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Congratulations, Class of 2007! On May 12, 2007, 18 students received diplomas for their B.S. and B.A. degrees from Physics Department Chair Prof. Beate Schmittmann, at the Physics Department Commencement Ceremony. This year's valedictorian address was presented by Linh Pham, followed by valecantorian(?) Brian Skinner who sang a ballad about getting a degree in physics to the accompanyment of his guitar. The event was well attended by family, friends, and faculty, and was followed by a reception in the Hall of the Chemistry-Physics Building. Photograph by Tatsu Takeuchi.
The LENSMEN. Profs. Bruce Vogelaar, Raju Roghavan, and Jonathan Link study the Sun through the observation of neutrinos that are emitted from the Sun's core. The detector they are developing is called LENS, for Low Energy Neutrino Spectrometer, and is capable of measuring solar neutrinos of very low energies which were invisible to existing detector technologies. This photograph, by John McCormick, superimposed with the image of the Sun appeared in the Winter 2008 issue of the Virginia Tech Research Magazine.
This photo of Prof. Beate Schmittmann, Chair of the Physics Department, appeared on the Virginia Tech homepage and the College of Science Magazine. The equation that Prof. Schmittmann is holding is part of a translation procedure. The translation procedure is needed in instances where theoretical physics relate the properties of a material on one scale (say 100 nanometers) to its properties on a very different scale (say a few centimeters). The mathematical framework, called renormalization, is used in other areas of physics, as well. Photograph by John McCormick.
This workshop, made possible by a generous donation of Mr. Mark Sowers, brought together young people working on a variety of aspects of string theory and related fields to discuss the most recent developments and exchange new ideas. Please see the workshop website at http://www.phys.vt.edu/~sowers/ for details. Ambigram design by Tatsu Takeuchi.
Virginia Tech Campus with the Allegheny Mountains in the background. The Kimballton Underground Research Facility and the Martin Observatory are both about a 30 minute drive away from campus into the Allegheny Mountains. Photograph by Rick Griffiths.
Robeson Hall in the Spring. Robeson Hall has been the home of the Physics Department since 1960. The building was named after Dr. Frank Leigh Robeson who was Department Head from 1918 to 1954.
Robeson Hall in the Winter. Robeson Hall has been the home of the Physics Department since 1960. The building was named after Dr. Frank Leigh Robeson who was Department Head from 1918 to 1954. Photograph by Tatsu Takeuchi.
The new Chemistry-Physics Building in the Fall. The building opened for classes starting from the Spring 2004 semester. The conch-shell shaped structure on the right houses the lecture theaters for both Chemistry and Physics. Photograph by Tatsu Takeuchi.
The new Chemistry-Physics Building in the Spring. The building opened for classes starting from the Spring 2004 semester. A Foucault pendulum is to be installed in the circular enclosure behind the large window. Photograph by Tatsu Takeuchi.
The Martin Observatory in the moonlight. The Martin Observatory is located at the Miles C. Horton Sr. Center, about a 30 minute drive from campus up toward Mountain Lake. The observatory houses a 14in Schmidt-Cassegrain telescope which is used for both teaching and research. Photograph by Kristin Hendershot.
Prof. John Simonetti (with cap) and Prof. Jean Heremans installing the new 14-in Schmidt-Cassegrain telescope at Martin Observatory, January 2007. The telescope will be used for both teaching and research.
The Prices Fork Observatory, a five minute drive from campus, hosts public open houses on 1st and 3rd Friday evenings of each month when classes are in session during the Fall and Spring Semesters, weather permitting. Photograph by Tatsu Takeuchi.
An image from the Virginia Tech Spectral-line Survey (VTSS) performed by Prof. Simonetti's group. This image is a mosaic of the Cygnus-Lacerta region.
An image from the Virginia Tech Spectral-line Survey (VTSS) performed by Prof. Simonetti's group. This image is a mosaic of the Taurus-Orion-Monoseros region.
The Spectral-Line Imaging Camera (SLIC, left) is located at the Martin Observatory (SLIC housing shown right), on the grounds of the Horton Center, a project of the Mary Moody Northen Endowment and Virginia Tech. SLIC is used by Prof. Simonetti's group to conduct the Virginia Tech Spectral-Line Survey (VTSS).
Aerial view of the Pisgah Astronomical Research Institute (PARI), located southwest of Asheville, NC. Prof. John Simonetti, together with Profs. Steven Ellingson and Cameron Patterson of ECE, is constructing a new radio telescope at PARI to search for low-frequency radio pulses associated with gamma ray bursts, neutron stars, and black holes. The site of this Eight-meter-wavelength Transient Array (ETA) project is indicated with the green arrow.
The Core Array of the ETA Radio Telescope at the Pisgah Astronomical Research Institute in North Carolina. This seemingly simple device is actually the most advanced radio telescope of its kind, keeping watch over a large area of the sky for low-frequency radio pulses associated with transient phenomena such as gamma ray bursts, neutron stars, and black holes. The ETA was constructed by Prof. Simonetti in collaboration with Profs. Ellingson and Patterson of ECE.
Proposed designs for the new SKA (Square Kilometer Array) radio-telescope. Prof. Simonetti and Prof. Ellingson (ECE) are the official representatives of Virginia Tech in this project.
Non-equilibrium statistical physics forms a central research interest of the theoretical condensed matter group. A simulation from the group of Professors Schmittmann and Zia shows coarsening "clouds" in a simple driven diffusive system, involving two species of particles drifting in opposite directions.
In the group of Professors Schmittmann and Zia, postdocs and students study simple many-particle systems driven far from thermal equilibrium. Some models can be interpreted in the language of vehicular traffic. The diagram shows a space-time plot of traffic jam formation. Time (space) runs vertically downwards (horizontally). Red (blue) pixels represent fast (slow) cars, driving from left to right and viewed from a co-moving frame. Black pixels are empty parts of the road.
Opinion formation in human societies is modeled on an adaptive network in a project of Profs. Schmittmann and Zia's group. The final prevalence M/N of an opinion is shown as a function of its initial prevalence. Individuals are influenced by both similar and opposing opinions, with probabilities p and q. (Top: q = 1-p; bottom: q= 0.1).
Prof. Täuber, in collaboration with Drs. Mauro Mobilia and Ivan Georgiev, has studied pattern formation in stochastic models for predator-prey interaction. In these snapshots, with time increasing from left to right, expanding fronts of "escaping" prey (blue) and "pursuing" predators (red) can be seen. The resulting stationary state is a dynamic equilibrium with oscillating population densities.
In a one-dimensional stochastic predator-prey competition model, the research group of Prof. Täuber has observed “coarsening” into segregated domains of predators (red) and prey (blue) - with few empty spaces in between (black). As time proceeds (downwards in the picture), the domains grow, until eventually all predators die out.
Structure of a single-molecule magnet Mn12-acetate [Mn (blue), O (red), C (gray)] whose electronic and magnetic properties were calculated by Prof. Park's group using heavily-computer-aided density-functional theory. Calculated ground-state spin and excited spin states are shown.
Structure of a single-molecule magnet Mn8Fe4 [Mn (blue), Fe (yellow), O (red)]. Prof. Park's group showed, within density-functional theory, that the magnetic anisotropy barrier decreases significantly with the number of extra electrons in the Mn12-acetate structure.
Calculated density of states for cyanide-bridged single-molecule magnet Fe2Ni2. Prof. Park's group studies electronic structure and magnetic anisotropy of various magnetic molecules.
Prof. Park's group group computationally models nanostructures in which magnetic molecules are adsorbed on various metal surfaces. Shown is a Mn12 molecule attached to a gold slab.
A schematic model for Min protein oscillations in E.coli. Prof. Rahul Kulkarni, in collaboration with the group of Prof. Ned Wingreen (Princeton University), is working on modeling the processes involved. (image courtesy of K. C. Huang, Princeton University)
Prof. Zallen applies condensed-matter concepts to study cell-pattern development during morphogenesis. This figure shows cell-pattern disordering during early development in the Drosophila embryo. Observed patterns interpolate from the perfectly ordered honeycomb lattice to the pattern of a highly disordered foam as time progresses (R. Zallen, in collaboration with J. A. Zallen of Sloan-Kettering Institute).
A small crystal (0.1mm × 0.1mm) of arsenic sulfide, a two-dimensional-network (layer structure) semiconductor, is shown here in a diamond-anvil cell at low pressure (yellow), moderate pressure (red), and high pressure (black). The effect of increasing pressure is to greatly enhance the interlayer coupling, broadening the valence and conduction bands and substantially reducing the bandgap. This results in the striking color change. (Work of Prof. Zallen, done in collaboration with J. M. Besson of the University of Paris.)
Polymer light-emitting diodes, such as the one produced by Martin Drees (Ph.D. 2003) in Prof. Heflin's laboratory, may potentially yield flexible, inexpensive flat-panel displays.
Prof. Heflin's group is developing organic solar cells that have the potential to be flexible, lightweight, efficient renewable energy sources. Photograph by John McCormick.
Prof. Heflin's group is examining how nanoscale control of the composition of organic solar cells consisting of semiconducting polymers and fullerenes can improve their power conversion efficiency.
Prof. Heflin's group is using self-assembly of nanoscale organic films to create organic electrochromic devices that change color when a voltage is applied at rates up to 50 Hz.
Prof. Heflin's group is using self-assembly of nanoscale organic films to create organic electrochromic devices that change color when a voltage is applied at rates up to 50 Hz.
"Introduction to Nanoscale Science and Technology", edited by Prof. Heflin, is one of the first textbooks written on the subject for a broad audience of graduates and undergraduates in any science or engineering discipline.
Trap and detector for single photoinjected electron spins. Prof. Robinson's group studies the physics of optically injected spin in semiconductor nanostructures such as this.
Using laser spectroscopic techniques, the group of Prof. Khodaparast can measure the spin life of carriers in semiconductors. As shown here, the spin relaxation can change drastically as a function of temperature.
Dr. Rajeev Kini and Kanokwan Nontapot in Prof. Khodaparast's group can generate Terahertz (THz) radiations using semiconductor materials. Panel a) shows the THz radiation in the time domain and panel b) in the frequency domain (at different excitation laser wavelengths). In this case, the THz radiation can be generated by using two intense near infrared radiations overlapping on the sample. One of the mechanism responsible for THz generation is the non-linear interaction between two optical fields of the laser beams which can produce a slowly varying field (the beats in the time domain) corresponding to THz radiation in the time domain. The sample is InAs film provided by Prof. Louis Guido of the Materials Science Department.
Prof. Indebetouw's group investigates the properties of scanning holographic microscopy for 3D phase and fluorescence biological imaging. Shown here are fluorescent pollen grains (excitation:532nm, emission:600nm). The bar is 20 microns long.
Prof. Indebetouw's students, in cooperation with the Mechanical Engineering Dept., are using ultra fast interferometric methods to measure aero-optics phase distortions in supersonic flows. The figure shows two interferograms taken apart, and the phase distortions due to a rapid temperature change.
Optical vortices and dislocations appear spontaneously in optical resonators with phase-conjugate photorefractive gain. The dynamics of these vortices are studied by Prof. Indebetouw's group.
Prof. Indebetouw's students are applying low coherence tomographic holography to obtain optical sections of micromechanical structures and biological specimens. In the figure, the profile and structure of an insect wing is revealed quantitatively by the phase distributions shown in b,d.
Prof. Indebetouw's students are applying low coherence tomographic holography to obtain optical sections of micromechanical structures (here an IC circuit), and biological specimens.
Prof. Indebetouw's group, in cooperation with the Electrical and Computer Engineering Dept. and Johns Hopkins University, is developing new methods of digital and scanning holography for 3D biological microscopy. The figure shows some unusual point-spread-functions that are synthesized to produce images with properties that cannot be obtained with conventional microscopy.
Prof. Soghomonian's group group studies physico-chemical properties of variously modified DNA molecules. Intercallation of metal cations into λ-DNA molecules not only influences its electronic properties, but also leads to different pattern formation on mica substrates as investigated by atomic force microscopy.
Gold electrodes separated by nanometer length scales are fabricated and utilized in the labs of Profs. Soghomonian and Heremans. The electrodes, imaged by scanning electron microscopy, are used to study the electronic properties of molecules (molecular electronics) and of organic semiconductors (organic electronics).
Micron-sized Hall device fabricated by My Linh Pham (Class of 2007) in Prof. Heremans' laboratory, on thin film (001) InSb. The Hall device, with arms oriented along the InSb <100> directions, was fabricated by electron beam lithography, and features mesa tops about 0.5 µm wide. The structure is utilized in an exploration of spin physics in systems with high spin-orbit coupling. SEM micrograph by My Linh Pham.
The electronic properties of nanoscale triangular structures such as these are studied in Prof. Heremans' laboratory. Under strong spin-orbit interaction, electrons experience the structure as a spin filter, of interest to achieve nanoscale spin electronics. The triangles were etched in an InSb/InAlSb heterostructure, and the image obtained by atomic force microscopy.
An atomic force microscope image of a mesoscale phase-coherent ring geometry etched in an InSb/InAlSb heterostructure, fabricated and studied by Prof. Heremans' group. Under a magnetic field, electron flow through this ring geometry shows effects due to quantum-mechanical phase coherence, and due to the electron's spin quantum number.
An atomic force microscope image of a mesoscopic sample geometry etched in an InSb/InAlSb semiconductor heterostructure studied by Prof. Heremans' group. Such structures show how electrons move in an environment where the sample walls, and not impurities, form the main electron scattering mechanisms, and where quantum-mechanical orbital and spin effects are strong.
Transverse magnetic focusing spectra obtained up to a temperature of 150K in an InSb/InAlSb semiconductor heterostructure. Such electronic transport phenomena in nanoscale structures are studied experimentally in Prof. Heremans' laboratory. InSb is of interest due to its high mobility and its potential in spin electronics.
The laboratory of Prof. Heremans performs experiments on quantum-mechanical phase and spin coherence in nanoscale semiconductor structures under strong spin-orbit interaction, of interest in spin electronics. The graph shows Altshuler-Aronov-Spivak quantum-mechanical oscillations in an InAs loop structure at various temperatures.
End view of the Belle detector, with the iron yoke endcaps opened to expose the interior, prior to its rolling into the KEKB beamline. Prof. Piilonen's group studies CP violation in B-meson decays using Belle, located at KEK in Japan.
Prof. Piilonen's group studies CP violation in B-meson decays using the Belle detector and the KEKB accelerator, located at KEK in Japan.
End view of the Belle detector and the KEKB accelerator beamlines. Prof. Piilonen's group studies CP violation in B-meson decays using this facility, located at KEK, Japan.
View of the KEKB accelerator beamlines, acceleration cavities, and steering magnets, at the intersection with one of the injection beamlines. Prof. Piilonen's group studies CP violation in B-meson decays using KEKB, located at KEK in Japan.
Event display at the Belle detector at the KEKB accelerator at KEK in Japan. By analyzing millions of events such as this, Debabrata Mohapatra (Ph.D. 2006) of Prof. Piilonen's group discovered the rare decay process b→d γ. Deb received a Sigma Xi Award for this achievement.
Prof. Vogelaar's group works on the Borexino solar neutrino detector, located at the Gran Sasso Lab in Italy. This detector is specifically designed to measure the 7Be solar neutrino flux.
Prof. Jonathan Link's group works on the MiniBooNE experiment at Fermilab. MiniBooNE is searching for the neutrino oscillation process νμ→ νe, the discovery of which will force physicists to rethink their current understanding of neutrino physics. Shown here is a schematic of a typical νμ event in the MiniBooNE detector.
Prof. Raghavan's group works on the development of the new LENS detector which uses Indium doped liquid scintillator technology to measure the low energy solar neutrino spectrum. This figure is a schematic of the LENS design, showing signal light from a nuclear event propagating through the detector lattice.
Entrance to the Kimballton mine where the Kimballton Underground Research Facility is located. Prof. Vogelaar is seen here in the green helmet on the right, and Henning Back (Ph.D. 2004) is in the white helmet in the center.
Dr. Christian Grieb (left, red helmet) and Prof. Bruce Vogelaar (right, white helmet) inside the Kimballton mine. The enclosure for the Kimballton Underground Research Facility is under construction in the background. When complete, the facility will house the LENS solar neutrino experiment, and other research projects which require a very low radiation environment.
The enclosure for the Kimballton Underground Research Facility under construction deep inside the Kimballton mine. When complete, the facility will house the LENS solar neutrino experiment, and other research projects which require a very low radiation background.
Cross Section of Butt Mountain, where the Kimballton Underground Research Facility is located. The site of the facility is in a limestone layer indicated in light blue.
Atomic Force Microscope images of the new diamond-like carbon coating developed by Mark Makela (Ph.D. 2005) for Ultra Cold Neutron guide tubes. The technology is used by Prof. Vogelaar's group in the UCNA experiment at Los Alamos National Lab.
Professor Pitt's group works on the G-zero parity-violating electron scattering experiment at Jefferson Lab. Shown here are the G-zero magnet and detector being readied for data-taking.
Prof. Pitt's group works on the development of the Qweak detector at Jefferson Lab. The objective of the Qweak experiment is to measure the weak charge of the proton to very high accuracy. The Standard Model prediction of the quantity is Qpw=1-4sin2θW, where sin2θW is a quantity that has already been measured accurately at LEP and SLD. Any deviation of Qweak's measurement of Qpw from the Standard Model prediction will be a signal of new physics.
In Prof. Takeuchi's book "No Equations! Relativity Illustrated" (published in 2005 in Japan in Japanese) the little character shown on the right explains Einstein's Special Theory of Relativity without using ANY equations. A Chinese translation has been published in Taiwan in 2007.
In his book "In Search for Another Miraculous Year" (published in 2005 in Serbian in Belgrade, Serbia) Prof. Djordje Minic reflects upon the signifance of Einstein's discoveries from the "miraculous year" (1905) on the major currents of physics developed during the 20th century. He then discusses certain contemporary directions in physics and speculates on the coming of "another miraculous year". The book is aimed at a broad spectrum of potential readers. The cover shown here was created by Joy Rosenthal of the Department of Art and Art History.
The Thunderbird computer cluster, constructed by the Physics Department's computer wizard Roger Link, consists of 137 Dell computer nodes, each node with dual Xeon 3.2GHz processors. The cluster has 2 terabytes of storage, with gigabit networking. Thunderbird is used in a variety of physics research projects.
The Tempest computer cluster, constructed by the Physics Department's computer wizard Roger Link, consists of 80 1 GHz AMD Athlon boxes. Each node has 1 gigabytes of RAM. System is running Rocks 4.1 clustering software. Tempest is primarily for student computing research.
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