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Friday Afternoon Seminar (2017-2018)

Date Speaker Presentation Abstract
September 22nd Hassan Arbab Terahertz Time-Domain Spectroscopic and Polarimetry Techniques for Biomedical Imaging and Non-Destructive Testing Applications In this seminar, we will first review the key concepts relevant to the generation and detection of terahertz electromagnetic waves in a standard Terahertz Time-Domain Spectroscopy (THz-TDS) setup, namely emissions from photoconductive antennas, non-linear optical rectification, and gas-plasma sources. We will further discuss a new class of plasmonic large-area high-power sources that can deliver up to 1 mW in the terahertz range custom-made for our biomedical imaging applications. We will then introduce a new variation of the THz-TDS technique, recently invented in our group, dubbed Terahertz Time-Domain Polarimetry (THz-TDP), which allows for real-time measurement of the polarization direction of the terahertz field without the need for any external polarizers. Finally, we will explore applications of both THz-TDS and THz-TDP techniques in biomedical imaging and non-destructive testing (NDT) in aerospace and pharmaceutical industries. The goal is to introduce the diverse set of terahertz imaging projects currently being pursued in the new Terahertz Biophotonics Lab.
September 29th Tom Allison Mastering the electromagnetic spectrum to study molecular dynamics or Using what we're good at to learn about what we're not Much of the technology developed in the 20th century derives from our ever increasing ability to control electromagnetic fields. From the early days of telephone and radio communication to the current era of the internet and GHz microprocessors, physicists and engineers have worked relentlessly to produce and utilize electromagnetic fields of higher frequency and larger coherent bandwidths. In this talk I will discuss our efforts at Stony Brook in coherent waveform synthesis, developing frequency combs from the mid-infrared all the way to the x-ray regime, and their application to understanding molecules - the very different technology platform that nature has mastered but for which our understanding is still comparatively primitive.
October 13th Ken Dill The role of statistical mechanics in some grand challenge problems of cell biophysics Cells make many clever and purpose-like decisions. Those decisions are encoded in chemical networks and other cellular machinery. How? We make models of the network dynamics, using the physics of protein folding and aggregation. We apply the same approach to evolutionary matters, to ask how cells evolved to be what they are. And, we are developing an approach to nonequilibrium statmech that contributes here.
October 20th Roy Lacey The dynamics and thermodynamics of heavy Ion collisions at RHIC and the LHC Characterization of the QCD phase diagram is central to ongoing research efforts at RHIC and the LHC. Quantification of the properties of the respective phases, as well as pinpointing the location of the phase boundaries and the critical endpoint (CEP), is key to this characterization. We will discuss new and ongoing measurements designed to give essential insights on reaction dynamics and the thermodynamic properties of the QCD phase diagram.
October 27th Tatiana Engel Discovering dynamic computations in the brain from large-scale neural recordings Neural responses and behavior are influenced by internal brain states, such as arousal, vigilance, or task context. Ongoing variations of these internal states affect global patterns of neural activity, giving rise to apparent variability of neural responses to sensory stimuli, from trial-to-trial and across time within single trials. Demultiplexing these endogenously generated and externally driven signals proved difficult with traditional techniques based on trial-averaged responses of single neurons, which dismiss neural variability as noise. In this talk, I will describe my recent work leveraging multi-electrode neural activity recordings and computational models to uncover how internal brain states interact with perception and goal-directed behavior. I will show that ensemble neural activity within single columns of the primate visual cortex spontaneously fluctuates between phases of vigorous (On) and faint (Off) spiking. These endogenous On-Off dynamics, which reflect global changes in arousal, are also modulated at a local scale during spatial attention and predict behavioral performance. I will also demonstrate that these On-Off dynamics provide a single unifying mechanism that explains general features of correlated variability classically observed in cortical responses (e.g., changes in neural correlations during attention). I will conclude by sketching out a roadmap for developing a general theory that will allow us to discover dynamic computations from large-scale neural recordings and to link these computations to behavior.
November 3rd Swagato Mukherjee Quarks, Gluons & Lattice QCD: Cooking Qurk-Gluon Soup With Supercomputers
November 17th Honghai Song Advances of Applied Superconductivity and Magnets for Future Accelerators and Colliders Thousands of magnets has been widely employed in numerous large scale accelerator systems and superconducting magnet/components are in much higher demands for future accelerator systems. I will introduce on-going research activities for EIC, LEReC, IBS 25T and LARP projects in our department and then share my researched experiences on high temperature superconductor – REBCO – quench and stability – magnetic field measurement, etc. I hope to build connections with professors and students at SBU for future collaborations and partnership.
March 2nd Tom Allison A table-top synchrotron with 1000x better time resolution Angle-resolved photoelectron spectroscopy (ARPES) is the best way to determine the ground states of the electrons in condensed matter systems, and every synchrotro has a beamline devoted to ARPES. However, synchrotron radiation is not suitable for studying excited states because the light pulses from synchrotrons are too long and excited electronic states are short lived. In this talk I will describe a new instrument we have developed for performing ARPES measurements from excited states with < 100 fs resolution, but synchrotron data rates. This instrument surpasses what was previously possible by several orders of magnitude, enabling many experiments previously considered impossible. A wide range of research directions for students are available for students who wish to use this unique and extraordinary tool, in addition to other opportunities in the Allison lab.
March 9th Ken Dill Biology interacting with statistical physics Biology is entering an era in which its theory and modeling comes increasingly from statistical physics. There are payoffs in deeper understanding of living cells, and their aging and evolutionary processes as well as the origins of life, in addition to the mitigation of diseases that we cannot now treat, and the development of new bio-inspired materials. The challenges in modeling living cells include not only their heterogeneous distribution functions, but their complex dynamics, involving feedback, delays and nonlinearities and magnification of small fluctuations. Life is so far out of equilibrium that it has not relaxed to that state in more than 3 billion years.
March 23rd Sergey Belomestnykh The frontiers of radio frequency superconductivity (SRF) for particle accelerators Over the past several years, the field of radio frequency superconductivity (SRF) for particle accelerators is going through a period of Renaissance. 4-5 years ago, most of the community thought that the technology reached maturity (even though we lacked understanding of some basic physics) and one can achieve only incremental gains in the niobium cavity performance. The field tended to be mostly technological with only few researchers trying to study fundamental issues of SRF in niobium. Big improvement steps were thought to be possible only with developing alternative materials (e.g. Nb3Sn). Recent discoveries of nitrogen doping and infusion, magnetic flux expulsion, opened new horizons and revived interest to studies of SRF basics, both experimental and theoretical. More unexpected and intriguing results have been obtained. In this talk I will try to shed light upon some exciting recent results at Fermilab, show new trends and hopefully inspire graduate students to turn their attention to this field of research.
March 30th Yimei Zhu Revealing Electron-Phonon Coupling and Interplay in Strongly Correlated Quantum Materials Using Ultrafast Electrons MeV-ultrafast electron diffraction (MeV-UED), taking advantage of its high-sensitivity to phonons and the large interaction cross-sections of electrons with matter, has been identified as one of the frontiers and future directions of modern electron microscopy. It allows us to reveal competing orders of electrons and phonons as well as hidden states far-from equilibrium to address some key issues in condensed matter physics and in quantum computing. In this presentation, I will first give a brief introduction on the nature of electrons and their advantages in probing the dynamic behavior of matter. I will then give examples on the observations of strong electron- lattice interactions and the disentanglement of various phonon modes in charge/orbital ordered systems. Finally, I will demonstrate the state-of-the-art electron-beam facilities at Brookhaven National Lab and how the new tools enable the expansion of human knowledge into previously unimaginable areas of science.
April 13th Tom Weinacht Strong Field Ultrafast Physics I will describe experiments that aim to capture quantum dynamics in real time. Ultrafast laser pulses can freeze the motion of electrons and nuclei to create frames of molecular movies. The large electric field in such pulses can also be used to influence the dynamics. I will describe the efforts of our group to make and direct molecular movies with intense ultrafast laser pulses.
April 27th Axel Drees Thermal radiation from the QGP: Research Opportunities in Heavy Ion Physics at Stony Brook In collisions of heavy ions at high energies small droplets of quark-gluon plasma (QGP) are formed in the laboratory at the BNL and CERN accelerator facilities, recreating the state of matter of the universe until about 10 micro seconds after the big bag. My group studies of these droplets of QGP using the PHENIX experiment at BNL’s relativistic heavy ion collider RHIC. In particular, we use the thermal radiation emitted by the QGP droplets to characterize the properties of this hot and dense form of matter. My talk will give an overview of the latest research results, including a sneak preview of results that will be submitted for publication in the next weeks, and future research opportunities.
May 4th Giacinto Piacquadio Using the Higgs boson as a tool to understand the Universe The main purpose of this talk is an introduction to actual research projects at the Energy Frontier performed within my Stony Brook group.I will start with a brief introduction to particle physics, present today’s status of the field with focus on the newly discovered Higgs boson and discuss how measurements of the Higgs boson using the giant ATLAS detector and plenty of LHC data could lead to explaining some of the greatest mysteries of the universe, such as the nature of dark matter, or understanding whether the Higgs boson is an elementary particle or not. I will highlight the novel techniques developed by my group that led to the recent evidence for Higgs boson decays to b-quark last year, and how a further enhancement of these techniques is needed in order to determine the parameters of the Higgs sector with high precision, and possibly lead to the discovery of new physics.