The study of exotic nuclei, and their implication for Astrophysics have become a driving force in low-energy nuclear science, nationally recognized by the construction of the Facility for Rare Isotope Beams (FRIB) laboratory. To maximize the potential provided by beams of exotic nuclei, novel detector systems and analysis techniques must be developed, a current focus of the Florida State University (FSU) group. Experimental results from commissioning experiments with the ANASEN and RESONEUT detectors at FSU are presented. The neutron deficient ⁹C nucleus was studied through the ⁸B+p resonant elastic scattering reaction. The experiment was conducted during the commissioning of the ANASEN detector in 2012. Due to cryogenics problems, the experiment was stopped prematurely. Through analysis of the partial data set, it was shown that a full analysis could be performed, on complete data sets, for future proton resonance elastic scattering experiments. Results from the ¹⁹O(d,p)²⁰O experiment, also conducted as a part of the commissioning of the ANASEN detector at FSU, will be presented. It was found that heavy ion recoils from the (d,p) reactions were reaching the active zone of the proportional counter, and subsequently producing UV-light radiation that degraded the proportional counter performance. This discovery lead to a re-design of the proportional counter, which is currently being constructed by the ANASEN group at Louisiana State University. An experimental study of low-lying proton resonances in ²⁰Na was performed using the proton transfer ¹⁹Ne(d,n)²⁰Na(p) reaction as part of the commissioning campaign of experiments with the RESONEUT detector. This reaction is comparable to the direct proton capture, ¹⁹Ne(p,ɣ)²⁰Na, which is of astrophysical significance in the breakout from the Hot CNO-cycle. Using protons detected from the decay of ²⁰Na, three resonances were observed, at energies of 0.44 MeV, 0.66 MeV, and 0.82 MeV above the proton threshold. The resonance strengths were determined, and the subsequent ¹⁹Ne(p,ɣ)²⁰Na stellar reaction rate was calculated. A discussion of this reaction rate in the context of the breakout from the Hot CNO-cycle is presented. / A Dissertation submitted to the Department of Physics in partial fulfillment of the requirements for the degree of Doctor of Philosophy. / Fall Semester 2015. / August 12, 2015. / Includes bibliographical references. / Ingo Wiedenhöver, Professor Directing Dissertation; Tomasz Plewa, University Representative; Alexander Volya, Committee Member; Paul Cottle, Committee Member; Nicholas Bonesteel, Committee Member.

The formation of sub-structures within an atomic nucleus, appropriately termed nuclear clustering, is one of the core questions of nuclear many-body physics. In this thesis, we put forward a new method for the study of nuclear clustering relying on the completely microscopic Configuration Interaction approach. We construct reaction cluster channels in a Harmonic Oscillator many-body basis that respect the symmetries of the Hamiltonian, are fully antisymmetrized, and carry a separable and controlled Center of Mass component. Such channels are then used to explore cluster signatures in Configuration Interaction many-body wavefunctions. The Resonating Group Method is then applied, utilizing the reaction channels as a basis to capture the essential cluster characteristics of the system. We investigate the emergence of nuclear clustering in 2α, 2α+n, 2α+2n and 3α systems using a No Core Shell Model approach from first principles, and traditional Shell Model studies of clustering in heavier nuclei. / A Dissertation submitted to the Department of Physics in partial fulfillment of the requirements for the degree of Doctor of Philosophy. / Summer Semester 2018. / May 11, 2018. / Includes bibliographical references. / Alexander Volya, Professor Directing Dissertation; David Kopriva, University Representative; Ingo Weidenhoever, Committee Member; Simon Capstick, Committee Member; Laura Reina, Committee Member.

This dissertation presents the first measurement of electron-muon azimuthal correlations at the PHENIX experiment at RHIC in 200 GeV proton-proton and deuteron-gold collisions. Electron-muon pairs result from the semileptonic decay of D mesons, which come from correlated charm pairs. The pairs are measured at forward rapidity, with η < 0.5 for the electron and 1.4 < η < 2.1 for the muon. Electron-muon pairs exhibit a characteristic peak at Δφ = π in the azimuthal distribution due to momentum conservation in the c\bar{c} decay, and this enables clear identification. The shape of the azimuthal pair distribution in p+p collisions helps us determine which hard scattering processes contribute to charm production, and it allows us to test NLO QCD predictions. The p+p result also serves as a baseline measurement for understanding heavy ion collisions. Pairs were also measured in d+Au collisions at forward rapidity in the deuteron-going direction, which is a kinematic region at which we expect suppression effects to be evident. The pair yield in d+Au was found to be suppressed relative to that in p+p. Also the peak in Δφ almost disappears in d+Au, indicating either a change in charm production mechanisms or interactions with the nuclear matter.

The study of strong interactions at very high energies has prompted a large interest in the small-x regime of quantum chromodynamics where partons carry a small fraction of the momentum of their parent hadrons. In this regime gluon occupation numbers are believed to be very high leading to saturation of the corresponding parton densities. This thesis is intended to explore the validity of factorization approaches in the small-x regime and establish a relation with partonic interpretations when possible. Two fundamental unintegrated (transverse momentum dependent) gluon distributions are proposed as fundamental building blocks to describe all processes sensitive to the small-x regime which admit a factorized description. Single-particle production processes and two-particle production processes are studied in asymmetric collisions of a dilute probe scattering from a dense target and it is shown that it is possible to recover factorized expression in a particular kinematical limit.

Collision of heavy nuclei at the Relativistic Heavy Ion Collider (RHIC) recreates the state of high temperature quark-gluon plasma that existed shortly after the Big Bang. Measurement using single particle spectra and two-particle correlation shows that this medium is largely opaque to the transit of a high energy quark or gluon. Reconstructing the kinematics of these quarks and gluons can provide additional constraints for the property of their interaction with the medium. While the direct reconstruction of quantum chromodynamics jets, the final state showers of quarks and gluons, has become an indispensable tool at hadron and electron accelerator experiments, the application of this technique to heavy ion collisions at the RHIC energy has been considered a hard problem. The relatively low yield of high transverse momentum jets would have to be detected within a large, fluctuating background that can give rise to a false jet signal. At the RHIC PHENIX experiment, jet reconstruction also has to cope with the limited aperture of the central arm spectrometers. To overcome both problems, which can distort the jet signal in the traditional reconstruction algorithms, this thesis develops an algorithm that reconstructs the jets as maxima of the Gaussian filtered event transverse momentum distribution. The Gaussian angular weighting causes the algorithm to become more sensitive to the jet core versus the jet periphery. It is then combined with a fake jet rejection discriminant to remove the background fluctuation from the jet signal. This algorithm is used to obtain the first jet measurement in heavy ion environment at PHENIX, using data from the 2004/2005 RHIC run. The result includes the proton-proton inclusive jet spectrum, the proton-proton fragmentation function, the copper-copper jet nuclear modification factor, the copper-copper jet central-to-peripheral modification factor, and the copper-copper dijet azimuthal correlation. The measured copper-copper jet nuclear modification factor shows that there is a significant initial state effect to the jet suppression. The observation of no broadening in the copper-copper dijet azimuthal correlation indicates that the traditional energy loss picture via multiple soft scattering may not be applicable to the quark-gluon plasma.

A new jet tomographic model and numerical code, CUJET, is developed in this thesis and applied to the phenomenological study of the Quark Gluon Plasma produced in Heavy Ion Collisions.

We perform an analysis dedicated to the search for new and unusual strangeonium states produced in the reaction γp → pφη. The data used for this analysis was recorded during the Spring 2017 physics run for Hall D of Thomas Jefferson National Accelerator Facility, where the GlueX experiment is located. The GlueX experiment uses a linearly polarized coherent bremsstrahlung beam of up to 12 GeV in energy. This photon beam interacts with a stationary liquid hydrogen target located inside the GlueX detector. The subsequent photoproduction will provide final states ideal for studying both exotic and non-exotic ss ̄ mesons. After all cuts, a total of four different selection methods were used to study the φη parent state. Three of these methods used an event by event probabilistic weighting method in order to separate signal from background, and the fourth method was simply an elliptical subtraction which did not utilize probabilistic weighting. After comparing the φη invariant mass spectra for all selection methods, two structures were consistently observed. One of the structures was found to have a mass of (m = 1.657 ± 0.008)GeV/c^2 and a width of (σ = 0.190 ± 0.024)GeV/^2 ; and the second structure was found to have a mass of (m = 1.879 ± 0.004)GeV/c^2 and a width of (σ = 0.042 ± 0.014)GeV/c^2 . / A Dissertation submitted to the Department of Physics in partial fulfillment of the requirements for the degree of Doctor of Philosophy. / Spring Semester 2019. / April 12, 2019. / GlueX, Jefferson Lab, Nuclear Physics, Photoproduction / Includes bibliographical references. / Paul Eugenio, Professor Directing Dissertation; Ettore Aldrovandi, University Representative; Simon Capstick, Committee Member; Horst Wahl, Committee Member; Volker Crede, Committee Member; Alexander Ostrovidov, Committee Member.

acase@tulane.edu / The Bohr-Mottelson collective model is central to the study of nuclear structure physics. The model treats nuclei as ellipsoids and focuses on their vibrational and rotational degrees of freedom. The rotational part of the model regards the moment of inertia of the nuclei as a falling between the extreme of a rigid body and an irrotational fluid. The true moment of inertia, as revealed by experiment, provides a parameter between these two extremes and acts as a way of interpolating the data. In this work, we show how the interpolating parameter between the two extreme moments of inertia can be treated theoretically using an algebraic and differential geometric framework. The essential idea is to couple the angular momentum of the nucleus with a ``magnetic" term that involves the Kelvin circulation into a covariant derivative. This coupling term or connection can be found by solving a Yang-Mills equation. Measuring the nuclear Kelvin circulation then reveals a theoretical justification for the determining the correct moment of inertia. / 1 / Nick Sparks

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