Nuclear Commons^™

A First Experimental Limit On The Relative Rates Of Muon Capture On Deuterium From The Quartet And Doublet Hyperfine Spin States Of The Μd Atom, Ray Kreswell Neely

Theses and Dissertations--Physics and Astronomy

The MuSun experiment will determine the muon capture rate on deuterium (µ− + d → n + n + ν_µ) from the doublet hyperfine spin state, Λ_d, of muonic deuterium to a precision of 1.5%. Muon capture can occur from either the quartet or doublet state of the 1S orbital of the µd atom; however, the V-A nature of the process strongly suppresses the rate of capture from the quartet state, Λ_q. Muons in ultrapure deuterium gas may also catalyze d+d → ³He+n fusion through the formation …

Neutron-Antineutron Transitions: Exploring B – L Violation With Quarks, Xinshuai Yan

Theses and Dissertations--Physics and Astronomy

In the Standard Model (SM), the quantity baryon number (B) − lepton number (L), B − L, is perfectly conserved. Therefore, the observation of B − L violation would reveal the existence of physics beyond the SM. Traditionally, given the severe experimental constraints on |∆B| = 1 processes, B − L violation with baryons is probed via neutron-antineutron (n − n̄) oscillations, although this process suffers from quenching in the presence of external fields or matter.

In this dissertation, we discuss another possibility, n − n̄ conversion, in which the |∆ …

Studying Transverse Momentum Dependent Distributions In Polarized Proton Collisions Via Azimuthal Single Spin Asymmetries Of Charged Pions In Jets, James Kevin Adkins

Theses and Dissertations--Physics and Astronomy

A complete, fundamental understanding of the proton must include knowledge of the underlying spin structure. The transversity distribution, h₁(x), which describes the transverse spin structure of quarks inside of a transversely polarized proton, is only accessible through channels that couple h₁(x) to another chiral odd distribution, such as the Collins fragmentation function (Δ^N D_π/q^↑(z,j_T)). Significant Collins asymmetries of charged pions have been observed in semi-inclusive deep inelastic scattering (SIDIS) data. These SIDIS asymmetries combined with e⁺e^- process asymmetries have allowed for …

Disconnected-Sea Quarks Contribution To Nucleon Electromagnetic Form Factors, Raza Sabbir Sufian

Theses and Dissertations--Physics and Astronomy

We present comprehensive analysis of the light and strange disconnected-sea quarks contribution to the nucleon electric and magnetic form factors. The lattice QCD estimates of strange quark magnetic moment G^s_M (0) = −0.064(14)(09) μ_N and the mean squared charge radius ⟨r²_s⟩_E = −0.0043(16)(14) fm² are more precise than any existing experimental measurements and other lattice calculations. The lattice QCD calculation includes ensembles across several lattice volumes and lattice spacings with one of the ensembles at the physical pion mass. We have performed a simultaneous chiral, infinite volume, and continuum extrapolation in …

A Measurement Of The Parity Violating Asymmetry In The Neutron Capture On 3He At Sns, Md Latiful Kabir

Theses and Dissertations--Physics and Astronomy

Weak nucleon nucleon couplings are largely unknown because of the involved theoretical and experimental challenges. Theoretically the topic is difficult due to the non-perturbative nature of the strong interaction, which makes calculations of the couplings challenging. Experimentally, the topic is difficult given that 1) the observables are determined by ratios between strong couplings and weak couplings which differ in size by seven orders of magnitude, and 2) theoretically clean and predictable measurements are almost always restricted to simple systems that do not allow for effects that enhance the size of the asymmetry. However parity violation (PV) can be used to …

Magnetic Field Non-Uniformity Challenges In Neutron Electric Dipole Moment Experiments, Nima Nouri

Theses and Dissertations--Physics and Astronomy

A new neutron Electric Dipole Moment (nEDM) experiment was proposed to be commissioned at the Fundamental Neutron Physics Beamline at the Spallation Neutron Source (SNS) of the Oak Ridge National Laboratory (ORNL). The underlying theme of this experiment (first conceived by Golub and Lamoreaux in 1994) is the search for new physics beyond the Standard Model of particle physics. The discovery of a non-zero nEDM would be of revolutionary importance to physics, with the discovery of such providing for evidence for new-beyond-the-Standard-Model physics required for a resolution to the unresolved puzzle of why the universe is dominated by matter, as …

Elastic Compton Scattering From Deuterium Near 100 Mev, Khayrullo Shoniyozov

Theses and Dissertations--Physics and Astronomy

Tagged photons from 81 to 116 MeV were used to measure elastic Compton scat- tering cross sections from deuterium and carbon targets at the MAX-lab facility in Lund. Scattered gamma rays were detected in three very large NaI(Tl) crystals with sufficient energy resolution to isolate deuterium elastic yields at scattering angles of 60°, 90°, 120° and 150°. Calculations indicate that back-angle Compton scattering on deuterium in this energy range is sensitive to the electric and magnetic polarizabilities of the nucleon. Results of this research were obtained with improved beam tagging system conditions compared to previous elastic Compton scattering experiments from …

Search For A Permanent Electric Dipole Moment Of 225Ra, Mukut R. Kalita

Theses and Dissertations--Physics and Astronomy

The observation of a permanent electric dipole moment (EDM) in a non-degenerate system would indicate the violation of discrete symmetries of Time reversal (T) or combined application of Charge (C) and Parity (P) symmetry violation through the CPT theorem. The diamagnetic ²²⁵Ra atom with nuclear spin I=1/2 is a favorable candidate for an EDM search. Experimental sensitivity to its EDM is enhanced due to its high atomic mass and the increased Schiff moment of its octupole deformed nucleus. An experimental setup is developed where laser cooled neutral radium atoms are collected in a …

Measurement Of The Dμd Quartet-To-Doublet Molecular Formation Rate Ratio (Λq : Λd) And The Μd Hyperfine Rate (Λqd) Using The Fusion Neutrons From Μ− Stops In D2 Gas, Nandita Raha

Theses and Dissertations--Physics and Astronomy

The MuSun experiment will determine the μd capture rate (μ−+d ->n+n+ν_e) from the doublet hyperfine state Λ_d, of the muonic deuterium atom in the 1S ground state to a precision of 1.5%. Modern effective field theories (EFT) predict that an accurate measurement of Λ_d would determine the two-nucleon weak axial current. This will help in understanding all weak nuclear interactions such as the stellar thermonuclear proton-proton fusion reactions, the neutrino reaction ν+d (which explores the solar neutrino oscillation problem). It will also help us understand weak …

The N-P Scattering Cross Section From 90 Kev To 1.8 Mev, Hongwei Yang

Theses and Dissertations--Physics and Astronomy

There have been very few measurements of the total cross section for n-p scattering below 500 keV. In order to differentiate among NN potential models, improved cross section data between 20 and 600 keV are required. We measured the n-p and n-C total cross sections in this energy region by transmission; a collimated neutron beam was passed through CH₂ and C samples and transmitted neutrons were detected by a BC-501A deuterated liquid scintillator. Cross sections were obtained by taking the ratios of normalized neutron yields with the samples in the beam and with no sample in the beam. Both …

A Measurement Of The Prompt Fission Neutron Energy Spectrum For 235U(N,F) And The Neutron-Induced Fission Cross Section For 238U(N,F), Zachariah W. Miller

Theses and Dissertations--Physics and Astronomy

Two measurements have been made, addressing gaps in knowledge for ²³⁵U(n,f) and ²³⁸U(n,f). The energy distribution for prompt fission neutrons is not well-understood below 1 MeV in ²³⁵U(n,f). To measure the ²³⁵U(n,f) prompt fission neutron distribution, a pulsed neutron beam at the WNR facility in Los Alamos National Laboratory was directed onto a ²³⁵U target with neutron detectors placed 1 m from the target. These neutron detectors were designed specifically for this experiment and employed a unique geometry of scintillating plastic material that was designed to reject backgrounds. Fission fragments were detected using an avalanche …

An Analysis Of The Parity Violating Asymmetry Of Polarized Neutron Capture In Hydrogen From The Npdgamma Experiment, Elise Tang

Theses and Dissertations--Physics and Astronomy

The NPDGamma Experiment is used to study the n + p to d + g reaction for the purpose of examining the hadronic weak interaction. The nucleon-nucleon interaction is overwhelmingly mediated by the strong force, however, the weak part can be extracted by a study of its parity violating manifestations. When neutrons are incident on protons, deuterons and 2.2 MeV gamma rays are produced. If the incoming neutrons are polarized, the parity violating weak interaction gives rise to a measured spatial asymmetry, A_g, in the outgoing gamma rays, as s_n · k_g is parity odd.

At …

The Dijet Cross Section Measurement In Proton-Proton Collisions At A Center Of Mass Energy Of 500 Gev At Star, Grant D. Webb

Theses and Dissertations--Physics and Astronomy

Polarized deep inelastic scattering experiments play a vital role in the exploration of the spin structure of the proton. The polarized proton-proton collider at RHIC provides direct access to the gluon spin distribution through longitudinal double spin asymmetry measurements of inclusive jets, pions, and dijets. This thesis presents the measurement of the dijet double differential cross-section in proton-proton collisions at center of mass energies of √s = 500 GeV. The data represent an integrated luminosity of 8.7 pb^-1 recorded by the STAR detector during the 2009 RHIC run. A comprehensive jet analysis was performed to determine the ideal …

Nuclear Structure Relevant To Double-Beta Decay: Studies Of ⁷⁶Ge And ⁷⁶Se Using Inelastic Neutron Scattering, Benjamin P. Crider

Theses and Dissertations--Physics and Astronomy

While neutrino oscillations indicate that neutrino flavors mix and that neutrinos have mass, they do not supply information on the absolute mass scale of the three flavors of neutrinos. Currently, the only viable way to determine this mass scale is through the observation of the theoretically predicted process of neutrinoless double-beta decay (0νββ). This yet-to-be-observed decay process is speculated to occur in a handful of nuclei and has predicted half-lives greater than 10²⁵ years. Observation of 0νββ is the goal of several large-scale, multinational efforts and consists of detecting a sharp peak in the summed β energies at the Q-value …

Investigation Of Spin-Independent Cp Violation In Neutron And Nuclear Radiative Β Decays, Daheng He

Theses and Dissertations--Physics and Astronomy

CP violation is an important condition to explain the preponderance of baryons in our universe, yet the available CP violation in the Standard Model (SM) via the so-called Cabibbo-Kobayashi-Maskawa mechanism seems to not provide enough CP violation. Thus searching for new sources of CP violation is one of the central tasks of modern physics. In this thesis, we focus on a new possible source of CP violation which generates triple-product correlations in momenta which can appear in neutron and nuclear radiative β decay. We show that at low energies such a CP violating correlation may arise from the exotic coupling …