Orientador: Kotaro Sawayanagi / Dissertação (mestrado) - Universidade Estadual de Campinas, Instituto de Fisica Gleb Wataghin / Made available in DSpace on 2018-07-14T09:50:43Z (GMT). No. of bitstreams: 1 Fauth_AndersonCampos_M.pdf: 1371288 bytes, checksum: 06e1353fb3e94790d264614367376eda (MD5) Previous issue date: 1986 / Resumo:É obtida a distribuição de momento transversal dos pions neutros de 32 C-jatos Mirins com SEg > 20 TeV através de dois métodos de acoplamento 2g ® pº. Estes resultados independem de qualquer modelo de produção de partículas. Realiza-se uma simulação, pelo método de Monte Carlo, da produção de pions e avalia-se que os dois métodos conseguem obter em média aproximadamente 50% de acoplamentos corretos. Constata-se que a forma da distribuição dos pions neutros depende fracamente da porcentagem de acoplamentos corretos. A distribuição de momento transversal dos pions neutros dos eventos Mirins é obtida por uma terceira maneira, a qual é completamente independente das duas primeiras, que consiste da composição entre uma solução analítica e o método de Monte Carlo. Os resultados dos três métodos são consistentes entre si / Abstract: Not informed. / Mestrado / Física / Mestre em Física

Three types of rare radiative meson decays are studied. The first type is the weak kaon decay [special characters omitted] The interest here is this decay's sensitivity to the loop-level and hence quantum structure of the standard model. Both short-distance and long-distance effects are considered, as well as possible contributions from horizontal gauge bosons. The second decay type studied is electromagnetic η decays into neutral pions, specifically [special characters omitted] and [special characters omitted] The main interest here is possible signals for electromagnetic charge-conjugation violation. The modelling method used is vector meson dominance. The third type studied is electromagnetic η decays into charged pions, specifically [special characters omitted] and [special characters omitted] The interest here is chiral perturbation theories that incorporate vector mesons. / Graduate

No description available.

This thesis discusses the pion double charge exchange (DCX) reaction ¹⁸0(π⁺,π⁻)¹⁸Ne at 50 MeV. Transitions to the ground state of ¹⁸Ne, which is the double-isobaric-analogue state (DIAS) of ¹⁸0, have been isolated. The differential cross sections for DIAS transitions have been measured at 6 scattering angles from 18.2° to 122.6°. The experiment was performed at TRIUMF in December 1984 using the QQD low energy pion spectrometer [26]. The differential cross section angular distribution is forward peaked, falling from 4.7±0.5 μb/sr at 0° (by extrapolation) to 0.61±0.11 μb/sr at 122.6°. The total (angle-integrated) cross section is 16.2±1.2 μb. DCX measurements are expected to give information on nuclear structure that is hard to obtain by other reactions. This information includes short range correlations and neutron-proton density differences. However, before such information can be extracted the mechanism for DCX must be understood. The aim of this experiment was to provide more data to test the various theories of the DCX mechanisms. The implications of the results for several theories of DCX are discussed. The forward peaking of DCX angular distributions at 50 MeV was unexpected. 50 MeV single charge exchange (SCX) angular distributions are forward dipped e.g. [14], a result of the cancellation of the 0° s and p wave scattering amplitudes for the reaction p(π⁺,π⁰)n. Early DCX calculations were based on the simple sequential mechanism. This assumes DCX proceeds via 2 successive SCX reactions, with the isobaric analogue as the intermediate state. These calculations predicted forward dipping and small cross sections for DCX [13,15]. The data shows this mechanism is an over-simplification. The standard model for π-nucleus scattering is the optical potential. Johnson and Siciliano are developimg a potential with which to calculate elastic, SCX and DCX cross sections [48,38,22]. They include second, order terms, important in DCX because the reaction must involve scattering by at least two nucleons. By using a general form for the optical potential they include contributions from excited intermediate states. Miller has suggested the forward peaking is due to the presence of six-quark clusters in the nucleus [16]. His model reproduces the data for 50 MeV DCX on ¹⁸0 and ¹⁴C at forward angles. Karapiperis and Kobayashi have used the Δ-hole model to calculate elastic, SCX and DCX cross sections [19]. They obtain fair agreement with data for a range of nuclei and energies. Jennings et al. [22] are developing a model in which short range correlations produce the forward peaking. This work is at an early stage. More DCX measurements are needed to choose between the various models. Measurements at 50 MeV are particularly valuable because the simple sequential mechanism is small, allowing other mechanisms to be observed. Further data such as excitation functions below 80 MeV and angular distributions for other nuclei are needed. / Science, Faculty of / Physics and Astronomy, Department of / Graduate

The polarized and unpolarized differential cross-sections and the analyzing power angular distributions of the pp→π⁺ d reaction have been measured to a statistical precision of better than one percent over several incident proton beam energies between 350 and 500 MeV for center-of-mass angles from 20° to 150°. The unpolarized differential cross-sections were measured at 350, 375, 425, and 475 MeV with unpolarized incident beams. The polarized differential cross-sections and analyzing powers were measured at 375, 450, and 498 MeV using polarized incident beams. Angular distributions of the unpolarized and polarized differential cross-sections are expanded into Legendre and Associated Legendre polynomial series respectively, and the ai°° and biⁿ° expansion coefficients fit to the respective measurements. The resulting coefficients are compared with existing data and recent theoretical predictions. The observation of significant non-zero a₆°° coefficent is interpreted as indication of a significant contribution from the ¹G₄ N-N partial wave channel at energies as low as 498 MeV. / Science, Faculty of / Physics and Astronomy, Department of / Graduate

An experimental study of the pion-induced fission, ⁶Li (π⁺, ³He) ³He, has been performed at TRIUMF using 60, 80 and 100 MeV pions. Angular distributions for this reaction at these energies, along with the energy dependence at fixed center-of-mass angles, are presented. Two theoretical models of this reaction predict widely differing angular and energy dependences. Prior to this experiment, the available data on the ⁶Li (π⁺, ³He) ³He reaction (and its inverse, ³He (³He, π⁺) ⁶Li) were insufficient to determine which of the two calculations better represent the reaction. The new data presented here have thoroughly tested these two models in this energy regime and have determined their suitability in their descriptions of the ⁶Li (π⁺, ³He) ³He reaction. From these data (and from results previously published for the inverse ³He (³He, π⁺) ⁶Li reaction at an equivalent pion energy of 15.4 MeV), the differential cross-sections were fit to an orthogonal Legendre polynomial series at each energy. These fits allowed the total cross-section to be extracted as a function of pion energy between 15.4 and 100 MeV. The total cross-section, and the center-of-mass differential cross-section at a fixed center-of-mass angle, were found to exhibit an exponential decrease with pion energy over this range. The coefficients of these polynomial fits also clearly show the growing importance of higher-order partial-waves with increasing energy. Finally, a phenomenological search for systematics in the world data of the ⁶Li (π⁺, ³He) ³He and ³He (³He, π⁺) ⁶Li reactions was made. This attempt was successful in finding a dependence of the reaction upon the spin-state of the exit channel which is similar to that previously seen in (p, π⁺) experimental data. / Science, Faculty of / Physics and Astronomy, Department of / Graduate

A proton polarimeter has been constructed at TRIUMF, with design specifications intended to measure the polarization of protons over an energy range of 100 MeV to 300 MeV. It was built as the principle detector in an experiment to determine three spin-transfer parameters of the fundamental π⃗d → p⃗p reaction. In this thesis, some theoretical and experimental design aspects of the spin-transfer measurement are discussed. The intent of this thesis is to describe an experiment¹ which measures the polarization of protons emitted from the πd→ p⃗p reaction, using an unpolarized target². The sole purpose of this experiment is to demonstrate that our polarimeter and general apparatus are capable of identifying the πd → pp events from a large background presence, and that the systematic errors associated with the polarization extraction have been identified. To this extent, the system is ready to produce the proton polarization required for the spin-transfer measurements. ¹This experiment is identical in all respects to the spin-transfer experiment, except that here, the target is unpolarized. ²The polarization of the protons is well know from the analyzing power, An₀, of the time reversed p⃗p → dπ reaction. / Science, Faculty of / Physics and Astronomy, Department of / Graduate

Differential cross sections for the elastic scattering of low energy (20 MeV) positive and negative pions from ¹²C and ⁴⁰Ca have been measured. This measurement was performed at TRIUMF using the QQD low energy pion spectrometer at 11 angles between 45° and 125°. The π⁺ ¹²C data are in good agreement with [OBG⁺83], as are the π⁻ ¹²C data with [WBB+87], indicating that the overall normalization of the cross sections is good. However, the π± ⁴⁰Ca data do not agree well with the previously published data of [WMR+88]. An optical potential model, whose parameters were determined from pionic atom data, was used to predict these differential cross sections. Two sets of parameters were used in the model. One set was determined from fits to "normal" pionic atom data, while another set was extracted from fits to "anomalous" data where level shifts and widths do not compare to theoretical values obtained when the normal set of parameters is used. In all the above cases, the experimental data best fits the optical model predictions of [FG80,Fri88b] when the normal set of parameters is used. The qualitative agreement of the data to the "normal" optical model predictions indicates that the pionic anomaly effects do not extend to positive pion energy values. / Science, Faculty of / Physics and Astronomy, Department of / Graduate

Orientador: Waldyr Alves Rodrigues Jr / Tese (doutorado) - Universidade Estadual de Campinas, Instituto de Fisica Gleb Wataghin / Made available in DSpace on 2018-07-16T18:32:15Z (GMT). No. of bitstreams: 1 TurtelliJunior_Armando_D.pdf: 4281240 bytes, checksum: bdec9999fa4424d1ffa0159ac75ee1b0 (MD5) Previous issue date: 1974 / Resumo: Não informado / Abstract: Not informed. / Doutorado / Física / Doutor em Ciências

Orientador: Jose Bellandi Filho / Tese (doutorado) - Universidade Estadual de Campinas, Instituto de Fisica Gleb Wataghin / Made available in DSpace on 2018-07-18T20:25:32Z (GMT). No. of bitstreams: 1 MundimFilho_LuizMartins_D.pdf: 2741839 bytes, checksum: 0e10a96eecd9913b91393fde1e789e3d (MD5) Previous issue date: 1993 / Resumo: Calcula-se nesta tese as soluções das equações de difusão dos fluxos de núcleons e píons na atmosfera, usando-se os livres caminhos médios de interação e inelasticidade média de núcleons dependentes da energia. A partir das soluções para os fluxos diferenciais verticais nucleônico e piônico, calcula-se o fluxo integral de hádrons e múons (diferencial). Baseando-se nas soluções calculadas e em dados experimentais de fluxo diferencial nucleônico (à várias profundidades), espectro integral de hádrons carregadas (à profundidade de 630 g/cm2) e espectro diferencial de múons (ao nível do mar), analise-se o comportamento da inelasticidade média pp e da seção de choque inelástica p -ar com relação à energia / Abstract: We have obtained the solutions of diffusion equations for pions and nucleons in the atmosphere by using energy-dependent inelasticity and interaction mean free path. From these solutions we are able to calculate the integral charged hadronic spectrum and the muon, nucleon differential spectrum, comparing the solutions with experimental data at mountain altitudes and sea level. Based on the results obtained with the solutions of the diffusion equations, we study the energy dependence of the inelasticity and p - ar inelastic cross section / Doutorado / Física / Doutor em Ciências