelo ToF e RICH). Essa análise é uma das primeiras a focar na composição isotópica do hidrogênio com dados do AMS-02, e os resultados estão razoavelmente em acordo com análises independendes semelhantes realizadas na colaboração AMS.

The Alpha Magnetic Spectrometer (AMS-02) is a cosmic ray detector operating aboard the International Space Station (ISS) since May 2011. The identification of cosmic ray deuterium and hydrogen particles is the main goal of this work. Using the data collected by the AMS-02 experiment between May 2011 and May 2014 we provide the measurement of the 2H to the 1H ratio between 0.7 and 7 GeV/n. Cosmic rays are mainly composed of hydrogen nuclei. No significant amount of deuterium nuclei is expected to be released from galactic sources since they are destroyed rather than formed in thermonuclear reactions inside stars. As a consequence of their production history, they are part of a class of secondary stable nuclei that provide information on the propagation of cosmic rays in the galaxy. Despite their relevance for propagation studies, very few measurements of deuterium exist above 1 GeV/n, due to the poor isotopic separation capacity of previous experiments. For this reason, the deuterium to hydrogen flux ratio is a very important measurement to be carried out using the data collected by the AMS-02 experiment. The mass and the isotopic composition of cosmic-rays nuclei can be measured by the AMS-02 experiment using measurements of the momentum (provided by the tracker) and velocity of the particles (provided by the Time-of-Flight and the RICH). This analysis is one of the first to be focused on hydrogen isotopic composition with AMS-02 data, and our results are in fair agreement with a similar and independent analysis that has been carried out within the Collaboration. / O Espectômetro Magnético Alpha (AMS-02) é um detetor de raios cósmicos operando na Estação Espacial Internacional (ISS) desde maio de 2011. O principal objetivo deste trabalho é a identificação de deutério e hidrogênio nos raios cósmicos. Usando dados coletados pelo experimento AMS-02 entre maio de 2011 e maio de 2014 foi medida a razão entre os fluxos de 2H e 1H entre 0.7 e 7 GeV/n. Raios cósmicos são compostos, principalmente, por núcleos de hidrogênio. Não é esperado que fontes galácticas de raios cósmicos liberem uma quantidade significativa de núcleos de deutério, já que eles são destruidos, em vez de formados, nas reações termonucleares no interior de estrelas. Assim, eles fazem parte de uma classe de partículas secundárias estáveis que fornecem informações acerca da propagação de raios cósmicos na galáxia. Apesar da relevância para o estudo da propagação de raios cósmicos, poucas medidas da sua quantidade acima de 1 GeV/n existem, devido à baixa capacidade de separação de isótopos de prévios experimentos. Por isso a razão entre os fluxos de deutério e hidrogênio é uma importante medida a ser feita com os dados do AMS-02. A massa, e portanto a composição isotópica dos raios cósmicos, pode ser medida pelo AMS-02 a partir das medições de momento (realizada pelo tracker) e velocidade (realizadas pelo ToF e RICH). Essa análise é uma das primeiras a focar na composição isotópica do hidrogênio com dados do AMS-02, e os resultados estão razoavelmente em acordo com análises independendes semelhantes realizadas na colaboração AMS.

This work presents the measurement of the deuterium flux, and the deuterium-to-hydrogen flux ratio from 0.6 to 10 GeV/n, using data collected between May 2011 and May 2015 by the Alpha Magnetic Spectrometer (AMS-02), a cosmic ray detector operating aboard the International Space Station (ISS) since May 2011. The isotope separation is performed by combining the measurements performed by the AMS-02 sub-detectors. In particular, the mass measurement is carried out by taking advantage of the precise momentum measurement provided by the silicon tracker and by the velocity measurement provided by the Cherenkov detector. The event counting method is performed using reference spectra of simulated signal and background events, where the agreement between data and Monte Carlo has been carefully checked and eventual differences have been mitigate by means of corrections based on the comparison between the resolution of the velocity and momentum as obtained from data and simulated vents. Production mechanisms, acceleration and propagation of cosmic rays are not completely clear, therefore precise measurements of the flux and composition of these particles may help to understand these phenomena. In the conventional model, supernova remnants are the sources of cosmic rays in the GeV to TeV energy range. The so called primaries, such as 1H, 4He, e- and C are believed to be produced and accelerated at the sources, while secondaries, such as e+, 2H, 3He and B originate from the collisions of primary cosmic rays with the interstellar medium. Hence, secondaries carry information about the propagation of cosmic rays in the galaxy, and, the measurement of their flux is used to constrain the parameters of cosmic ray propagation models; in particular, studying secondary-to-primary ratios is useful as it factors out the unknown source spectrum of the progenitor. One of such commonly studied ratios is the B/C ratio, but other ratios, such as 2H/1H and 3He/4He, can be used to probe a different A/Z regime and test the universality of the propagation mechanisms. / Este trabalho apresenta a medida do fluxo de deutério e da razão deutério sobre hidrogênio nos raios cósmicos, de 0.6 até 10 GeV/n, utilizando dados coletados entre maio de 2011 e maio de 2015 pelo Espectrômetro Magnético Alfa (AMS-02), um detecto de raios cósmicos instalado na Estação Espacial Internacional desde maio de 2011. A separação dos isótopos é feita através da combinação de medidas feitas pelos subdetectores do AMS-02. Em particular, a medida da massa é feita utilizando as medidas do momento fornecidas pelo tracker de silício e a velocidade medida pelo detector Cherenkov. A contagem de eventos é feita através da utilização de espectros de referência obtidos a partir de simulações de eventos de sinal e fundo, os quais foram utilizados para checar a concordância entre dados e simulações de Monte Carlo, corrigindo eventuais diferenças através de correções baseadas em comparações das resoluções de velocidade e momento obtidas nos dados e em simulações. Mecanismos de produção, aceleração e propagação dos raios cósmicos partículas não são completamente claros, portanto medidas precisas dos fluxos e composição dessas partículas podem auxiliar na compreensão desses fenômenos. Remanescentes de supernovas são as fontes de raios cósmicos com energias entre GeV e TeV. Acredita-se que os chamados raios cósmicos primários, tais como 1H, 4He, e- e C são produzidos e acelerados nas fontes, enquanto os secundários, tais como e+, 2H, 3He e B, têm origem na colisão dos raios cósmicos primários com o meio interestelar. Portanto, os secundários carregam informação sobre a propagação dos raios cósmicos na galáxia, sendo as medidas dos seus fluxos utilizada para restringir os parâmetros de modelos de propagação de raios cósmicos; em particular, estudar a razão entre secundários e primários é útil pois remove o desconhecido espectro da fonte da espécie progenitora. Uma das razões comumente utilizadas é B/C, mas outras, tais como 2H/1H e 3He/4He podem ser utilizadas para estudar outro regime de A/Z e testar a universalidade dos mecanismos de propagação.

The existence of a Fisk-type heliospheric magnetic field (HMF) is one of the most debated questions in cosmic-ray modulation. Recently, Burger and Hitge [2004] developed a divergence-free Fisk-Parker hybrid magnetic field model to demonstrate the behaviour of cosmic rays in the heliosphere due to such a field. This approach has been refined and the properties of the consequent field are investigated. It is found that randomly directed magnetic field diffusion in and above the photosphere significantly influences the solar magnetic field both at the solar poles and near the polar coronal hole boundary. The solar cycle dependence of this field is investigated, a study which is of particular importance for studies of the long-term behaviour of cosmic rays, such as those undertaken at the SANAE base in Antarctica. The amplitudes of the 26-day recurrent cosmic-ray variations are modelled as function of both latitudinal gradient and heliolatitude and are found to agree qualitatively and in some cases quantitatively with the observational results reported by Zhang 119971 and Paizis et al. 119991. Although magnetic field data do not clearly indicate the existence of the Fisk field [see, e.g., Fursyth et al., 20021, this study supports the existence of a Fisk-type HMF. / Thesis (M.Sc. (Physics))--North-West University, Potchefstroom Campus, 2006.

Radiocarbon content in tree-rings can be an excellent proxy of the past incoming cosmic ray intensities to the Earth. Although such past cosmic ray variations have been studied by measurements of 14C contents in tree rings with ≧10 year time resolution for the Holocene (1), there are few annual 14C data. There is a little understanding about annual 14C variations in the past with the exception of a few periods including the AD774-775 annual 14C excursion (2). Here, we report the result of 14C measurements using the bristlecone pine tree rings for the period from 5490 BC to 5411 BC with 1-2 year resolution, and a finding of an extraordinarily large 14C increase (20‰) from 5481 BC to 5471 BC (the 5480 BC event). The 14C increase rate of this event is much larger than that of the normal Grand Solar Minima. We propose the possible causes of this event are a special phase of grand solar minimum, or a combination of successive solar proton events and a normal grand solar minimum.

Abstract The thesis is focused on the reconstruction of long-term cosmic ray variability using proxy data. The 11-year solar cycle in production/deposition rates of cosmogenic nuclides ¹⁰Be and ¹⁴C has been modelled for the conditions of grand minima and maxima of solar activity (namely, Maunder Minimum and Grand Modern Maximum). The result shows that contrary to the observed strongly suppressed amplitude of the solar cycle in sunspots during Maunder Minimum relatively to Grand Modern Maximum, the cosmic ray proxies have the comparable amplitudes during the two periods. This phenomenon is caused by the nonlinear relation between solar activity and production of cosmogenic nuclides. In addition to well-established proxies of cosmic rays, nitrate in polar ice has been recently proposed as a new proxy for the long-term variability of galactic cosmic rays. The thesis contains two tests of its applicability for this purpose with TALDICE and EPICA-Dome C ice core data from Central Antarctica. The results support the proposal for the multimillennial time scales. Lunar samples acquired during the Apollo missions are important data for estimating the averaged energy spectra of galactic cosmic rays and solar energetic particles at the Earth’s orbit. The development in modelling of the interaction between energetic particles and matter makes it necessary to revise the earlier results. Because of that, new production rates of ¹⁰Be and ¹⁴C in lunar samples by galactic cosmic rays and solar energetic particles have been computed. New accurate cosmic ray reconstructions from natural archives containing cosmogenic nuclides use sophisticated climatic models requiring yield functions of the nuclides with high altitude resolution. These functions have been computed for ⁷Be, ¹⁰Be, ¹⁴C, ²²Na, and ³⁶Cl in the Earth’s atmosphere. Overall, the major purpose of the studies presented in the thesis is to increase the quality of reconstructions of the long-term cosmic ray variability for better understanding of the solar and heliospheric physics. / Original papers The original publications are not included in the electronic version of the dissertation. Poluianov, S. V., Usoskin, I. G., & Kovaltsov, G. A. (2014). Cosmogenic Isotope Variability During the Maunder Minimum: Normal 11-year Cycles Are Expected. Solar Physics, 289(12), 4701–4709. https://doi.org/10.1007/s11207-014-0587-6 Poluianov, S., Traversi, R., & Usoskin, I. (2014). Cosmogenic production and climate contributions to nitrate record in the TALDICE Antarctic ice core. Journal of Atmospheric and Solar-Terrestrial Physics, 121, 50–58. https://doi.org/10.1016/j.jastp.2014.09.011 Poluianov, S., Artamonov, A., Kovaltsov, G., & Usoskin, I. (2015). Energetic particles in lunar rocks: Production of cosmogenic isotopes. Proceedings of Science, 30-July-2015, art. no. 051 . Traversi, R., Becagli, S., Poluianov, S., Severi, M., Solanki, S. K., Usoskin, I. G., & Udisti, R. (2016). The Laschamp geomagnetic excursion featured in nitrate record from EPICA-Dome C ice core. Scientific Reports, 6(1). https://doi.org/10.1038/srep20235 Poluianov, S. V., Kovaltsov, G. A., Mishev, A. L., & Usoskin, I. G. (2016). Production of cosmogenic isotopes 7Be, 10Be, 14C, 22Na, and 36Cl in the atmosphere: Altitudinal profiles of yield functions. Journal of Geophysical Research: Atmospheres, 121(13), 8125–8136. https://doi.org/10.1002/2016jd025034

Bibliography: p. 157-167. / ii, 180 p. : ill. ; 30 cm. / Title page, contents and abstract only. The complete thesis in print form is available from the University Library. / Presents results of searches made with the Buckland Park and SUGAR data sets for Ultra High Energy gamma-ray emission from certain astrophysical objects. / Thesis (Ph.D.)--University of Adelaide, Dept. of Physics and Mathematical Physics, 1994

Thesis (M.Sc. (Physics))--North-West University, Potchefstroom Campus, 2008.