Bulletin of the American Physical Society
2005 APS April Meeting
Saturday–Tuesday, April 16–19, 2005; Tampa, FL
Session S1: Poster Session III |
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Room: Marriott Tampa Waterside Florida Salon IV-V |
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S1.00001: UNDERGRADUATE EDUCATION
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S1.00002: Helping students succeed by helping them improve their long-term memory Nouredine Zettili, A. Boukahil In this work, we focus on one of the most useful techniques of efficient study habits: How to improve long-term memory. We show that if a student carries a number of recalling sessions of the material studied and if he/she carries them at specific times, the student will be able to retain this material for a long time and hence be prepared for the exams. We argue that a student who conscientiously uses the proper techniques of efficient study habits will be able to achieve higher results than the student who does not. Moreover, a student equipped with the proper study skills will spend much less time to learn a subject than a student who has no effective study habits. After providing a summary of the most essential personal skills needed to be a successful student--concentration skills, how to take notes in class, how to prepare for and take exams---we give an extensive presentation on the techniques of improving long-term memory. [Preview Abstract] |
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S1.00003: Effective Physics Major Recruiting Robert Mitchell Only the high school students that are in the top 2\% in math of those that are college bound do well as physics majors. These students you recruit face to face in April by telling them your program is academically the toughest that they will find at your school. You promise that while crippling their social life and assuring that their lowest grades will be in their physics major, they will get to find out just how good they are. We will discuss:\\ \\ How to get face to face with that top 2\% high school student.\\ Why high school teachers and counselors will not help you.\\ Why wait until April to recruit.\\ What parents want to know about your physics program.\\ Which activities are a waste of time when recuiting.\\ \\ By investing 20 hours spread over 2 weeks expect to get about 8 good physics majors. [Preview Abstract] |
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S1.00004: PR2EPS: Preparation, Recruitment, Retention and Excellence in the Physical Sciences Hugh Gallagher, Sunil Labroo, Paul Bischoff, John Schaumloffel, Nancy Bachman PR2EPS, is an NSF-DUE sponsored program at SUNY Oneonta designed to attract students to pursue physics, chemistry and related physical science degrees in college. For those students who choose to study at SUNY Oneonta, the program also seeks to increase the retention rate of all students in the physical sciences by providing specialized skills and professional development courses, an evening tutoring center, and exposure to research and professional activities early in their undergraduate careers. A key focus of the project is drawing students from the five, primarily rural and agricultural, counties surrounding Oneonta, NY. Their first direct exposure to the program will be in recruiting visits to local high schools where promising candidates will be invited to participate in a weeklong summer camp designed to demonstrate to them that they possess the requisite skills and potential to succeed in these technically demanding disciplines. We will provide a brief description of the program and discuss outcomes of the first year including the inaugural summer camp. [Preview Abstract] |
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S1.00005: UNDERGRADUATE RESEARCH
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S1.00006: Generating Fiducial Cuts for CLAS E5 Kristen Greenholt, Gerard Gilfoyle The Thomas Jefferson National Accelerator Facility, located in Newport News, Virginia, is home to CLAS (CEBAF Large Acceptance Spectrometer) which observes the scattering effects of high-energy collisions of an electron beam and a proton or deuteron target. When data are collected with CLAS, one of the properties measured is the cross-section, which is proportional to the number of events and the efficiency and inversely proportional to the solid angle. The efficiency, or acceptance of the detector, is the ratio between the data one expects to observe in an ideal detector and the data that we actually measure with the real CLAS detector. In outlying azimuthal regions, the efficiency is less clearly understood, which leads to measurements which are reliant on the conditions of the detector itself. In order to analyze data which fall in regions of stable and well-understood efficiency, we generated fiducial cuts on CLAS. Our fiducial cuts fit a function to the edges of regions of stable efficiency. These cuts enable us to focus on the data with good acceptance/efficiency. When examining at the fiducial cuts, we required stable efficiency, or flat regions, a good visual fit, a minimized chi squared, and a reasonable behavior in each in azimuthal versus polar angle plane for each electron-momentum bin. Generating these fiducial cuts enables us to focus on data from CLAS where the efficiency of the detector is well understood. [Preview Abstract] |
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S1.00007: Momentum Corrections for the CLAS E5 Data Set Robert Burrell, Gerard Gilfoyle The Thomas Jefferson National Accelerator Facility located in Newport News, Virginia, is home to the CLAS (CEBAF Large Acceptance Spectrometer) detector, which measures scattered particles from high-energy collisions of an electron beam and a nuclear target. Initial measurement of the momentum of charged particles is done by reconstructing tracks using several different detecting elements and a toroidal magnetic field. To improve the accuracy and precision of these momentum measurements for the electron and proton, we have applied the following algorithm. (1) Establish a known standard using the neutron peak in the $ep\rightarrow e^\prime \pi^+ X$ reaction and applying the missing mass technique. (2) Calculate the curvature, $qB/p_m$, event by event where $q$q is particle charge, $B$ is the ratio of torus magnet current to 3860A, and $p_m$ is the reconstructed particle momentum. (3) Calculate the curvature again using the particle momentum $p_c$ derived from only the polar angle of the track. This angle is measured with high precision. (4) Plot the difference between these two curvatures $\Delta(qB/p)$ versus $qB/p_c$ and fit the results to a line. (5) Use these fit results to calculate a new corrected momentum and use it to calculate the missing mass in Step 1. We will present the results of this procedure for the E5 running period at a beam energy of 2.56 GeV on a deuterium target. [Preview Abstract] |
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S1.00008: Structure sensitive photoionization via Rydberg levels Narayanan Kuthirummal, Peter Weber We introduce Rydberg level spectroscopy as a new method to fingerprint molecular structures, and demonstrate it on the example of the azulene/naphthalene system. To access the Rydberg levels and measure their electronic energies, we employed the double resonant, one- color, 3-photon ionization scheme using 266 nm, 180 fs laser pulses. The observed Rydberg spectra show a rich set of peaks in the range of principal quantum numbers $n$ = 3 and 5. The corresponding quantum defects have also been calculated. The results indicated that the present technique has the useful attributes of sensitivity toward large-scale molecular structure features, universal applicability from small molecules to large composite or polymeric systems, and the ease of combination with traditional mass spectrometry. We have performed similar experiments on several other molecules, including phenol, toluene, and various fluorophenols. We found that in all cases the photoionization experiment gives rise to molecule-specific Rydberg spectra. We conclude that the ionization via the Rydberg levels is a generally applicable scheme that can provide fingerprints of the molecular shape during the ionization process. [Preview Abstract] |
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S1.00009: Study of D* Production in Proton-Proton Collisions Using the STAR Detector at RHIC Stephen Hansen Charged D* meson production was studied in proton-proton collisions at a center of mass energy of 200 GeV using the Solenoidal Tracker at RHIC (STAR) at Brookhaven National Laboratory. Methods for the identification of D* mesons will be outlined. In the decay channel considered, the charged D* goes into a charged pion and a neutral D meson. The neutral D further decays into a charged pion and a charged kaon. The study provides baseline data for charm production in heavy ion collisions. [Preview Abstract] |
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S1.00010: SLAC Experiment E158: A Precision Measurement of the Weak Mixing Angle by Moller Scattering Michael Gary SLAC Experiment E158 is a precision measurement of the weak mixing angle at low $Q^2$. The experiment is a mesurement of the left-right asymmetry ($A_{LR}$) in M{\o}ller scattering ($e^- e^-\rightarrow e^- e^-$) of polarized electrons off unpolarized electrons in a liquid Hydrogen target. E158 tests electroweak theory at the quantum loop level and is sensitive to new physics at the TeV scale. The experiment has recently been completed and results are now being released. [Preview Abstract] |
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S1.00011: Climatic and Biotic Effects of a Gamma Ray Burst near Earth Daniel Hogan, Brian Thomas, Adrian Melott A gamma ray burst (GRB) within the Milky Way has been recently proposed as a novel mechanism for triggering a mass extinction on earth. Thomas et al have modified the two-dimensional Goddard Spaceflight Center Atmospheric Model to simulate the effects of a 100kJ/m$^{2}$ GRB-induced influx of energy to Earth. The model's output, atmospheric composition as a function of time and latitude, was further analyzed to elicit possible effects on the biosphere. Using a biological weighting function for UV-induced DNA damage, it was found that in such a scenario peak DNA damage exceeded 16 times its normal global average value as a consequence of atmospheric disruption. Decreases in estimated photosynthesis levels and energy flux at the surface were also identified. [Preview Abstract] |
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S1.00012: Liquid Scintillator Response at Low-Energy Daniel Passmore, Yuri Efremenko The brightest source of neutrinos in our solar system is the sun. Neutrinos from the sun are especially hard to detect because they arrive to the Earth with energies less than 15MeV. KamLAND, a sensitive one-kiloton liquid scintillator detector allocated in a deep underground mine in central Japan, is preparing to detect solar neutrinos. To do this we must better understand the detectors response at the low energy region. Low energy particles have a different response because when traveling inside liquid scintillator at low energies they have a lower probability of emitting Cherenkov light. It is important to understand the amount of energy produced from these Cherenkov emissions and how this will affect neutrino energy reconstruction. This group has built a high precision Compton Spectrometer designed to study the response of the KamLAND liquid scintillator to the Cherenkov light. The spectrometer has high precision amplitude and time measurements by a data acquisition system based on the VME standard of electronics. The analysis of this data will be important for the future use of the KamLAND detector in detecting solar neutrinos. [Preview Abstract] |
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S1.00013: COMPUTATIONAL PHYSICS
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S1.00014: Modeling of Magnetostriction in Particulate Composite Materials Zhou Yan, F.G. Shin The objective of the present work is to develop a conceptually simple and convenient approach to magnetostriction for particulate composites of magnetostrictive polycrystalline inclusions in elastically isotropic matrices applicable to the whole range of volume fraction of the inclusions, since these composites are often fabricated with a high content of magnetostrictive particles. For illustrative purposes, the calculation for the magnetostriction of composites containing Terfenol-D or Nickel are presented. Beginning with the basic elasticity and magnetostriction equations, we use a self-consistent model to calculate the effective elastic and magnetostrictive behaviors of Nickel/epoxy and Terfenol-D/glass composites. The longitudinal magnetostriction of pure polycrystalline Terfenol-D is deduced from the experimental data of the composite having 60{\%} volume fraction of Terfenol-D; Nickel data is taken from literature. Through numerical calculation, we have obtained the macroscopic longitudinal strains parallel to the applied magnetic field for Terfenol-D/glass composites and both longitudinal and transverse strains for the Nickel/epoxy composites. Goodness of fit for both material systems shows our model is applicable up to very high volume fraction of inclusions. Our magnetostriction model can be useful in providing a general guide for the evaluation and technical improvement of magnetostrictive composites currently under development. [Preview Abstract] |
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S1.00015: A fragment-based ab initio study of some organometallics having interesting nonlinear optical effects Guru Das, Jeane-Phillippe Blaudeau The \textit{Ab initio} Fragment Orbital Theory (AFOT), which is essentially an approximate \textit{ab initio} scheme that builds wavefunctions from those of its constituent fragments, is applied to study the singlet and triplet excited states of some Platinum containing organometallic compounds. These molecules have interesting nonlinear optical properties. AFOT is programmed as an extension onto GAMESS-US. Relativistic Effective Core Potential (RECP) theory of the Stevens et al. (SBK) variety is used. The results are compared with the corresponding Time-Dependent-Density-Functional-Theory (TDDFT) results. [Preview Abstract] |
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S1.00016: Cosmic Mechanics Charles H. Ross Cosmic Mechanics is the first complete cosmology derived specifically for an expanding universe. It provides insights into the origin, composition, expansion, geometry, and structure of the universe. It is based on the premise that the laws of nature are universal, non-varying, and mechanically obeyed. CMB analyses indicate that time, motion, and energy are absolute. Cosmic energy analysis indicates that the universe started with zero total energy and still has it, i.e. the sum of the universe’s total energy (radiation, kinetic, and gravitational debt) has always been precisely zero. The presumption of zero total energy allows the CMB temperature to be computed to within 0.1$^{\circ}$K of COBE’s measured value. It also results in zero curvature in four-dimensions (flat-4D). The parameter-free energy propagation models computed using flat-4D geometry directly (1) predict the CMB’s extreme isotropy, (2) predict the age of the universe at 15.03 Gyr in agreement with the 14.0 Gyr age of the oldest known globular clusters, and (3) allow the derivation of simple trend and dispersion models that precisely match Reiss’s 2004 consolidated supernovae dataset and WMAP’s CMB anisotropy dataset. [Preview Abstract] |
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S1.00017: POST-DEADLINE POSTERS
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S1.00018: A Global Fitting Method for Extracting Electroweak Cross-Sections in the Dilepton Decay Channel Shan-Huei Chuang, Mircea Coca, Mark Kruse We present a search for Higgs bosons in a mass range between 140 GeV and 180 GeV using CDF Run 2 proton-antiproton collision data taken at $\sqrt{s}$ = 1.96 TeV. Higgs bosons with such a mass decay predominantly to a W boson pair. After selecting events with two high-$P_T$ leptons and optimizing the event selection for $H \rightarrow WW$, we perform a likelihood technique to the data and the expected signal and background (which is dominated by standard model $WW$ production) to extract cross-secton limits as a function of Higgs mass. For this we use the $\Delta \phi (\ell, \ell)$ spectrum (the azimuthal angle between the two leptons in the event) which is a good discriminator between $H \rightarrow WW$ and SM $WW$ production. Future plans are to include additional $WW$ decay modes. [Preview Abstract] |
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S1.00019: Measuring neutron star tidal Love numbers with gravitational wave detectors Tanja Hinderer, Eanna Flanagan Coalescing binary neutron stars are one of the most important sources for gravitational wave detectors such as LIGO. The possibility of extracting information about the nuclear equation of state from the early, low frequency part of the signal is investigated. In this regime, the influence of the tidal effects on the waveform's phase depends only on one parameter, the tidal Love number of the star, even for fully relativistic stars. We compute relativistic Love numbers for a range of equations of state. We also calculate how accurately this internal structure constant could be measured with LIGO. [Preview Abstract] |
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S1.00020: A Global Fitting Method for Extracting Electroweak Cross Sections in CDF Dilepton Data Sebastian Carron, Mircea Coca, Mark Kruse We present an analysis of the high-$p_T$ dilepton sample in which we simultaneously extract the $t\bar{t}$, $WW$, and $Z \rightarrow \tau\tau$ cross-sections, with improved precision over more conventional analyses. After selecting events with two high-$p_T$ leptons, we find a 2-D kinematical phase space in which these signals are well separated. We perform a likelihood fit of the data in this phase space to the known contributions in order to extract cross sections of the three predominant processes in the high-$p_T$ dilepton data. [Preview Abstract] |
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S1.00021: Classical Wave Structure Description for the Atom Terrence McGrath A radically new atomic model has been formulated which illustrates how classical wave structures can provide a supersymmetric four-dimension quantized metric. This model offers the discrete physical structure and natural regularization for mass scales using lattice circle solution sets and quantum loops following spindle torus geometries. The model duplicates the measured mass scales of electrons and protons to eight orders of magnitude and identifies discrete structures for quarks, pentaquarks, and confinement. The model scales over a broad range of lengths represented by going from the Planck length up to atomic diameters, allowing for quarks and atoms to be simultaneously described. The model also provides a mechanism for representing the scale of gravitation to the electromagnetic force at 9.39E-39 for Iron, consistent with observed values. [Preview Abstract] |
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S1.00022: Shifted-contour Shell Model Monte Carlo Application to $fp$ Shell Nuclei Gergana Stoitcheva, David Dean The formalism of the auxiliary-field Monte Carlo method as applied to the nuclear shell-model is one of the most powerful approaches for nuclear structure studies. The method is based on a representation of the imaginary-time many-body propagator as a superposition of one-body propagators describing non-interactive fermions moving in auxiliary fields. It allows exact calculations in spaces far larger than those accessible for conventional methods. However, the applicability of the shell model Monte Carlo method has been limited by the sign problem associated with the Monte Carlo weight function when using realistic two-body interactions. We propose a new approach for alleviating the sign problem. We show that this method, which is based on using mean-field, yield significant improvement and delay of the sign problem. Based on that, we study thermal properties of nuclei using realistic interactions in $fp$-shell, including ${}^{54}$Fe. [Preview Abstract] |
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S1.00023: SUSY: Beyond Discovery Robert Group The discovery of a signal of new physics at the LHC or ILC, which is consistent with low energy Supersymmetry, will also require precision measurements of model parameters in order to differentiate between alternative models. We present techniques to constrain the parameter space to regions compatible with measurements of certain physical observables. [Preview Abstract] |
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S1.00024: Influence of Nitrogen Stoichiometry on Properties of Low-Compressibility Advanced Nitrides J. E. Lowther The properties of two classes of recently synthesized advanced nitrides are investigated with the aim of considering how nitrogen stoichiometry affects the cohesive properties of this material. One is the class of cubic nitrides with a I43d structure of which Zr- and Hf-nitrides and the other a hexagonal P6$_{3}$/mmc structure and of which MoN and CoN have also recently been synthesized. All materials are considered to have low compressibility and thus speculated to have a high material hardness. Both categories of materials have an underlying nitrogen sub-lattice structure. Using ab-initio techniques the sublattice structure is considered as being a way through which properties of non-stoichiometric forms of these materials can be examined. Consequences of N stoichiometry on the crystal structure and elastic properties of these materials are suggested. [Preview Abstract] |
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S1.00025: Combining Programs to Benefit Current and Future K-12 Science Teachers Gay Stewart Many institutions have one or more summer programs to benefit in-service teachers. Some institutions are now starting to offer discipline-specific pedagogy classes for future teachers. At the University of Arkansas we have found a way to combine these two programs to provide an especially rich environment for pre-service and in-service professional development. We pair in each lab group an in-service teacher, who has expertise in the classroom, with a pre-service teacher, who has more recent content knowledge. We do team-building activities with these pairs, and pay careful attention to acknowledging each member's expertise. Assignments are constructed to allow the pairs to learn from each other as well as from the instructor, who serves as more of a facilitator. After the first learning year for the instructor, both groups see the class as extremely valuable, and the instructor finds it an extremely rewarding experience. Details, evaluations and how to avoid what went wrong the first year will be discussed. [Preview Abstract] |
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S1.00026: Applying the Socratic Method to Physics Education Ed Corcoran, Gay Stewart We have restructured University Physics I and II in accordance with methods that PER has shown to be effective, including a more interactive discussion- and activity-based curriculum based on the premise that developing understanding requires an interactive process in which students have the opportunity to talk through and think through ideas with both other students and the teacher. Studies have shown that in classes implementing this approach to teaching as compared to classes using a traditional approach, students have significantly higher gains on the Force Concept Inventory (FCI). This has been true in UPI. However, UPI FCI results seem to suggest that there is a significant conceptual hole in students' understanding of Newton's Second Law. Two labs in UPI which teach Newton's Second Law will be redesigned replacing more activity with students as a group talking through, thinking through, and answering conceptual questions asked by the TA. The results will be measured by comparing FCI results to those from previous semesters, coupled with interviews. The results will be analyzed, and we will attempt to understand why gains were or were not made. [Preview Abstract] |
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S1.00027: More and better prepared K-12 science teachers; How do we know? Jean Dockers, Donna Owen, Gay Stewart In an effort to inform instruction and meet the varying needs of our students, the University of Arkansas Department of Physics and College of Education utilize many formal and informal assessments. The objective is to measure student achievement in physics and attitudes and beliefs concerning the nature of math and science. This poster will attempt to show the various assessment strategies that are currently utilized in the physics reform courses and teacher education courses at the University of Arkansas. [Preview Abstract] |
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S1.00028: Using Quantitative Observations of the Use of Language in an Introductory Science Class to Better Understand Student Learning James Roller Results of a measurement of the total written output of students in an introductory science class at the University of Arkansas are presented. This measurement is used to construct quantitative measures of the quantity and quality of the quantitative, qualitative, and graphical expression in the course. Correlations of these measures with test average, Hake Gain, and behavior data allow the determination of the importance of written expression in quantitative and conceptual learning. [Preview Abstract] |
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S1.00029: Are Different Velocity Surveys Consistent With Each Other? Devdeep Sarkar The study of velocity fields is one of the most effective methods to constrain the cosmological density parameter $\Omega_m$ and the amplitude of density fluctuation $\sigma_8$. I will present a comparison of the estimates of the bulk flows of samples of galaxies in some recent surveys, namely, MARK III, SFI, ENEAR, and RFGC. In some earlier attempts of this type with LP and RPK galaxy catalogs (Watkins and Feldman, 1995) and with SMAC, LP and three other surveys (Hudson et al., 2000), the samples were too sparse to put significant constraints on the power spectrum and resulted in a low level of expected correlation between the bulk flow estimators. The order of magnitude larger sample sizes of the recent independent proper distance catalogs help us get a much higher correlation and thus, better constraints. The method I discuss could, in principle, be used to test the consistency of all the latest velocity field surveys. [Preview Abstract] |
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S1.00030: Status of VERITAS Brian Humensky VERITAS is an array of $12\rm{-m}$ diameter imaging atmospheric Cherenkov telescopes dedicated to gamma-ray astronomy in the $50\rm{GeV}\ -\ 50\ \rm{TeV}$ energy band. The first telescope has been completed at the Whipple Observatory base camp site (elevation: $1280\ \rm{m}$) and is currently conducting observations. In this talk, preliminary results characterizing the data quality from Telescope 1 and an update on the construction of the full four-telescope array will be presented. The performance of Telescope 1 has been characterized using data from a detection of the Crab Nebula. The reflector, the camera, and the $500\rm{-MHz}$ FADC readout system have met all expectations. Telescope 1 will be operated at the Whipple base camp site for both engineering and science observations over the next year during construction of the remainder of the VERITAS array at the Kitt Peak site. That construction is on schedule and we plan to begin observations with the full four-telescope array in October 2006. [Preview Abstract] |
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S1.00031: Neutrino Redshifts -- A Search for Information. Charles Gallo Neutrinos will undergo Redshifts due to Doppler and/or Space Expansion effects similar to Electromagnetic Radiation (Photons). However, in some situations (ex., Quasars, etc), Photon Redshifts may be due to cumulative energy-loss mechanisms with the intervening medium. In this situation, the corresponding Neutrino Redshifts will be much smaller since the interaction cross-section for neutrino-medium interactions will be much smaller than any photon-medium cross-section. Thus, observation and comparison of photon redshifts vs corresponding neutrinos redshifts will be very informative. If the photon and neutrino redshifts are similar, then a Doppler and/or Space Expansion interpretation is justified. If the neutrino redshift is much smaller than any corresponding photon redshift, then an interpretation via a cumulative energy-loss mechanism is justified. This is a very definitive experimental test of redshift interpretations. The latest neutrino data will be examined, particularly relevant to quasars and supernova. Reference: ``Redshifts of Cosmological Neutrinos as Definitive Experimental Test of Doppler versus Non-Doppler Redshifts'' by C. F. Gallo in IEEE Trans. Plasma Science, vol. 31, No. 6, pgs. 1230-1231, Dec. 2003. [Preview Abstract] |
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S1.00032: Heat Bath Efficiency with Metropolis-Type Updating Oleksiy Bazavov, Bernd Berg We illustrate for 4D SU(2) lattice gauge theory that sampling with a biased Metropolis scheme is essentially equivalent to using the heat bath algorithm. Only, the biased Metropolis method can also be applied when an efficient heat bath algorithm does not exist. An example of this situation is U(1) lattice gauge theory. Similar considerations apply to spin systems of statistical physics. [Preview Abstract] |
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S1.00033: Search for Primordial Black Holes with the Whipple Atmospheric Cerenkov Telescope Eric Linton \begin{document} Stephen Hawking's prediction that black holes should radiate like black bodies has several important consequences, including the possibility for the detection of small ($\sim 10^{15}$ g) black holes created in the very early universe. The detection of such primordial black holes (PBHs) would not only validate Hawking's theory, but would provide useful insights into the history of the early universe. A search through 5.5 years of archival data from the Whipple Atmospheric Cerenkov Telescope was made for TeV gamma-ray bursts on 1~s, 3~s, and 5~s timescales. Based on a null result, an upper-limit on the evaporation rate of PBHs of $2.69 \times 10^6$~pc$^{-3}$~yr$^{- 1}$ ($99\%$ CL) was made, assuming the Standard Model of particle physics. When combined with the results of an earlier search through Whipple data, this limit was lowered to $1.33 \times 10^6$~pc$^{-3}$~yr$^{-1}$, which is nearly a factor of 2 better than the previous limit at this energy range. \end{document} [Preview Abstract] |
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S1.00034: Casimir Energy for a Dielectric Cylinder Ines Cavero-Pelaez, Kimball Milton In this paper we calculate the Casimir energy for a dielectric-diamagnetic cylinder with the speed of light differing on the inside and outside. Although the result is in general divergent, special cases are meaningful. The well-known results for a uniform speed of light are reproduced. The self- stress on a purely dielectric cylinder is shown to vanish through second order in the deviation of the permittivity from its vacuum value, in agreement with the result calculated from the sum of van der Waals forces. [Preview Abstract] |
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S1.00035: Recent Advances in Plasma Accelerators Chan Joshi In this talk I will review the recent progress on the production, manipulation, transport, acceleration, and focusing of relativistic electron beams using plasma techniques. In particular, I will report recent progress on cathode-less electron injectors, plasma accelerating and transport structures, and electron and positron beam focusing using plasmas. The plasma structures for acceleration can be excited either by laser beams or charged-particle beams. The acceleration gradients in either case can be enormous. For unmatched beams the betatron radiation loss, as the beam oscillates transversely in the high gradient accelerating structure, can generate a high brightness x-ray beam. These x-rays can, in turn, be used to generate positrons. I will describe recent work on the Laser Wakefield Accelerator that has produced the first quasi-monoenergetic beams from plasma accelerators. Work on beam-driven Plasma Wakefield acceleration done by the UCLA, USC, SLAC collaboration that has yielded first greater than a GeV energy gain from a plasma structure will also be described. Work done by different groups around the world will be reviewed. [Preview Abstract] |
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S1.00036: Molecular Orbital Calculations on the Adsorption Mode of n-Hexane above a Graphite Surface. Commensurate Binding is Not a Critical Factor Thomas Baker, Ronald See Molecular orbital calculations were preformed to investigate the binding of n-hexane physisorbed on a graphite surface. In the model proposed by Groszek the binding mode of the alkyl chain is commensurate with the graphite surface. However, for the alkane to be perfectly commensurate with the graphite surface, the equilibrium length of the alkane must be distorted. Calculations were preformed to compare the binding of n-hexane constrained in the graphite-commensurate geometry to the binding of n-hexane in its equilibrium geometry. In each computational protocol used, the optimum hexane-surface distance was found to be 4.2 Angstroms for both the constrained and geometry-optimized molecules. The cost of constraining n-hexane to the graphite-commensurate geometry was calculated to be 18 kJ/mol, but the energetic advantage for perfectly commensurate binding, over binding of undistorted n-hexane, is much smaller; ranging from 4.6-12.2 kJ/mol. Therefore, the hexane-surface systems containing undistorted n-hexane are always favored over the graphite-commensurate hexane, with an advantage of 13.9 kJ/mol in the B3LYP/6-31G* calculation. [Preview Abstract] |
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S1.00037: Vibrational Analysis of Rippled Nanoparticles Annalisa Pawlosky The formation of mixed self-assembled monolayers on a flat gold surface (SAMs) results in randomly distributed phase separated domains. Rippled nanoparticles, however, control the formation and ordering of their domains on the nanoparticle surface. A particular combination of thiols produces surfaces that are rippled in nature giving these nanoparticles special properties. The morphology and domain spacing are directly controlled by the stoichiometric ratio of ligands used to synthesize the nanoparticles. Spectroscopy was used to observe certain CH stretching such as: hydrogen bonded dimers, OH stretch bands, C double bond O stretch bands and the C single bond O stretch bands. It was found that the rippled nanoparticles showed strong peaks in the hydrogen bonded dimer region, much stronger than its homogenous ligand counterparts. The trends that were seen related the symmetry of the frequency of the bonds to the order of the ligands on the nanoparticle. The more symmetric the frequencies of the bonds, the more ordered the bonds are. Nanoparticles with ripples from mixed ligands are seen to have an increase in their order of bond movement. Also, intermolecular forces change as a function of order and therefore, we can control the intermolecular forces with the ripples on the nanoparticles. We have found a vibrational spectroscopic signature of the ripples on the nanoparticles. [Preview Abstract] |
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S1.00038: Cosmic Ray Energetics And Mass: First flight for 42 days Young Soo Yoon The Cosmic Ray Energetics And Mass (CREAM) balloon-borne experiment had its first flight for nearly 42 days in Antarctica from Dec 15, 2004 to Jan 26, 2005. It made three circumnavigations around the South Pole, which broke both the duration and distance records for a long-duration balloon flight. CREAM was designed to measure the energy spectra and composition of cosmic rays with energies between 1 TeV and 1000 TeV. Incident particles are identified with both a timing charge detector and a silicon charge detector. Energy measurements are made with both a tungsten/scintillating-fiber calorimeter and a transition radiation detector. During the flight about 19 GBytes of data were transmitted to the Science Operation Center at the University of Maryland through telemetry. An onboard flash disk was used to record and store about 36 GBytes of additional heavy nuclei data. Preliminary results from the flight data will be presented. [Preview Abstract] |
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S1.00039: To study the emittance dilution in Superconducting Linear Accelerator Design for International Linear Collider (ILC) Kirti Ranjan, Nikolay Solyak, Shekhar Mishra, Peter Tenenbaum Recently the particle physics community has chosen a single technology for the new accelerator, opening the way for the world community to unite and concentrate resources on the design of an International Linear collider (ILC) using superconducting technology. One of the key operational issues in the design of the ILC will be the preservation of the small beam emittances during passage through the main linear accelerator (linac). Sources of emittance dilution include incoherent misalignments of the quadrupole magnets and rf-structure misalignments. In this work, the study of emittance dilution for the 500-GeV center of mass energy main linac of the Superconducting Linear Accelerator design, based on adaptation of the TESLA TDR design is performed using LIAR simulation program. Based on the tolerances of the present design, effect of two important Beam-Based steering algorithms, Flat Steering and Dispersion Free Steering, are compared with respect to the emittance dilution in the main linac. We also investigated the effect of various misalignments on the emittance dilution for these two steering algorithms. [Preview Abstract] |
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S1.00040: Compact wave functions for variational calculations diatomic system Odil Yusupov A study of diatomic quantum-mechanical systems is important for molecular theory, chemical physics, theory of few particle coulomb systems, etc. Early we propose [1,2] new type of variational wave function for quantum-mechanical two Coulomb center problem, where one light particle moves in field of two immovable particles. Our function, which is product of binomial combinations of exponential functions of spheroidal coordinates is very compact and accurate. We obtain that electronic energy of molecular hydrogen ion with this 4-term wave function equals -1.10263418 a. u. and very close to the ``exact'' value -- 1.10263422 a.u. To improve the method we realize variational calculations of molecular hydrogen and some other diatomic two-electron ions with these compact exponential functions. To reduce calculations difficulties we apply uncorrelated one-electron approach and scaled basis wave functions. In these calculations we find electronic energies with accuracy about 0.005-0.01 percent. Our results show that improved exponential functions is physical valid, very compact and have acceptable accuracy. These functions can be used as molecular orbitals in quantum-mechanical calculations of diatomic molecules and in modeling few particle coulomb systems. T.K.Rebane and O.N.Yusupov. Opt. and spectr. 72, I6, 1289 (1992) T.K.Rebane and V.S.Zotev. Opt. and spectr. 77, N5, 730 ( 1994) [Preview Abstract] |
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S1.00041: The Conceptual Basis for the Possible Use of a Quantum Eraser to Send Binary Data to a Remote Location Douglas M. Snyder The possible use of a quantum eraser to send information to a remote location depends on the ability in quantum mechanics to separate a measurement into two pieces, one which can be called determining the value of a quantity and one which is making the result of this determination available to the environment. Schrodinger noted these two pieces in making a measurement in his cat gedankenexperiment. Later, Greenberger and YaSin showed how in the absence of making the information available to the environment one could ``reverse'' the ``result'' obtained in the first piece of a measurement. Scully and his colleagues developed the discussion further by allowing the possibility of developing which-way information concerning a particle and its subsequent loss in one sense without directly affecting the motion of this particle and by tying these measurement results to the manipulation of the first piece of a measurement of a distant entangled photon while this entangled photon remained ``hidden.'' The present extension of the quantum eraser assures one particle distribution upon erasure and another where there is no erasure, thus making information transmission reliable. [Preview Abstract] |
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S1.00042: GEANT4 code for Simulation of RPC for Resistive Plate Chamber Detector M. Jamil, J.T. Rhee For more than 20 years nuclear Physicists have used the GEANT code to simulate particle-matter interaction. In most recent version, GEANT4 is a toolkit for simulating the passage of particles though matter, which contains a complete range of functionality including tracking, geometry, physics models, and hits. In this article, the first attempt to use GEANT4 to model a double-gap Resistive Plate Chamber (RPC) with its improved efficiency is presented. The efficiencies of the double-gap RPC has been evaluated as a function of gamma energy range 0.005-1000 MeV. A Comparison to available previous simulation work is also performed, which indicates the performance of GEANT4 is better than GEANT3. [Preview Abstract] |
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S1.00043: Further Studies of Binary Kerr-Schild Superposition Initial Data Scott Hawley Several choices of initial data sets for binary black hole evolutions (and gravitational-wave-source simulations) are currently available. The question of which of these (if any) is suitably "astrophysically relevant" will be answered in part by in-depth studies of the initial data themselves. We present a survey of Kerr-Schild type initial data sets for binary black hole spacetimes. The parallel multigrid method we use is an extension of a simpler solver [Hawley \& Matzner, CQG 21, 2004] to the full set of Einstein equations. This method allows for high-resolution, large-domain solutions which constitute a substantial improvement over those of Bonning et. al [Phys.Rev. D68, 2003]. The results are in good agreement with those of the spectral code of Pfeiffer et al. [Phys.Rev. D66, 2002]. We continue the survey of parameter space begun in these earlier works to include a study of binding energy as a function of orbital parameters such as separation, spins, and velocities. [Preview Abstract] |
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S1.00044: Constraining the equation of state of hyperon stars with astronomical observations Mohit Nayyar, Benjamin Lackey, Benjamin Owen Glendenning and Moszkowski (1991; PRL 67, 2414) constrained the parameters of a relativistic mean field equation of state (EOS) with hyperons by fitting them to observed neutron star masses and hypernuclear energy levels. However, they did not consistently include measurements from hypernuclear experiments. We determine the correct constraints and thereby find that the softest EOS is inconsistent with observed neutron star masses. We also find that a gravitational redshift of 0.35 (Cottam et al 2002; Nature 420, 51) rules out all but the stiffest hyperonic EOS. [Preview Abstract] |
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S1.00045: Fast CMB Power Spectrum Prediction using Kernel Density Estimation Chad Fendt, Benjamin Wandelt We provide a method to quickly calculate cosmic microwave background power spectra and transfer functions using kernel density estimation. Given a training set of cosmological parameters and corresponding power spectra, we construct a probability distribution over the joint space by placing a normal distribution over each point in the training set. For a given set of cosmological parameters we sample the most likely power spectrum from this distribution. This method has the advantage of being scalable to an arbitrary number of cosmological parameters and multipole $l$-values. [Preview Abstract] |
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S1.00046: Energy Gain Greater Than 1GeV in a Plasma Wakefield Accelerator Mark Hogan, Christopher Barnes, Franz-Josef Decker, Paul Emma, Richard Iverson, Patrick Krejcik, Caolionn O'Connell, Robert Siemann, Dieter Walz, Chris Clayton, Chengkun Huang, Devon Johnson, Chan Joshi, Wei Lu, Kenneth Marsh, Warren Mori, Suzhi Deng, Tom Katsouleas, Patric Muggli, Erdem Oz In the plasma wakefield accelerator, a short relativistic electron bunch drives a large amplitude wave or wake. In experiment E-164X, we use the 28.5 GeV, ultra-short ($>$80femtosecond), high peak current ($<$30kiloampere) bunch now available in the Final Focus Test Beam Facility. The head of the bunch field ionizes a lithium vapor and excites the wake while the tail samples the accelerating field. The latter is accomplished by setting the plasma density to match the plasma wavelength to the bunch length. Preliminary analysis shows that gradients in excess of 30 GeV/m are excited over a plasma length of approximately 10cm, leading to energy gains on the order of 3GeV or about an order of magnitude greater than gains reported to date and three orders of magnitude larger than that in the three-kilometer long Stanford Linear Accelerator that produces the incoming beam. The current status of the experiment as well as future plans will be discussed. [Preview Abstract] |
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S1.00047: Mixed Wino Cold Dark Matter Eun-Kyung Park, Howard Baer, Jorge O'Farrill, Azar Mustafayev We examine the Wino content in neutralino Dark Matter with Nonuniversal Gaugino Masses. In our study, we increase $M_2$ so the ratio of $M1/M2 \sim 1.2-1.8$ to get exact DM density $\Omega h^2$ in accord with WMAP value. We investigate rates for indirect detection of neutralinos via detection of muons in neutrino telescope, and detect of photons, positrons and anti-protons by balloon and space based detectors. We compare the reach of DM for indirect detection with the reach for direct detection, and with the reach for collider searches. We find the measured wino content of the LSP and reduced mass difference of $m_{\tilde W_1}-m_{\tilde Z_1}$ can have effects on the depletion of relic neutralino density. If mixed wino DM solves CDM problem, the mass reconstructions at LHC should be simpler. [Preview Abstract] |
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S1.00048: Size-dependence evolution of quasiuniform states in thin circular dots Z. Wei, M. Lai, C.R. Chang, J. C. Wu, J. Lai The three-dimensional micromagnetic simulations of submicron-sized permalloy dots are carried out by the integration of the Landau-Lifshitz-Gilbert equation. We take into account the exchange interactions, magnetostatic interactions, and anisotropy field in our simulation. Each dot is divided into many cubic cells, and the side length of each cubic cell is set to be 3 nm, which is much smaller than the exchange length R$_{0}$ = C$^{1/2}$/M$_{s}$ of the permalloy, to promise the accuracy of our simulation. When the largest angular variation between successive iterations is below 10$^{-8}$, the system is assumed to reach the equilibrium state. From the micromagnetic simulation, it is found that as the diameter of the permalloy thin circular dot becomes larger than some critical size, the single-domain state turns out to be unstable and transforms to a `C' state. When the diameter is above another larger critical diameter the `C' state becomes unstable and a vortex enters the dot. Above another even larger critical diameter only the `S' state and vortex state can exist. In the diameter range between the upper diameter limit of `C' state and the lower diameter limit of `S' state, only the vortex state can exist. [Preview Abstract] |
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S1.00049: Comparing Methods for Determining Quasi-Circular Orbits in Binary Black-Hole Initial Data Miranda H. Dettwyler, Mark Hannam, Carlos O. Lousto We locate quasi-circular orbits and the inermost stable circular orbit (ISCO) for binary black hole systems of equal mass using the effective-potential and mass-comparison methods applied to Bowen-York puncture initial data. We compare the accuracy and precision of the results of these two methods and find that near the ISCO the two methods disagree within uncertainty. We are currently investigating which method gives the most physically accurate results. [Preview Abstract] |
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