Seminars

Special Seminar: Thursday, April 16, 2015

Optics Building 234, 2:30PM

True Polar Wander: The Hidden Physical Evidence for Lunar Re-Orientation Revealed using Orbital Geochemistry

Dr. Richard Miller (UAH/Physics)

Neutron measurements of the Moon’s polar regions are a robust measure of water ice (hydrogen). While popular hypotheses suggest the water should be correlated with permanently shadowed regions, some of the coldest locations in the solar system, the actual distribution shows strong off-polar enhancements that are not easily explained by the current thermal environment. A new hypothesis will be presented that supports the notion of ancient hydrogen deposits indicative of a lunar paleo-pole. I will show that re-orientation of the Moon from the paleo-pole to it’s current rotational axis 3-4 billion years ago is supported in dramatic fashion by data from NASA’s Lunar Reconnaissance Orbiter and GRAIL missions. Of particular note is a fundamental connection to the nearside feature known as the Procellarum KREEP Terranae (PKT). This work represents the first use of orbital geochemistry as a tracer of the internal evolution of a planetary body.


Tuesday, April 14, 2015

Optics Building 234, 2:30PM

Star Formation and the Dynamics of Multiphase Gas amid Kinetic and Radiative Feedback from Active Galaxies whose Central Engines are Powered by Accreting Supermassive Black Holes

Dr. Grant Tremblay (Yale)


Tuesday, April 7, 2015

Optics Building 234, 2:30PM

No Seminar (UAH Honors Day)


Tuesday, March 31, 2015

Optics Building 234, 2:30PM

Measuring Everything You've Always Wanted to Know about a Light Pulse

Prof. Rick Trebino (Georgia Tech/Physics)  

The vast majority of the greatest scientific discoveries of all time have resulted directly from more powerful techniques for measuring light. Indeed, our most important source of information about our universe is light, and our ability to extract information from it is limited only by our ability to measure it. 

Interestingly, the vast majority of light in our universe remains immeasurable, involving long pulses of relatively broadband light, necessarily involving ultrafast and extremely complex temporal variations in their intensity and phase. So we have been developing techniques for measuring, ever more completely, light with ever more complex submicron detail in space and ever more complex ultrafast variations in time. The problem is severely complicated by the fact that the timescales involved correspond to the shortest events ever created, and measuring an event in time seems to require a shorter one, which, by definition, doesn’t exist! 

Nevertheless, we have developed simple, elegant methods for completely measuring these events, yielding a light pulse's intensity and phase vs. time and space. One involves making an optical spectrogram of the pulse in a nonlinear optical medium and whose mathematics is equivalent to the two-dimensional phase-retrieval problem—a problem that’s solvable only because the Fundamental Theorem of Algebra fails for polynomials of two variables. And we have recently developed simple methods for measuring the complete spatiotemporal electric field of an arbitrary light pulse.

Biography: Rick Trebino received his B.A. from Harvard in 1977 and his Ph.D. in Applied Physics from Stanford in 1983. He is currently at Georgia Tech, where he holds the Georgia Research Alliance-Eminent Scholar Chair of Ultrafast Optical Physics. He develops techniques for measuring ultrashort laser pulses, for which he has received numerous awards, including the SPIE’s Edgerton Award and an R&D 100 award in 2003. He is a Fellow of the Optical Society of America, the Society of Photo-Instrumentation Engineers, the American Physical Society, and the American Association for the Advancement of Science.


Tuesday, March 17, 2015

Optics Building 234, 2:30PM

High-energy cosmic ray acceleration in individual and multiple shocks of relativistic jets

Dr. Athina Meli (University of Gent/Physics & Astronomy)

Active Galactic Nuclei and Gamma Ray bursts are relativistic, extragalactic sources which are believed to be the main candidates of the high-energy cosmic-rays. Relativistic shocks, either single or multiple, have been inferred by observations or have been theorized to be forming within a high-speed plasma jet in these extragalactic sources. The acceleration of protons mainly, but also nuclei, via the Fermi acceleration mechanism in these jets is believed to be responsible for the observed cosmic-ray power-law distributions and consequently for the radiation of gamma-rays and neutrinos. Here, I will focus on the relativistic cosmic-ray shock acceleration mechanism, and will present test-particle simulation studies for single and multiple shocks occurring in these extragalactic jets. Then, I will briefly discuss the secondary production and extragalactic propagation of the accelerated high-energy cosmic-rays, giving insights into understanding their relevance to a multi-messenger physics approach.


Tuesday, March 10, 2015

Optics Building 234, 2:30PM

Higher Order Polarimetry and Intensity Fluctuations for Target Discrimination

Dr. Thomas Kohlgraf-Owens (Kord Technology)

The interaction of optical waves with material systems often results in seemingly random scattered fields. Because the fluctuations in the response from a system are typically difficult to analyze directly, they are regarded as noise to be suppressed. Nevertheless, the statistical properties of the scattered fields can be employed for a variety of sensing and discrimination tasks because at each instant the scattered field is the result of a deterministic, albeit complicated, interaction between the optical field and the scattering system. This talk will focus on some of the work done by the Photonic Diagnostics of Random Media group at CREOL related to sensing tasks with disordered materials.


Tuesday, March 3, 2015

Optics Building 234, 2:30PM

IceCube: The Beginning of Neutrino Astronomy

Prof. Dawn Williams (Physics&Astronomy/University of Alabama)

The IceCube Neutrino Observatory is the largest neutrino detector in the world, instrumenting one cubic kilometer of ice at the geographic South Pole. IceCube was designed to detect high energy neutrinos from possible cosmic ray acceleration sites such as active galactic nuclei, gamma ray bursts and supernovae. In 2013, IceCube announced the first detection of a diffuse flux of high energy neutrinos whose characteristics are consistent with astrophysical origin. The IceCube signal includes the highest energy neutrinos ever detected. I will discuss the latest results from IceCube and future prospects for the next generation of neutrino detection at the South Pole.


Tuesday, February 24, 2015

Optics Building 234, 2:30PM

Ordinary thunderstorms as particle accelerators

Dr. Michael Briggs (CSPAR/UAH)

Terrestrial gamma-ray flashes are bright, sub-ms flashes of gamma-rays observed from orbit. The gamma-rays are produced from bremsstrahlung from electrons that are accelerated in thunderstorms. Observations with the Fermi Gamma-ray Burst Monitor (GBM) discovered positrons in a particular subset of TGFs, showing that thunderstorms are injecting gamma-rays, electrons and positrons into space. Combining GBM observations with ground-based radio, specific storms that produce TGFs are identified. A wide range of thunderstorms, including very ordinary ones, are found to produce TGFs. Relativistic particle acceleration is a common atmospheric phenomena.


Tuesday, February 17, 2015

Optics Building 234, 2:30P

Towards ultrafast plasmonic dynamics without decoherence

Prof. Seyed  Sadeghi (UAH/Physics)

A main signature of quantum systems is the ultrafast decay of their quantumness. This is mostly related to the inevitable interaction of these systems with their environments. In semiconductor quantum dots a prime impact of quantum decoherence is the rapid decay of quantum coherent effects generated by a laser field. This is an undesirable process which many exotic applications of quantum dots difficult to observe and use, particularly those related to quantum computation and quantum optics effects. In this talk my objective to discuss a novel path that hybrid systems consisting semiconductor quantum dots and metallic nanoparticle can offer. This path may lead to the ultrafast coherent dynamics associated with plasmons and excitons that are free of decoherence or damping. For this I discuss systems that can convert rather static plasmon fields of metallic nanoparticles into field oscillations or ultrashort pulses with undamped amplitudes.


Tuesday, February 10, 2015

Optics Building 234, 2:30PM

Seminar Cancelled


Tuesday, February 3, 2015

Optics Building 234, 2:30PM

Cosmological Highlights from the Sloan Digital Sky Survey

Prof. David Weinberg (Astronomy/OhioState)

I will describe some of the scientific highlights from the Sloan Digital Sky Survey (SDSS), concentrating on those connected to cosmology and galaxy formation.  In the three phases to date, SDSS-I, II, and III, the Sloan collaboration has carried out several of the largest and most ambitious surveys of the distant universe and the Milky Way galaxy, with deep digital imaging over one third of the sky and spectroscopy of more than 2 million galaxies, 200,000  quasars, and half a million stars.  Cosmological achievements include: probing the epoch of reionization with the most distant known quasars; comprehensively characterizing the properties of galaxies and the relations between galaxies and their parent dark matter halos; discovering ubiquitous substructure in the outer Milky Way and more than a dozen new companion satellite galaxies; mapping cosmic expansion over the last four billion years with more than 500 Type Ia supernovae; and, through its precision  measurements of structure on very large scales, providing a central  pillar of the standard cosmological model based on inflation, cold  dark matter, and dark energy.  I will review these highlights, with particular attention to recent progress in measuring the properties of dark energy through baryon acoustic oscillations. I will summarize plans and prospects for SDSS-IV, which began in July 2014.


Tuesday, January 27, 2015

Optics Building 234, 2:30PM

Night Vision Goggle Performance and Bottlenose Dolphin Vision

Mr. Andre Rivamonte (USATA Metrology Engineering Division, AMSAM-TMD-LW)

Night Vision Goggle Performance and Bottlenose Dolphin Vision GEN III Night vision goggles (NVG) and the dolphin eye are more similar than different. Both are fixed focus, monochromatic, very light sensitive, similar in resolution and highly adapted for their intended use. However, while NVGs are well understood and characterized, the dolphin eye is not. Techniques used to determine resolution and sensitivity of Army NVGs and dolphin vision will be reviewed.
  Both optical systems are complex and sophisticated. With an image intensifying micro channel plate accounting for the high sensitivity and resolution of NVGs, there is no consensus as to how a dolphin can see well both under water and in air. This is because axial ophthalmoscope refractive state measurements in air range from 16 to 20 diopters of myopia yet behavioral studies indicate a 0.5 diopter error or at most a few diopters of myopia in both air and underwater. The optical elements involved in this paradox will be discussed. If time permits, a pictorial trip starting from Huntsville, Alabama and ending with a visit to the Kewalo Basin Marine Mammal Laboratory in Honolulu will be presented.
  Note: The paradoxical dolphin eye has interestingly evolved (1) two off axis, high retinal summation, areae centrali, (2) a double slit pupil, (3) a gradient index spherical lens, (4) a highly reflecting tapetum lucidum, (5) a stable visual environment with independent eye movement, (6) a low curvature ellipsoidal, inelastic cornea and (7) edge enhancing retinal neural processing.


Tuesday, January 20, 2015

Optics Building 234, 2:30PM

From supermassive black holes to the large-scale structure of the Universe

Dr. Norbert Werner (KIPAC/Stanford)

I will present recent observational results on the nature and origin of the multi-phase interstellar medium (ISM) in giant elliptical galaxies, and its role in galaxy evolution and in fueling the central supermassive black holes. Our results show that the cold gas in these systems is produced chiefly by thermally unstable cooling from the hot phase, and that active galactic nuclei are likely to play a crucial role in clearing giant elliptical galaxies of their cold gas, keeping them 'red and dead'. Then I will 'zoom out' to the outskirts of galaxy clusters where we also find hints that supermassive black holes played an important role in the distant past. Suzaku observations reveal a remarkably homogeneous distribution of iron out to the virial radius of the nearby Perseus Cluster, requiring that most of the metal enrichment of the intergalactic medium occurred before the cluster formed, probably more than ten billion years ago, during the period of maximal star formation and black hole activity. Finally, I will talk about the upcoming Astro-H mission which will revolutionize X-ray spectroscopy and our understanding of the dynamics of the intra-cluster medium.


Tuesday, January 13, 2015

Optics Building 234, 2:30PM

High recognition specificity remote sensing of chemical vapor using IR/THz double resonance spectroscopy

Dr. Henry Everitt (AMRDEC)

Molecular rotational motion is quantized, just as its vibrational and electronic states are quantized. Molecular rotational energy levels depend sensitively on the shape of the molecule and the masses of the constituent atoms.  As a result, gas phase molecular rotational transitions, whose wavelengths are in the milIimeter and sub-millimeter region, provide signatures that allow chemical identification with exquisite selectivity.  This tutorial will review the basics of molecular spectroscopy, then explore its application for chemical sensing.  Specifically, a new double resonance spectroscopic technique will be described that exploits this remarkable specificity for remote chemical sensing.  The technique overcomes intrinsic limitations of atmospheric attenuation and collisional broadening that have hindered other approaches.  The hardware requirements and challenges for constructing such a spectrometer will be described.