College of Arts and Sciences

One of the prime reasons the Large Hadron Collider (LHC) was built is to resolve the question how particles acquire their mass. While it is very simple to measure particle masses, and we have a model (the Standard Model of Particle Physics) which explains quite accurately all presently available measurements, the seemingly trivial mechanism of how particle acquire their mass remains a mystery. The Standard Model invokes a new scalar gauge field to resolve this mystery, but we have until very recently not been able to find experimental evidence for its existence. On July 4, 2012, the CMS and ATLAS experiments announced the discovery of a new Higgs-like particle at a mass of about 125 GeV.

Continue reading… Unveiling the Mystery of Mass – Christoph Paus

Colloids and liquid crystals are two important classes of soft matter, usually explored independently of each other. The most studied colloids represent a dispersion of solid or liquid particles in an isotropic fluid such as water. The simplest liquid crystal, a nematic, is a fluid with long-range orientational order of molecules. This presentation reviews recent studies of liquid crystal colloids, i.e., dispersions of particles in a liquid crystal. The long-range orientational order imparts anisotropic elastic interactions of colloidal particles [1]. Elastic repulsion from the bounding walls opposes gravity and keeps the particles levitating in the liquid crystal bulk [2]. The levitating particles can be set into motion by applying an electric field.

Continue reading… Statics and Dynamics of Colloidal Particles in Liquid Crystals – Oleg Lavrentovich

This talk addresses key questions associated with nuclear energy and weapons technologies and their impact on society. The intended audience includes journalists, politicians, scientists, political-scientists, activists, and students from high-schoolers through post-docs. The informal powerpoint presentation steps through key questions about nuclei, uranium, enrichment, reactors, weapons, and treaties. The goal is to better inform the public on critical issues which are often discussed but not very well understood. CWRU physics faculty and students should find these details useful in their role as responsible informed citizens.

Continue reading… Nuclear Q & A – William Fickinger

The usual means of storing electrical energy are either batteries, where the current induces chemical reactions, or capacitors, where especially chosen dielectrics enhance the stored energy. Since capacitors can be discharged far more quickly than batteries and fuel cells, they have much higher power densities. At present, highly insulating polymers with large breakdown fields, such as polypropylene, are the dielectrics of choice. Nevertheless, their energy densities are quite low because of small dielectric constants. Ferroelectric polymers from the polyvinylidene fluoride (PVDF) family have significantly larger dielectric constants, yet their energy densities are still rather low. However, an admixture of a small amount of another polymer results in a dramatic (up to sevenfold) increase in the stored energy.

Continue reading… Electro-active polymers and high-power-density energy storage – Jerry Bernholc

In Biology, many tools exist to study individual cells in culture but there is a paucity of tools to study the microenvironment in which cells live and grow in vivo. The microenvironment is the complex milieu of chemical and physical signaling that enables cells to form and function as organisms. Signaling between cells and extracellular structures is critical to normal growth and wound healing as well as malignant transitions and cancer growth. We have been exploring the use of magnetic nanoparticles to explore the microenvironment in vivo. It is not yet possible to image structures at microscopic scales in vivo as AFM does in vitro or as MRI does at macroscopic scales in vivo,

Continue reading… Biosensing with Magnetic Nanoparticles – John Weaver

As we are just attempting to understand how galaxy formation is connected to the growth of supermassive black holes, one fundamental challenge remains. Observations show us that the first quasars were assembled when the universe was only a tenth of its current age, yet their black holes are as massive as the ones in today’s galaxies. I will discuss state-of-the-art large-scale simulations which attempt to study directly the growth of the first, rare, supermassive black holes within the context of our standard structure formation models.

Continue reading… The First Quasars in Cosmic Structure Formation – Tiziana DiMatteo

Beyond graphene there exist a rich family of two-dimensional crystals with a broad spectrum of electronic properties, which remain largely unexplored. For instance, a valley Hall semiconductor emerges by breaking the sublattice symmetry in the honeycomb structure. I will present our recent study of monolayer molybdenum disulfide as a protocol. The observation of an indirect-to-direct band gap crossover in the 2D limit and the optical orientation of its long-lived coupled valley-spins will be discussed. Furthermore, in some of the small-band-gap semiconductors with strong spin-orbit coupling, a new insulating phase with topologically protected surface states appears, due to inverted conduction and valence orbitals.

Continue reading… Beyond graphene: band insulators and topological insulators – Kin Fai Mak

Pulsars, which are rapidly rotating magnetized neutron stars, are natural laboratories for physics under extreme conditions. Gamma radiation has now been seen from more than 100 pulsars, thanks to observations with the Large Area Telescope on the Fermi Gamma-ray Space Telescope. Found in approximately equal numbers are three types of gamma-ray pulsars: young radio-loud pulsars, young radio-quiet pulsars, and older millisecond pulsars. Fermi observations have also led to the discovery of new radio pulsars. This talk will present an overview of the Fermi observatory, how gamma-ray pulsars are found, what we have learned about these energetic objects, and how you might discover a gamma-ray pulsar.

Continue reading… Gamma-ray Pulsars with the Fermi Gamma-ray Space Telescope [joint with Astronomy] – David J. Thompson

Three physics faculty have their 50th birthday this year, three have their 60th, and three their 80th. We celebrate their achievements in this mini-symposium.

Continue reading… Decades of Achievement — a tribute to nine of our number having birthdays ending in a zero – Various

Continue reading… “How we fixed the Hubble Space Telescope” – James Breckinridge

InAs nanowires provide an interesting nanomaterial platform for spintronic device and thermoelectric energy conversion applications, owing to their strong quantum confinement and spin orbit interaction (SOI) effects. Manipulating the SOI and thermoelectric transport in InAs nanowires is thus of great interest for both fundamental quantum transport and applied nanotechnology research. First, we will discuss our recent results of gate induced generation and control of the Rashba SOI (a momentum dependent splitting of spin bands) in InAs nanowires, which is essential for the realization of many spintronic devices. Second, we present a study of the thermoelectric properties of InAs nanowires where the gate was used to sweep the electrons’

Continue reading… Gate Controlled Spin-Orbit Interaction and 1D Thermoelectric Transport in InAs Nanowires – Xuan Gao

After spending a year working as a staffer in the US Senate’s Commerce, Science, and Transportation Committee, Dr. Chris Martin of Oberlin College brings a scientist’s perspective to how national policy reacts to and in turn drives science. Using examples covering the range of congressional interests, including climate change, earthquakes, human space exploration, and nanotechnology, Dr. Martin shows how politicians and scientists can communicate about issues in completely different ways leading to humorous conflicts and surprising synergies. If you have ever wondered what happens in the halls of Congress and how you can most effectively make a difference, this is a talk you should not miss!

Continue reading… The Intersection between Science and Politics: How Science is Used and Abused in Congress – Chris Martin

Ever since the profound effect of the invention of the transistor in 1947, the impact of inorganic semiconductors on our technology world has continued to expand. The III-nitrides (GaN, AlN and InN) are a current example of a class of semiconductors that is increasing ‘exponentially’ in its impact on technology. While the II-IV nitrides are intimately related to the III-nitrides, to date surprisingly little research has been done on the former. Using recent results, the context of the III-nitrides, and focusing in particular on band gaps, structural characterization and phonon properties, I will attempt to convince you that the II-IV-nitrides are of scientific interest,

Continue reading… Development of the II-IV Nitride Semiconductors; Considerations from Science, Technology and Sociology – Kathy Kash