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Articles 1 - 9 of 9
Full-Text Articles in Physical Processes
Determining The 17f(Α,P)20ne Reaction Rate For Application In Type I X-Ray Bursts, William Braverman
Determining The 17f(Α,P)20ne Reaction Rate For Application In Type I X-Ray Bursts, William Braverman
LSU Doctoral Dissertations
The 17F(α, p)20Ne reaction has been identified as an alternate pathway for breakout from the hot-CNO cycle that can be important in some X-ray burst scenarios. The 17F(α, p)20Ne reaction rate was previously determined through a parameterized exponential S-factor with a large enhancement from thermally-excited states based on statistical models with large uncertainties. We have measured the time-inverse 20Ne(p,α)17F cross section at center-of-mass energies ranging from 5.50 to 7.10 MeV using an activation method with a proton beam on a neon gas cell. Coincident detections of 511-keV γ-rays, resulting from electron-positron …
Three-Dimensional Spreading Of Magnetic Reconnection Between Non-Parallel Flux Ropes With A Guide Field, Regis John
Three-Dimensional Spreading Of Magnetic Reconnection Between Non-Parallel Flux Ropes With A Guide Field, Regis John
Graduate Theses, Dissertations, and Problem Reports (ETD)
Magnetic reconnection is a fundamental plasma process that facilitates the rapid conversion of magnetic energy into particle acceleration, plasma flows, and heating. It plays a central role in explosive astrophysical events such as solar flares, where vast amounts of magnetic energy are released on short time scales. A key structure in many reconnection sites is the magnetic flux rope, a column of plasma carrying current threaded by helical magnetic fields, which is frequently involved in or generated by reconnection. Understanding how reconnection unfolds in such flux rope systems is critical for interpreting both space weather phenomena and laboratory plasma dynamics. …
Stellar Nucleosynthesis: Direct Measurement Of The Neutron-Capture Cross Sections Of Stable Germanium Isotopes And Design Of A Next Generation Ion Trap For The Study Of Beta-Delayed Neutron Emission, Alexander Laminack
LSU Doctoral Dissertations
Knowledge of stellar nuclear reaction rates is critical to understanding the cosmic origins of the abundances of elements. In order to determine these reaction rates, accurate measurements of nuclear cross sections are needed. This thesis presents the results of an experiment to directly measure the neutron capture cross sections of 70-Ge, 72-Ge, 74-Ge, and 76-Ge. These measurements were performed at the Los Alamos Neutron Science CEnter (LANSCE) using the Detector for Advanced Neutron Capture Experiments (DANCE). This is the first direct measurement for many of these isotopes across the neutron energy spectrum of 10 eV to 1 MeV using the …
Determination Of Multi-Messenger Signals From Matter Outflows Of Merger Systems, Ronny Nguyen
Determination Of Multi-Messenger Signals From Matter Outflows Of Merger Systems, Ronny Nguyen
Honors Theses and Capstones
In 2017, LIGO detected gravitational waves from GW170817. This presented for the first time, gravitational waves originating from a neutron star - neutron star merger. Studies of neutron star mergers are significant because the multi-messenger signals in the form of gravitational waves and electromagnetic waves can inform us on the nuclear physics of neutron stars and the creation of heavy elements in the universe. Matter is ejected in the merging process and forms the outflow which provides a neutron-rich environment for rapid neutron capture (r-process) to occur leading to the nucleosynthesis of heavy elements. What we detect on Earth are …
Magnetic Field Design To Reduce Systematic Effects In Neutron Electric Dipole Moment Measurements, James Ryan Dadisman
Magnetic Field Design To Reduce Systematic Effects In Neutron Electric Dipole Moment Measurements, James Ryan Dadisman
Theses and Dissertations--Physics and Astronomy
Charge-Conjugation (C) and Charge-Conjugation-Parity (CP) Violation is one of the three Sakharov conditions to explain via baryogenesis the observed baryon asymmetry of the universe (BAU). The Standard Model of particle physics (SM) contains sources of CP violation, but cannot explain the BAU. This motivates searches for new physics beyond the standard model (BSM) which address the Sakharov criteria, including high-precision searches for new sources of CPV in systems for which the SM contribution is small, but larger effects may be present in BSM theories. A promising example is the search for the electric dipole moment of the neutron (nEDM), which …
Low Intensity Gamma-Ray Spectroscopy Of The Lake Labyrinth Meteorite, Tristan C. Paul
Low Intensity Gamma-Ray Spectroscopy Of The Lake Labyrinth Meteorite, Tristan C. Paul
Physics
A 23.7g fragment of the Lake Labyrinth Meteorite (fell in 1924, collected in 1934 at Lake Labyrinth in South Australia, Australia) was re-investigated for evidence of the presence of 98Tc using a two dimensional low-intensity gamma-ray spectrometer. A new calibration technique using 26Al sources found the gamma-rays previously thought to be due to 98Tc are more likely from 166Ho. The presence of 166Ho is most likely due to activation of the stable 165Ho in the meteorite from terrestrial background sources where it was stored.
Laboratory Astrophysics: Using Ebit Measurements To Interpret High Resolution Spectra From Celestial Sources, Carey Scott, Joshua Thompson, N. Hell, Greg V. Brown
Laboratory Astrophysics: Using Ebit Measurements To Interpret High Resolution Spectra From Celestial Sources, Carey Scott, Joshua Thompson, N. Hell, Greg V. Brown
STAR Program Research Presentations
Astrophysicists use radiation to investigate the physics controlling a variety of celestial sources, including stellar atmospheres, black holes, and binary systems. By measuring the spectrum of the emitted radiation, astrophysicists can determine a source’s temperature and composition. Accurate atomic data are needed for reliably interpreting these spectra. Here we present an overview of how LLNL’s EBIT facility is used to put the atomic data on sound footing for use by the high energy astrophysics community.
Time Projection Chamber's Efficiency, Obtained Using Cern's Geant Code, Christine A. Byrd, Charles M. Byrd, Wilfred J. Braithwaite
Time Projection Chamber's Efficiency, Obtained Using Cern's Geant Code, Christine A. Byrd, Charles M. Byrd, Wilfred J. Braithwaite
Journal of the Arkansas Academy of Science
Geometrical acceptance and reconstruction of tracks have been carried out for a Time Projection Chamber (TPC) used in Experiment NA35: the 35th experiment in the North Area of the Super Proton Synchrotron (SPS), located at the European Organization for Nuclear Research (CERN). NA35 used the SPS at CERN to produce 6.4 TeV beams of 32S for central collisions with Au nuclei. The TPC modeling effort used a modified version of CERN's Monte Carlo program GEANT, which simulates the response of the NA35 TPC to output from CERN's primary event generators. GEANT was used to simulate three-dimensional pixel data in the …
Monte Carlo Director Modeling And Display, Using The Cern Laboratory, Christine A. Byrd, Charles M. Byrd, Wilfred J. Braithwaite
Monte Carlo Director Modeling And Display, Using The Cern Laboratory, Christine A. Byrd, Charles M. Byrd, Wilfred J. Braithwaite
Journal of the Arkansas Academy of Science
Detectors for high energy nuclear physics experiments are being modeled using programs developed and maintained at CERN, the European Organization for Nuclear Research. These programs include data handling and display routines, as well as those using random-sampling Monte Carlo techniques to calculate energy depositions for high energy particles as they pass through the various parts of the detector system. The complete CERN library has been imported for use with our Workstation computers in a multiple user environment. The enormous CERN Monte Carlo program GEANT(French for GIANT) tracks the progress of a particle through a detector on a simulated event-by-event basis. …