Colloquium Schedule
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Thursday October 31, 2024 3:00 PM MSPB 250
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Professor MACHINE LEARNING IN SCIENCE This talk will introduce machine learning techniques in particle physics experiments. After covering the basic concepts of machine learning, a variety of techniques for classification and related problems will be described. Examples of applications in various areas of experimental detectors and data analysis will be provided. We will use some cases to illustrate important fundamental connections to statistics, and in order to demystify the "magic" of machine learning. Finally, we will describe ongoing work in machine learning in physics, one simple case of data analysis, and discuss how newer machine learning techniques might be applied to problems. |
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Thursday October 3, 2024 3:00 PM MSPB 250
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Associate Professor NANOPHOTONICS: THE ROLE OF ULTRAFAST SPECTROSCOPY IN SHRINKING LIGHT-BASED TECHNOLOGIES Our ability to develop disruptive technologies is intimately tied with our ability to mold the flow of light at length scales below the optical diffraction limit. Equally important is our ability to collect information on the dynamics of these systems in order to understand novel and unexpected fundamental nanoscale physical and chemical processes. In some cases, understanding the first few picoseconds after light absorption can be critical to tailoring the overall performance of nanoscale devices. In this talk, I describe our nanophotonics research program at UAB that develops novel building blocks for next-generation technologies in the energy conversion, communications and quantum sectors. Specifically, I discuss how our group employs advanced laser spectroscopy, electron microscopy and machine-learning techniques to interrogate nanophotonic materials—testing how key parameters such as size, geometry, dielectric function and carrier density modify light-matter interaction at nanometer length and femtosecond time scales. These studies, sometimes performed while the device is under operation, include (i) fabricating and testing state-of-the-art photovoltaic thin-film materials such as hybrid organic-inorganic perovskites; (ii) designing and fabricating metasurfaces capable of squeezing light to nanoscale dimensions to enable novel collective optical and electronic phenomena that cannot be obtained with natural materials; (iii) using subwavelength, highly crystalline nanospheres to fabricate a solution-processed thin-film laser with thickness and energy-input threshold at least an order of magnitude lower than previously demonstrated. Overall, these experimental studies coupled with machine-learning techniques provide physical insights on how to couple elementary excitations in materials with nanoscale light fields to mitigate losses, thus providing a means to develop robust nanoscale architectures for integration in energy and quantum systems. |
Colloquium Schedule Archive
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Thursday April 4, 2024 3:00 PM MSPB 250
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Associate Professor Mechanical and Thermal Properties of Carbon Linear Chains Encapsulated by Carbon Nanotubes Linear carbon chains (LCCs) are one-dimensional materials with unique properties and restricted selection rules for phonon-phonon and electron-phonon interactions. When encapsulated by carbon nanotubes (CNTs), these LCCs find a suitable environment to keep themselves stable. In this colloquium, the Raman spectroscopic signature C-band around 1850 cm−1 from LCCs encapsulated by CNTs is monitored against pressure (P) and temperature (T) and its behavior reveals: (1) unique mechanical properties showing that the LCCs’ Young’s modulus, Grüneisen parameter and strain follow universal P−1 and P2 laws, respectively; and (2) unique thermal properties showing that the LCCs’ thermal properties are well described within the Debye formalism even at room temperatures leading to unique universal relations for their internal energy, heat capacity, coefficient of thermal expansion and thermal strain in terms of the number of carbons atoms and T. If time permits, a short discussion about the observation of an elusive phonon mode at 1637 cm-1 will also be addressed. |
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Thursday November 16, 2023 3:00 PM MSPB 250
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Soil Health Specialist Physics in the Field: Measuring Cattle Methane Emissions using Dual Comb Spectroscopy Modern agricultural demands can often be seen at odds with growing concerns over greenhouse gas emissions. Amidst these concerns is a blaring lack of field studies of the largest anthropogenic source of methane emissions in the United States: the livestock industry. Current understandings of methane emissions from cattle in particular stem from disruptive methods such as chamber measurements or mask measurements that invade upon natural forage intake and animal behaviors, as well as disregarding the role of other factors within a farm system that can contribute or negate net methane emissions. A noninvasive, continuous interrogation of cattle methane emissions in the field can be achieved with dual comb spectroscopy, where measurements can span kilometer-scale paths ideal for farm-scale operations. The evolution of this technique in outdoor practice will be discussed, including a previous study of a feedlot system comparing the dual comb spectroscopy system to a commercially available cavity ring-down spectrometer. Adaptation of this technique for high-precision, low-concentration methane emission sensing in pasture systems now provides a unique challenge for the system, beginning with a controlled release of methane to test limitations of the system in detecting a small herd of far-roaming cattle. Expansion of this measurement to live cattle sensing began in the summer of 2023, further testing the ability to detect small concentrations of methane (precision of ~6 ppb in 3600 s) while tracking a moving source. |
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Thursday September 28, 2023 3:00 PM MSPB 250
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Associate Professor / Chair Exploring Molecular Dynamics and Corehole Localization in Dichloroethene after L-Edge Photoionization The interaction between light and matter is a basic phenomenon in nature and of fundamental importance. Understanding the correlated dynamics involved in photoionization and photofragmentation is a significant challenge for experimental and theoretical physics. The COLd Target Recoil Ion Momentum Spectroscopy (COLTRIMS) technique has been developed to investigate the many-particle dynamics that result from photoionization. This apparatus is used to conduct photoionization experiments on small polyatomic molecules. By measuring and recording the initial 3D momentum vector of every charged particle that results from ionization, it is often possible to reconstruct the molecule's spatial orientation at the moment of ionization. This information is then used to examine the dynamics of how the molecule fragmented following ionization. One technique for doing this is the Molecular Frame Photoelectron Angular Distribution (MFPAD). The results of several recent experimental studies will be presented, including unpublished results on 1,1 dichloroethene (C2H2Cl2), photoionization from the Cl 2p, where there is evidence of corehole localization in some molecular configurations. |
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Thursday March 23, 2023 3:00 PM MSPB 250
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Professor Wide Bandgap Silicon Carbide Technology and Challenges High voltage metal-oxide-field-effect transistors based on wide bandgap semiconductor SiC are the enabling technology for next-generation power electronics to meet the world’s stringent energy and carbon emission requirements. While these devices are superior to traditional technologies, they do not perform to their full potential due to the high density of atomic-scale defects or trap states at the gate dielectric SiO2/SiC interface which result in device instability and low mobility of channel carriers. In the first part of this talk, SiC physical properties, device physics and application will be reviewed. Next, the physics of interface charge trapping and the classic channel mobility problem in SiC will be introduced. The importance of interface passivation by nitridation for improving channel transport will be highlighted and the main scattering mechanisms for channel electrons and holes will be characterized and contrasted with traditional silicon. The final part of the talk will focus on latest results obtained using deposited dielectrics that motivate how effective SiC surface termination processes are key to nextgeneration gate dielectrics for SiC. The talk will also describe the thrust of key research programs at the Auburn University condensed matter physics and discuss our graduate program. |
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Thursday March 16, 2023 3:00 PM MSPB 250
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Distinguished Professor Spatial Dimensions, Time-Frequency Relationship, and the Human Auditory System Human senses have mind-boggling capabilities, sensitivity, and dynamic range. Our auditory system has a microseconds temporal resolution in apparent violation of the reciprocal time-frequency relationship. The synthesis of dimensions—both in natural localization and stereo spatialization—conflicts with the expectation from vector superposition. And the ear can detect a picometer cochlear basilar-membrane amplitude. These extraordinary attributes of hearing impact the perception and reproduction of musical sounds, which have been shrouded in misconceptions and controversies for half a century. The present research is correcting this situation by developing incisive physical measurements, sensitive psychophysical tests, and a quantitative understanding of auditory neurophysiology and memory hierarchy. This has led to some surprising results that are being hotly discussed on Youtube and other forums. |
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Thursday November 10, 2022 3:00 PM MSPB 250
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Associate Professor A song of energy scales and technology: The elusive challenge of Heusler alloys Fabrication of ternary intermetallic alloys with high atomic ordering is a critical step to realizing their predicted functional properties. For instance, Heusler alloys have long been predicted with high spin polarization, low spin damping, and high ferromagnetic ordering temperatures. Unfortunately, experimental realization and applications have proven stubbornly elusive: Models and rules-of-thumb have found limited success when expanded to a wider range of elemental choices, and atomic ordering has typically been lower than predicted, with deleterious effect on their material properties. In this talk, I will outline our theoretical and experimental efforts to understand the root causes behind the experimental disconnect with theory in Heusler systems, and our efforts to find and realize materials that do not have deleterious atomic disorder or melting temperatures too high to allow layered growth. First, we use first principles calculations to screen for the convergence of useful material properties, alloy melting points as a fraction of our practical growth temperature maximum (1000 °C), and either an atomic ordering configuration robust against site swapping or a material system whose desired properties are robust against some amount of site swapping. We then grow thin films of material systems that meet the criteria using sputter beam epitaxy deposition and characterize their atomic ordering and material properties for comparison to theory. Using this procedure, compositional series across elemental choices will determine the veracity and limits of hypotheses and lead to basic rules governing atomic ordering in complex alloys. |
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Thursday October 13, 2022 3:00 PM MSPB 250
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Associate Professor Computational Materials Physics: Understanding and tailoring the properties of materials using atomistic calculations Quantum mechanical effects and atomistic details define a wide range of physical properties of materials. These features are not only important to gain insights at the atomic level interactions but also towards the development applications such as opto-electronic devices and sensors. To this end, first principles calculations offer means to elucidate the underlying physics and envision mechanisms to control their properties materials, offering valuable guidance to experiments. In this talk I will discuss our work on the physical properties of two-dimensional materials using large scale first principles calculations. I will particularly focus on the control of the physical properties of these atom-thick materials that have shown novel physical phenomena and promising qualities for nanoscale applications that range from biological sensors and molecular filters to spintronics. |
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Thursday March 10, 2022 4:00 PM MSPB 250
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Assistant Professor Precision Physics and the Belle II Experiment Subatomic particles and interactions are generally well described by the Standard Model of particle physics, yet several experimental anomalies defy simple explanation. These anomalies hint at the presence of new particles and interactions that may manifest as very small deviations from theoretical expectations. The Belle II experiment, an asymmetric electron-positron collider experiment at the SuperKEKB accelerator facility in Japan, aims to expose the presence of new particles and interactions by making highly precise measurements of processes that are rare or forbidden according to the Standard Model. In this talk, Dr. Jake Bennett will introduce the Belle II experiment, review some recent results with early data, and comment on prospects for precision measurements with larger data samples that will be collected over the next decade. |
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Thursday February 10, 2022 4:00 PM MSPB 250
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Professor of Physics Over the last few decades several experiments have used atomic nuclei as unique laboratories to probe the internal structure of the strongly interacting particles, namely hadrons. Indeed, the nucleus can be used as a revealing medium of the time evolution of elementary configurations of the hadron wave function. One of the ordinary approaches used to probe this picture involves searching for the onset of various phenomena which are naturally predicted by Quantum ChromoDynamics (QCD), the theory of strong interactions. One such phenomena is Color Transparency (CT) which refers to the production and propagation of a small size hadron-like configuration which, under specific conditions, stays intact in a transparent nuclear medium. In this talk, I will review the status of the experimental search for CT covering experiments spanning over decades. I will also highlight the 12 GeV CT experiments that have been either completed or being planned at Jefferson Lab, Newport News, Virginia. |
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Thursday November 11, 2021 4:00 PM MSPB 250
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Associate Professor of Physics Nanoscale Imaging of Surface Processes at the Heterogenous Interface Imaging morphological, structural, chemical, and optical properties of material during surface processes is critical for catalytic and optical applications of the materials. In this talk, I will present the development and application of imaging techniques to understand how the molecular environment affects various properties of MoS2 and doped tungsten oxide, phase transition of single micro-sized TiO2 crystals, and synthesis of aluminum nanosheets. In the second part of my talk, I will present our recent development of plasmonic fiber nano-probes for nanoscale chemical imaging. The proposed Fiber-based Tip-Enhanced Raman Spectroscopy (F-TERS) combines the spatial (<1 nm) and chemical resolution of TERS with the ease of use of Scanning Near-field Optical Microscopy. F-TERS can operate in virtually any gaseous and liquid environment, enabling new avenues of nanoscale chemical data collection from any sample analysis in most real-world environments. I will report the design, fabrication, and characterization of various photonic-plasmonic probes. |
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Thursday October 21, 2021 4:00 PM
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Thomas and Jean Walter Assistant Professor New Approaches to Atomic Scale Oxide Films Synthesis for Electronic and Energy Applications Complex oxides comprised of multiple positively charged metal cations exhibit a host of intriguing and useful properties for new technologies. Perovskite oxides with the chemical formula ABO3 and spinel oxides with the formula AB2O4 have some of the richest behavior. These materials may be metallic, semiconducting, or insulating, and exhibit ferroelectricity, with a built-in electric polarization, ferromagnetism, or superconductivity. This combination of properties in a single class of materials offers rich opportunities for engineering of unusual combinations of behavior through the design of multi-layer thin film materials. Through the use of hybrid molecular beam epitaxy (MBE), we are able to engineer these materials down to the atomic level so that interfaces between two different materials can be controlled to produce desirable properties. In this talk I will show how we can optimize electronic properties using in situ techniques to understand the film growth process and resulting electronic properties. I will show how hybrid MBE can enable synthesis of hard to grow materials using metalorganic precursors, including SrTiO3, SrNbO3, and SrHfO3. Using XPS surface studies, we have answered fundamental questions regarding this emerging growth technique. Ongoing work focuses on the use of these materials to produce novel oxide heterostructures for topological phases, high electron mobility 2D electron gases, and spintronic devices. I will also discuss our work on spinel and perovskite oxide nanocomposites that can be used in the oxygen reduction and oxygen evolution reactions. Using a combination of x-ray photoelectron spectroscopy (XPS), x-ray absorption spectroscopy (XAS), scanning transmission electron microscopy (STEM), and spectroscopic ellipsometry we have answered fundamental questions about the properties of CoMn2O4 and MnFe2O4. |
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Thursday October 14, 2021 11:00 AM MSPB 250
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Regents’ Professor of Physics Physics of Optoelectronics (History of Electronics leading to Infrared Detectors & Applications) We will present a brief history of the development of semiconductor electronics, with the emphasis of contributions from physicists to the development we enjoy even now. These days, infrared detectors are used in almost all applications from Astronomy, defense, product testing security etc. More recently, IR techniques are making a mark in biomedical advances too. We will describe a few detector ideas developed in our lab and address the development of a minimally invasive technique to screen for diseases using IR absorption. In this approach, the goal is to develop a screening test for these diseases which is Affordable, Sensitive, Specific, User-friendly, Rapid, Equipment-free, and Deliverable (ASSURED). |
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Thursday October 14, 2021 4:00 PM MSPB 250
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Doctoral Student PExotic Hadronic Molecules in the QCD Spectrum The discovery of the X(3872) ushered in the era of exotic hadrons (hadrons with more than three quarks). Since then, these particles have resisted any theoretical consensus. Of particular interest in this talk are the X(3872) and the T_cc^+(3895) which both lie very closely to D^0 D ̅^(*0) and D^0 D^(*+) thresholds, respectively. Their quantum numbers and tiny binding energy imply these should be loosely bound molecules; under these assumptions, we calculate production cross section. It is shown that these cross sections have a narrow peak due to a kinematic singularity. The observation of this peak would be strong evidence for the molecular interpretation of the X(3872) and T_cc^+(3895). |
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Thursday November 12, 2020 4:00 PM
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National Energy Technology Laboratory Multiple Representations for STEM Disciplines-applications from the Learning Sciences Low-cost and ubiquitous sensing can allow for early detection of conditions that would otherwise lead to potential catastrophic failures and can also more accurately identify low-level leaks to characterize better and ultimately minimize the environmental impacts. National Energy Technology Laboratory (NETL) Research and Innovation Center research efforts focus on enabling ubiquitous chemical sensing functionality through functionalized sensor devices targeted at key parameters relevant for monitoring of the fossil energy infrastructure including CO2, CH4, H2, corrosion, water condensation, and others. Here, an overview of relevant research efforts on functionalized surface acoustic wave (SAW) sensor devices and enabling technology for energy infrastructure monitoring will be presented. In particular, NETL’s efforts on the development of the wireless and passive SAW sensors for applications in natural gas infrastructures, wellbore integrity, and fossil energy power plants will be discussed. |
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Thursday February 27, 2020 4:00 PM MSPB 250
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Executive Director, Innovation in Learning Center Multiple Representations for STEM Disciplines-applications from the Learning Sciences Graphs, diagrams, formulae, numbers and verbal descriptions form the vocabulary of STEM experts in describing phenomena encountered either in the laboratory or the natural world. Whereas students of STEM disciplines might form various internal representations that constitute their memory and knowledge structure, as instructors we must often rely on the external representations they share with us through homework or exams as evidence of their learning. In this talk, I shall present my perspective on the value of multiple representations for learning in introductory physics and explore a special case of a teaching technique called Interactive Lecture Demonstrations. I shall reference the learning sciences framework from How People Learn (1999) and tie into recent European work from the field of computer supported collaborative learning (CSCL). Invoking terms like ‘actors’, ‘scripts’ and ‘orchestration’, this framework for describing active learning in STEM classrooms will undoubtedly provide connections points for instructors and students across the STEM disciplines. |
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Thursday February 6, 2020 4:00 PM MSPB 250
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Associate Professor Searches for Extra Dimensions at the Large Hadron Collider Discovery of extra dimensions of space would revolutionize our view of the universe. They may also provide a solution to the hierarchy problem of the Standard Model, through modifications of the strength of the gravitational force. This talk explores the theoretical motivations to search for evidence of extra dimensions in proton-proton collisions at the Large Hadron Collider, and presents recent results of such searches by the CMS experiment. |
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Thursday January 16, 2020 4:00 PM MSPB 250
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Howard Carr Prof. of Physics Atoms and Molecules Illuminated from Within Molecules in the gas phase are unique quantum systems in that they exhibit many fundamental quantum mechanical effects and are yet complex enough to challenge the most rigorous theoretical treatments. Exploring these quantum systems in detail is challenging in large part because molecules in the gas phase are randomly oriented as molecules tumble and translate through space. I will describe a series of experiments that allows us to look at molecules that are “fixed-in-space,” enabling observation of collective quantum phenomena in the gas phase. In particular, I will give examples that show 1) how a resonant electron “wave” propagates through a molecular potential, interrogating the molecule as it emerges from one of the core atomic/molecular orbits, 2) how simultaneously measuring multiple particles allows for a “complete” determination of the quantum states of an isolated molecule, and 3) how these three-dimensional measurements allow new discoveries dissociative anion formation. |
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Thursday November 21, 2019 4:00 PM MSPB 250
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Assistant Professor, Department of Physics Structure-property relationship in multiferroic oxides Multiferroic materials are characterized by the presence of more than one ferroic orders, for example, ferromagnetic and ferroelectric orders. These multiferroic materials are considered to be useful in electronic devices due to possibility of tuning magnetic properties by electric field and vice versa. Presence of non-centrosymmetry in the crystal structure and presence of magnetism are two fundamental requirements for multiferroic materials. I will discuss in detail about the choice of multiferroic materials, their synthesis, and characterization using electrical and neutron scattering techniques. |
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Thursday October 31, 2019 4:00 PM MSPB 250
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Assistant Professor, Department of Physics Rational Computational Design of Efficient Electro-catalysts for Hydrogen Fuel Cell Cathodes Hydrogen-fuel-cells (HFC) are one of the most promising means to obtain energy from renewable and environmentally sustainable resources. Yet, the design of inexpensive, stable and active electro-catalysts for the oxygen reduction reaction (ORR) that takes place on HFC cathodes is severely limited because only expensive and scarce elements such as gold and platinum-group elements do not dissolve or oxidize in the reaction environment at acceptable operating cathode potentials. In order to reduce the cost of our catalysts, we explore AE/MS systems, in which only one monolayer of a catalytically active element (AE) is deposited on an inexpensive metal substrate (MS). Our rational approach to do so includes these steps: a. Apply the existing knowledge to select AE and MS as candidates to build an ORR catalyst; b. Evaluate the electrochemical and thermodynamic stability of the preselected systems via first-principles calculations and narrow down the selection, if necessary; c. For systems that are electrochemically and thermodynamically stable according to our calculations, evaluate the ORR thermodynamics from first principles (by calculating the ORR free-energy diagrams), and estimate the ORR onset potential, which is a critical quantity determining the activity of a catalyst; In this presentation we will explain and exemplify how to apply this methodology. For instance, we preselected AE/ETM systems, where AE=Ag, Au and ETM stands for an early transition metal which acts as the MS. Interestingly, Ag dissolves relatively easily in the ORR environment - i.e., Vdiss is not high enough- yet our calculations confirm our prediction that the binding of a Ag monolayer to reactive ETMs increases Vdiss significantly, making it even higher than the Vdiss of Pt. Indeed, Ag/Nb structure is thermodynamically and electrochemically stable and has an onset potential as high as that of Pt. Au, on the other hand, has the highest Vdiss, yet, it has to be activated to facilitate the ORR. This can be done by binding it to reactive ETMs. Our calculations confirm that Au/Ta is thermodynamically and electrochemically stable, as well as a highly active catalyst toward ORR. Finally, we will also explore metal-doped defected graphene to find that Au-doped graphene is also a promising ORR catalyst |
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Thursday October 17, 2019 4:00 PM MSPB 250
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U.S. Army CCDEVCOM AvMC Atomic Physics-Based Sensors I will present our lab's research in atomic physics, in particular the physics of laser-real-atom interactions, resonant atoms in optical cavities, atomic hyperfine structure, and atomic collisions at low densities. Research in each of these basic science areas may lead to potential applications in laser sources for precision measurements and sensors, such as enhanced- sensitivity accelerometers and gyroscopes. |
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Thursday January 31, 2019 4:00 PM MSPB Room 250
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Associate Professor Materials in Extreme Environments: Unlocking New Materials Physics in High Magnetic Fields We are constantly pushing materials into new regimes and extremes to try to understand how they function. How fast can the electronic or optical properties of a material be modulated? How do they operate under thermodynamic extremes of temperature, pressure, and/or magnetic field? As we push these materials to these new extremes, are we elucidating new physics or can they be explained using extensions to conventional descriptions of their properties? Novel two-dimensional materials are one promising platform for next-generation devices that push the limits of both speed and size, but they also require new descriptions and experimental tools to describe their novel properties. In these newer two-dimensional materials like graphene and transition metal dichalcogenides, the relatively short coherence times of these still-developing materials masks some of their unique capabilities for next generation novel electronics. The modulation doped gallium arsenide two-dimensional electron gas (2DEG), in contrast, has seen and continues to see extensive study as one of the more “traditional” platforms for 2D materials. High quality samples with mobilities exceeding >106 cm2 V-1 s-1 are currently available, which provides a model system to study the electronic and optical properties of two-dimensional materials in the “clean” limit. Traditional measurement in these materials have included a variety of electrical transport measurements [e.g. Phys. Rev. Lett. 48, 1559 (1982)] and time-integrated optical measurements [e.g. Phys. Rev. B 31, 5253 (1985)], while the study of their dynamic properties on subpicosecond time-scales is relatively recent [e.g. Phys. Rev. B 93, 155437 (2016)]. Ultrafast spectroscopic techniques are a powerful technique that can be used to unravel complex and often competing processes in condensed matter systems on a femtosecond time scale. High magnetic field spectroscopy is also a particularly useful optical tool for unraveling complex interactions in these systems, which are a particularly rich source of novel materials physics due to the relative absence of disorder in two-dimensional electron gases. In this talk, I will discuss our work using terahertz time-domain spectroscopy to study Landau level populations and coherences in high mobility two-dimensional semiconducting systems and our extensions of these techniques to higher magnetic field spectroscopy. We model our results using the Optical Bloch Equations to determine the dephasing lifetime as a function of temperature and explain our low temperature results using ionized impurity and bound interface charge scattering in the conducting layer. In the second part of my talk, I will discuss our recent work to study these materials in high magnetic field using the 25 Tesla Split-Florida Helix at the National High Magnetic Field Lab. Our results reveal a complex interplay between conventional (electron transport) and complex (many-body) electronic interaction on an extremely fast time scale. These results have their origin in the breakdown of the frequency used uniform electron gas description of conductivity in high quality two-dimensional electron gas systems that happens when the magnetic length is on the same order as the material’s lattice constants. |
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Thursday December 6, 2018 4:00 PM MSPB Room 250
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Assistant Professor Exploring the extreme universe with gamma rays The study of the gamma ray sky has revealed a large population of extreme astrophysical objects capable of emitting electromagnetic radiation up to the highest observable energies, in the TeV range. The VERITAS gamma-ray observatory is an array of telescopes located in southern Arizona designed and built to study some of the most powerful gamma-ray sources in the Universe, such as the remnants of supernova explosions in our Galaxy and supermassive black holes at the centers of distant ones. This talk will present highlights from the VERITAS science program and introduce the Cherenkov Telescope Array project, the next generation very-high-energy gamma ray observatory. |
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Thursday November 29, 2018 4:00 PM MSPB Room 250
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Postdoctoral Fellow In 1998 it was discovered that neutrinos oscillate and have mass which led to the award of the 2015 Nobel Prize in Physics. That discovery generated a global campaign to better understand neutrino properties using oscillations of neutrinos produced in the Sun, in the atmosphere, at reactors, and by accelerators. The community has learned much but several important questions remain such as: Which neutrino is heaviest? Do neutrinos break the symmetry between matter and antimatter? Are there more than three neutrino types? In my talk, I will introduce neutrinos and the questions surrounding them, their chameleon-like flavor-changing behavior, and the experiments that hunt for them. One such neutrino hunter is the NOvA experiment which sends a beam of neutrinos 810 km to a 14,000-ton detector in northern Minnesota. NOvA gets special attention in my talk as I summarize its most recent neutrino and antineutrino measurements. |
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Thursday November 15, 2018 4:00 PM MSPB Room 250
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Associate Dean, Professor Physics and Engineering of Pianos Of all of the traditional musical instruments, rigorous scientific and engineering principles have been applied most comprehensively to the modern piano. This seminar will explore some of the main aspects of the design compromises and developments that have been implemented in all commercial piano designs since the late 19th century. The focus will be particularly upon the scientific details of sound production by pianos and how pianos have been engineered to exploit the principles of acoustics, dispelling some common misconceptions along the way. The intended audience is pure and applied scientists interested in design evolution, and musicians interested in how science and engineering have influenced instrument design. A basic knowledge of physics and only a little musical theory will be assumed. |
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Thursday October 18, 2018 4:00 PM MSPB Room 250
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Associate Professor Penetrating the Particle Frontier at the Large Hadron Collider The discovery of the Higgs Boson in 2012 was a great triumph for elementary particle physics, marking the end of a decades-long search for the elusive particle. That event prompted physicists to examine the properties of this new boson in great detail. Now, six years later, the ATLAS and CMS collaborations at the Large Hadron Collider have published two new observations regarding the Higgs. This presentation summarizes our current knowledge of the Higgs boson in light of these new developments, its connection to our broader understanding of the universe, and implications for future searches for new phenomena. |
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Thursday September 27, 2018 4:00 PM MSPB Room 250
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Professor of Physics Students’ understandings of Newton’s second law Perhaps the most important topic taught in a first semester introductory physics course is that of Newton’s laws. Research in physics education suggests that students bring to the classroom their own understandings of the physical world. This previous knowledge often conflicts with the concepts defined in class, thus making the teaching and learning of physics a challenge. Of particular interest is the understanding of Newton’s second law, which can be expressed with the simple mathematical equation F = ma. I will present results from physics education research in which we investigated Newton’s second law mental models used by students in a two-semester calculus-based physics course. I will also present some ideas that may assist in the transfer of understanding of forces from Mechanics to EM topics. |
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Thursday March 8, 2018 4:00 PM MSPB (formerly ILB) Room 250
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Assistant Professor Neutrino Interaction Results from the NOvA Neutrino Experiment Precisely measuring neutrino properties, such as mass and flavor mixing, is the focus of a set of current and future international experimental efforts. In order to optimize these measurements, the nature of neutrino-nucleus interactions must be well established in relevant energy ranges. This talk will survey the physics of neutrino-nucleus interactions and present recent results from the NOvA neutrino experiment. |
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Thursday November 30, 2017 4:00 PM MSPB (formerly ILB) Room 250
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Senior Research Scientist Results from the NOvA Neutrino Oscillation Experiment The NOvA experiment detects neutrinos sent from Fermilab, near Chicago, to Northern Minnesota. The detector is one of the largest neutrino detectors, observing neutrinos beamed from over 800km away. I will describe the technology of the detectors and recent results from the first 2 years of operation, and what is yet to come. |
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Thursday September 28, 2017 4:00 PM MSPB (formerly ILB) Room 250
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Mu2e Spokesperson A Rare Opportunity — the Mu2e Experiment at Fermilab The muon, a heavy cousin of the electron, was discovered in 1936. Since that time they have only ever been observed to do one of two things: 1) interact with a nucleus, or 2) decay into an electron and two neutrinos. But a new experiment at Fermilab - the Mu2e experiment - is going to look for a third thing: a muon interacting with a nucleus to produce an electron and nothing else. This is a process that's predicted to occur very very rarely, maybe once every quadrillion muon decays, (or less!). But this very rare decay may hold the key to understanding physics at its most fundamental level. The Mu2e experiment is an ambitious endeavor whose goal is to observe this very rare decay for the first time - a discovery that could help reveal a new paradigm of particle physics. |
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Thursday September 14, 2017 2:30 PM ILB Room 250
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Kansas State University REU Design and Construction of an Efficient Atomization Tool for Strong Field Science at the Nanoscale In order to better understand ultrafast light interaction with nanoparticles (such as Coulomb explosion), we must choose a light source capable of resolving images at the nanoscale. Free electron lasers (such as the Linear Coherent Light Source at SLAC or the Free-Electron Laser in Hamburg at DESY) have the capability to produce femtosecond infrared (50 fs) and x-ray (10-100 fs) pulses to perform pump-probe experiments at the nanoscale. A prior beamtime successfully used SiO2 nanoparticles to study Coulomb explosions at the nanoscale, but metallic nanoparticles prove a challenge for future experiments. These fragile nanoparticles require gentle handling in order to prevent clustering, which means a single-nanoparticle delivery system is a key factor for future studies. Commercial atomizers use the Bernoulli Effect to pull a large amount of nanoparticle solution into a cavity where a jet of pressured gas can blast away droplets to create an aerosol. Unfortunately, this violent process has a tendency to strip the ligand shell from more fragile, metallic nanoparticles, as well as produces aerosol with high waste in return. Over a 10 week period, we tested a new design for the atomizer, which implemented a double tube design to allow liquid to flow onto the gas jet and produce just enough aerosol to match the liquid provided, eliminating high waste production and leading to a gentle process that would not threaten the fragile ligand shell of metallic nanoparticles. Kevin Ingles Fermilab SIST Monte Carlo Investigation of Muons in a Liquid-Argon TPC The DUNE Far Detector is a Liquid-Argon TPC that resides at the 4850 ft level at the Sanford Underground Research Facility. This detector allows for both the visualization and the measurement of charged particle energy deposition. Cosmic rays that penetrate down to the detector have a wide energy range. This study focuses on momenta between 0.2 GeV to 1000 GeV. The detector response to the muons is simulated using GEANT4. Mean energy loss and most probable energy loss are presented as a function of momentum. Preliminary results are given that will help develop an algorithm that determines energies from energy deposition of high-energy muons. |
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Thursday September 7, 2017 4:00 PM ILB Room 250
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Professor of Physics Molecular Astronomy: Cool Stars and Exoplanets The spectra of “cool” astronomical objects such as low mass stars, brown dwarfs and exoplanets are dominated by molecular absorption features. Of particular interest are methane, water, ammonia and diatomic hydrides at high temperatures. An overview of this area of molecular astronomy will be presented from a spectroscopic perspective. The talk will include emission and absorption laboratory measurements of hot molecules by Fourier transform spectroscopy related to exoplanets. Comparisons with the latest theoretical predictions will be presented. |