The proton and neutron, known as nucleons, are the fundamental building blocks of all atomic nuclei and make up essentially all the visible matter in the universe, including the stars, the planets, and us. The nucleon is not static but has complex internal structure, and both theory and technology have now reached a point where human is capable of exploring the inner dynamics and structure of nucleons and nuclei at the sub-femtometer distance, which is expected to lead to a new emerging science of nuclear femtography.  In this talk, I will demonstrate that the newly proposed Electron-Ion Collider (EIC) with its unique capability to collide polarized electrons with polarized protons and light ions at unprecedented luminosity, and with almost all elements of heavy nuclei at high energy, will be the most powerful tomographic scanner able to precisely image quarks and gluons inside the proton and nuclei. It is also a precision microscope that allows us to “see” and explore the dynamics binding quarks and gluons together to form hadrons. The EIC will address the most compelling unanswered questions about the elementary building blocks of the visible world to take us to the next frontier of the Standard Model of physics

In the last several decades neutrino oscillation experiments have given us a consistent picture of neutrino mass and mixing among three neutrino flavors. However, a series of longstanding and more recent anomalies hint at the existence of additional “sterile” neutrino flavors and complicates this simple picture. In order to improve on previous short baseline sterile neutrino searches, new detector technologies are required.  Liquid Argon time projection chambers (LArTPCs) promise to have the sensitivity needed by current and next generation neutrino oscillation experiments looking for the appearance of electron-flavor neutrinos in a predominantly muon-flavored accelerator-based neutrino beam.  MicroBooNE is the first of three LArTPC detectors planned for the newly re-established Short Baseline Neutrino program at Fermilab built to address the sterile neutrino hypothesis and to develop the technologies and expertise necessary to deploy a kiloton-scale LArTPC for future long baseline neutrino oscillation experiments.  Latest results from the MicroBooNE experiment will be presented along with the prospects and status of the Fermilab neutrino program

Topological crystalline insulators (TCI's) are a class of materials which support non-trivial topology in their electronic structure, "protected" by an underlying crystal symmetry.   We will discuss how certain aspects of this topology can be uncovered at surfaces of such crystals when they are magnetically doped, and show that the system hosts a surprisingly rich variety of ferromagnetic 

states and phase transitions.  After discussing how band topology can be characterized, and the unavoidable presence of conducting surface states even as the bulk is insulating when the topology is non-trivial, we examine the impact of magnetic dopants on the surface states. By breaking the symmetry that protects the topology, the system can become ferromagnetic, but the number of degenerate groundstates is dependent on both the symmetry of the surface as well as the density of electrons there. Moreover, the same surface may support a very "stiff" ferromagnet or a rather "floppy" one. The nature of the ferromagnet realized is in principle externally controllable, and for different cases it disorders at finite temperature through phase transitions of different universality classes. The type of system realized for a specific set of circumstances can be probed via the unique properties of domain walls which appear when the system is thermally excited.

The laws of nature that emerge from string theory are in essence discrete: they contain no continuous parameters.  The possible laws correspond to the possible topologies of spacetime.  I will first explain what quantum gravity is, and why it is essential for interpreting measurements of the polarization of the cosmic microwave background (CMB). I will then develop the connection between discrete laws and topology, and show how we have exploited this connection to systematically enumerate inflationary cosmologies in string theory.  The brightness of the primordial gravitational wave signal in the CMB is controlled by integers that count the number of holes in the spacetime.

Understanding the fundamental relationship between atomic structure and material properties is the holy grail of the science of materials. Towards this goal we are working to develop a real-time and atomistic understanding of the mechanistic steps taken during the growth and transformation of crystalline materials. To do this we employ a combination of complementary synthetic and characterization approaches, in particular using in situ ultra-high resolution transmission electron microscopy (TEM) to observe key structural transformations in real-time. Our in situ experiments include directly performing nanomaterial synthesis in the TEM as well as determining the kinetics of structural phase transformations of as-synthesized inorganic nanocrystals. Further, based on an unexpected observation made during one of these in situ measurements, we have developed a new approach to directly synthesize arrays of crystallographically well-defined nanoscale interfaces. Several examples will be presented to illustrate our approach, including: the real-time observation of the solid-state reaction of an individual nanowire; a post-synthetic structural phase transformation within an individual nanorod, and finally, the creation of new nanostructured architectures using liquid metal nanodroplets.

p { margin-bottom: 0.1in; direction: ltr; line-height: 120%; text-align: left; }

For most wireless communication systems, the signal environment is dominated by ambient noise and interference, which means that improving the efficiency of the antenna does not increase performance much. When the signal comes from the sky (think radio astronomy and satellite communications), the situation is very different. High aperture efficiency, radiation efficiency, spillover efficiency, and low noise electronics are everything in terms of the performance of a receiver. Bent metal antennas (horns and parabolic dishes) are very efficient and for the last century have been working just fine. The catch is that these kinds of receivers are “dumb” and offer only a fixed beam pattern. We would like to use smart antennas, phased arrays, and adaptive antennas for astronomy and satellite applications to have more control over the beam and more flexibility in selectively receiving signals of interest, but existing phased array technologies are too expensive, lossy, noisy, and most of all, too inefficient. Over more than a decade, my group has used numerical modeling, antenna design optimization, network theory, microwave noise analysis, and array signal processing theory to produce some of the most sensitive phased arrays ever built. This presentation will tell the story of this research field and show how the results have enabled new sensors, satellite receivers, scientific instruments, and influenced the IEEE’s latest version of the governing standard for definitions of antenna terms.