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Colloquia & Seminars, Spring 2012

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Dark Matter in the Smallest Galaxies

Speaker:Dr. Matthew Walker
Date: May 1, 2012(Tuesday),
Time: 4 pm
Room: 205 Currens Hall

Abstract
At present the Milky Way's dwarf spheroidal (dSph) satellite galaxie are the smallest objects associated empirically with the phenomenology of dark matter. They also exhibit the largest dynamical mass-to-light ratios, with some estimates reaching several thousand times the solar value in optical wavelengths. Insofar as their baryons are dynamically negligible, dSphs provide a relatively clear window onto the properties of dark matter within galaxies. I will present empirical constraints, derived from stellar kinematics, on the amount and spatial distribution of dark matter within individual dSphs and will briefly discuss potential implications for cosmology and particle physics.

About the speaker:
Matthew G. Walker graduated from Western Illinois University summa cum laude in 1999 with a double major, concluding a B.S. Degree in Physics and a B.A. Degree in Philosophy. During his time at Western Illinois University, he actively participated in undergraduate research in Dr. Mark S. Boley's magnetoelasticity research laboratory and presented his work at several midwestern conferences, including the Undergraduate Research Symposium at Argonne National Laboratory. His faculty at WIU remember his work as always being thorough, creative, and insightful. After finishing at WIU, Matthew headed off to University of Michigan Ann Arbor, where he concluded his Ph.D. Degree in Astronomy and Astrophysics in May of 2007. (Shortly after this, he actually visited the WIU Physics Department for an invited colloquium on the internal kinematics of dwarf spheroidal galaxies, his dissertation topic.) For the next three years, until 2010, Matthew served as a postdoctoral research associate at the Institute of Astronomy, a part of the University of Cambridge in the UK, where much of his research centered around observational tests of cosmological models, mass measurements, and the search for dark matter. He has been an invited speaker at prestigious physics/astrophysics/astronomy research centers located around the world, in Chile, Germany, France, Sweden, Scotland, and Switzerland, as well as at Oxford, Cambridge, and Princeton. Currently, he holds a prestigious Hubble Fellowship at the Harvard-Smithsonian Center for Astrophysics in Cambridge, MA. It is a pleasure and a privilege for our current faculty and students to have Matthew return for a visit and an invited colloquium within the WIU Physics Department.

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PHYS 490 Student Seminar

A Brief Overview of Lagrangian Mechanics: Finding a Way to Conceptualize the Lagrangian Equations of Motion

Speaker:Matt Sprengel
Date: April 30, 2012(Monday),
Time: 4:30 pm
Room: 205 Currens Hall

Abstract
The goal of this talk is to spread a firm conceptual grasp on Lagrangian Mechanics, and in particular the Lagrangian equations of motion. I will discuss the fundamental principles behind such physics as well as the history behind the formulations and why they are useful. A lot of students simply take equations from the book as fact without truly striving to understand where they come from, and what they mean. I will attempt to alleviate this tendency to simply take the mathematical operations for what they are and explain the true nature of the physics behind them.

About the speaker:
Matt Sprengel , Undergraduate Student, Physics Department, WIU

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PHYS 490 Student Seminar

The Effect of Magnetic Fields on Algal Growth

Speaker:Jacob Redenius
Date: April 30, 2012(Monday),
Time: 4:30 pm
Room: 205 Currens Hall

Abstract
This presentation focuses on the effect of exposure to weak, static magnetic fields on cellular growth of algae specimen. This topic is becoming more of interest to scientific investigation due to the potential for algae to be used in the production of biodiesel, a reasonable alternative to conventional fuel. The research methodology involves algae grown in test tubes so that factors such as pH and temperature can be kept constant for all samples. Our samples will first be exposed to varying degrees of magnetic fields to determine the optimal field strength for producing cellular abnormalities in the algae. Ring magnets will surround the test tubes, a reasonable and affordable way to produce a static, measurable magnetic field within the samples. The number of ring magnets used on each sample will provide a way of altering the field strength for the first stage of the study. Each individual test tube will be kept at distance from the others in order to ensure that the magnetic fields do not pollute one another. The second stage of the investigation begins once the optimal field strength has been determined. New samples, prepared identically to the previous ones, will be exposed to the field strength determined in the first stage. However, this time the duration of exposure will vary for each sample. Since the literature suggests that magnetic field strengths of ten milliTeslas will produce the greatest abnormalities in the algal growth, this will be the focus of our research effort.

About the speaker:
Jacob Redenius , Undergraduate Student, Physics Department, WIU

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Tunnel diode resonator (TDR) measurements of the London penetration depth in superconductors

Speaker: Dr. Ryan Gordon
Date: April 25, 2012 (Wednesday)
Time: 4 p.m.
Room: 205 Currens Hall

Abstract
The London penetration depth, l , characterizes the rate at which applied magnetic fields are screened from the interior of a superconductor. Since the penetration depth is also related to the density of electronic carriers in the superconducting state, l (T) µ ns-1/2(T), by measuring its temperature dependence, one is able to probe the symmetry of the electronic interactions that give rise to superconductivity. One such way of measuring l (T) is to use a tunnel diode resonator (TDR) circuit. This is a type of radio frequency LC resonating circuit sustained by a tunnel diode and is specifically designed for making extremely sensitive measurements of physical properties of materials. In this presentation, I will give a historical introduction to superconductors and a general overview of their properties. I will also share the details of my experience using the TDR to measure the London penetration depth in newly discovered and unconventional iron-based superconductors.

About the speaker:
Dr. Ryan Gordon graduated from Western Illinois University in May 2005 and then went on to earn his Ph. D. from Iowa State University in Condensed Matter Physics. He currently works at Universitè de Sherbrooke in Shebrooke, Quèbec conducting research on electrical and thermal transport measurements in unconventional superconductors.

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PHYS 600 Student Seminar

Universality of Arbitrary Quantum Logic Gate

Speaker:Kamal Chapagain
Date: April 25, 2012(Wednesday)
Time: 4:00-4:50 pm
Room: 205 Currens Hall

Abstract
Time evolution of a quantum system is governed by a unitary operation given by the exponential of the Hamiltonian of the system. In the field of quantum information the goal is to obtain a certain output state as a desired result mathematically described through a certain unitary operation on the initial quantum state of the system. In general, any complicated unitary operator can be decomposed into set of simple unitary operators (quantum logic gates) that are physically easy to realize in the given quantum system. Here we want to show that any quantum logic gate is universal.

About the speaker:
Kamal Chapagain , Graduate Student, Physics Department, WIU

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PHYS 600 Student Seminar

Fluorescence of trivalent samarium in bismuth borate glasses

Speaker: Atif Alhabbad
Date: April 18, 2012(Wednesday)
Time: 4:00-4:50 pm
Room: 205 Currens Hall

Abstract
We studied the effect of host glass composition on the fluorescence properties of trivalent samarium ions in bismuth borate glasses, with Bi2O3 contents varying from 24 mol% to 64 mol %. Bismuth borate glasses containing 0.5 mol% samarium were prepared by the usual melt quench method. Glasses were then annealed near the glass transition temperature (4000 C) for 3 hrs. Fluorescence spectra of all these samples were obtained using two different excitation wavelengths. The intensity of the samarium fluorescence depends on the Bi2O3 content and excitation wavelengths. This could be due to the structural changes occurring in the vicinity of samarium ions with increase in bismuth content as well as the energy transfer from the bismuth ions to samarium ions.

About the speaker:
Atif Alhabbad, Graduate Student, Physics Department, WIU

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PHYS 490 Student Seminar

Modeling of Formaldehyde Maser Variability in Massive Star-Forming Regions

Speaker: Jeff Carlson
Date: April 16, 2012(Wednesday)
Time: 4:30 pm
Room: 205 Currens Hall

Abstract
Formaldehyde (H2CO) masers are rare astrophysical phenomenon associated with massive star-forming regions. The H2CO masers associated with the star-forming regions of NGC 7538 and IRAS 18566+0408 have shown periodic variability due to a currently unknown mechanism. Our work attempts to demonstrate that a simple geometric model of the H2CO regions may account for this variability.

About the speaker:
Jeff Carlson, Undergraduate Student, Physics Department, WIU

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PHYS 490 Student Seminar

Using Magnetic Force Microscopy to Study Magnetic Ordering of Functionalized Doped Multi-Wall Carbon Nanotubes

Speaker: Brandon Selph
Date: April 16, 2012(Wednesday)
Time: 4:30 pm
Room: 205 Currens Hall

Abstract
Carbon nanotubes are well known for their superior chemical, mechanical, thermodynamic, and electrical properties. Due to these unique characteristics, the potential applications are almost endless. In particular, carbon nanotubes are of great use for conductive and high strength nano-composites, bio-sensors, and targeted delivery of bio-active substances. In this talk, I will introduce the experimental methods used to image the carbon nanotubes. A highly ordered magnetic pattern is essential to the effectiveness of any application using carbon nanotubes, and producing an image of them is one way to ensure the viability of the sample.

About the speaker:
Brandon Selph, Undergraduate Student, Physics Department, WIU

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PHYS600 Student Seminar

Compositional Variation of Refractive Index in Lead Borate Glasses

Speaker: Abdelsalam Talafha
Date: April 11, 2012(Wednesday)
Time: 4:00-4:50 pm
Room: 205 Currens Hall

Abstract
Lead borate glasses have low melting temperatures, wide glass formation regions, and good radiation shielding properties. We prepared lead borate samples by varying PbO concentration from 30 to 70 mol% and their refractive indices were measured using the Brewster angle method. Theoretically, the refractive index is expected to increase linearly with PbO concentration. However, the experimental values show refractive indices do not follow the linear behavior at higher values of PbO concentration.

About the speaker:
Abdelsalam Talafha, Graduate Student, Physics Department, WIU

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PHYS600 Student Seminar

An Ultraviolet Laser Source with Continuously Adjustable Energy

Speaker: Thomas Asafuah
Date: March 28, 2012(Wednesday)
Time: 4:00-4:50 pm
Room: 205 Currens Hall

Abstract
Ultraviolet lasers are extensively used in studying the multi-photon ionization of molecules. The amount of ionization depends strongly on the input laser intensity. In order to identify the physical processes occurring at different intensities, a continuous and fine adjustment of the input laser energy is required. In this talk I will present our experiment of producing an ultraviolet laser at 266 nm with continuously variable energy by frequency-doubling a green laser at 532 nm.

About the speaker:
Thomas Asafuah, Graduate Student, Physics Department, WIU

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Making little big bangs at RHIC

Speaker: : Dr. Marzia Rosati
Date: March 23, 2012 (Friday)
Time: 4:00 p.m.
Room: 205 Currens Hall

Abstract
Relativistic heavy ion collisions at the Relativistic Heavy Ion Collider (RHIC) at Brookhaven National Laboratory create an extremely hot system at temperatures (T) expected within only the first microseconds after the Big Bang. At these temperatures (T ~ 1012 K), which are several hundred thousand times hotter than the sun's core, normal hadrons cannot exist and nuclear matter "melts" to form a "soup" of quarks and gluons. Many observables point to a picture of the medium as rapidly equilibrating and expanding as a nearly perfect fluid perhaps the most perfect found in nature since the Big Bang.

About the speaker:
Dr. Marzia Rosati is a physics professor at Iowa State University and she works in the area of experimental nuclear physics with a focus on relativistic heavy ion collisions. Dr.Rosati is also interested in the study of quarkonium suppression in relativistic heavy ion collisions. She participated in the PHENIX experiment at RHIC at Brookhaven National Laboratory. In the past ten years, Dr. Rosati has studied AuAu, CuCu, pp, and dAu collisions. Results of this research have been reported in several papers and news articles on RHIC.

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PHYS600 Student Seminar

On Time-Splitting / Pseudo-Spectral Approximations for the Schrodinger Equation in the Semi-Classical Regime

Speaker: Oluwaseye Dada
Date: March 21, 2012(Wednesday)
Time: 4:00-4:50 pm
Room: 205 Currens Hall

Abstract
In my presentation, I will show how time splitting spectral methods can be used numerically to solve the Schrodinger equation and nonlinear Schrodinger equation. I will discuss the numerical discretizations of the time-dependent Schrodinger equation based on the pseudo-spectral methods in space and the exponential operator splitting methods in time. Finally, I will talk about the use of time-splitting spectral approximation method in the semi-classical regime. The considered discretizations are favorable in view of accuracy and efficiency, and the geometric properties of the equation are also well captured.

About the speaker:
Oluwaseye Dada, Graduate Student, Physics Department, WIU

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PHYS600 Student Seminar

APPLICATION OF ATOMIC COHERENCE EFFECTS TO SUPERRESOLUTION

Speaker: Ademola A Jinadu
Date: March 7, 2012(Wednesday)
Time: 4:00-4:50 pm
Room: 205 Currens Hall

Abstract
Interaction of light with two-level atoms is well understood through the phenomena of absorption and stimulated emission of light. However, real atoms always have more than two levels and this multi-level structure can be exploited for variety of interesting applications. In general, interaction of light with multi-level atoms generates interference effects that are commonly termed as atomic coherent effect, for example coherent population trapping and electromagnetically induced transparency. Through these atomic coherent effects one has controllable handle on the response of an atomic medium to the light fields that are incident on it. In this presentation I will talk about interaction of three level atoms with two light fields and how it can cause emergence of structures smaller than the wavelength of both the light fields that the atom is interacting with. These ideas are applicable to atom localization, Nano-lithography, and microscopy beyond the Rayleigh limit.

About the speaker:
Ademola A Jinadu, Graduate Student, Physics Department, WIU

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Graphene -- The Amazing 2D Membrane

Speaker: Dr. Yan Lwin
Date: February 24, 2012 (Friday)
Time: 4 p.m.
Room: 205 Currens Hall

Abstract
Graphene is a most peculiar and unique material which consists simply of one atomic layer of carbon atoms arranged in a honeycomb lattice. As such graphene is the ultimate two-dimensional crystal since it is only one atom thick in the third dimension. The great technological possibilities of graphene are actually just one aspect of its interesting properties. Andre Geim is the 2010 Physics Nobel Prize winner for his “groundbreaking experiments on the two-dimensional material graphene”. He is a professor of physics at Manchester University in UK. Dr. Lwin will be presenting the basic physics on graphene and recent developments and advancements.

About the speaker:
Dr. Lwin is a retired professor from the Physics Department at Western Illinois University. His research interests include studies of defects in metals, and superconductors, and their correlations with physical properties like electrical and thermal conductivity in bulk and thin film materials. He is also interested in the radiation defects in nano-structured materials and computer simulation of defect production by radiation damage in metals using molecular dynamics (MD) methods.

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Study of water diffusion on single-supported bilayer lipid membranes by neutron scattering

Speaker: Dr. Haskell Taub
Date: February 9, 2012 (Thursday)
Time: 4 p.m.
Room: 205 Currens Hall

Abstract
Neutron scattering and molecular dynamics simulations have been used to elucidate the diffusion of water molecules associated with single bilayer lipid membranes supported on a silicon substrate. This system serves as a physicist's model of biological membranes that surround all living cells. Knowledge of the water motion is important for understanding the membrane function. We first characterize the structure of our supported membranes as a function of temperature using Atomic Force Microscopy. We then perform high-energy-resolution quasielastic neutron scattering experiments at the NIST Center for Neutron Research and the Spallation Neutron Source at Oak Ridge National Laboratory on similarly prepared samples. By varying both membrane temperature and level of hydration, we find evidence of three different types of water motion: bulk-like, confined, and bound. The motion of bulk-like and confined water molecules is fast compared to those bound to the head groups of the lipid molecules, which move on the same nanosecond time scale as the molecular center of mass.

About the speaker:
Dr. Taub is currently a member of the Department of Physics and Astronomy at the University of Missouri-Columbia. He received his B.S. from Stanford, his Ph. D. from Cornell and did postdoc work at New York University. While working at Brookhaven National Laboratory, Dr. Taub was introduced to neutron scattering research and has since been conducting experiments to study the structure, phase transitions, and dynamics of adsorbed films. Currently, he is directing a large NSF-funded project aimed at training the next generation of scientists and engineers in neutron scattering research.

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Lecture Series on Nobel Prizes

Quasicrystals

Speaker: : Dr. P. K. Babu
Date: February 3, 2012 (Friday)
Time: 4:00 p.m.
Room: 205 Currens Hall

Abstract
The Nobel Prize in Chemistry 2011 was awarded to Daniel Shechtman"for the discovery of quasicrystals". In quasicrystals, we find the fascinating mosaics of the Arabic world reproduced at the level of atoms: regular patterns that never repeat themselves. The configuration found in quasicrystalswas considered impossible according to text books. Discovery of quasicrytalsfundamentally altered our description of crystals. The story of quasicrystalsis yet another example where a researcher had to fight the established knowledge to get recognition of his discovery.

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