Bulletin of the American Physical Society
2017 Fall Meeting of the APS Prairie Section
Saturday–Sunday, November 11–12, 2017; University of Illinois at Chicago, Chicago, Illinois
Session P1: Poster Session |
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Chair: Zhenyu Ye, University of Illinois at Chicago Room: UIC Student Center East East Terrace |
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P1.00001: Einstein's Photoelectric Relation Must Also Include Rotation and Vibration Kinetic Energies As Well As Linear Kinetic Energies of the Ejected Electron Stewart Brekke Every material body has no motion, linear, rotational and/or vibrational motion singly or in some combination. In Einstein's proposed analysis of the Photoelectric Effect through collisions in the material all linear kinetic energy is lost and only the energy from the impacting photon affects the ejected electron. However, the electron is also rotating and vibrating in the material and these kinetic energies may also be lost through collisions with other electrons in the material. Therefore, the ejected electron may have rotational and vibrational motion as well as linear motion resulting from the transferred energy of the incident photon. Therefore, the current values of the work functions may have to be slightly adjusted. Also, the current formula for the Photoelectric Effect must be modified to include the possibility of rotational and vibrational as well as linear motion in the resulting ejected electron. Therefore, relation for the Photoelectric Effect must be $hf = (1/2mv^2 + 1/2I\omega^2 + 1/2kx^2)max + \phi$. [Preview Abstract] |
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P1.00002: A Study of the Hyperfine Structure of a 4.8 GHz Formaldehyde Maser in a Massive Star Forming Region Arup Barua, Esteban Araya Spectral lines from molecular transitions exhibit hyperfine structure due to nuclear spins of the atoms in the molecule. Hyperfine structure has been detected in laboratory experiments as well as in spectral lines from molecular clouds in space. To investigate the hyperfine structure of a molecular transition, narrow spectral lines are required because the energy difference between hyperfine lines is typically very small. Masers are characterized by narrow spectral linewidths, thus, they can be used to investigate the hyperfine structure of molecular transitions in space. We present a study of the 6 cm formaldehyde maser in the G32.74-0.07 star forming region. Analysis of the spectral line indicates that the maser is unsaturated and predicts a background radio continuum level of the order of 1 mJy. VLA continuum observations show that the maser is indeed coincident with a weak radio continuum source, which supports the unsaturated maser model. [Preview Abstract] |
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P1.00003: Assessing Phase Calibration Reliability of Continuum and Spectral Line Observations of a High-Mass Star Forming Region MD Nazmus Sakib, Esteban Araya Interferometry is a fundamental tool in astronomy because of imaging capabilities at high angular resolution. The data obtained from an interferometer has two components, amplitude and phase. Calibration of interferometric data is typically based on observations of a point-source (quasar) for which the expected amplitude and phase is known, and thus, the observations can be used to derive corrections to obtain the final deconvolved image of the astronomical source. Phase calibration errors can result in erroneous astrometry and imaging artifacts such as extended structures and spurious sources, particularly when self-calibration is performed. We assess the reliability of the phase calibration of radio continuum and spectral line (6 cm formaldehyde maser) observations of a high-mass star forming region obtained with the Very Large Array (VLA). We generated continuum images of right-hand and left-hand circular polarizations and different scans to check for consistency. In the case of the spectral line data, we find that the position of the maser in different frequency channels is within 0.082'' in right ascension and 0.095'' in declination, which is well within the VLA synthesized beam (0.53'' x 0.41''), and we detect no trend in position offsets as a function of frequency. We find no evidence of significant phase calibration errors in the dataset that could compromise analysis of the images [Preview Abstract] |
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P1.00004: Neutron Star Mergers and the R process Ronald Joniak, Claudio Ugalde About half of the elements of the periodic table that are present today in the Solar System were synthesized before the formation of the Sun via a rapid neutron capture process (r process). However, the astrophysical site of the r process is a longstanding problem that has captivated both experimental and theoretical astrophysicists. Up to date, two possible scenarios for the site of the r process have been suggested: the first involves the high entropy wind of core collapse supernovae, and the second corresponds to the merger of two compact stellar objects such as neutron stars. We study the robustness of the nucleosynthesis abundance pattern between the second and third r process peaks as produced by neutron star mergers with r process-like neutron exposures. First, we will vary parameters to obtain an understanding of the astrophysical mechanisms that create the r process. Next, we will create a program to obtain the best possible parameters based on a chi-squared test. Once we have the best fits, we will test the effect of fission in the overall isotope abundance pattern distribution. Later on, we will vary the ratio of masses of the two fission fragments and study its effect on elemental abundances. [Preview Abstract] |
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P1.00005: A Survey of Big Bang-era Nuclear Reactions Zachary Nabor, Claudio Ugalde In the earliest moments of the Big Bang, an enormous portion of the light elements that exist today (hydrogen, helium, deuterium, lithium) where produced by a mechanism called “Big Bang nucleosynthesis (BBN)”. This model is successful for matching theoretical predictions to observed abundances. However, BBN isn’t without its own shortcomings. In particular, BBN makes predictions of higher abundances for lithium than the ones obtained from actual astronomical observations. Using “ALTERBBN,” a computational program of BBN, and experimental reaction rates, we are studying the influence of nuclear reaction rates during BBN (around 1-100 gigakelvin), and how these reactions influence the abundances of light elements produced during the Big Bang. The analysis examines the responses of elemental abundances due to changes in nuclear reaction rates. Of particular interest, we will examine closely those rates that lead to a lower abundance of lithium isotopes. First simulations of the nuclear reaction $^{3}He(\alpha,\gamma)^{7}Be$ have yielded decreases in lithium abundances without significant alterations to the abundances of other light elements. The behavior of this reaction will be the primary investigation. [Preview Abstract] |
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P1.00006: A Computational Study of Catalytic Dehydrogenation of Propane to Propene Using Transition Metal Atoms Michal Scherer-Berry, Christopher Bean, Daniel Dunevant, Nick Lewis, Stan Zygmunt Developing more reactive and selective catalysts for petrochemical refining and synthesis, specifically the dehydrogenation of propane to form propylene, is extremely important for the US and global economy. The use of single atom catalysts can potentially tune their catalytic properties for specific reactions. Using computational methods, the dehydrogenation reaction pathways of possible catalysts with propane can be tested; however, this can be very time consuming. By looking at possible simple descriptors of promising catalytic behavior, the time spent testing specific alloys can be greatly reduced. We have evaluated various descriptors and hope to find correlations between these and the more time-consuming factors in order to help discover which transition metal clusters can be used to lower the cost of propane dehydrogenation. [Preview Abstract] |
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P1.00007: Enhancement of magnetic dipole emission at optical frequencies Daniel Eggena, Krishna Pandey, Mahua Biswas, Uttam Manna In general, the magnetic dipole (MD) transition rates are orders of magnitude smaller than the electric dipole (ED) transition. As a result, the MDs interact very weakly with the magnetic field component of incident light. However, for a focused cylindrical azimuthal incident beam, the ratio of the maximum magnetic and electric field intensities can be significantly enhanced compared to a plane wave in free space. Here, we demonstrate that that the focused azimuthally polarized beam can enhance the MD emission by approximately 4 times compared to ED emission in Europium ions, which are otherwise comparable for linear excitation. [Preview Abstract] |
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P1.00008: Effect of CdSe Nanoparticles on the Optical Properties of Bismuth Borate and Boro-tellurite Glasses Owen Huff, Saisudha Mallur, P.K. Babu The inclusion of cadmium selenide nanoparticles in bismuth borate and bismuth boro-tellurite glasses causes changes in optical band gap and fluorescence spectra that dependent on the size of the nanoparticles, which can be increased by annealing. We started with ionic compounds in powder form, and then melted, quenched, and polished samples into glass pieces. Then using a furnace, we annealed five samples (of both bismuth borate and bismuth boro-tellurite) for 3, 6, 11, 16, and 26 hours. We recorded the optical absorption spectra using a Varian Cary 5 UV-VIS-IR spectrometer, and fluorescence spectra using a CCD spectrometer. The samples were excited with a 380-nm wavelength Titanium-Sapphire laser in order to observe the fluorescence spectra. The optical band gap of the samples was determined from the absorption edge data. The fluorescence spectra was deconvoluted in order to identify the characteristic emission peaks of the CdSe nanoparticles, and to observe the change in peak wavelength and width of fluorescence maximum. The optical band gap, the peak wavelength and width of fluorescence maxima vary with the annealing hours. Through analysis of the characteristic emission peaks of the CdSe nanoparticles, we also determined the approximate size of these nanoparticles. [Preview Abstract] |
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P1.00009: Optical Properties of Dy$^{\mathrm{3+}}$ Doped Calcium Bismuth Borate and Barium Bismuth Borate Glasses Zachary Foreman, P.K. Babu, Saisudha Mallur The optical properties of dysprosium ions (Dy$^{\mathrm{3+}})$ in calcium and barium bismuth borate glasses were analyzed as a function of the glass composition with Bi$_{\mathrm{2}}$O$_{\mathrm{3\thinspace }}$content varying from 29.5 to 59.5mol{\%}. These glasses were prepared using the melt-quench method. Refractive index was measured using a Brewster's angle set up. Absorption and fluorescence spectra were then recorded using a Cary 5g UV-VIS-NIR spectrometer and a CCD spectrometer, respectively. The absorption edge was analyzed for glasses with and without Dy$^{\mathrm{3+}}$ ions to calculate the optical band gap of the glasses. Absorption spectra of Dy$^{\mathrm{3+}}$ ions were then analyzed using the Judd-Ofelt theory. The intensity of an absorption band can be expressed in terms of the oscillator strength. Using the oscillator strength for each transition, we obtained the intensity parameters which represent changes in the asymmetry of the ligand field at the Dy$^{\mathrm{3+}}$ ion site (due to structural changes) and to changes in Dy-O covalency. Radiative transition probabilities, the radiative lifetime of the excited states and the branching ratios are then obtained from these intensity parameters. The compositional dependence of these parameters are discussed. [Preview Abstract] |
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P1.00010: Wavelets and Evolutionary Algorithms on the Eletronic Wavefunctions. Iury Steiner Bezerra, Marco Aurelio Pacheco The simulation of the electronic structure of atoms and molecules has been shown to be, from the beginning of 90's, an indispensable tool for the development of strategic areas, that are still emergent, but fundamental, like nanotechnology. However, this type of simulation is still of great complexity today and demands high computational power. Thus, the creation of more precise and less costly methods becomes fundamental. With the elaboration of this research, the intention is to create alternatives basis that can be used in the traditional methods of simulation of electronic structure, such as the Hartree-Fock method, GVB, among others. This essay show new developments used in the calculations of electronic structure, in order that can create disruptive approaches, related to the precision or velocity of the obtainment of relevant results. The new methods are based on Computational Intelligence and concepts of Functional Analysis like Wavelets. Here, the wavelet series is considered a particular case of Fourier Series, where the basis for linear space is a set of wavelet functions. Here is introduced a fast way to use wavelet in analytic calculations and a is built a new kind of linear basis. [Preview Abstract] |
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P1.00011: Analysis of Stimulated Emission Cross-sections of Sm$^{\mathrm{3+}}$ Doped Lead Telluro-borate Glasses Containing Semiconducting CdSe Nanoparticles Grija Thapa, Saisudha Mallur, P.K. Babu A series of lead telluro-borate glasses, doped with trivalent Samarium (Sm$^{\mathrm{3+}})$, and CdSe nanoparticles, has been prepared by conventional melt-quenching technique followed by controlled annealing to grow nanoparticles. The optical properties of the Sm$^{\mathrm{3+\thinspace }}$doped lead telluro-borate glasses have been studied for the following compositions: 29.5PbO:(67-x) B$_{\mathrm{2}}$O$_{\mathrm{3}}$: xTeO$_{\mathrm{2}}$: 0.5Sm$_{\mathrm{2}}$O$_{\mathrm{3}}$: 3CdSe, where x $=$ 10 and 20 mol{\%}, and also as a function of the annealing time of the glasses (which determines the average size and distribution of the CdSe nanoparticles). From the optical absorption measurements, the intensity parameters which measure the asymmetry of the crystal field at the Sm$^{\mathrm{3+}}$ site and Sm-O covalency, are obtained. These are indicators of properties of the host glass, including optical basicity, rigidity and viscosity. Furthermore, the stimulated emission cross-section has been obtained by evaluating the radiative transition probability, the fluorescence bandwidth, peak position of the fluorescence band and the refractive index of the host glass. We find that the stimulated emission cross-section is comparatively large enough to suggest possible utilization of these materials for photovoltaic applications. [Preview Abstract] |
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P1.00012: Study of the Physical and Optical Properties of Sm$^{\mathrm{3+}}$doped Lead Boro-tellurite Glasses Tanjina Ahmed, P. K. Babu, Saisudha Mallur Density, refractive index and optical absorption of Sm$^{\mathrm{3+}}$ doped lead boro-tellurite glasses are studied with varying PbO content (29.5 to 49.5 mol{\%}). These glasses are prepared using appropriate amounts of PbO, B$_{\mathrm{2}}$O$_{\mathrm{3}}$, TeO$_{\mathrm{2\thinspace }}$and Sm$_{\mathrm{2}}$O$_{\mathrm{3\thinspace }}$of high purity (99.9{\%}). The raw materials are homogenously mixed and melted in a porcelain crucible at 950$^{\mathrm{0}}$C.The melt is air quenched by pouring it on a thick brass plate and covering it immediately with another brass plate. The glass samples obtained are annealed at 350$^{\mathrm{0}}$C for 3hrs to remove the thermal and then polished to obtain well reflecting surfaces. The sample density is measured by the Archimedes' method using xylene. The refractive index of the glasses is measured by a Brewster angle set up using a diode laser operating at 650 nm. Optical absorption spectra of these glasses are obtained using UV--VIS-NIR spectrometer. Fluorescence spectra are obtained by using a 404 nm laser as the excitation source. The dependence of intensity parameters with composition reveals the variation of local symmetry of Sm$^{\mathrm{3+\thinspace }}$in the glass matrix as well as the covalency of Sm-O bonds. Large stimulated cross sections obtained from fluorescence measurements indicate that these glasses could be used for photonic applications. [Preview Abstract] |
(Author Not Attending)
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P1.00013: Stimulated emission and optical pumping of lasing from ZnO nanostructures: effect of morphology and surface treatment. Ketaki Sarkar, Richard D Schaller, Michael A Stroscio, Mitra Dutta Optical probing of ZnO nanostructures elucidates many insightful knowledges of the carrier dynamics and recombination mechanisms. Morphology and surface conditions of these nanostructures have strong role to play in the surface mediated demeanor of the excited carriers. As the size of nanostructures decreases from the bulk, the surface to volume ratio increases thereby introducing traps, surface states and other scattering processes. Due to this sensitivity of structural factors and concentration of the defects, it is decisive to study the evolution of the emission properties as a function of the morphology and any kind of surface treatment. In this work is discussed how surface morphology and improved surface quality has to do with the transition from spontaneous emission to stimulated emission under high photo-excitation. Lasing from ZnO ribbons by optical pumping has also been studied. The effect of surface treatment on the threshold and lasing efficiency has been particularly highlighted. The underlying mechanism of the transition from spontaneous to stimulated emission and finally lasing has also been analyzed. [Preview Abstract] |
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P1.00014: Computational Study of bimetallic dimers for Electrochemical CO$_{\mathrm{2}}$ Reduction Christopher Morrissey, Haiying He, Peter Zapol CO$_{\mathrm{2}}$ reduction requires a large energy input due to the high thermodynamic stability of CO$_{\mathrm{2}}$. As a result, the challenge in CO$_{\mathrm{2}}$ reduction is to find highly efficient, low costing catalysts. Recently, subnanometer metal clusters have shown promise as catalysts due to their unique electronic and catalytic properties. In this study, we have used density functional theory to study bimetallic dimers anchored on a defective graphene sheet for CO$_{\mathrm{2}}$ reduction. Better performance were identified for some clusters. The results of this study will inform further experimental research in CO$_{\mathrm{2}}$ reduction using subnanometer metal clusters. [Preview Abstract] |
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P1.00015: Dynamics and interactions of particles in a thermophoretic trap Benjamin Foster, Frankie Fung, Connor Fieweger, Mykhaylo Usatyuk, Anita Gaj, BJ DeSalvo, Cheng Chin We investigate dynamics and interactions of particles levitated and trapped by the thermophoretic force in a vacuum cell. Our analysis is based on footage taken by orthogonal cameras that are able to capture the three dimensional trajectories of the particles. In contrast to spherical particles, which remain stationary at the center of the cell, here we report new qualitative features of the motion of particles with non-spherical geometry. Singly levitated particles exhibit steady spinning around their body axis and rotation around the symmetry axis of the cell. When two levitated particles approach each other, repulsive or attractive interactions between the particles are observed. Our levitation system offers a wonderful platform to study interaction between particles in a microgravity environment. [Preview Abstract] |
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P1.00016: ABSTRACT WITHDRAWN |
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P1.00017: Sequential Atomic Entangler for Heisenberg-Limited Atom Interferometry Sylvester Amoah, Kishor Kapale Interferometry, where two light or matter waves are mixed with each other, allows precision measurement of small phase differences between the constituent waves. We are interested in the applications of interferometry to the fields of metrology, which deals with measuring physical quantities such as small electric, magnetic, and gravitational fields and small rotational velocities. Precise measurements of these quantities are important to meet a large class of technological needs of the humankind. Atomic interferometers offer sensitivities higher by a factor of about $(m c^2)/\hbar \omega\approx 10^{10}$, in comparison with optical interferometers employing laser light of angular frequency $\omega$, even when the atoms passing through the interferometer are not entangled. We aim to employ Heisenberg-limited interferometric techniques, which employ correlated input states as opposed to traditional uncorrelated input states and have been successfully attained for optical interferometers, to atomic interferometry. We propose a cavity quantum electrodynamics based sequential N-atom Greenberger-Home-Zeilinger (GHZ) state generator, as a first step. The GHZ states can be easily converted to path-entangled N00N states, opening up new pathways for Heisenberg-limited atom interferometry. [Preview Abstract] |
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P1.00018: Application of the HI-5 Model to Proton-Impact Ionization of Lithium Alex Plumadore, Jesse Lyon, Mason Bates, Allison Harris The study of heavy-ion collisions with atoms is an increasingly active area of collision physics. We introduce the Heavy-Ion 5-Body (HI-5) model for charged particle collisions, which is only recently possible due to improvements in computing capabilities. Using our model, we present fully differential cross sections for proton-impact ionization of lithium. Results are compared to other theoretical models, and the role of electron correlation is studied. [Preview Abstract] |
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P1.00019: Angular Momentum Transfer in Oriented Collisions Allison Harris, Sadek Amami, Torrey Saxton, Don Madison We present fully differential cross sections (FDCS) for two collision processes with oriented atoms. The first collision is electron-impact ionization of oriented Mg (3p), and the second collision is electron-impact excitation-ionization of helium with an oriented final state He$^{\mathrm{+}}$(2p0) ion. Surprisingly, the theoretical functional form of the FDCS is the same for both processes, despite the fact that the only physical similarity is an oriented excited state in both processes. We use the common theoretical functional form to explore possible physical similarities between the two processes. The contributions to the FDCS of individual partial waves of the ionized electron and projectile are examined, and we show that for the ionization of oriented Mg, the FDCS are dominated by larger partial waves of the ejected electron. For the excitation-ionization process, the FDCS is dominated by the L $=$ 2 partial wave. [Preview Abstract] |
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P1.00020: Emergence of bound state from a free state, is it possible? Richard Pelphrey, Creighton Lisowski, Rainer Grobe, Q. Charles Su It is often assumed that bound states of quantum mechanical systems are intrinsically non-perturbative in nature and therefore any power series expansion methods should be inapplicable to predict the energies for attractive potentials. We propose a new truncated Borel-like summation technique that can recover the correct bound state energy from the diverging sum. It can be used to calculate bound-state energies and wave functions for quantum field theoretical models. We illustrate this approach for a Yukawa-like interaction between fermions and bosons in one spatial dimension. [1,2]. We acknowledge the support by the National Science Foundation. [1] C. Lisowski, S. Norris, R. Pelphrey, E. Stefanovich, Q. Su, R. Grobe, Ann. Phys. 373, 456 (2016). [2] Q. Z. Lv, S. Norris, R. Brennan, E. Stefanovich, Q. Su and R. Grobe, Phys. Rev. A 94, 032110 (2016). [Preview Abstract] |
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P1.00021: Applications of the first digit law to measure correlations Reid Gramm, Jack Yost, Rainer Grobe, Q. Charles Su The quasiempirical Benford law predicts that the distribution of the first significant digit of random numbers obtained from mixed probability distributions is surprisingly meaningful and reveals some universal behavior. We generalize this finding to examine the joint first-digit probability of a pair of two random numbers and show that undetectable correlations by means of the usual covariance-based measure can be identified in the statistics of the corresponding first digits.We illustrate this new measure by analyzing the correlations and anticorrelations of the positions of two interacting particles in their quantum mechanical ground state. This suggests that by using this measure, the presence or absence of correlations can be determined even if only the first digit of noisy experimental data can be measured accurately. [1] R. Gramm, J. Yost, Q. Su and R. Grobe, Phys. Rev. E 95 042136 (2017). [Preview Abstract] |
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P1.00022: Temperature Dependence of the Dielectric Constant of PMMA for the nEDM Experiment Callista Christ, Shirvel Stanislaus The nEDM experiment at Oak Ridge National Laboratory is searching for the electric dipole moment of the neutron~to an accuracy of order 10$^{\mathrm{-28\thinspace }}$e-cm. In the experiment, ultra cold neutrons are stored in a cell made from PolyMethylMethAcrylate (PMMA) and will be subjected to a 75 kV/cm electric field at 0.4K. In order to calculate the electric field precisely, the dielectric constant of PMMA must be known as a function of temperature. A measurement made last summer (2016) showed that the dielectric constant does change with temperature as measured down to 150K. ~This summer, we have improved the cryostat and have measured the temperature dependence of the dielectric constant down to 120K. ~These results are presented. [Preview Abstract] |
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P1.00023: Analysis of Neutral Pion Helicity Asymmetry with the STAR Detector Adam Gibson, Alec Hauck, Noah Strand The gluon contribution to the proton spin is poorly constrained compared to the quark contribution. To further constrain the gluon contribution, the STAR collaboration at RHIC analyzes the asymmetry in neutral pion ($\pi^0$) production as a function of spin alignment in longitudinally polarized proton beam collisions. These $\pi^0$s mostly decay into photon pairs, some of which are identified in the Endcap Electromagnetic Calorimeter (EEMC) within the STAR detector. The EEMC has a pseudorapidity range of $1 < \eta < 2$ with full azimuthal coverage. The EEMC's Shower Max Detector (SMD) determines the positions of photon showers. A first step in identifying photons is reconstructing clusters of energy in each layer of the SMD. Knowing the position and energy of these photons allows us to reconstruct the $\pi^0$s they decayed from. From these reconstructed $\pi^0$s, a corrected count is determined by fitting signal and background templates from Monte Carlo simulation to the $\pi^0$ candidate invariant mass distributions. We will describe the state of our analysis on the $\sqrt{s} = 510$ GeV dataset from 2012 (integrated luminosity 82 pb$^{-1}$) including cluster identification, Monte Carlo simulation, and data. We will also give a first glimpse of the 2013 dataset (300 pb$^{-1}$). [Preview Abstract] |
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P1.00024: Minimizing the Residual Field and Field Gradient in a Magnetically Shielded Room for nEDM at LANL Chamindu Amarasinghe The LANL neutron Electric Dipole Moment (nEDM) experiment is an effort to set a sensitivity limit of 3.2 \texttimes 10$^{\mathrm{-27}}$ e\textbullet cm on the electric dipole moment of the neutron, an order of magnitude smaller than the current upper limit. This measurement uses Ramsey's method of oscillating magnetic fields. The magnetic field and field gradient have to be low enough to avoid the smearing of the Ramsey fringes and increase the neutron dephasing time respectively. The experiment is enclosed in a two layer Mu-metal magnetically shielded room (MSR) to null any external magnetic fields from the environment. The MSR is degaussed to sufficiently reduce its residual magnetic field and field gradient. The MSR is designed for residual fields as low as 30 nT. The experiment further requires a field gradient of 1 nT/m or smaller. Here we report on the degaussing procedure and the resulting improvement in the shielding prowess of the MSR. [Preview Abstract] |
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P1.00025: An Ultracold Neutron Turntable Switcher for the LANL nEDM Experiment Jackson Heise The goal of a new nEDM experiment at Los Alamos National Laboratory (LANL) is to measure the neutron's electric dipole moment (nEDM) with 1-sigma sensitivity \textasciitilde 3x10-27 e * cm. The experiment will make use of the Ramsey method of separated oscillatory magnetic field pulses to determine the value of the neutron's precession frequency with a strong electric field applied parallel or antiparallel to the holding field. The change in this precession frequency can then be used to calculate the nEDM. ~In the experiment, ultra-cold neutrons (UCNs) travel from the LANL UCN source via guides into a chamber, where the Ramsey magnetic field pulses are applied. The chamber is then unloaded into a detector that measures the polarization of the neutrons. A turntable switcher was constructed to form connections between the source, Ramsey field chamber, and detector. Controlled by a rotary motor, the switcher turns to orient guide pipe sections, first connecting the source to the precession chamber inside a magnetically shielded room, and then to connect the precession chamber to the detector for spin analysis. Discussion of switcher assembly, as well as results of switcher configuration, will be presented. [Preview Abstract] |
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P1.00026: A Study on the Injection of Drugs for Anaesthesia Using Biophysical and Computational Analysis Jehun Shin, Sieun Lee, Seunghyun Kim Biomedical engineering in dental or epidural anaesthesia research requires a combination of all physical and numerical calculations and simulations. Although a finer needle used in modern medicine makes the injection easier and less painful, this type of needle requires a higher force to deliver the drugs at a given rate due to its smaller bore. In this research, factors such as dynamic viscosity of drugs, pressure changes along a tube, and flow rate are considered to model the syringing environment. In addition to these factors, the paper also addresses the dimensions of the syringe tube and the size of the needle for a given injection. In general, while using a small and short needle is safe, it is important to carefully consider the appropriate size of the needle and syringe for each type of medication that is delivered through the injection. Throughout this paper, numerical calculations and fluid dynamics are used in modeling the realities of injection performance. If the results are applied properly, the presented numerical and computational modeling can enable better and earlier decisions to be taken in the syringe injections. The decisions can not only reduce risk, but also support device designs that health care professionals can use more effectively. [Preview Abstract] |
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P1.00027: A Study on the Thermophysical Properties of Functionalized Single-Walled Carbon Nanotubes (SWNT) as Potential Neuroprotective Agents Yoon Jin Kwon, Gyeongeun Park Oxidation of neural tissues in the human brain cause neurodegenerative disease. The information on the sub-cellular localization of oxidative molecules, however, is not provided in detail so far. This research investigates the physical and chemical functionality and stability of anti-oxidant molecules to find better chemical compounds with lower optimization energy. The more functionality there is, the more heat or enthalpy it can give off, meaning that it requires more effort to stabilize the anti-aging compound. Reduction of the immune function due to aging is accompanied by an increased susceptibility to neurodegenerative infections, and higher risks of developing diseases, such as Alzheimer's disease, a progressive disease that destroys mental functions. In this paper, the functionalized single-walled carbon nanotubes (SWNT) molecules are thermodynamically studied to determine whether the molecules stabilize or destabilize the cells that are affected by Alzheimer's disease. To assess the thermodynamic properties of SWNT as potential agents to suppress reactive oxygen species, physical and chemical programs are used that model, optimize, and compare the resulting molecular energy of the various SWNT clusters. [Preview Abstract] |
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P1.00028: Spectrum and Frequency Analysis of the Cello Using Physical and Mathematical Transformations Bumjoon Choi, Richard Kyung A sound spectrum is a reduced sample representation of the original frequencies of a sound, in terms of dB or Pascal. The spectrum shows the amount of energy concentrated in a given frequency band and displays the frequencies that are present in a sound. In this paper, the spectral aspects of Cello and other musical instruments are studied and compared by transforming the sound wave from time domain to frequency domain. The purpose of this research is to find and compare the vibrational characteristics, including the spectra of various selected musical instruments. A function that plots the spectrum for the Cello is built. Subsequently, the script to create the plots of the spectra for all other different instruments can be written. A computer program with sample sound files are used to carry out vibrational analysis and computational experiment for the Cello. The string instrument, including the Cello, shows strong peaks at the first and third harmonic components. Also, compared to the violin, the cello generates more pure tone. While the most of them generate a fuzzy tone, it shows that wood wind instruments show much more energy in the second and/or third harmonics than in the first frequency. [Preview Abstract] |
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P1.00029: Understanding movement of Cholesterol in membrane by measuring the compressibility constant Neti Bhatt The objective of the research is to understand the lipid structures in membrane. Phosphatidylserine is the most abundant negatively charged phospholipid in eukaryotic cells comprising about 10{\%} of the total phospholipids. It is highly enriched in the plasma membrane where much of the cellular inventory of cholesterol partitions. Indeed, how the spatial distribution of cholesterol in the plasma membrane and the nature of its embedding lipidic environment impact cholesterol's ability to desorb/absorb from/into the membrane has not been fully elucidated. We investigate the movement of Cholesterol in two specific lipid membranes by first understanding the characteristics of these membranes, specifically the compressibility of the membranes. Compressibility of phosphatidylserine (POPS) membrane and phosphatidylcholine (POPC) were measured using the Langmuir--Blodgett trough by compressing a monolayer of lipid. Understanding the how compressible a membrane is could potentially explain how the cholesterol moves in these membranes. A higher rigidity could reduce or slow the movement and permeability could fasten the movement of cholesterol. This could then lead to the understanding of distribution of cholesterol in plasma membrane. [Preview Abstract] |
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P1.00030: New Crafting Method for Constructing Asymmetric Vesicles Ursula Perez-Salas, Michael Stanfield We measured the diffusion between of dipalmitoyl-phosphocholine (DPPC) and dimyristoyl-phosphocholine (DMPC) 100nm in diameter unilamellar vesicles using calorimetry to detect the formation of asymmetric membranes. From previous measurements on the transfer of pure DMPC between vesicles done by time resolved small angle neutron scattering (TR-SANS) it was inferred that lipids move slowly across the lipid bilayer, and that this flop-flop motion within the lipid bilayer is slower than the time it takes the lipids to exchange between different vesicles. DPPC, being similar to DMPC, but with longer hydrophobic tails, behaves similarly though the process of exchange and flip-flop is also slower than in DMPC. Using calorimetry we observed signatures of asymmetry in DPPC vesicles as this population exchanged lipids with DMPC vesicles. The fact that asymmetry is detected DPPC vesicles shows that the counter-intuitive flip-flop rate (found to be slower than the exchange rate) inferred. [Preview Abstract] |
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