The LHC, with its center-of-mass energy of 7 TeV, offers the chance to investigate the fundamental constituents of matter at a higher energy scale than ever before. Using the data acquired by the ATLAS detector in the summer of 2010, two different measures of the angular distributions of dijet final states are studied and compared to Standard Model QCD expectations. Such a comparison is used to set new stringent limits on the existence of quark substructure.

The LHC, with its center-of-mass energy of 7 TeV, offers the chance to investigate the fundamental constituents of matter at a higher energy scale than ever before. Using the data acquired by the ATLAS detector in the summer of 2010, two different measures of the angular distributions of dijet final states are studied and compared to Standard Model QCD expectations. Such a comparison is used to set new stringent limits on the existence of quark substructure.

<p> The (t,p) reaction has been performed on targets of 151Sm, 176Yb and 178Hf. The experiment was performed with 15 MeV tritons. The outgoing protons were analyzed with the Enge split-pole spectrograph. Angular distributions were measured for all three nuclei with special emphasis being placed on L=0 transitions.</p> <p> The angular distributions for the 151Sm(t,p)153Sm reaction showed that the distribution of L=0 strength among the low-lying states is not consistent with expectations based on the detailed wavefunctions for 151Sm and 153Sm calculated by two independent groups; Katajanheimo and Hammaren (1978) and Rekstad et al. (1978). The distributions also showed that the total L=0 strength, summed over the four observed states in 153Sm, is much less than for neighbouring nuclei.</p> <p> Angular distributions of the (t,p) reaction on 176Yb and 178Hf targets showed strong L=0 transitions to levels at ~ 1.3 MeV excitation. It is believed that the N=108 energy gap in the Nilsson diagram is the cause of the large L=0 strength observed. At present no quanitative calculation has reproduced the observed phenomenon, however a calculation based on the Volkov model is presently being considered.</p> / Thesis / Master of Science (MSc)

Doctor of Philosophy / Department of Physics / Tim Bolton / This thesis represents the first study of the helicity distributions of Z[gamma] di-boson production at hadron colliders. I use 5 fb⁻¹ of [radical]s = 7 TeV center of mass energy proton-proton collision data, collected by the Compact Muon Solenoid (CMS) experiment at the Large Hadron Collider (LHC), to look at the angular distribution of the Z[gamma] [right arrow] e⁺e⁻[gamma] / [mu]⁺ [mu]⁻ [gamma] process and measure the helicity amplitudes that govern it. This study provides sensitivity to the interference terms between different quantum states and through the interference terms to the possible new physics. The final state is comprised of leptons (muon-antimuon or electron-positron pairs) with transverse momentum over 20 GeV and a photon with transverse energy over 30 GeV. Helicty amplitudes are measured for the total angular momentum of the quark-antiquark system up to J[subscript]q[subscript bar]q = 2. Four-dimensional multivariate analysis of the 2011 CMS data shows no significant deviations from the standard model prediction for the measured amplitudes.

Utilizando tecnicas de espectroscopia-GAMA em linha e reacoes do tipo (hi, xnypGAMA) que populam estados de alto spin estudou-se a estrutura do nucleo duplamente impar ANTPOT.136 PR atraves das reacoes ANTPOT.123 SB (ANTPOT.16 O, 3n)ANTPOT.136 PR e ANTPOT.126 TE (ANTPOT.14 N 4n)ANTPOT.136 PR. Foram realizadas medidas de funcoes de excitacao em quatro energias, e coincidencias GAMA-GAMA-t e distribuicoes angulares em 69mev e 56mev, respectivamente, utilizando detetores hpge de alta resolucao (2kev) e alvos de isotopos enriquecidos de ANTPOT.123 SB (99%) e ANTPOT.126 TE (94%) com espessuras de aproximadamente 9mg/CENTIMETROS QUADRADOS. O esquema de niveis de energia do ANTPOT.136 PR evidencia duas bandas rotacionais que populam um estado isomerico com meia-vida de 92ns. A banda yrast e caracterizada por um staggering em seus niveis de energia, com transicoes m1 intensas e e2 fracas baseada na configuracao PI (h ind.11/2) IND.1/2 TETA NI (h ind.11/2) IND.9/2, de acordo com a sistematica da regiao de massa a=130, mostrando um pequeno energy splitting de 40kev. Na banda secundaria pressupoe-se a configuracao PI (d ind.5/2) IND.3/2 TETA NI (h ind.11/2) IND.11/2. Os resultados experimentais foram interpretados com base no cranked shell model que predizem deformacoes GAMA pequenas e negativas na regiao dos LA e PR / The structure of the doubly odd nucleus 136pr has been studied using techniques of on-line -spectroscopy with the reactions 123Sb (16O,3n) 136 Pr and 126Te(14 N,4n)136 Pr populating high spin states. The excitation functions were measured at four energies, and - t coincidences and angular distributions at 69MeV and 56MeV , respectively, using high resolution HPGe detectors (2keV) and targets of enriched isotopes of 123 Sb (99%) and 126Te (94%) with thicknesses of approximately 9mg/cm². The energy level scheme of 136Pr shows two rotational bands which populate one isomeric state with a half-life of 92s. The Yrast band is characterized by the staggering in energy levels with intense M1 transitions and weak E2 transitions, based on a configuration (h11/2)1/2 v(h11/2)9/2 in agreemment with the sistematics of the mass region A = 130. There is a small energy splitting of 40keV. For the secondary band a configuration n(d5/2)3/2 (h11/2)11/2 is possible. Experimental results were interpreted within the framework of the Cranked Shell Model which predicts small negative deformations in the La and Pr region.

The interactions, with emulsion nuclei, of O-16 ions accelerated at 2.1 GeV/nucleon in the Berkeley accelerator, are analyzed. A phenomenological study of the events, particularly reaction cross sections and multiplicities is exposed to nuclear theories with nucleons acting individually and collectively An study of the angular distributions of the reaction products and their correlations, particularly in the transversal space, is shown. Finally, a discussion of the present parton model of the nucleon structure is done, comparing it with the experimental results.

Utilizando tecnicas de espectroscopia-GAMA em linha e reacoes do tipo (hi, xnypGAMA) que populam estados de alto spin estudou-se a estrutura do nucleo duplamente impar ANTPOT.136 PR atraves das reacoes ANTPOT.123 SB (ANTPOT.16 O, 3n)ANTPOT.136 PR e ANTPOT.126 TE (ANTPOT.14 N 4n)ANTPOT.136 PR. Foram realizadas medidas de funcoes de excitacao em quatro energias, e coincidencias GAMA-GAMA-t e distribuicoes angulares em 69mev e 56mev, respectivamente, utilizando detetores hpge de alta resolucao (2kev) e alvos de isotopos enriquecidos de ANTPOT.123 SB (99%) e ANTPOT.126 TE (94%) com espessuras de aproximadamente 9mg/CENTIMETROS QUADRADOS. O esquema de niveis de energia do ANTPOT.136 PR evidencia duas bandas rotacionais que populam um estado isomerico com meia-vida de 92ns. A banda yrast e caracterizada por um staggering em seus niveis de energia, com transicoes m1 intensas e e2 fracas baseada na configuracao PI (h ind.11/2) IND.1/2 TETA NI (h ind.11/2) IND.9/2, de acordo com a sistematica da regiao de massa a=130, mostrando um pequeno energy splitting de 40kev. Na banda secundaria pressupoe-se a configuracao PI (d ind.5/2) IND.3/2 TETA NI (h ind.11/2) IND.11/2. Os resultados experimentais foram interpretados com base no cranked shell model que predizem deformacoes GAMA pequenas e negativas na regiao dos LA e PR / The structure of the doubly odd nucleus 136pr has been studied using techniques of on-line -spectroscopy with the reactions 123Sb (16O,3n) 136 Pr and 126Te(14 N,4n)136 Pr populating high spin states. The excitation functions were measured at four energies, and - t coincidences and angular distributions at 69MeV and 56MeV , respectively, using high resolution HPGe detectors (2keV) and targets of enriched isotopes of 123 Sb (99%) and 126Te (94%) with thicknesses of approximately 9mg/cm². The energy level scheme of 136Pr shows two rotational bands which populate one isomeric state with a half-life of 92s. The Yrast band is characterized by the staggering in energy levels with intense M1 transitions and weak E2 transitions, based on a configuration (h11/2)1/2 v(h11/2)9/2 in agreemment with the sistematics of the mass region A = 130. There is a small energy splitting of 40keV. For the secondary band a configuration n(d5/2)3/2 (h11/2)11/2 is possible. Experimental results were interpreted within the framework of the Cranked Shell Model which predicts small negative deformations in the La and Pr region.

L'étude des noyaux exotiques riches en neutrons est l'un des enjeux actuels majeurs de la physique nucléaire expérimentale. Le spectromètre S ³ , aujourd'hui en construction, pourrait permettre de les produire "en vol" grâce aux hautes intensités de l'accélérateur linéaire de Spiral2. Le mécanisme de réaction utilisé serait celui des collisions profondément inélastiques, pour ses caractéristiques telles que l'échange de nombreux nucléons et l'équilibre en N/Z des produits obtenus. Les recherches sur ce mécanisme, débutées dans les années 1970, bénéficient aujourd'hui des progrès technologiques, en particulier concernant les spectromètres de particules chargées. On a mesuré, pour la première fois sur une gamme de 0° à 35°, les sections efficaces de réactions d2sigma/dOmegadE pour différents noyaux riches en neutrons formés par collisions profondément inélastiques entre un faisceau de ⁴⁸Ca¹ ⁹ ⁺ à 10 A MeV et une cible de ² ³ ⁸U de 170(+-10%) ug/cm ². L'expérience a été réalisée au Ganil, avec le spectromètre Vamos couplé à sept clovers Exogam afin de confirmer l'identification des noyaux produits par leur signature gamma. De plus, un détecteur BaF₂ a permis la mesure de l'intensité du faisceau, essentielle au calcul des sections efficaces absolues. Les distributions angulaires, en énergie et en masse des sections efficaces double différentielles absolues sont présentées pour une large plage de quasi-projectiles. Les résultats sont comparés à ceux donnés par le couplage des modèles DIT (Deep Inelastic Transfers) et Gemini++. Les résultats obtenus montrent une production importante qui laisse envisager ce mécanisme pour la formation de noyaux riches en neutrons. Les modèles sont globalement cohérents avec les résultats et les différences majeures concernent généralement les quasi-projectiles très proches ou au contraire très éloignés du faisceau. Les implications pour la production de faisceau avec S³ sont également discutées. / The study of neutron-rich nuclei is one of the main challenges nowadays in experimental nuclear physics. Thanks to the future high intensity beams delivered by the linear accelerator of Spiral2, the S ³ spectrometer might allow their production using the "in-flight" method. The deep inelastic reaction mechanism might be used due to the important multi-nucleon transfer and the N/Z equilibration. Studies on this topic, started in the seventies, take advantages of the new available devices. We measured, for the first time between 0° and 35° in the laboratory frame, the reactions cross-sections d2sigma/dOmegadE for the neutron-rich nuclei formed by deep inelastic collisions between a 10 A MeV ⁴⁸Ca ¹ ⁹ ⁺ beam and a 170(+-10%) ug/cm² ² ³ ⁸U target. The experiment was performed at Ganil using the Vamos spectrometer coupled to seven Exogam to confirm the nuclei identification using their gamma signature. Moreover, a BaF2 detector was used to extract the beam intensities, essential for the absolute cross sections measurements. Momentum, angular and mass distributions of absolute differential cross-sections are presented for a wide range of quasi-projectiles. The results are compared with those of DIT (Deep Inelastic Transfers) coupled with Gemini++ theoretical calculations. The models are generally consistent with the results. Important differences appear for quasi-projectiles very close and very far from the beam. Relevant implications for S³ beam production are pointed out.

In this work, experimental and theoretical approaches are applied to the study of chemical reaction dynamics. In Chapter 2, two applications of transition state theory are presented: (1) Application of microcanonical transition state theory to determine the rate constant of dissociation of C2F3I after π∗ ← π excitation. It was found that this reaction has a very fast rate constant and thus is a promising system for testing the statistical assumption of molecular reaction dynamics. (2) A general rate constant expression for the reaction of atoms and molecules at surfaces was derived within the statistical framework of flexible transition state theory. In Chapter 4, a computationally efficient TDDFT approach was found to produce useful potential energy surface landscapes for application to non-adiabatic predissociative dynamics of the molecule CS2 after excitation from the ground state to the singlet C-state. In Chapter 5, ultrafast experimental results of excitation of CS2 to the predissociative neutral singlet C-state is presented. The bandwidth of the excitation laser was carefully tuned to span a two-component scattering resonance with each component differently evolving electronically with respect to excited state character during the quasi-bound oscillation. Scalar time-resolved photoelectron spectra (TRPES) and vector time-resolved photoelectron angular distribution (TRPAD) observables were recorded during the predissociation. The TRPES yield of photoelectrons was found to oscillate with a quantum beat pattern for the photoelectrons corresponding to ionization to the vibrationless cation ground state; this beat pattern was obscured for photoelectron energies corresponding to ionization from the vibrationally excited CS2 cation. The TRPAD data was recorded for two general molecular ensemble cases: with and without a pre-excitation alignment laser pulse. It was found that in the case of ensemble alignment (Chapter 6), the “molecular frame” TRPAD (i.e. TRMFPAD) was able to image the purely valence electronic dynamics of the evolving CS2 C-state. The unaligned ensemble TRPAD observable suffers from excessive orientational averaging and was unable to observe the quantum beat. Engineering efforts were also undertaken to eliminate scattered light background signal (Chapter 7, Appendix A) and improve laser stability as a function of ambient pressure (Appendix B) for TRMFPAD experiments. / Thesis (Ph.D, Chemistry) -- Queen's University, 2012-09-11 22:18:20.89