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2010

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Articles 1 - 30 of 939

Full-Text Articles in Physics

Measurement Of Single- And Double-Spin Asymmetries In Deep Inelastic Pion Electroproduction With A Longitudinally Polarized Target, H. Avakian, Gerard P. Gilfoyle, Et. Al. Dec 2010

Measurement Of Single- And Double-Spin Asymmetries In Deep Inelastic Pion Electroproduction With A Longitudinally Polarized Target, H. Avakian, Gerard P. Gilfoyle, Et. Al.

Physics Faculty Publications

We report the first measurement of the transverse momentum dependence of double-spin asymmetries in semi-inclusive production of pions in deep-inelastic scattering off the longitudinally polarized proton. Data have been obtained using a polarized electron beam of 5.7 GeV with the CLAS detector at the Jefferson Lab (JLab). Modulations of single spin asymmetries over the azimuthal angle between lepton scattering and hadron production planes φ have been measured over a wide kinematic range in Bjorken x and virtual photon squared four-momentum Q2. A significant nonzero sin2φ single spin asymmetry was observed for the first time indicating strong spin-orbit …

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ϒ(1s)→Γf'2(1525); F'2(1525)->K0sk0s Decays, Raymond Mountain, Marina Artuso, T. Skwarnicki, S. Stone Dec 2010

ϒ(1s)→Γf'2(1525); F'2(1525)->K0sk0s Decays, Raymond Mountain, Marina Artuso, T. Skwarnicki, S. Stone

Physics - All Scholarship

We report on a study of exclusive radiative decays of the Upsilon(1S) resonance into a final state consisting of a photon and two K0s candidates. We find evidence for a signal for Upsilon(1S)->gamma f_2'(1525); f_2'(1525)->K0sK0s, at a rate (4.0+/-1.3+/-0.6)x10^{-5}, consistent with previous observations of Upsilon(1S)->gamma f_2'(1525); f_2'(1525)->K+K-, and isospin. Combining this branching fraction with existing branching fraction measurements of Upsilon(1S)->gamma f_2'(1525) and J/psi->gamma f_2'(1525), we obtain the ratio of branching fractions: B(Upsilon(1S)->gamma f_2'(1525))/B(J/psi->gamma f_2'(1525))=0.09+/-0.02, approximately consistent with expectations based on soft collinear effective theory.

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Measurements Of The Electric Form Factor Of The Neutron Up To Q(2)=3.4 Gev2 Using The Reaction (3)(He)Over-Right-Arrowe((E)Over-Right-Arrow, E ' N)Pp, S. Riordan, Timothy Holmstrom Dec 2010

Measurements Of The Electric Form Factor Of The Neutron Up To Q(2)=3.4 Gev2 Using The Reaction (3)(He)Over-Right-Arrowe((E)Over-Right-Arrow, E ' N)Pp, S. Riordan, Timothy Holmstrom

Chemistry & Physics Faculty Publications

The electric form factor of the neutron was determined from studies of the reaction 3He⃗(e⃗,e′n)pp in quasielastic kinematics in Hall A at Jefferson Lab. Longitudinally polarized electrons were scattered off a polarized target in which the nuclear polarization was oriented perpendicular to the momentum transfer. The scattered electrons were detected in a magnetic spectrometer in coincidence with neutrons that were registered in a large-solid-angle detector. More than doubling the Q2 range over which it is known, we find GEn=0.0236±0.0017(stat)±0.0026(syst), 0.0208±0.0024±0.0019, and 0.0147±0.0020±0.0014 for Q2=1.72, 2.48, and 3.41  GeV2, respectively.

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Upsilon(1s)->Gamma+F2'(1525); F2'(1525)->K0sk0s Decays, Raymond Mountain, Marina Artuso, S. Blusk, T. Skwarnicki Dec 2010

Upsilon(1s)->Gamma+F2'(1525); F2'(1525)->K0sk0s Decays, Raymond Mountain, Marina Artuso, S. Blusk, T. Skwarnicki

Physics - All Scholarship

We report on a study of exclusive radiative decays of the Upsilon(1S) resonance into a final state consisting of a photon and two K0s candidates. We find evidence for a signal for Upsilon(1S)->gamma f_2'(1525); f_2'(1525)->K0sK0s, at a rate (4.0+/-1.3+/-0.6)x10^{-5}, consistent with previous observations of Upsilon(1S)->gamma f_2'(1525); f_2'(1525)->K+K-, and isospin. Combining this branching fraction with existing branching fraction measurements of Upsilon(1S)->gamma f_2'(1525) and J/psi->gamma f_2'(1525), we obtain the ratio of branching fractions: B(Upsilon(1S)->gamma f_2'(1525))/B(J/psi->gamma f_2'(1525))=0.09+/-0.02, approximately consistent with expectations based on soft collinear effective theory.

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Next-To-Next-To-Leading Soft-Gluon Corrections For The Top Quark Cross Section And Transverse Momentum Distribution, Nikolaos Kidonakis Dec 2010

Next-To-Next-To-Leading Soft-Gluon Corrections For The Top Quark Cross Section And Transverse Momentum Distribution, Nikolaos Kidonakis

Faculty Articles

I present results for top quark production in hadronic collisions at LHC and Tevatron energies. The soft-gluon corrections to the differential cross section are resummed at next-to-next-to-leading-logarithm accuracy via the two-loop soft anomalous dimension matrices. Approximate next-to-next-to-leading-order differential and total cross sections are calculated. Detailed theoretical predictions are shown for the t (t) over bar cross section and the top quark p(T) distribution at the Tevatron and the LHC.

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Comparative Study Of Field Enhancement Between Isolated And Coupled Metal Nanoparticles: An Analytical Approach, Greg Sun, Jacob B. Khurgin Dec 2010

Comparative Study Of Field Enhancement Between Isolated And Coupled Metal Nanoparticles: An Analytical Approach, Greg Sun, Jacob B. Khurgin

Physics Faculty Publications

We present an analytical model that takes into account the coupling between the surface plasmon modes in complex metal nanostructures. We apply this model to evaluate the field enhancement in the gap of two coupled Au metal spheres embedded in GaN dielectric and compare the result with that obtained by the single sphere. The results show additional improvement can be obtained in the gap depending on the width of the gap. This approach offers a clear physical insight for the enhancement and a straightforward method for optimization.

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Coherent Heteroepitaxy Of Bi2se3 On Gaas (111)B, Anthony Richardella, Duming M. Zhang, Joon S. Lee, Alison E. Patteson (Koser), David W. Rench, Andrew L. Yeats, Bob B. Buckley, David D. Awschalom, Nitin Samarth Dec 2010

Coherent Heteroepitaxy Of Bi2se3 On Gaas (111)B, Anthony Richardella, Duming M. Zhang, Joon S. Lee, Alison E. Patteson (Koser), David W. Rench, Andrew L. Yeats, Bob B. Buckley, David D. Awschalom, Nitin Samarth

Physics - All Scholarship

We report the heteroepitaxy of single crystal thin films of Bi2Se3 on the (111)B surface of GaAs by molecular beam epitaxy. We find that Bi2Se3 grows highly c-axis oriented, with an atomically sharp interface with the GaAs substrate. By optimizing the growth of a very thin GaAs buffer layer before growing the ⁠Bi2Se3, we demonstrate the growth of thin films with atomically flat terraces over hundreds of nanometers. Initial time-resolved Kerr rotation measurements herald opportunities for probing coherent spin dynamics at the interface between a candidate topological insulator and a large class of GaAs-based heterostructures.

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D-Dimensional Bose Gases And The Lambert W Function, Sree Ram Valluri, J Tanguay, M Gil, D J. Jeffrey Dec 2010

D-Dimensional Bose Gases And The Lambert W Function, Sree Ram Valluri, J Tanguay, M Gil, D J. Jeffrey

Physics and Astronomy Publications

The applications of the Lambert W function (also known as the W function) to D-dimensional Bose gases are presented. We introduce two sets of families of logarithmic transcendental equations that occur frequently in thermodynamics and statistical mechanics and present their solution in terms of the W function. The low temperature T behavior of free ideal Bose gases is considered in three and four dimensions. It is shown that near condensation in four dimensions, the chemical potential μ and pressure P can be expressed in terms of T through the W function. The low T behavior of one- and two-dimensional ideal …

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Detecting Electron Motion In Atoms And Molecules, Hua-Chieh Shao, Anthony F. Starace Dec 2010

Detecting Electron Motion In Atoms And Molecules, Hua-Chieh Shao, Anthony F. Starace

Anthony F. Starace Publications

The detection of spatial and temporal electronic motion by scattering of subfemtosecond pulses of 10 keV electrons from coherent superpositions of electronic states of both H and T+2 is investigated. For the H atom, we predict changes in the diffraction images that reflect the time-dependent effective radius of the electronic charge density. For an aligned T+2 molecule, the diffraction image changes reflect the time-dependent localization or delocalization of the electronic charge density.

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Unl Physicists Model Potential 4-D Imaging Technique, Tom Simons, Hua-Chieh Shao, Anthony F. Starace Dec 2010

Unl Physicists Model Potential 4-D Imaging Technique, Tom Simons, Hua-Chieh Shao, Anthony F. Starace

Anthony F. Starace Publications

A long-standing goal of science is to be able to understand how matter behaves at the atomic and subatomic level. How electrons rearrange when atoms or molecules come together is the essence of chemistry, and the ability to manipulate those rearrangements is the goal of the emerging sphere of nanotechnology. A fuller understanding could lead to enormous scientific and technological breakthroughs. Unfortunately, significant problems confront scientists and engineers in attacking the question. Not only are atoms and molecules very small, requiring highly specialized equipment to "see" them, everything at the atomic level happens very, very fast. For example, an electron …

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Does Entropic Gravity Bound The Masses Of The Photon And Graviton?, Jonas R. Mureika, R. B. Mann Dec 2010

Does Entropic Gravity Bound The Masses Of The Photon And Graviton?, Jonas R. Mureika, R. B. Mann

Physics Faculty Works

If the information transfer between test particle and holographic screen in entropic gravity respects both the uncertainty principle and causality, a lower limit on the number of bits in the universe relative to its mass may be derived. Furthermore, these limits indicate particles that putatively travel at the speed of light -- the photon and/or graviton -- have a non-zero mass m≥10−68 kg. This result is found to be in excellent agreement with current experimental mass bounds on the graviton and photon, suggesting that entropic gravity may be the result of a (recent) softly-broken local symmetry. Stronger bounds emerge …

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Crystalline Order On Catenoidal Capillary Bridges, Mark Bowick, Zhenwei Yao Dec 2010

Crystalline Order On Catenoidal Capillary Bridges, Mark Bowick, Zhenwei Yao

Physics - All Scholarship

We study the defect structure of crystalline particle arrays on negative Gaussian curvature capillary bridges with vanishing mean curvature (catenoids). The threshold aspect ratio for the appearance of isolated disclinations is found and the optimal positions for dislocations determined. We also discuss the transition from isolated disclinations to scars as particle number and aspect ratio are varied.

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Crystalline Order On Catenoidal Capillary Bridges, Mark Bowick, Zhenwei Yao Dec 2010

Crystalline Order On Catenoidal Capillary Bridges, Mark Bowick, Zhenwei Yao

Physics - All Scholarship

We study the defect structure of crystalline particle arrays on negative Gaussian curvature capillary bridges with vanishing mean curvature (catenoids). The threshold aspect ratio for the appearance of isolated disclinations is found and the optimal positions for dislocations determined. We also discuss the transition from isolated disclinations to scars as particle number and aspect ratio are varied.

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Metastable Anions Of Dinitrobenzene: Resonances For Electron Attachment And Kinetic Energy Release, A. Mauracher, S. Denifl, A. Edtbauer, M. Hager, M. Probst, Olof E. Echt, T. D. Maerk, P. Scheier, T. A. Field, K. Graupner Dec 2010

Metastable Anions Of Dinitrobenzene: Resonances For Electron Attachment And Kinetic Energy Release, A. Mauracher, S. Denifl, A. Edtbauer, M. Hager, M. Probst, Olof E. Echt, T. D. Maerk, P. Scheier, T. A. Field, K. Graupner

Physics & Astronomy

Attachment of free, low-energy electrons to dinitrobenzene (DNB) in the gas phase leads to DNB as well as several fragment anions. DNB, (DNB-H), (DNB-NO), (DNB-2NO), and (DNB-NO(2)) are found to undergo metastable (unimolecular) dissociation. A rich pattern of resonances in the yield of these metastable reactions versus electron energy is observed; some resonances are highly isomer-specific. Most metastable reactions are accompanied by large average kinetic energy releases (KER) that range from 0.5 to 1.32 eV, typical of complex rearrangement reactions, but (1,3-DNB-H)(-) features a resonance with a KER of only 0.06 eV for loss of NO. (1,3-DNB-NO)(-) offers a rare …

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Precision Frequency Measurements With Interferometric Weak Values, David J. Starling, P. Ben Dixon, Andrew N. Jordan, John C. Howell Dec 2010

Precision Frequency Measurements With Interferometric Weak Values, David J. Starling, P. Ben Dixon, Andrew N. Jordan, John C. Howell

Mathematics, Physics, and Computer Science Faculty Articles and Research

We demonstrate an experiment which utilizes a Sagnac interferometer to measure a change in optical frequency of 129 ± 7 kHz/√Hz with only 2 mW of continuous-wave, single-mode input power. We describe the measurement of a weak value and show how even higher-frequency sensitivities may be obtained over a bandwidth of several nanometers. This technique has many possible applications, such as precision relative frequency measurements and laser locking without the use of atomic lines.

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Implementation Of The Clas12 Htcc Into Gemc, Nathan A. Harrison Dec 2010

Implementation Of The Clas12 Htcc Into Gemc, Nathan A. Harrison

Master's Theses

No abstract provided.

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Movies Of Electrons In Atoms, Michael Schirber, Hua-Chieh Shao, Anthony F. Starace Dec 2010

Movies Of Electrons In Atoms, Michael Schirber, Hua-Chieh Shao, Anthony F. Starace

Anthony F. Starace Publications

Physicists have long been able to snap atomic-scale pictures by shining a beam of electrons at a target, but filming the electronic structure of an atom as it changes in time is the next goal. A rapid "strobing" of electron pulses less than a millionth of a billionth of a second long should do the trick, according to a theoretical analysis in the 24 December Physical Review Letters. The authors demonstrate with computer simulations that ultrafast electron pulses could track the "breathing" state of an excited atom or the hopping of electrons between atoms in a molecule. Such movies open …

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Parity Violation In The N + 3he → 3h + P Reaction: Resonance Approach, Vladimir Gudkov Dec 2010

Parity Violation In The N + 3he → 3h + P Reaction: Resonance Approach, Vladimir Gudkov

Faculty Publications

The method based on microscopic theory of nuclear reactions has been applied for the analysis of parityviolatingeffects in few-body systems. Different parity-violating and parity-conserving asymmetries and theirdependence on neutron energy have been estimated for the n + 3He → 3H + p reaction. The estimated effectsare in a good agreement with available exact calculations.

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Chaos And Universality In Two-Dimensional Ising Spin Glasses, Alan Middleton, Creighton K. Thomas, David A. Huse Dec 2010

Chaos And Universality In Two-Dimensional Ising Spin Glasses, Alan Middleton, Creighton K. Thomas, David A. Huse

Physics - All Scholarship

Recently extended precise numerical methods and droplet scaling arguments allow for a coherent picture of the glassy states of two-dimensional Ising spin glasses to be assembled. The length scale at which entropy becomes important and produces "chaos", the extreme sensitivity of the state to temperature, is found to depend on the type of randomness. For the $\pm J$ model this length scale dominates the low-temperature specific heat. Although there is a type of universality, some critical exponents do depend on the distribution of disorder.

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Pauli Spin Blockade And Lifetime-Enhanced Transport In A Si/Sige Double Quantum Dot, C. B. Simmons, Teck Seng Koh, Nakul Shaji, Madhu Thalakulam, L. J. Klein, Hua Qin, H. Luo, D. E. Savage, M. G. Lagally, A. J. Rimberg Dec 2010

Pauli Spin Blockade And Lifetime-Enhanced Transport In A Si/Sige Double Quantum Dot, C. B. Simmons, Teck Seng Koh, Nakul Shaji, Madhu Thalakulam, L. J. Klein, Hua Qin, H. Luo, D. E. Savage, M. G. Lagally, A. J. Rimberg

Dartmouth Scholarship

We analyze electron-transport data through a Si/SiGe double quantum dot in terms of spin blockade and lifetime-enhanced transport (LET), which is transport through excited states that is enabled by long spin-relaxation times. We present a series of low-bias voltage measurements showing the sudden appearance of a strong tail of current that we argue is an unambiguous signature of LET appearing when the bias voltage becomes greater than the singlet-triplet splitting for the (2,0) electron state. We present eight independent data sets, four in the forward-bias (spin-blockade) regime and four in the reverse-bias (lifetime-enhanced transport) regime and show that all eight …

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Do Cosmological Perturbations Have Zero Mean?, Christian Armendariz-Picon Dec 2010

Do Cosmological Perturbations Have Zero Mean?, Christian Armendariz-Picon

Physics - All Scholarship

A central assumption in our analysis of cosmic structure is that cosmological perturbations have zero ensemble mean. This property is one of the consequences of statistically homogeneity, the invariance of correlation functions under spatial translations. In this article we explore whether cosmological perturbations indeed have zero mean, and thus test one aspect of statistical homogeneity. We carry out a classical test of the zero mean hypothesis against a class of alternatives in which perturbations have non-vanishing means, but homogeneous and isotropic covariances. Apart from Gaussianity, our test does not make any additional assumptions about the nature of the perturbations and …

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Uncertainty Associated With Modeling The Global Ionosphere, Janelle V. Jenniges, Ariel O. Acebal, Larry Gardner, Robert W. Schunk, Lie Zhu Dec 2010

Uncertainty Associated With Modeling The Global Ionosphere, Janelle V. Jenniges, Ariel O. Acebal, Larry Gardner, Robert W. Schunk, Lie Zhu

Physics Student Research

A study has been conducted of the effect that different physical assumptions have on global models of the electron density distribution. The study was conducted with the Ionosphere Forecast Model (IFM) and the Ionosphere Plasmasphere Model (IPM) developed by Utah State University. Both physics-based, time-dependent, global models use the same empirical models for the neutral atmosphere (MSIS) and neutral wind (Horizontal Wind Model, HWM), but the altitude range, thermal structure, number of ion species, and magnetic 2ield are different. The IFM covers the altitude range from 90-1400 km, calculates the densities for four ions (NO+, O2+, N2+, O+), has a …

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Nanoparticle Doped Photopolymer With Reduced Shrinkage For Holographic Recording, Mohesh Moothanchery, Svetlana Mintova, Izabela Naydenova, Vincent Toal Dec 2010

Nanoparticle Doped Photopolymer With Reduced Shrinkage For Holographic Recording, Mohesh Moothanchery, Svetlana Mintova, Izabela Naydenova, Vincent Toal

Conference Papers

We demonstrate holographic recording with Si-MFI zeolite doped acrylamide based photopolymerfilm. The influence of silicate nanoparticles on photopolymer shrinkage has been studied and compared withshrinkage in undoped photopolymer layers The shrinkage of the material (1.03%) is significantly lower forrecording in Si-MFI zeolite nanoparticle doped samples than for undoped layers (1.77%).

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Tunable Optical Delay In Doppler-Broadened Cesium Vapor, Monte D. Anderson Dec 2010

Tunable Optical Delay In Doppler-Broadened Cesium Vapor, Monte D. Anderson

Theses and Dissertations

Variable-delay tunable optical delay line or optical buffers are critical for the development of all-optical networks components as well as interferometry and analytic instruments. Recent research on slow light may hold the key for the development of the first practical tunable optical delay device. In this research the linear dispersion delay effects in an alkali vapor. The hyperfine relaxation observations present insight into the complex bleach wave dynamics during a high-intensity pulsed pump in DPAL systems.

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Equation Of State Of A Dense And Magnetized Fermion System, Efrain J. Ferrer, Vivian De La Incera, Jason P. Keith, Israel Portillo, Paul L. Springsteen Dec 2010

Equation Of State Of A Dense And Magnetized Fermion System, Efrain J. Ferrer, Vivian De La Incera, Jason P. Keith, Israel Portillo, Paul L. Springsteen

Physics & Astronomy Faculty Publications

The equation of state of a system of fermions in a uniform magnetic field is obtained in terms of the thermodynamic quantities of the theory by using functional methods. It is shown that the breaking of the O(3) rotational symmetry by the magnetic field results in a pressure anisotropy, which leads to the distinction between longitudinal- and transverse-to-the-field pressures. A criterion to find the threshold field at which the asymmetric regime becomes significant is discussed. This threshold magnetic field is shown to be the same as the one required for the pure field contribution to the energy and pressures to …

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Erratum: Scaled Momentum Spectra In Deep Inelastic Scattering At Hera (Journal Of High Energy Physics (2010) 06 (009)), H. Abramowicz, I. Abt, L. Adamczyk, M. Adamus, S. Antonelli, P. Antonioli, A. Antonov, M. Arneodo, V. Aushev, Y. Aushev, O. Bachynska, A. Bamberger, A. N. Barakbaev, G. Barbagli, G. Bari, F. Barreiro, D. Bartsch, M. Basile, O. Behnke, J. Behr, U. Behrens, L. Bellagamba, A. Bertolin, S. Bhadra, M. Bindi, C. Blohm, T. Bołd, E. G. Boos, M. Borodin, K. Borras, D. Boscherini, Margarita C. K. Mattingly Dec 2010

Erratum: Scaled Momentum Spectra In Deep Inelastic Scattering At Hera (Journal Of High Energy Physics (2010) 06 (009)), H. Abramowicz, I. Abt, L. Adamczyk, M. Adamus, S. Antonelli, P. Antonioli, A. Antonov, M. Arneodo, V. Aushev, Y. Aushev, O. Bachynska, A. Bamberger, A. N. Barakbaev, G. Barbagli, G. Bari, F. Barreiro, D. Bartsch, M. Basile, O. Behnke, J. Behr, U. Behrens, L. Bellagamba, A. Bertolin, S. Bhadra, M. Bindi, C. Blohm, T. Bołd, E. G. Boos, M. Borodin, K. Borras, D. Boscherini, Margarita C. K. Mattingly

Faculty Publications

No abstract provided.

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Global Dimension Of Ci: Compete Or Collaborate, Arden L. Bement Jr. Dec 2010

Global Dimension Of Ci: Compete Or Collaborate, Arden L. Bement Jr.

PPRI Digital Library

No abstract provided.

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Information-Preserving Structures: A General Framework For Quantum Zero-Error Information, Robin Blume-Kohout, Hui Khoon Ng, David Poulin, Lorenza Viola Dec 2010

Information-Preserving Structures: A General Framework For Quantum Zero-Error Information, Robin Blume-Kohout, Hui Khoon Ng, David Poulin, Lorenza Viola

Dartmouth Scholarship

Quantum systems carry information. Quantum theory supports at least two distinct kinds of information (classical and quantum), and a variety of different ways to encode and preserve information in physical systems. A system’s ability to carry information is constrained and defined by the noise in its dynamics. This paper introduces an operational framework, using information-preserving structures, to classify all the kinds of information that can be perfectly (i.e., with zero error) preserved by quantum dynamics. We prove that every perfectly preserved code has the same structure as a matrix algebra, and that preserved information can always be corrected. We …

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Source Attribution Of Ozone In Southeast Texas Before And After The Deepwater Horizon Accident Using Satellite, Sonde, Surface Monitor, And Air Mass Trajectory Data, Gary A. Morris, Barry Lefer, Bernhard Rappenglueck, Christine Haman, Marc Taylor, Mark R. Schoeberl Dec 2010

Source Attribution Of Ozone In Southeast Texas Before And After The Deepwater Horizon Accident Using Satellite, Sonde, Surface Monitor, And Air Mass Trajectory Data, Gary A. Morris, Barry Lefer, Bernhard Rappenglueck, Christine Haman, Marc Taylor, Mark R. Schoeberl

Physics and Astronomy Faculty Presentations

Since the summer of 2004, over 300 ozonesondes have been launched from Rice University (29.7 N, 95.4 W) or the University of Houston (29.7 N, 95.3 W), each < 5 km from downtown Houston. The Texas Commission on Environmental Quality maintains a large database of hourly surface ozone observations in Southeast Texas. In this study, we identify the contributions to surface ozone pollution levels from natural and anthropogenic sources, both local and remote in nature. This source identification is performed two ways: 1) through an analysis of sonde data, including ozone concentrations, wind speed and direction, and relative humidity data, and 2) through an analysis that combines trajectory calculations with surface monitor data. We also examine regional changes in Ozone Monitoring Instrument (OMI) measurements of formaldehyde and ozone from 2004 – 2010. In particular, we compare the 2010 sonde, surface monitor, and satellite data after the Deepwater Horizon accident with data from previous years to determine the impact, if any, of the large source of hydrocarbons in the Gulf of Mexico on air quality in Southeast Texas.

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Doppler-Broadening Of Light Nuclei Gamma-Ray Spectra, Melinda D. Whitfield Dec 2010

Doppler-Broadening Of Light Nuclei Gamma-Ray Spectra, Melinda D. Whitfield

Masters Theses & Specialist Projects

Non-destructive methods of material interrogation are used to locate hidden explosives and thwart terrorism attempts. In one such method materials are bombarded with neutrons which react with the nuclei of the atoms within causing a de-excitation process emitting a gamma-ray. The spectrum displayed by the collection of these gamma-rays gives valuable information regarding the material’s elemental make-up. It has been hypothesized that gamma-rays from neutron-induced gamma-ray reactions on light elements with atomic numbers less than 20, including most of the gamma-rays of interest in explosives detection, are Doppler-broadened. This thesis focuses on the gamma ray spectra from the 4438 keV …

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