Physical Sciences and Mathematics Commons^™

The Beam-Helicity Asymmetry For Two Pseudoscalar Mesons In Photoproduction And A Partial Wave Analysis For Excited Hyperons, Rafael A. Badui

FIU Electronic Theses and Dissertations

The first-time measurement of the angular dependence of the beam-helicity asymmetry for $\gamma p \rightarrow pK^{+}K^{-}$ is shown and compared to $\gamma p \rightarrow p\pi^{+}\pi^{-}$. The data obtained were from the CLAS g12 experiment at Jefferson Lab. The experiment utilized a beam of circularly polarized photons with energies between 1.1 and 5.4 GeV incident on an unpolarized liquid hydrogen target, which produced an unprecedented number of strange hadrons in photoproduction. The production mechanism for strange hadrons is not well understood. The beam-helicity asymmetry is a polarization observable that provides information on interfering production mechanisms in the reaction. It is shown …

Measurements Of Photon Beam Intensity At The High Intensity Gamma-Ray Source (Higs) Facility For Astrophysically Relevant Photodisintegration Reaction Cross Section, Evan G. Meekins

Senior Honors Projects, 2010-2019

How nuclear reactions in stars and stellar explosions such as supernovae have forged the elements out of hydrogen and helium leftover from the Big Bang is a longstanding, still timely research topic in nuclear astrophysics. Although there is a fairly complete understanding of the production of the chemical elements and their isotopes up to iron by nuclear fusion in stars, important details concerning the production of the elements from iron to uranium remain puzzling. Current knowledge is that the nucleosynthesis beyond iron proceeds mainly via neutron capture reactions and subsequent electron decays to stability. However, some 35 proton-rich stable isotopes, …

Hard Qcd Processes In The Nuclear Medium, Adam Freese

FIU Electronic Theses and Dissertations

The environment inside the atomic nucleus is one of the most fascinating arenas for the study of quantum chromodynamics (QCD). The strongly-interacting nature of the nuclear medium affects the nature of both QCD processes and the quark-gluon structure of hadrons, allowing several unique aspects of the strong nuclear force to be investigated in reactions involving nuclear targets. The research presented in this dissertation explores two aspects of nuclear QCD: firstly, the partonic structure of the nucleus itself; and secondly, the use of the nucleus as a micro-laboratory in which QCD processes can be studied.

The partonic structure of the nucleus …

On The Spin Evolution Of Isolated Pulsars, Oliver Quinn Hamil

Doctoral Dissertations

Neutron stars are the remnants of supernova explosions, and harbor the densest matter found in the universe. Because of their extreme physical characteristics, neutron stars make superb laboratories from which to study the nature of matter under conditions of extreme density that are not reproducible on Earth. The understanding of QCD matter is of fundamental importance to modern physics, and neutron stars provide a means of probing into the cold, dense region of the QCD phase diagram.

Isolated pulsars are rotating neutron stars that emit beams of electromagnetic radiation into space which appear like lighthouses to observers on Earth. Observations …

Relativistic And Non-Relativistic Proton-Nucleus Scattering, Kinsey Ann Elisabeth Zarske-Williamson

Honors Theses

Calculations for proton-nucleus scattering often rely on transition amplitudes. We implement new transition amplitudes [7] with the relativistic equations. We can find the matrix elements of the operators between the usual Dirac spinor basis or the helicity spinor basis. The operators can also be written as a linear combination of non-relativistic spin operators. To transform from one basis to another, we need to find a transformation matrix. We must establish what one of the factors that appears in the transformed expression means in order to correctly complete our transformation matrix. Once this is resolved, our transformation matrix will be complete.

Design And Model Of The Frame For Hagrid (Hybrid Array Of Gamma Ray Detectors), Santiago Munoz

Masters Theses

Transfer reactions in inverse kinematics have provided critical information in the study of exotic nuclei. However, transfer reactions with charged particles suffer from poor resolution. The measurement of gamma-rays offers several advantages: they provide not only good resolution in measurements but also other information about the nuclei like lifetimes of unstable states. The combination of these two methods would be the ideal situation to gather information about nuclear structure.

HAGRiD, which stands for The Hybrid Array of Gamma Ray Detectors, is a LaBr3(Ce) [lanthanum bromide crystal with a cerium activator] scintillation array to measure gamma rays from transfer reactions and …

Re-Analysis Of The World Data On The Emc Effect And Extrapolation To Nuclear Matter, Stacy E. Karthas

Honors Theses and Capstones

The EMC effect has been investigated by physicists over the past 30 years since it was discovered at CERN. This effect shows that the internal nucleon structure varies when in the nuclear medium. Data from SLAC E139 and JLab E03 103 were studied with the Coulomb correction and directly compared. The Coulomb distortion had a greater impact on the JLab data due to slightly lower energies and different kinematics. The EMC ratio was found to have a dependence on a kinematic variable, which was removed when Coulomb corrections were applied. The methodology was developed to apply Coulomb corrections, which had …

First Observation Of 15be, J. Snyder, T. Baumann, G. Christian, R. A. Haring-Kaye, P. A. Deyoung, Z. Kohley, B. Luther, M. Mosby, S. Mosby, A. Simon, J. K. Smith, A. Spyrou, Sharon L. Stephenson, M. Thoennessen

Physics and Astronomy Faculty Publications

The neutron-unbound nucleus 15Be was observed for the first time. It was populated using neutron transfer from a deuterated polyethylene target with a 59 MeV/u 14Be beam. Neutrons were measured in coincidence with outgoing 14Be particles and the reconstructed decay energy spectrum exhibits a resonance at 1.8(1) MeV. This corresponds to 15Be being unbound by 0.45 MeV more then 16Be thus significantly hindering the sequential two-neutron decay of 16Be to 14Be through this state.

The Role Of Llnl's Fast Calibration Facility In Diagnosing Nif Fusion Plasmas, Joshua G. Thompson, Carey Scott, Greg V. Brown

STAR Program Research Presentations

The Fusion and Astrophysics (FAST) Calibration and Diagnostic Facility uses the original Electron Beam Ion Trap (EBIT-I) to profile x-ray filters that are used in the Dante Soft X-Ray Diagnostic at the National Ignition Facility (NIF). FAST has an advantage over any other facility not only for its high accuracy, but also for its proximity to NIF in the Lawrence Livermore National Laboratory (LLNL). This makes for highly accurate and near-instantaneous filter calibration turnover.

EBIT-I was first constructed to create, trap, and observe static highly charged ions (HCIs) and conduct experimental astrophysics (creating an x-ray spectroscopy catalogue of ions). To …

Isomers And Seniority In The Trans-Pb Nuclei, J. J. Ressler, C. W. Beausang, R. F. Casten, N. V. Zamfir, H. Ai, H. Amro, M. Babilon, R. Cakirli, J. A. Caggiano, G. Gurdal, A. Heinz, R. O. Hughes, S. D. Langdown, E. A. Mccutchan, D. A. Meyer, C. Plettner, J. Qian, P. H. Regan, M.J. S. Sciacchitano, N. J. Thomas, E. Williams, A. Yamamoto

Physics Faculty Publications

Low-energy excited states of ²¹⁰Ra and ²⁰⁸Ra were investigated at the Wright Nuclear Structure Laboratory of Yale University. Fusion evaporation recoils were selected using the gas-filled spectrometer, SASSYER. Delayed γ -rays, following isomeric decays, were detected at the focal plane of SASSYER with a small array of HPGe detectors. Transitions following the proposed J ^π = 8⁺ isomers were observed, and the half-lives measured. The experiments are discussed and results compared to expectations from the seniority scheme.

Theoretical Status Of The Top Quark Cross Section, Nikolaos Kidonakis, Ramona Vogt

Faculty and Research Publications

We discuss the most recent calculations of the top quark total cross section and transverse momentum distributions at the Tevatron and the LHC. These calculations include the soft-gluon corrections at next-to-next-to-leading order (NNLO). The soft NNLO corrections stabilize the scale dependence of the cross section.

Pion-Induced Transport Of Π Mesons In Nuclei, S. G. Mashnik, R. J. Peterson, A. J. Sierk, Michael R. Braunstein

All Faculty Scholarship for the College of the Sciences

A large body of data for pion-induced neutral pion continuum spectra spanning outgoing energies near 180 MeV shows no dip there that might be ascribed to internal strong absorption processes involving the formation of Δ’s. This is the same observation previously made for the charged pion continuum spectra. Calculations in an intranuclear cascade model or a cascade exciton model with free-space parameters predict such a dip for both neutral and charged pions. We explore several medium modifications to the interactions of pions with internal nucleons that are able to reproduce the data for nuclei from ⁷Li through Bi.

Triple Gamma Directional Correlations In The Decay Of Europium-154, Gary Lewis

Gary C. Lewis

The ('154)Eu nucleus decays by beta emission to an excited state of the ('154)Gd nucleus. The resulting ('154)Gd nucleus decays to its ground state by emission of gamma rays. One series of gamma rays emitted in this process is a cascade of energies 723 keV, 873 keV, and 123 keV. The 873 keV gamma ray is a mixture of E2 and M1 radiation. The mixing ratio of this transition has been measured using the triple gamma directional correlation technique. The experiments used a planar geometry with one angle fixed at 90 degrees. Two Ge(Li) detectors and one NaI(T1) detector were …