Physics Commons^™

Development Of Dose Conversion Coefficients For Radionuclides Produced In Spallation Neutron Sources: Quarterly Progress Report 9/1/04 – 12/31/04, Phillip W. Patton, Mark Rudin

Transmutation Sciences Physics (TRP)

The research consortium comprised of representatives from several universities and national laboratories has successfully generated internal and external dose conversion coefficients for twenty radionuclides produced in spallation neutron sources. In addition, the group has identified twenty radionuclide that are missing electron capture files and eighteen additional radionuclides missing substantial physical data.

Tidal Perturbations And Variability In Mesopause Region Over Fort Collins, Co(41n, 105w): Continuous Multi-Day Temperature And Wind Lidar Observations, C. Y. She, T. Li, R. L. Collins, Tao Yuan, B. P. Williams, T. Kawahara, J. D. Vance, P. Acott, D. A. Krueger, H. L. Liu, M. E. Hagan

All Physics Faculty Publications

An unusually long data set was acquired at the sodium lidar facility at Colorado State University (41N, 105W), between Sep 18 and Oct 01, 2003, including a 9-day continuous observation. This time is long enough to average out the perturbations of gravity waves and short-period planetary waves. As such, it can be used to define tidal-period perturbations in temperature and horizontal wind. Assuming the sodium mixing ratio is a constant of motion, the observed tidal-period oscillation in sodium density follows that of vertical wind. Thus, the data set defines tidal-period perturbations of temperature and wind vector. The observed amplitudes and …

Leptonic Cp Violation In A Two Parameter Model, Joseph Schechter, Samina S. Masood, Salah Nasri

Physics - All Scholarship

We further study the "complementary" Ansatz, Tr(M_\nu)=0, for a prediagonal light Majorana type neutrino mass matrix. Previously, this was studied for the CP conserving case and the case where the two Majorana type CP violating phases were present but the Dirac type CP violating phase was neglected. Here we employ a simple geometric algorithm which enables us to "solve" the Ansatz including all three CP violating phases. Specifically, given the known neutrino oscillation data and an assumed two parameter (the third neutrino mass m_3 and the Dirac CP phase \delta) family of inputs we predict the neutrino masses and Majorana …

Exploring The Optimal Sensitivity Of Sum-Variance Nonseparability Criteria For Spin-1/2 Systems, Irfan Ali Khan, John C. Howell

Mathematics, Physics, and Computer Science Faculty Articles and Research

We report on experimental and theoretical studies on recently introduced entanglement measures which use a sum of spin-variance criteria for two spin-1∕2 particles. Three inequalities are explored which exhibit useful concatenating properties. They are each shown to have greater sensitivities than a Bell’s measurement, while each requiring fewer measurements than a Bell’s measurement to obtain. The simplest inequality, requiring just four measurements, is shown to be efficient at testing for entanglement in down-conversion sources which naturally exhibit maximally polarized noise. The most complex inequality, requiring just 12 measurements, is shown to have a sensitivity equal to that of the Peres …

Pseudorapidity Asymmetry And Centrality Dependence Of Charged Hadron Spectra In D+Au Collisions At √SNn=200 Gev, Star Collaboration, T.D. Gutierrez

Physics

The pseudorapidity asymmetry and centrality dependence of charged hadron spectra in d+Au collisions at √s_NN=200 GeV are presented. The charged particle density at midrapidity, its pseudorapidity asymmetry, and centrality dependence are reasonably reproduced by a multiphase transport model, by HIJING, and by the latest calculations in a saturation model. Ratios of transverse momentum spectra between backward and forward pseudorapidity are above unity for p_T below 5GeV ∕ c. The ratio of central to peripheral spectra in d+Au collisions shows enhancement at 2 < p_T < 6GeV ∕ c, with a larger effect at backward rapidity than forward rapidity. Our measurements are in qualitative agreement with gluon saturation and in contrast to calculations based on incoherent multiple partonic scatterings.

Fixed-Connectivity Membranes, Mark Bowick

Physics - All Scholarship

The statistical mechanics of flexible surfaces with internal elasticity and shape fluctuations is summarized. Phantom and self-avoiding isotropic and anisotropic membranes are discussed, with emphasis on the universal negative Poisson ratio common to the low-temperature phase of phantom membranes and all strictly self-avoiding membranes in the absence of attractive interactions. The study of crystalline order on the frozen surface of spherical membranes is also treated.

Scattering Of Low- To Intermediate-Energy Positrons From Molecular Hydrogen, David D. Reid, William B. Klann, J. M. Wadehra

Physics and Astronomy Faculty Research Publications

Using a complex model potential, we have calculated the total, integrated elastic, momentum transfer, absorption, and differential cross sections for positrons scattered from molecular hydrogen. The widely available software package GAUSSIAN is used to generate the radial electronic charge density of the molecule which is used to produce the interaction potentials. The quasifree absorption potential, previously developed and used for positron-atom scattering, is extended to positron scattering from molecular targets. It is shown that this model potential approach produces accurate results even into the low-energy regime.

Magnetoelectronics With Magnetoelectrics, Christian Binek, Bernard Doudin

Christian Binek Publications

Magnetoelectric films are proposed as key components for spintronic applications. The net magnetic moment created by an electric field in a magnetoelectric thin film influences the magnetization state of a neighbouring ferromagnetic layer through exchange coupling. Pure electrical control of magnetic confi gurations of giant magnetoresistance spin valves and tunnelling magnetoresistance elements is therefore achievable. Estimates based on documented magnetoelectric tensor values show that exchange fields reaching 100 mT can be obtained. We propose a mechanism alternative to current-induced magnetization switching, providing access to a wide range of device impedance values and opening the possibility of simple logic functions.

An Informatics Search For The Low-Molecular Weight Chromium-Binding Peptide, Deendayal Dinakarpandian, Vincent Morrissette, Shveta Chaudhary, Kambiz Amini, Brian Bennett, J David Van Horn

Physics Faculty Research and Publications

Background

The amino acid composition of a low molecular weight chromium binding peptide (LMWCr), isolated from bovine liver, is reportedly E:G:C:D::4:2:2:2, though its sequence has not been discovered. There is some controversy surrounding the exact biochemical forms and the action of Cr(III) in biological systems; the topic has been the subject of many experimental reports and continues to be investigated. Clarification of Cr-protein interactions will further understanding Cr(III) biochemistry and provide a basis for novel therapies based on metallocomplexes or small molecules.

Results

A genomic search of the non-redundant database for all possible decapeptides of the reported composition yields three …

Azimuthal Anisotropy And Correlations At Large Transverse Momenta In P+P And Au+Au Collisions At √SNn=200 Gev, Star Collaboration, T.D. Gutierrez

Physics

Results on high transverse momentum charged particle emission with respect to the reaction plane are presented for Au+Au collisions at √s_NN=200  GeV. Two- and four-particle correlations results are presented as well as a comparison of azimuthal correlations in Au+Au collisions to those in p+p at the same energy. The elliptic anisotropy v₂ is found to reach its maximum at pt∼3  GeV/c, then decrease slowly and remain significant up to p_t≈7–10  GeV/c. Stronger suppression is found in the back-to-back high-p_t particle correlations for particles emitted out of plane compared to those emitted in plane. The …

Optimal Cooling Strategies For Magnetically Trapped Atomic Fermi-Bose Mixtures, Michael Brown-Hayes, Roberto Onofrio

Dartmouth Scholarship

We discuss cooling efficiency for different-species Fermi-Bose mixtures in magnetic traps. A better heat capacity matching between the two atomic species is achieved by a proper choice of the Bose cooler and the magnetically trappable hyperfine states of the mixture. When a partial spatial overlap between the two species is also taken into account, the deepest Fermi degeneracy is obtained for an optimal value of the trapping frequency ratio between the two species. This can be achieved by assisting the magnetic trap with a deconfining light beam, as shown in the case of fermionic 6Li mixed with 23Na, 87Rb, and …

Medical Image Processing Using Transient Fourier Holography In Bacteriorhodopsin Films, Sri-Rajasekhar Kothapalli, Pengfei Wu, Chandra S. Yelleswarapu, D.V.G.L.N. Rao

Physics Faculty Publications

Real time image processing is demonstrated by recording and reconstructing the transient photoisomerizative grating formed in the bR film using Fourier holography. Desired spatial frequencies including both high and low band in the object beam are reconstructed by controlling the reference beam intensity. The results are in agreement with a theoretical model based on photoisomerization grating. We exploit this technique to process mammograms in real-time for identification of microcalcifications buried in the soft tissue for early detection of breast cancer. A feature of the technique is the ability to transient display of selected spatial frequencies in the reconstructing process which …

The Strange Physics Of Low Frequency Mirror Mode Turbulence In The High Temperature Plasma Of The Magnetosheath, R. A. Treumann, C. H. Jaroschek, O. D. Constantinescu, R. Nakamura

Dartmouth Scholarship

Mirror mode turbulence is the lowest frequency perpendicular magnetic excitation in magnetized plasma proposed already about half a century ago by Rudakov and Sagdeev (1958) and Chandrasekhar et al. (1958) from fluid theory. Its experimental verification required a relatively long time. It was early recognized that mirror modes for being excited require a transverse pressure (or temperature) anisotropy. In principle mirror modes are some version of slow mode waves. Fluid theory, however, does not give a correct physical picture of the mirror mode. The linear infinitesimally small amplitude physics is described correctly only by including the full kinetic theory and …

Comparisons Of Long-Term Trends And Variability In The Middle Atmosphere, Troy Wynn, Joshua P. Herron, Vincent B. Wickwar

Posters

The USU Rayleigh Lidar (41.74°N 111.81°W) has been regularly used to measure temperatures in the middle atmosphere from 45 to 90 km. It is well suited for nightly observation; provides excellent vertical temperature resolution; and does not need external calibration. It began operation in August 1993 and a dataset spanning more than ten years has been collected. The analysis here includes 593 nightly temperature profiles from September 1993 through July 2003.

With many sources of variation in the atmosphere, all temperature effects cannot be easily detected. The largest source of temperature variation, and the easiest to measure, is the annual …

Quantum Entanglement Of Anisotropic Magnetic Nanodots, Ralph Skomski, Andrei Y. Istomin, Anthony F. Starace, David J. Sellmyer

Department of Physics and Astronomy: Faculty Publications

Anisotropic magnetic nanodots are promising physical realizations of qubits for quantum computing at finite temperature owing to their well-separated low-lying energy levels and scalability. The entanglement of two interacting magnetic nanodots is investigated and shown both analytically and numerically to be resonantly dependent on their interaction strength and on differences in their properties. These results provide criteria for fabricating and coupling magnetic nanodots so that their low-lying eigenstates can be significantly entangled.

Atomic Force Microscope Conductivity Measurements Of Single Ferritin Molecules, Degao Xu

Theses and Dissertations

Conductive Atomic Force Microscope (c-AFM) was used to measure the conductivity of single horse spleen ferritin (HoSF) and azotobacter vinelandii bacterial ferritin (AvBF) molecules deposited on flat gold surfaces. A 500 micron diameter gold ball was also used as a contact probe to measure the conductivity of a thin film of ferritin molecules. The average current measured for holo HoSF was 13 and 5 times larger than that measured for apo HoSF as measured by c-AFM at 1V and gold ball at 2V and respectively, which indicates that the core of ferritin is more conductive than the protein shell and …

Femtosecond Laser-Induced Formation Of Submicrometer Spikes On Silicon In Water, M. Y. Shen, Catherine Hirshfeld Crouch, J. E. Carey, E. Mazur

Physics & Astronomy Faculty Works

We fabricate submicrometer silicon spikes by irradiating a siliconsurface that is submerged in water with 400 nm, 100 fs laser pulses. These spikes are less than a micrometer tall and about 200 nm wide—one to two orders of magnitude smaller than the microspikes formed by laser irradiation of silicon in gases or vacuum. Scanning electron micrographs of the surface show that the formation of the spikes involves a combination of capillary waves on the molten siliconsurface and laser-induced etching of silicon. Chemical analysis and scanning electron microscopy of the spikes show that they are composed of silicon with a 20-nm-thick …

Relativistic And Radiative Corrections To The Mollow Spectrum, Jorg Evers, Ulrich D. Jentschura, Christoph H. Keitel

Physics Faculty Research & Creative Works

The incoherent inelastic part of the resonance fluorescence spectrum of a laser-driven atom is known as the Mollow spectrum [B. R. Mollow, Phys. Rev. 188, 1969 (1969)]. Starting from this level of description, we discuss theoretical foundations of high-precision spectroscopy using the resonance fluorescence light of strongly laser-driven atoms. Specifically, we evaluate the leading relativistic and radiative corrections to the Mollow spectrum, up to the relative orders of ( Z α )² and α ( Z α )² , respectively, and Bloch-Siegert shifts as well as stimulated radiative corrections involving off-resonant virtual states. Complete results are provided for …

Single Muon Production And Implications For Charm In √Sn N = 200 Gev Au+Au Collisions, Andrew Miles Glenn

Doctoral Dissertations

The PHENIX experiment, located at the Brookhaven National Laboratory’s Rela- tivistic Heavy Ion Collider, is designed to study high energy proton+proton and nu- cleus+nucleus collisions in order to characterize hot and dense nuclear matter. This dissertation presents the first analysis of single muon production in √sN N = 200 GeV Au+Au reactions. Implications of the forward rapidity measurements for charm pro- duction are discussed. Motivation for charm production measurements and the role of open charm in characterizing the medium created in relativistic heavy ion collisions are presented, and the importance of measurements at forward rapidity is established. The results of …

Metallic Ferroelectricity And Superconductivity In The Transition Metal Oxide Pyrochlore Cd2Re2O7, Jian He

Doctoral Dissertations

Single crystalline samples of transition metal oxide Cd₂Re₂O₇, the first superconductor among pyrochlore oxides with general formula A₂B₂O₇ and the first example of “ferroelectric metal” theoretically proposed by P.W. Anderson and E.I. Blount back in 1960s, have been grown using vapor transport and carefully characterized, regarding its chemical stoichiometry and structure. In addition to the superconductivity transition, two normal state phase transitions and the anomalous high temperature phase have been comprehensively investigated, by means of transport, thermodynamic and spectroscopy techniques. The system undergoes a subtle continuous cubic-to-tetragonal phase transition …

Teacher In The Spotlight, Aaron Beaumont

Lake Union Herald

No abstract provided.

Spectral Degree Of Coherence Of A Random Three-Dimensional Electromagnetic Field, Olga Korotkova, Emil Wolf

Physics Articles and Papers

The complex spectral degree of coherence of a general random, statistically stationary electromagnetic field is introduced in a manner similar to the way it is defined for a beamlike field, namely, by means of Young’s interference experiment. Both its modulus and its phase are measurable. We illustrate the definition by applying it to blackbody radiation emerging from a cavity. The results are of particular interest for near-field optics.

High Statistics Search For The Θ+ (1.54) Pentaquark State, M. J. Longo, Timothy Holmstrom, Hypercp Collaboration

Chemistry & Physics Faculty Publications

We have searched for θ⁺(1.54)→K⁰p decays using data from the 1999 run of the HyperCP experiment at Fermilab. We see no evidence for a narrow peak in the K_S⁰p mass distribution near 1.54  GeV/c among 106 000 K_S⁰p candidates, and obtain an upper limit for the fraction of θ⁺(1.54) to K_S⁰p candidates of

Low Background Techniques For The Borexino Nylon Vessels, Andrea Pocar

Andrea Pocar

Borexino is an organic liquid scintillator underground detector for low energy solar neutrinos. The experiment has to satisfy extremely stringent low background requirements. The thin nylon spherical scintillator containment vessel has to meet cleanliness and low radioactivity levels second only, within the detector, to the scintillator itself. Overall, the background from the vessel in the fiducial volume of the detector must be kept at the level of one event per day or better. The requirements, design choices, results from laboratory tests, and fabrication techniques that have been adopted to meet this goal are presented. Details of the precautions taken during …

The Rotundity Of Large Planetary Objects, Adesanwo Moradeyo

Graduate Student Papers (Physics)

The most obvious structural feature of planetary bodies is their roundness. This arises because of the dominate roles of the two effects of gravity and case of the deformation of matter, whether gas, liquid or solid. This project is about proving and solving out the time scale (τ ) of flow restoring the body to spherical shape when we consider a slightly deformed self-gravitating sphere and also checking for spherical of different planetary objects.

The Electrochemical Separation Of Curium And Americium: Quaterly Report August-December 2004, David W. Hatchett, Kenneth Czerwinski

Separations Campaign (TRP)

This research report outlines the current status and progress associated with the electrochemical separation of Curium and Americium. The following pages outline the progress on our project to date. We have been actively performing research on this project for three months and are currently on schedule in terms of the proposed timelines.

The initial focus of the project involved setting up the laboratories for the studies outlined in the grant proposal. The instrumentation needed included an electrochemical work station that will perform the bulk of the electrochemical studies. This instrument will complement the electrochemical instrumentation in Dr. Hatchett’s laboratory and …

Neutron Multiplicity Measurements For The Afci Program Quarterly Progress Report September-December 2004, Denis Beller

Transmutation Sciences Physics (TRP)

The U.S. Advanced Fuel Cycle Initiative (AFCI) is a program to develop economic and environmental methods to reduce the impact of waste from commercial nuclear fuel cycles. One concept for near-complete destruction of waste isotopes from used nuclear fuel is accelerator driven transmutation. High-power accelerators would be used to produce high-energy charged particles, which then collide with heavy metal targets to create a cascade of neutrons. These neutrons then cause a nuclear chain reaction in subcritical systems. Fission neutrons then transmute fissile waste isotopes as well as other problematic isotopes such as technetium-99 and iodine-129. To design these systems, complex …

Reactor Physics Studies For The Afci Race Project: Reactor-Accelerator Coupling Experiments Project: Quarterly Progress Report September-December 2004, Denis Beller

Transmutation Sciences Physics (TRP)

In the RACE Project of the U.S. Advanced Fuel Cycle Initiative (AFCI), a series of accelerator driven subcritical systems (ADSS) experiments will be conducted at the Idaho State University’s Idaho Accelerator Center (ISU-IAC), at the University of Texas (UT) at Austin, and at the Texas A&M University. In these experiments we will use electron accelerators to induce bremsstrahlung photon-neutron reactions in heavy-metal targets; this source of about 10¹² to 10¹³ n/s will then initiate fission reactions in the subcritical systems. These systems will include a compact, transportable assembly at ISU and TRIGA reactors at UT-Austin and Texas A&M. …

Dissolution, Reactor, And Environmental Behavior Of Zro2-Mgo Inert Fuel Matrix: Quarterly Report, October 2004 To December 2004, Earl Wolfram, Thomas Hartmann, Kenneth Czerwinski

Fuels Campaign (TRP)

This project will examine inert matrix fuels containing ZrO₂ and MgO as the inert matrix, with the relative amount of MgO varied from 30% to 70% in ZrO₂. Reactor physics calculations will be used to examine suitable quantities of burnable poisons from the candidate elements Gd, Er, or Hf with reactor grade Pu providing the fissile component, with up to 10% of ²³⁹Pu. Ceramics will be synthesized and characterized based on the reactor physics results. The solubility the fuel ceramics, in reactor conditions, reprocessing conditions, and repository conditions, will be investigated in a manner to provide …

Afci Quarterly Input – Unlv October Through December, 2004, Harry Reid Center For Environmental Studies. Nuclear Science And Technology Division

Transmutation Research Program Reports (TRP)

Quarterly report highlighting research projects, activities and objectives of the Transmutation Research Program at the Nuclear Science & Technology Division, Harry Reid Research Center.

The University of Nevada, Las Vegas supports the AFCI through research and development of technologies for economic and environmentally sound refinement of spent nuclear fuel. The UNLV program has four components: infrastructure, international collaboration, student-based research, and management and program support. Management and program support highlights are the following: the UNLV TRP hosted the Eighth Annual IAEA Actinide and Fission Product Partitioning & Transmutation Information Exchange Meeting (Nov. 9 – 11). 120 people from 22 countries …