The 15th Annual Pappalardo Fellowships
in Physics Symposium

THURSDAY, MAY 12, 2016

2:00 - 5:00 PM

MIT Department of Physics
Pappalardo Community Room
Building 4, Room 349
Cambridge, MA

Five members of the Department's premier postdoctoral fellowship program, the Pappalardo Fellowships in Physics, will present highlights from their independent research projects.The talks are designed for the enjoyment of all members of the MIT physics community.

Refreshments available for attendees in the foyer of 4-349 beginning at 1:30 pm.



  1:30 pm   Refreshments for attendees served in foyer outside the Pappalardo Community Room
2:00 pm

Jesse Thaler, Associate Professor of Physics; Member, 2016-17 Pappalardo Fellowships Executive Committee

Introductory Remarks
2:15 pm

Or Hen,
2015-18 Fellow,
Experimental Nuclear & Particle Physics

From Nuclei to Neutron-Stars: Short-Range Fermion Correlations

The recent observation by the LIGO collaboration of black hole mergers opens the window to the potential observations of neutron star mergers. Such merges are thought to be a primary source for the formation of the heaviest elements in the universe and can potentially act as an extraordinary laboratory for testing high-field gravity models. As the structure of neutron stars is a delicate balance between the gravitational and nuclear forces, taking full advantage of our newly advanced astrophysical capability requires parallel development of our understanding of the properties of dense, cold, nuclear matter.

Remarkably, the physics of atomic nuclei provide certain valuable analogies to the physics of neutron stars. In this talk, I will present the study of short-range correlations in nuclei: high-density fluctuations of nuclear matter. I will show how our experiments open a portal to the structure of nuclear matter at densities much larger than that of standard matter on earth and discuss their implications to various fields of physics, especially neutron stars.

  2:30 pm Question & Answer
2:45 pm

Itamar Kimchi,
2015-18 Fellow,
Hard Condensed Matter Theory

Many-electron Quantum Entanglement

Quantum entanglement, a key feature of two-body quantum mechanics, can produce counterintuitive phenomena such as fractional charge when a many-body system develops collective entanglement. However, macroscopic systems often develop classical symmetry-breaking order instead. What mechanisms can support entanglement in 3-D solids? Spin-orbit coupling, a relativistic effect which links the electron spin to the crystalline lattice, suggests a new approach.

I will present theoretical work on this approach in the context of new iridium-based materials, and argue for its relevance and consequences using analytical and numerical results together with simple intuitive pictures.

  3:00 pm   Question & Answer
3:15 pm

Taritree Wongjirad,
2014-17 Fellow,
Experimental Nuclear & Particle Physics

From Pixels to Neutrinos in the MicroBooNE Experiment

Neutrino physics is in the midst of a major transition from the operating mode of searching for new phenomena to one of seeking a detailed understanding of what we have found. For this next step, we need new detectors that can provide unprecedented detail about the interactions. At MIT, we are leaders in developing a new, state-of-the-art detector technology called the liquid argon time-projection chamber (LArTPC). This detector produces beautiful, high-resolution images that are sometimes compared to Bubble Chamber photographs. Now we need an efficient way to parse and analyze these images.

Luckily, there is Deep Learning: a machine-learning algorithm using convolutional neural network. This new, rapidly developing technique has found a vast number of applications ranging from automated human face recognition to real-time object detection for self-driving cars–and even to playing Go. It can be used for neutrino physics, too. In this talk, I will discuss how we are applying Deep Learning to the MicroBooNE LArTPC neutrino data to elucidate the events.

  3:30 pm Question & Answer
3:45 pm I N T E R M I S S I O N
4:00 pm

Benjamin Safdi,
2014-17 Fellow,
Theoretical High Energy Physics

The Milky Way’s Gamma-ray Mystery: Dark Matter or Astrophysical Point Sources?

An excess of gamma rays has been observed by the Fermi Large-Area Telescope around the center of the Milky Way. At present, the origin of this excess in unknown. One hypothesis is it arises from the theorized but never-before-seen process of dark matter annihilation. Direct confirmation of dark matter annihilation would revolutionize our understanding of the dark sector and provide a pathway towards understanding what lies beyond the Standard Model.

On the other hand, the gamma-ray excess may have a more astrophysical origin, for example from a population of dim, unresolved point sources, such as millisecond pulsars, centered around the Galactic Center.

I will present a new statistical framework than can be applied to the data to distinguish between the dark matter and astrophysical point-source hypotheses. I will also show evidence that the Galactic Center excess is likely arising from a population of point sources, with characteristics consistent with expectations from millisecond pulsars. Finding direct evidence for such a population of millisecond pulsars may itself indicate a new chapter in the formation history of the Milky Way.

  4:15 pm Question & Answer
4:30 pm Inna Vishik,
2013-16 Fellow,
Experimental Condensed Matter Physics

A Picosecond in the Life of a Superconductor

Condensed matter systems have phenomena that happen in picoseconds (one trillionth of a second) or faster, and improvements in pulsed laser technology increasingly allow us to catch them in the act. One of the most cryptic classes of materials in condensed matter physics are the cuprate high temperature superconductors, in which superconductivity and most other electronic phases lack a microscopic explanation. In this talk, I will discuss how ultrafast optics can be used to learn about superconductivity and adjacent electronic phases in high temperature superconductors.

  4:45 pm Question & Answer
5:00 pm F I N I S