京都大学 / 新制・課程博士 / 博士(理学) / 甲第23699号 / 理博第4789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)教授 永江 知文, 准教授 銭廣 十三, 教授 中家 剛 / 学位規則第4条第1項該当 / Doctor of Science / Kyoto University / DGAM

In this thesis, two studies of the diffractive phenomena in the electron proton collisions with the H1 detector at HERA are presented.<p>The first is the study of the inclusive elastic diffractive events $ep \ / Doctorat en Sciences / info:eu-repo/semantics/nonPublished

No description available.

No description available.

A análise da Interferência Coulombiana-Nuclear (ICN) foi aplicada à distribuição angular experimental do espalhamento inelástico de 6Li de 28,0 MeV em 76Ge, na excitação do estado 2_1^+. Os dados foram adquiridos no sistema Pelletron-Espectrógrafo Magnético Enge do LAFN do IFUSP. Na detecção dos íons emergentes, no plano focal do imã, foi utilizado um detector sensível à posição (PSD) de barreira de superfície (área de detecção de 47 × 8 mm^2 e espessura útil de 500 m). No presente trabalho foi introduzida a técnica de processamento digital de pulsos (PDP) no sistema de aquisição. Foram medidos espectros associados a vinte e seis ângulos de espalhamento na região angular de interesse: 10^o_Lab 55^o. A análise foi realizada na aproximação de Born com ondas distorcidas (DWBA) utilizando o potencial nuclear de transição descrito pelo modelo do potencial óptico deformado (DOMP) e parâmetros ópticos globais. O ajuste das previsões sobre a distribuição angular experimental foi realizado pela minimização do ^2 através do método iterativo de Gauss. O ajuste permitiu a extração dos parâmetros correlacionados: _2^N, comprimento de deformação nuclear e C_2=(_2^C)(_2^N ), razão entre os comprimentos de deformação de carga e nuclear. Os valores dos parâmetros correlacionados obtidos neste trabalho foram C_2=1,101(20) e _2^N=1,08(21) fm. Testes estatísticos através da simulação de Monte Carlo de 5000 novos conjuntos de dados comprovaram a qualidade do método empregado no ajuste dos parâmetros correlacionados. A metodologia aplicada na análise da ICN, permitiu a extração da razão (B(E2))B(IS2) ,que é proporcional ao quadrado de C_2, com boa precisão devido ao cancelamento da incerteza no fator de escala, das seções de choque absolutas. Os resultados obtidos no presente trabalho são inéditos e permitiram análise da evolução da coletividade ao longo da cadeia de isótopos pares de germânio, em conjunto com os valores obtidos nos isótopos 70,72,74Ge estudados previamente. Os resultados ao longo da cadeia indicaram que, apesar de uma leve predominância da contribuição dos prótons em relação aos nêutrons na excitação dos primeiros estados quadrupolares dos 70,72,76Ge, a contribuição dos nêutrons é consideravelmente maior para o 74Ge. Este aumento sugere forte mistura de configurações na descrição do estado fundamental deste isótopo. / The inelastic scattering of 28,0 MeV 6Li on 76Ge in the excitation of the 2_1^+ state, has been studied with the Coulomb-Nuclear Interference (CNI) analysis. The data were measured at the Pelletron-Enge-Spectrograph facility at LAFN-IFUSP. A solid-state position sensitive silicon detector (PSD) (500 m thickness and 47 × 8 mm^2 area) was used to measure the data at the spectrometer focal plane. Digital pulse processing (DPP) was implemented in the acquisition system. Twenty-six spectra were measured at carefully chosen scattering angles in the range of 10^o_Lab 55^o to obtain an angular distribution. The analysis was performed with the Distorted Wave Born Approximation (DWBA) and applied for the nuclear transition potential, the Deformed Optical Potential Model (DOMP), under well-established global optical parameters. The fit of the predicted cross sections to the experimental data through ^2 minimization, using the iterative method of Gauss, allowed for the extraction of the correlated parameters, _2^N, the mass deformation length, and C_2=(_2^C)(_2^N ), the ratio between charge and mass deformation lengths. The correlated parameters obtained in the present work were C_2=1,101(20) and _2^N=1,08(21) fm. Statistical tests, through a Monte Carlo simulation of 5000 new data sets, validated the method employed in the correlated parameters fit. The methodology applied for the CNI analysis allowed the extraction of ratio(B(EL))(B(ISL)), which is proportional to the square of C_2, with a good precision due to the scale uncertainties cancellation of the absolute cross sections. The values of B(IS2) and of the ratios (B(E2))(B(IS2)) obtained in the present work have not been reported before and allow the study of the evolution of the collectivity throughout the even-A germanium chain together with former results obtained for the 70,72,74Ge isotopes. The results along the chain indicate that although the protons relative to the neutrons reveal a small predominant contribution in 70,72,76Ge to the first quadrupole excitation, the neutron role is strongly enhanced in 74Ge. This behaviour suggests a strong mixing configuration in the 74Ge ground state description

Medidas em coincidência gamma-partícula da reação 7Li+120Sn foram realizadas na faixa de energia de 2.6 a 3.9 MeV por nucleon. Além do canal inelástico, foram observados os canais de pick-up de próton e stripping de um e dois nêutrons, sendo que, para o último caso, cálculos teóricos de DWBA e CRC comparados com o canal elástico demonstram que esta transferência ocorre de maneira sequencial (two-step) e não direta. Este trabalho consolida a existência de canais já anteriormente observados (pick-up de próton e stripping de um nêutron) além de observar pela primeira vez a existência do canal de strippinp de dois nêutrons, no entanto, ele tem um caráter pioneiro pois é o primeiro a medir distribuições angulares de todos esses canais. Tanto o pick-up de próton quanto o stripping de dois nêutrons tiveram de levar em conta na análise cálculos de Monte Carlo que simulassem o efeito da quebra dos projéteis 8Be e 5Li, respectivamente. Fatores espectroscópicos para alguns estados desses canais foram obtidos e são condizentes com os valores esperados considerando o modelo de single particle e a indistinguibilidade de partículas nos casos dos núcleos 119In e 122Sn. Por outro lado, são muito pequenos (ordem de 10e-2) para estados do 121Sn, fato esse gerado pela provável falta de acoplamento de mais canais de reação que reduzem o fluxo da transferência de nêutron. Foram observados também núcleos gerados a partir da transferência seguida de emissão de partículas. / $\\gamma$-particle coincidence measurements of the $^7$Li$+^{120}$Sn reaction were made in the $2.6$ to $3.9$ MeV/nucleon energy range. Besides the inelastic channel, the proton {\\it pick-up} and one/two neutron {\\it stripping} were observed, whereas, for the last case, DWBA and CRC calculations were compared to experimental elastic scattering data and demonstrated that this transfer occurs in a sequential ({\\it two-step}) rather than a direct way. This work consolidates the existence of some channels that have already been observed (proton {\\it pick-up} and neutron {\\it stripping}) and also observes for the first time the existence of the two neutron {\\it stripping} channel, however, it still retains its pioneering as it is the first one to measure the angular distributions for all these channels. The proton {\\it pick-up} and the two neutron {\\it stripping} channels had to take into account in their analysis Monte Carlo calculations to simulate the projectile breaking effect ($^8$Be and $^5$Li, respectively). Spectroscopic factors for some states of these channels were found and are consistent with the expected values considering the {\\it single particle} model and the particle indistinguishability for the $^{119}$In and $^{122}$Sn cases, however, these factors are too small (magnitude order of $10^{-2}$) for the $^{121}$Sn case. This was generated most likely by the lack of coupling of some of the reaction channels that would reduce the one neutron transfer flux. Nuclei generated by the transfer followed by particle emission were also observed.

La thermoélectricité est un phénomène physique permettant la conversion directe de l’énergie thermique en énergie électrique, ou inversement. Cependant l’augmentation du rendement des modules thermoélectriques passe par un défi de taille : optimiser les propriétés électroniques du matériau pour obtenir un coefficient Seebeck élevé et une résistivité électrique faible, tout en minimisant la conductivité thermique. Une des voies d'optimisation consiste à réduire la dimensionnalité des matériaux afin de diminuer la contribution des phonons dans le transport thermique. Les matériaux siliciures sont prometteurs en raison de leur faible toxicité et coût. Parmi eux, le disiliciure de chrome, CrSi2, possède des propriétés de transport électronique intéressantes, mais ses performances sont limitées par une conductivité thermique trop élevée. L’objectif de cette thèse est d’étudier les propriétés thermoélectriques de ce composé sous différentes formes, monocristal, couche mince et nanofil. Dans ce but, le disiliciure de chrome a été élaboré sous formes de monocristal par la méthode Bridgman, de couche mince par pulvérisation cathodique, et de nanofil par dépôt chimique en phase vapeur. Ces différentes techniques d'élaboration ont été associées à des techniques de caractérisation spécifiques à chacune de ces formes afin d'étudier la relation entre les propriétés physiques et la microstructure du matériau. En couplant des modèles théoriques aux mesures thermoélectriques, les mécanismes de transport électronique et thermique ont été mis en évidence. L’étude de dynamique du réseau a été complétée par la première mesure de diffusion inélastique des neutrons sur monocristal et sur poudre nanométrique de CrSi2. Dans le cas des couches minces, l'effet de l'état de cristallinité et de l'épaisseur a été étudié. Enfin, dans le cas des nanofils, un microdispositif de mesure des propriétés thermoélectriques sur nanofil isolé a été conçu. L’ensemble des résultats présentés ouvre des perspectives intéressantes pour aborder l’amélioration des propriétés thermoélectriques de CrSi2. / Thermoelectricity is a physical effect related to the direct conversion between thermal and electrical energy. To improve the thermoelectric efficiency, the electronic properties of the materials must be optimized to get a large Seebeck coefficient and a low electrical resistivity while lowering the thermal conductivity. One of the optimization ways is to reduce the dimensionality of the materials to decrease the phonon contribution to the thermal conductivity. Silicides are promising materials because of their low toxicity and cost. Among them, chromium disilicide, CrSi2, shows interesting electronic transport properties, but a too high thermal conductivity, limiting its performance. The objective of this thesis is to study the thermoelectric properties of this compound with various forms, single crystal, thin film and nanowire.For this purpose, the chromium disilicide was elaborated in the forms of single crystal by the Bridgman method, thin film by sputtering, and nanowires by chemical vapor deposition. These elaboration routes have been associated with characterization techniques specific to each form in order to study the relationship between the physical properties and the microstructure of the material. By coupling theoretical models with thermoelectric measurements, the mechanisms of electronic and thermal transports have been determined. The vibrational study was completed by the first inelastic neutron scattering measurement on CrSi2 single crystal and nano-powder. In the case of thin films, the effect of the crystallinity state and the thickness has been studied. Finally, in the case of nanowires, a micro-device has been designed to measure the properties of a single nanowire. The presented results open interesting perspectives to improve the thermoelectric properties of CrSi2.

What constitutes the spin of the nucleon? The answer to this question is still not completely understood. Although we know the longitudinal quark spin content very well, the data on the transverse quark spin content of the nucleon is still very sparse. Semi-inclusive Deep Inelastic Scattering (SIDIS) using transversely polarized targets provide crucial information on this aspect. The data that is currently available was taken with proton and deuteron targets. The E06-010 experiment was performed at Jefferson Lab in Hall-A to measure the single spin asymmetries in the SIDIS reaction n↑(e,éπ±/K±)X using transversely polarized 3He target. The experiment used the continuous electron beam provided by the CEBAF accelerator with a beam energy of 5.9 GeV. Hadrons were detected in a high-resolution spectrometer in coincidence with the scattered electrons detected by the BigBite spectrometer. The kinematic coverage focuses on the valence quark region, x = 0.19 to 0.34, at Q2 = 1.77 to 2.73 (GeV/c)2. This is the first measurement on a neutron target. The data from this experiment, when combined with the world data on the proton and the deuteron, will provide constraints on the transversity and Sivers distribution functions on both the u and d-quarks in the valence region. In this work we report on the single spin asymmetries in the SIDIS n↑(e,éπ+)X reaction.

We develop the theory of parton distributions f(_a)(π, k(^t2), μ(^2), unintegrated with respect to transverse momentum k(_t), from a phenomenological standpoint. In particular, we demonstrate a convenient approximation in which the unintegrated functions are obtained by explicitly performing the last step of parton evolution in perturbative QCD, with single-scale functions a(π, Q(^2) as input. Results are presented in the context of DGLAP and combined BFKL-DGLAP evolution, but with angular ordering imposed in the last step of the evolution. We illustrate the application of these unintegrated distributions to predict cross sections for physical processes at lepton-hadron and hadron-hadron colliders. The use of partons with incoming transverse momentum, based on k(_t)-factorisation, is intended to replace phenomenological "smearing" in the perturbative region k(_t) > k(_o) (k(_o) ≈ 1 GeV), and enables the full kinematics of a process to be included even at leading order. We apply our framework to deep inelastic scattering and the fitting of F(_2)(π, Q(^2), to the transverse momentum spectra of prompt photons in hadroproduction and in photoproduction, and to the topical problem of bb production at HERA. Finally, we address the issue of parton-parton recombination (shadowing) at very low values of π, building on recent work by Kovchegov and others to make predictions for the likely magnitude of shadowing effects at the LHC.

No description available.