Physics Colloquia

All lectures are in CTLM102 unless otherwise noted.  Lecture starts at 4:00pm.  Questions, contact Barbara Shellenberger (formerly Pratt-Johnson), 303.273.3830 or bpjohnso@mines.edu

SPRING SEMESTER 2017

 

Tuesday, January 17, 2017

Jason Clark

Physics Division, Argonne National Lab

"Ion Traps For Astrophysics: Where No Trap Has Gone Before"

Abstract:  How were all the elements in the universe created? Scientists across many disciplines have been trying to answer this question for decades. Much progress in our understanding of nucleosynthesis has been made, but the origin of half the elements heavier than iron is still unknown. Supernovae are possible sources of heavy-element production, whereby elements are produced through a rapid series of nuclear reactions on neutron-rich nuclei in a process termed the astrophysical 'r' process. In an attempt to reproduce the observed distribution of element abundances in the universe, models are generated which inherently rely upon many nuclear physics inputs, including the masses of the nuclides involved and their beta-decay properties. However, the uncertainties in these nuclide properties are often too large and limit our understanding of heavy-element nucleosynthesis.

Ion traps have revolutionized mass spectroscopy and have the potential to do the same for beta-decay spectroscopy as well. Precise mass measurements of radioactive nuclides are now routinely performed around the world, but nuclides involved in the astrophysical r process are often too challenging to produce for study at accelerator facilities. The newly commissioned CARIBU facility, an upgrade to Argonne National Laboratory's ATLAS facility, provides copious amounts of these previously elusive neutron-rich nuclei. A program of mass measurements at CARIBU is underway, where the Canadian Penning trap mass spectrometer has already been used to determine the masses of more than 100 of these nuclides to a mass precision of 100 parts per billion or better. In addition, a specially designed ion trap is currently being developed to facilitate a new program of beta-decay spectroscopy using nuclides produced by CARIBU. Results from a recent set of measurements have indicated this new technique of using ion traps to perform beta-decay studies could significantly advance the field. Indeed, ion traps for astrophysics are going where no trap has gone before.

 

Tuesday, January 24, 2017

Melanie Kay

Daniels Fund Ethics Initiative, University of Colorado Law School

"Behavioral Ethics and Responsible Research” - joint Lecture: PHGN502/602-Graduate Seminar and PHGN503-Responsible Conduct of Research

Abstract:  Traditionally, the study of ethics has focused on philosophical reasoning and introspection.  Students considered various schools of ethical thought and debated the “right thing to do” in hypothetical situations.  Yet ethics educators spent little time analyzing actual human behavior and decision-making— namely, why we do the (sometimes unethical) things we do.  Recently, behavioral psychologists have investigated how humans actually behave when confronted with ethical dilemmas, and come to better understand the sometimes surprising ways our brains can trick us into making and rationalizing unethical choices.  Their research has important implications for the business, legal, and scientific communities, where ethics scandals erupt with unfortunate frequency.  In her talk, Ms. Kay will explain how concepts such as ethical blindspots, overconfidence bias, ethical fading, confirmation bias, slippery slopes, and conformity can affect decision-making, and how you can overcome these psychological forces so as to conduct research with integrity, honesty, and transparency.

 

Tuesday, January 31, 2017

Kristine Callan, CSM Physics Dept.

and

Stephanie Fanselow, Univ. of Northern Colorado, Dept. of Science Education / Wendy Adams, Univ. of Northern Colorado, Dept. of Physics & Astronomy

"The Teacher Education Alliance, Mines-UNC Partnership (TEAM-UP): What Is It, Why Is It Needed, and How Can You Help?”

Abstract:  To help battle the shortage of highly qualified science and math teachers, Colorado School of Mines and University of Northern Colorado have recently created a unique partnership that plays on each institution’s strengths to produce highly qualified STEM teachers. Mines prepares students with a strong understanding of STEM subjects, and UNC provides the coursework in education and pedagogy necessary to become a secondary science or mathematics teacher in Colorado. TEAM-UP began enrolling students in the fall semester of 2015, with additional students adding each semester. In this talk, we will describe: the evolution of TEAM-UP, common (and surprising) misconceptions about the K-12 STEM teaching landscape, the grant activity that has supported the program and our students, and our future plans for TEAM-UP and how you can help.

 

Tuesday, February 7, 2017

Kirk Hansen

Univ. of Colorado, School of Medicine

"New Methods to Characterize the Extracellular Matrix in Health and Disease"

Abstract:  The composition and architecture of the extracellular matrix (ECM) largely defines the mechanical features of an organ and the biochemical environment experienced by cells. Changes in the ECM with disease progression can lead to treatment resistance, further disease progression and eventually organ failure. Traditional analytical methods fail to identify a significant percentage of the extracellular matrix and yield inaccurate quantification. As a result, extracellular architectures and compositional changes in tissue micro-environments are largely unknown. We have been developing methods to identify and understanding the role of specific ECM proteins and modifications involved in disease progression.

 

Tuesday, February 14, 2017

Angus Rockett

CSM Metallurgy & Materials Engineering

"Characterizing Electronic Defects in Semiconductors and Application to Photovoltaic Devices"

Abstract:  This talk reviews selected measurements we have made to characterize and understand electrically-active defects in polycrystalline thin film semiconductors.  The talk will focus primarily focusing on Cu(In,Ga)Se2 (CIGS) and related materials but also on CdTe, both of which are the key materials in high performance solar cells.  These devices are particularly relevant because they are very sensitive to the lifetime of photo-generated carriers which tend to be lost through trapping by defects.  Selected results will be presented from a variety of characterization methods such as photomodulated admittance spectroscopy, microchemical and microstructural analysis, scanning tunneling microscopy, and other techniques showing how defects in the materials can be studied and their interaction with moving carriers determined.  Results of theoretical calculations showing the effect of lattice strain on defect ionization energies will also be considered.  The ways in which the results relate to both the underlying bonding and electronic structure of the material and to solar cell performance will be discussed.

 

Tuesday, February 21, 2017

No colloquium - extended President's Day holiday

 

Tuesday, February 28, 2017

Bethany Frew

NREL, Energy Forecasting & Modeling Group, Strategic Energy Analysis Center

"Renewable Energy: Alternatives No More"

Abstract:  Advances in technology, reduction in costs, and improvements in how to plan and operate a highly renewable power system have enabled variable generation (VG) resources, namely wind and solar power, to become mainstays of a clean, reliable, and affordable grid. The operational capabilities of VG have evolved to now allow these resources the potential to provide balancing and stability grid services traditionally delivered only by conventional generators. But are there limits to these services and how much VG we can put on the grid? This talk will cover the basics of the electric grid with a high level overview of renewable energy, including a discussion on how VG resources impact the grid.

 

SPECIAL COLLOQUIUM - Thursday, March 2, 2017, 4pm in Coolbaugh room 219 

Eli Levenson-Falk

Stanford University

"Grooming Schrodinger's Cat: Basic and Applied Physics with Superconducting Quantum Electronics"

Abstract:  Superconducting materials enable the creation of novel electronics with fundamentally non-classical behavior.  These quantum circuits can be used as detectors, magnetic field sensors, artificial atoms, and quantum bits, with applications ranging from chemistry to cryptography to studies of basic quantum mechanics.  Fully realizing this potential requires us to cleverly design our circuits and experiments, to improve the performance of basic circuit elements, and to engineer scale-able systems.  This work goes hand-in-hand with fundamental physics research, as each incremental improvement in performance opens up new experimental avenues.  In this talk I will present some results from my own work tackling these practical challenges for applied and basic research, including studies of quasiparticle behavior in superconducting resonators and improvements of quantum-limited parametric amplifiers.

 

Tuesday, March 7, 2017 - 4pm - Student Center Ballroom A

Materials Science Distinguished Lecture presented jointly by the Colorado School of Mines and the National Renewable Energy Laboratory

Peter K. Davies

University of Pennsylvania, Materials Science & Engineering

"Modulated Perovskites: Frustration and Hidden Nanoscale Order"

Abstract:  Abstract: Perovskites constitute one of the most widely studied and technologically important families of inorganic oxides.  The flexibility of the structure in accommodating multiple substitutions of cations has enabled a myriad of functional responses both in film and bulk form.  Their complex chemistries can lead to many frustrations in their local bonding and to ordering phenomena and defect formation that are often critical in mediating the property response.  This talk will focus on families of alkali-based perovskite oxides where the multiple occupancy of the “A-site” position in the ABO3 structure induces the formation of unusual nanoscale “checkerboard” modulations.  Studies of their local atomic structures using aberration corrected TEM indicate these modulations produce unusual periodic ferrielectric nanodomain structures. The factors responsible for the formation of these unique structures and their remarkable sensitivity to small changes in bulk stoichiometry will be discussed.

Bio:  Peter K. Davies is the Class of 1942 Professor in the Department of Materials Science and Engineering in the School of Engineering and Applied Science at the University of Pennsylvania.  He received his B.A. degree in Chemistry from New College, Oxford University and his Ph.D. in Solid State Chemistry from Arizona State University. His primary interests lie in the synthesis, stability, crystal chemistry and properties of electronic ceramic materials.  Areas of focus have included the role of cation ordering reactions in enhancing the resolution of microwave resonators in wireless communication systems, the preparation of new lead-free ferroelectric and piezoelectric materials, development of crystal chemical models for PMN-type relaxors, the formation of nanoscale modulated perovskite oxides and the stabilization of semiconducting ferroelectrics for photovoltaic applications. Dr. Davies is a Fellow of the American Ceramic Society and a recipient of the National Science Foundation Creativity Award.  He serves on the editorial and advisory boards of several ceramic and solid-state science journals and has received multiple teaching awards from the University of Pennsylvania. He has authored or co-authored over 175 publications, holds 3 patents and co-edited 5 books, and advised more than 50 graduate students and post-docs. Dr. Davies also served as Chair of the Materials Science Department at Penn for 14 years and headed the University Materials Council of North America.

 

Tuesday, March 14, 2017

No colloquium today

 

SPECIAL COLLOQUIUM - Monday, March 20, 2017, 4pm, Berthoud Hall room 108

Michael Kolodrubetz

University of California @ Berkeley / Lawrence Berkeley National Laboratory

“Dynamics and Topology of Driven Quantum Systems”

Abstract:  Topological physics is one of the most active areas in condensed matter, giving rise to a host of novel phases of matter from integer and fractional quantum Hall systems to topological insulators and Weyl semimetals. These materials exhibit robust electronic properties that arise from non-trivial structures in the Berry phase, a geometric property of the quantum wave function that was originally considered in adiabatic transport of spin systems. In this talk, I will explore the natural connection between geometry, topology and dynamics. I will highlight a variety of ways in which non-equilibrium quantum physics can be used to engineer and measure interesting geometric and topological properties. In particular, I will  illustrate these ideas with two recent works of experimental relevance, namely the dynamics of periodically-driven surface states in topological insulators and the ground state topology of systems of interacting superconducting qubits.

 

Tuesday, March 21, 2017

Zhe-Xuan Gong

University of Maryland and NIST

"Many-Body Physics in Long-Range Interacting Quantum Systems"

Abstract: Condensed matter systems often have short-range interactions, and this locality of interactions has profound effects on the properties of both ground states and states created out of equilibrium. However, in numerous systems of current interest, ranging from frustrated magnets, spin glasses, and low-dimensional materials to various atomic, molecular, and optical systems, long-range interactions are ubiquitous and can lead to qualitatively new physics. In this talk, I will review our recent work on how long-range interactions can give rise to novel dynamical behaviors, exotic quantum phases, and significant speedups in quantum information processing. In particular, I will introduce the notion of emergent locality, which is crucial in understanding a wide range of many-body physics in long-range interacting quantum systems.

 

SPECIAL COLLOQUIUM - Thursday, March 23, 4pm, Coolbaugh 209

CANCELLED

 

Tuesday, March 28, 2017

No colloquium - CSM Spring Break

 

SPECIAL COLLOQUIUM - Monday, April 3, 11am, Green Center 210 South

“Self-Correcting Quantum Devices”

Abstract:  Superconducting quantum circuits are among the most promising platforms for quantum computing and simulation. However, like all qubit technologies, they suffer from unavoidable noise and dissipation, which has thus far stymied the construction of a workable quantum computer. This can be mitigated by digital quantum error correction, or intriguingly, by introducing further noise, in the form of engineered dissipation, carefully tuned to passively correct errors and stabilize many-body states. In this talk, I describe an extremely simple and practical mechanism for doing so. I first review a quantum simulation experiment with the Google quantum hardware team that demonstrated artificial magnetic fields for strongly interacting photons— a vector potential for light. I then describe a proposal for combining some of those concepts with high frequency microwave driving and tuned dissipation sources to create a simple and efficient quantum error correction device, called the Very Small Logical Qubit, that promises order of magnitude coherence increases over any of its component parts. Finally, I show that in a larger system, combining all these ideas can generate and passively stabilize fractional quantum Hall states of photons, which are exotic, topologically ordered states of matter that are analogous to the anyonic states of 2d electrons in strong magnetic fields. FQH states of bosons have yet to be realized in nature, and are expected to demonstrate a wide array of strange and novel properties.

 

SPECIAL COLLOQUIUM - Monday, April 3, 4pm, CTLM102

Alex Frano

University of California @ Berkeley, Physics Department

"Periodically Modulated Electronic Wavefunctions in Transition Metal Oxides Explored by Resonant X-Ray Scattering"

Abstract: Familiar x-ray diffraction experiments produce a Fourier transform of the atomic landscape via elastic scattering and are routinely used to study the structure of solids. Resolving the inelastic energy exchange between photons and atomic ions probes the dynamical structure factor, a quantity that reveals collective dynamics of the atomic lattice and their dispersion. These techniques provide unambiguous windows into atomic order in solids. What if the principle could be used analogously to probe electronic order in correlated “quantum materials”?  By tuning the x-ray energy to electronic transitions and judiciously exciting electrons into states near the Fermi level, spatial modulations and temporal dynamics of electronic wavefunctions can be studied in Fourier space. Propelled by technological advances in synchrotron science over the last decades, Resonant (in)elastic X-Ray Scattering (RXS) provides this exciting and powerful tool to investigate the electronic structure of solids. Quintessential cases are transition metal oxides, where strong electronic correlations yield nontrivial, ordered patterns of the spin, charge and orbital character of the d-wavefunctions.  In this talk, let us discuss examples of how these subtle phases can be detected using RXS and how they can be tuned by external conditions like strain, interfacial geometries, and applied magnetic fields. These include the discovery and stabilization of charge density wave order in superconducting cuprates, dimensionality-induced magnetism in perovskite nickelates, and ‘Kitaev frustration’ exposed by external magnetic fields in the honeycomb iridate Li2IrO3. Finally, I will discuss the potential future of x-ray scattering with new coherent light sources.

 

Tuesday, April 11, 2017

 

Jason Wilde

American Institute of Physics Publishing, Melville, NY

“Evolution or Revolution: Publishing in the 21st Century”

Abstract:  Since the first journal went online (1995) the processes around publishing scientific research have changed dramatically. This talks attempts to outline: how the industry has changed; how, as authors, researchers should create their manuscripts to navigate the publishing machine; and how authors can ensure their manuscripts are read by their community once published.   

 

Tuesday, April 18, 2017

Krister Shalm

National Institute of Science and Technology, Physical Measurements Laboratory

"A Strong Loophole-Free Test of Local Realism"

Abstract:  Eighty-one years ago Einstein, Podolsky, and Rosen published a paper with the aim of showing that the wave function in quantum mechanics does not provide a complete description of reality. The gedanken  experiment showed that quantum theory, as interpreted by Niels Bohr, leads to situations where distant particles, each with their own “elements of reality”, could instantaneously affect one another. Such action at a distance seemingly conflicts with relativity. The hope was that a local theory of quantum mechanics could be developed where individual particles are governed by elements of reality, even if these elements are hidden from us. This concept is known as local realism.  In 1964 John Bell, continuing Einstein’s line of investigation, showed that the predictions of quantum mechanics are fundamentally incompatible with any local realistic theory. Bell’s theorem has profoundly shaped our modern understanding of quantum mechanics, and lies at the heart of quantum information theory. However, all experimental tests of Bell’s theorem have had to make assumptions that lead to loopholes.  This past year, a loophole-free violation of Bell's 1964 inequalities, a 'holy grail' in the study of the foundations of quantum mechanics for half a century, was finally achieved by three different groups. Here I will present the loophole-free Bell experiment carried out at the National Institute of Standards and Technology that requires the minimal set of assumptions possible. We obtain a statistically significant violation of Bell’s inequality using photons that are space-like separated, and therefore forbidden by relativity from communicating. Local realism,as defined by Bell, is dead. 

 

Tuesday, April 25, 2017

Jose de la Venta

Colorado State University, Department of Physics

"Magnetic Properties of Hybrid Systems"

Abstract:  Hybrid magnetic heterostructures allow the engineering of new material properties by creative uses of proximity effects. When two dissimilar materials are in close physical proximity the properties of each one may be radically modified or occasionally a completely new material emerges. By properly designing hybrid ferromagnet/oxides new magnetic properties arise unlike any known magnetic materials. Moreover, controlling the magnetic properties of ferromagnetic thin films, without magnetic fields, is an on-going challenge with multiple technological implications for low-energy consumption memory and logic devices.

In a series of recent studies, we have investigated the static and dynamic magnetic properties of different hybrids of ferromagnets (Ni, Co and Fe) and oxides (VO2 and V2O3). The vanadium oxides (VO2 and V2O3) are canonical examples of materials showing a first order metal to insulator transition and structural phase transformation. Static properties such as the coercivity, anisotropy and magnetization and dynamical properties such as the microwave response are clearly modified by the proximity effect. Our results indicate that the structural transformation and the nanoscale phase coexistence across the first-order phase transition of the oxides are responsible for the observations in these hybrid materials. The results suggests the existence of similar effects in other hybrid materials and give rise to interesting perhaps useful properties.

 

Tuesday, May 2, 2017

Senior design poster session

 

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FALL SEMESTER 2016

Tuesday, August 30, 2016

Tim Sweitzer

CSM Department of Environmental Health & Safety

"Safety/Hazardous Waste Refresher Training"

MANDATORY safety training for faculty, staff, postdocs, grad students, and undergraduates working in laboratories.

 

Tuesday, September 6, 2016

Ines de Vegas

University of Munich

"Quantum Open Systems: From Theory to Applications"

Abstract:  Quantum systems are in general not isolated from their surroundings and thus the influence of the environment upon the system dynamics should be considered. Such 'open’ quantum systems appear in many different contexts, from quantum optics to solid state physics or quantum information. In this talk, I will review some of the tools that have been developed in the past few years to describe them. We will analyze in more detail the non-Markovian dynamics that appears when the open quantum system is coupled to an environment that does not recover instantaneously from the interaction.
I will also discuss some physical situations where non-Markovian effects are relevant, like for instance atoms in photonic crystals, superconducting qubits in an open transmission line, or atoms in an optical lattice.

 

Tuesday, September 13, 2016

Angela Olinto

University of Chicago

"The Extreme Energy Cosmic Frontier"

Abstract:  Thanks to giant extensive air-showers observatories, such as the Pierre Auger Observatory and the Telescope Array (TA), we now know that the sources of ultrahigh energy cosmic rays (UHECRs) are extragalactic. We also know that either they interact with the CMB as predicted or they run out of energy at the same energy scale of the CMB interactions! Their composition is either surprising (dominated by heavier nuclei at the highest energies) or the hadronic interactions at 100 TeV are not a standard extrapolation of LHC interaction energies. Hints of anisotropies begin to appear as energies reach 60 EeV, just when statistics become very limited.

Basic questions remain unanswered: What generates such extremely energetic particles that reach above 10^20 eV (100 EeV)? Where do they come from? How do they reach these energies? What are they composed of? How do they interact on their way to Earth and with the Earth’s atmosphere?

In addition to the need to increase the statistics of UHECRs observations, neutrino and gamma-ray observations will help resolve this mystery. An international collaboration is currently building at CSM a super pressure balloon (SPB) Extreme Universe Space Observatory (EUSO) to be the first to detect UHECR fluorescence from above. EUSO-SPB will inform future space missions designed to unveil the extreme energy cosmic frontier.

 

Tuesday, September 20, 2016

David Flammer

CSM Physics Department

"The Problem with Electromagnetism"

Abstract:  By 1892, Maxwell, Lorentz, and others had developed electromagnetic theory as we know it today. This theory is very effective at describing the interaction between different charged objects. However, if you take into account the force of a charge on itself (its self-interaction), the theory has difficulties. Solutions appear to violate causality, violate Newton's first law, violate Einstein's mass-energy equivalence, and more. These difficulties continue to be discussed in the literature. However, as well as being the source of difficulties, this self-interaction is the source of electromagnetic radiation, and is therefore very important.  In this talk, I will discuss some of the theoretical history of the dynamics of charged objects. We'll see that extended charged objects (objects of finite size) lead to intractable equations (or violate causality), and the only way to produce a theory that can be solved is if all charges in the theory are point particles. Point particles, however, create new theoretical problems: the theoretical mass of a charged point particle is infinity, and point particle theories are incompatible with General Relativity. I will then discuss options for relaxing the point particle assumption, such as String Theory, and present recent developments in studying the motion of extended charged objects.

 

Tuesday, September 27, 2016

Axel Klix

Karlsruhe Institute of Technology

"Neutronics Aspects of Fusion Reactor Research"

Abstract:  Nuclear fusion is considered a source of safe, non-carbon emitting and virtually limitless energy. However, the road to a fully developed fusion power technology as a substantial source of energy for mankind turns out to be long and littered with obstacles...
A basic requirement for a "burning" plasma is the confinement. The two main design lines of fusion reactors apply inertia or magnetic forces to achieve confinement. Although the presentation will focus on magnetic confinement and in particular on Tokamak-type reactors, the topics discussed are relevant in general for reactors based on the deuterium-tritium (DT) fusion reaction.
  The presentation will discuss the working principle of a DT power fusion reactor and briefly the challenges to reactor materials caused by the intense neutron irradiation.
Detailed focus will be put on current experimental neutronics research utilizing DT neutron generators as well as experimental fusion reactors such as the Joint European Torus (JET). Neutron generators provide a well characterized neutron field but with maximum flux densities a few orders of magnitude lower than expected in a fusion reactor. However, they are well suited for measurements of neutron and photon transport in reactor materials and mock-ups of tritium breeding blankets. These measurements are used to check radiation transport codes and nuclear data libraries which are basic design tools for reactors. One of the most important aims of neutron transport experiments in the last decade were measurements of the tritium production rate in breeding blanket mock-ups. DT neutron generator experiements are also used to investigate activation and gas production properties of reactor-relevant materials. Neutronics experiments will be extended to more complex structures and performed in a new DT campaign at the worlds largest currently available Tokamak reactor.  The progress of the construction of ITER (The Way) in Cadarache in southern France led to grown interest in neutronics instrumentation for the extremely harsh environment in the so-called ITER Test Blanket Modules (TBM). ITER is supposed to achieve a net energy gain of 10 in later operational stages, and it is considered a key experimental step between today's fusion research machines and a future fusion power plant. At this point, conditions in the TBM will be similar to the conditions in the breeding blanket of a fusion power reactor. The presentation will close with an overview of R&D work on suitable measurement methods and detectors for neutron flux in the harsh environment of the TBM.

 

Tuesday, October 4, 2016

Robert Brown

American Institute of Physics

"Novel Nano-sensors for Improved Airplane Safety"

Abstract:  From plasmonic and polaritonic physics - we can invent new classes of photo-detector for different spectral regions. Such novel detectors can have very high responsivities and low noise properties. They may find valuable applications in enhanced airplane-safety.  Because of new photo-detection sensitivities, we can invent novel methods to detect - far ahead of an airplane in flight - clear-air turbulence, airborne volcanic ash - and ice-crystals in clouds, all of which can cause airplane failure unless flown around.  I’ll explain the basic and applied physics - and the applications - that may one day lead to safer flying conditions for airplane passengers.

 

Tuesday, October 11, 2016

Mike Scarpulla

University of Utah

"Excess Carrier Effects on Semiconductor Growth and Processing"

Abstract:  The most useful property of semiconductors is not the ability to dope, but rather the ability to appreciably modulate their carrier density as a function of time.  For their operation, all semiconductor devices rely in some manner on excess minority and or majority carriers – that is concentrations of electrons and holes above those found in thermal equilibrium – in the form of either currents, recombination, or generation.  It is well-known that the material processing of semiconductors, which encompasses all steps from crystal growth to long-term use, is critical in determining the behavior of excess carriers because processing determines the concentrations of intrinsic and extrinsic point defects.  However, the converse coupling - the effects of excess carriers on semiconductor defects - has typically been ignored or at best underappreciated.  In this colloquium, I will introduce concepts of intrinsic or native point defects and some lesser-known yet clearly-observed phenomena by which excess carriers affect the behaviors of point defects in semiconductors.  After this survey, I will discuss a theory I developed with Kirstin Alberi (NREL) [1] that predicts how the presence of excess carriers affects the steady-state formation energies of charged semiconductor (particularly native) defects via the quasi-Fermi levels acting as chemical potentials.  This modifies the concentrations of defects formed during processing and thus can be used to solve heretofore intractable problems with semiconductor properties and to enable new regimes of doping and minority carrier lifetime depending on the specifics of the particular semiconductor and its point defects.  Lastly I will discuss experiments by which these effects can be explored and harnessed and contrast the behavior to changing the charge state and thus configuration of metastable point defects.  

[1] K. Alberi and M.A. Scarpulla, Suppression of native defect formation during semiconductor processing via excess carrier generation, Scientific Reports 6, 27954 (2016). 

Predicted Effects of excess carriers on compensation and mobility in doped and undoped GaSb.  

 

Tuesday, October 18, 2016

NO COLLOQUIUM - FALL BREAK

 

Tuesday, October 25, 2016

David L.Andrews

University of East Anglia

"Finding the Photon in Photonics"

Abstract:  The term 'photonics', first proposed in the 1950's and greatly boosted by the arrival of the laser shortly afterwards, now characterizes a huge sector of modern technology.  Advances in photonics continually bring the fundamental nature and properties of the photon under fresh scrutiny.  The state of knowledge even a couple of decades ago is an uncertain guide to current understanding: several of the most important current research topics were undreamt of at that point.  What we now understand about photons has become much richer, though indeed less simple, than the original notion.  This lecture outlines numerous properties that characterize photons and their interactions, highlighting some of the recent discoveries, and giving a few clues to puzzles that now need to be resolved. 

 

Tuesday, November 1, 2016

Danny Caballero

Michigan State University

"How Might Physics Education Research Facilitate the Coming Computational Revolution?"

Abstract:  Computation has revolutionized how modern science is done. Modern scientists use computational techniques to reduce mountains of data, to simulate impossible experiments, and to develop intuition about the behavior of complex systems. Much of the research completed by modern scientists would be impossible without the use of computation. And yet, while computation is a crucial tool of practicing scientists, most modern science curricula do not reflect its importance and utility. In this talk, I will discuss the urgent need to construct such curricula in physics and present research that investigates the challenges at a variety of all scales -- from the largest (institutional structures) to the smallest (student understanding of a concept). I will discuss how the results of this research can be leveraged to facilitate the computational revolution.  This research will help us understand and develop institutional/departmental incentives, effective teaching practices, evidence-based course activities, and valid assessment tools. 

 

Tuesday, November 8, 2016 (combination Physics/Materials Science)

Artem R. Oganov

Stony Brook University

"Computational Materials Discovery"

Abstract:  Recent methods of crystal structure prediction have opened wide opportunities for exploring materials at extreme conditions and perform computational screening for materials with optimal properties for various applications. In my laboratory, we have developed a very powerful evolutionary algorithm USPEX, enabling prediction of both the stable compounds and their crystal structures at arbitrary conditions, given just the set of chemical elements. Recent developments include major increase of efficiency and extensions to low-dimensional systems and molecular crystals (which allowed large structures to be handled easily, e.g. Mg(BH4)2 and H2O-H2) and a new technique called evolutionary metadynamics.
Some of the results that I will discuss include:  1. Theoretical and experimental evidence for a new partially ionic phase of boron, γ-B, and an insulating and optically transparent form of sodium.  2. Predicted stability of “impossible” chemical compounds that become stable under pressure – e.g. Na3Cl, Na2Cl, Na3Cl2, NaCl3, NaCl7, Mg3O2 and MgO2.  3.  Novel surface structures (e.g. boron surface reconstructions).  4.  Novel dielectric polymers, confirmed by experiment and ready for applications.

 

Tuesday, November 15, 2016

James Kakalios

University of Minnesota

"The Uncanny Physics of Superhero Comic Books"

Abstract:  In 2001 I created a Freshman Seminar class at the University of Minnesota entitled: "Everything I Know About Science I Learned from Reading Comic Books." This is a real physics class, that covers topics from Isaac Newton to the transistor, but there’s not an inclined plane or pulley in sight.  Rather, ALL the examples come from superhero comic books, and as much as possible, those cases where the superheroes get their physics right!

This class drew a great deal of media attention in 2002 with the release of the first Spider-Man film, and led to my writing a popular science book THE PHYSICS OF SUPERHEROES. My talk will show how superhero comic books can be used to illustrate fundamental physics principles.  For example, was it “the fall” or “the webbing” that killed Gwen Stacy, Spider-Man’s girlfriend in the classic Amazing Spider-Man # 121?  How does Kitty Pryde from the X-Men comics and movies use quantum mechanics to walk through walls?  Why does the Flash become heavier as he tries to run at the speed of light? All this, and the answers to such important real life questions as the chemical composition of Captain America’s shield, and who is faster: Superman or the Flash? will be discussed. 

Brief Biography:  James Kakalios is the Taylor Distinguished Professor in the University of Minnesota’s School of Physics and Astronomy.  He received his Ph.D. in Physics from the University of Chicago in 1985; he worked as a post-doctoral research associate at the Xerox – Palo Alto Research Center; and then in 1988, having had enough of those California winters, joined the faculty of the School of Physics and Astronomy at the University of Minnesota.  His popular science book THE PHYSICS OF SUPERHEROES was published in 2005 in the U.S. and the U.K., and has been translated into German, Spanish, Korean, Chinese and Italian. The SPECTACULAR SECOND EDITION was published in November 2009, and his second book THE AMAZING STORY OF QUANTUM MECHANICS was released in October 2010. In 2007, in response to a request from the National Academy of Sciences, he served as the science consultant for the Warner Bros. superhero film Watchmen.  In 2009 Kakalios made a short video on the Science of Watchmen, which was viewed over 1.8 million times on youtube.com.  This video won an Upper Midwest Regional Emmy award in the alternative Media: Arts/Entertainment category in 2009 and was nominated for a WEBBY award in 2010. His research interests include nanocrystalline and amorphous semiconductors, pattern formation in sandpiles and fluctuation phenomena in neurological systems.  He was the Chair of the American Physical Society (A.P.S.) Committee on Informing the Public, Past-Chair of the A.P.S. Forum on Outreach and Engaging the Public, winner of the 2014 American Association for the Advancement of Science (AAAS) Public Engagement with Science Award, and the 2016 Andrew Gemant Award for outreach efforts from the American Institute of Physics.  He has been reading comic books longer than he has been studying physics.

 

Tuesday, November 22, 2016

Steve Pain

Oak Ridge National Laboratory

"Transfer Reactions for Nuclear Astrophysics"

Abstract:  It is crucial to quantify nuclear reaction rates in astrophysical environments in order to understand the energetics of stars and explosive stellar environments, and the origin of the chemical elements from which we are made. However, many of the critial reactions involve short-lived nuclides and/or very low cross sections, making direct measurements of the reaction rate at stellar temperatures currently infeasible. However, it is possble to determine these reaction rates by using alternative, more favorable, reactions to constrain the proprties of the nuclei involved. The Oak Ridge Rutgers University Barrel Array (ORRUBA) was developed a decade ago with a primary focus on studying nuclei of astrophysical interest. More recently, ORRUBA has been coupled to other instruments, such as Gammasphere and JENSA, in order to further its scope. An overview of the instrument, some of its scientific results, and future implementations will be presented.

 

Tuesday, November 29, 2016

Xerxes Steirer

Colorado School of Mines, Physics Department

"Emerging Areas in Photoelectron Spectroscopy: Yes You Can Teach Old Spectrometers New Tricks!"

Abstract:  Beginning with the early descriptions of the photoelectric effect, we will build an understanding of how the chemical and electronic properties of materials are measured using photoelectron spectroscopy (PES). Applications of PES to the study of semiconductors, nanostructures, devices and electrochemical systems are discussed with an overarching goal to advance sustainable energy systems such as biofuels, solar power and energy storage. We will discuss in depth a hybrid organic-inorganic perovskite photovoltaic study where PES has indicated a remarkable tolerance to point defects suggesting that certain defects may reside on all octahedra without impacts to the material’s predominant electronic structure.1 Our discussion will conclude with new directions in PES including those on the horizon at Colorado School of Mines.

1. Steirer, K. X., Schulz, P., Teeter, G., Stevanovic, V., Yang, M., Zhu, K. & Berry, J. J. Defect Tolerance in Methylammonium Lead Triiodide Perovskite. ACS Energy Lett. 1, 360–366 (2016).

Tuesday, December 6, 2016

Graduate student poster session in CTLM231

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SPRING SEMESTER 2017

All lectures are in CTLM102 unless otherwise noted.  Lecture starts at 4:00pm.  Questions, contact Barbara Johnson, 303.273.3830 or bpjohnso@mines.edu

 

Tuesday, January 17, 2017

Jason Clark

Argonne National Laboratory

"Ion Traps For Astrophysics: Where No Trap Has Gone Before"

Abstract:  How were all the elements in the universe created? Scientists across many disciplines have been trying to answer this question for decades. Much progress in our understanding of nucleosynthesis has been made, but the origin of half the elements heavier than iron is still unknown. Supernovae are possible sources of heavy-element production, whereby elements are produced through a rapid series of nuclear reactions on neutron-rich nuclei in a process termed the astrophysical `r' process. In an attempt to reproduce the observed distribution of element abundances in the universe, models are generated which inherently rely upon many nuclear physics inputs, including the masses of the nuclides involved and their beta-decay properties. However, the uncertainties in these nuclide properties are often too large and limit our understanding of heavy-element nucleosynthesis.  Ion traps have revolutionized mass spectroscopy and have the potential to do the same for beta-decay spectroscopy as well. Precise mass measurements of radioactive nuclides are now routinely performed around the world, but nuclides involved in the astrophysical r process are often too challenging to produce for study at accelerator facilities. The newly commissioned CARIBU facility, an upgrade to Argonne National Laboratory's ATLAS facility, provides copious amounts of these previously elusive neutron-rich nuclei. A program of mass measurements at CARIBU is underway, where the Canadian Penning trap mass spectrometer has already been used to determine the masses of more than 100 of these nuclides to a mass precision of 100 parts per billion or better. In addition, a specially designed ion trap is currently being developed to facilitate a new program of beta-decay spectroscopy using nuclides produced by CARIBU. Results from a recent set of measurements have indicated this new technique of using ion traps to perform beta-decay studies could significantly advance the field. Indeed, ion traps for astrophysics are going where no trap has gone before.

 

Tuesday, January 24, 2017

Melanie Kay, J.D.

Director, Daniels Fund Ethics Initiative University of Colorado Law School

"Behavioral Ethics and Responsible Research” (joint lecture: PHGN 502/602-Graduate Seminar and PHGN503-Responsible Conduct of Research)

Abstract:  Traditionally, the study of ethics has focused on philosophical reasoning and introspection.  Students considered various schools of ethical thought and debated the “right thing to do” in hypothetical situations.  Yet ethics educators spent little time analyzing actual human behavior and decision-making— namely, why we do the (sometimes unethical) things we do.  Recently, behavioral psychologists have investigated how humans actually behave when confronted with ethical dilemmas, and come to better understand the sometimes surprising ways our brains can trick us into making and rationalizing unethical choices.  Their research has important implications for the business, legal, and scientific communities, where ethics scandals erupt with unfortunate frequency.  In her talk, Ms. Kay will explain how concepts such as ethical blindspots, overconfidence bias, ethical fading, confirmation bias, slippery slopes, and conformity can affect decision-making, and how you can overcome these psychological forces so as to conduct research with integrity, honesty, and transparency.

 

Tuesday, January 31, 2017

Kristine Callan, CSM Department of Physics and

Stephanie Fanselow, Univ. of Northern Colorado, Dept. of Science Education

"The Teacher Education Alliance, Mines-UNC Partnership (TEAM-UP): What Is It, Why Is It Needed, and How Can You Help?”

Abstract:  To help battle the shortage of highly qualified science and math teachers, Colorado School of Mines and University of Northern Colorado have recently created a unique partnership that plays on each institution’s strengths to produce highly qualified STEM teachers. Mines prepares students with a strong understanding of STEM subjects, and UNC provides the coursework in education and pedagogy necessary to become a secondary science or mathematics teacher in Colorado. TEAM-UP began enrolling students in the fall semester of 2015, with additional students adding each semester. In this talk, we will describe: the evolution of TEAM-UP, common (and surprising) misconceptions about the K-12 STEM teaching landscape, the grant activity that has supported the program and our students, and our future plans for TEAM-UP and how you can help.

 

Tuesday, February 7, 2017

Speaker and topic to be announced

 

Tuesday, February 14, 2017

Speaker and topic to be announced

 

Tuesday, February 21, 2017

Speaker and topic to be announced

 

Tuesday, February 28, 2017

Speaker and topic to be announced

 

Tuesday, March 7, 2017

Speaker and topic to be announced

 

Tuesday, March 14, 2017

NO COLLOQUIUM - SPRING BREAK

 

Tuesday, March 21, 2017

Speaker and topic to be announced

 

Tuesday, March 28, 2017

Speaker and topic to be announced

 

Tuesday, April 4, 2017

Speaker and topic to be announced

 

Tuesday, April 11, 2017

Speaker and topic to be announced

 

Tuesday, April 18, 2017

Speaker and topic to be announced

 

Tuesday, April 25, 2017

Speaker and topic to be announced

 

Tuesday, May 2, 2017

Speaker and topic to be announced

 

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Last Updated: 03/28/2017 07:57:03