Bulletin of the American Physical Society
2018 Annual Meeting of the APS Mid-Atlantic Section
Volume 63, Number 20
Friday–Sunday, November 9–11, 2018; College Park, Maryland
Session G05: Light and Atoms |
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Chair: Marianna Safronova, University of Delaware Room: Edward St. John 2204 |
Saturday, November 10, 2018 4:00PM - 4:36PM |
G05.00001: Resonant energy transfer among ultracold highly-excited atoms Invited Speaker: Michael W Noel Ultracold highly-excited atoms can interact strongly through a field tuned dipole-dipole interaction. We observe this interaction by measuring how population is redistributed among energy eigenstates as the atoms exchange energy. Selective field ionization is often used to measure the population distribution in highly-excited atoms. In this technique, a ramped electric field ionizes the atoms, with weakly bound electrons ionizing at low field (early in time) and tightly bound electrons ionizing at high field (later in time). Unfortunately, it is often difficult to resolve the signals from states that are close in binding energy. We have recently developed an improved selective ionization technique that allows us to separate the signals from closely spaced states. Using this technique, we can precisely quantify the dipole-dipole interaction among atoms. |
Saturday, November 10, 2018 4:36PM - 4:48PM |
G05.00002: MeV Photoelectron Spectrometer for Ultrastrong field Laser-Atomic and Molecular Interactions: Next Generation Spectroscopy Siyu Luo, Chris Sweet, Zach Germain, Rachael McIntyre, Amylia Hoos, Zahide Demircioglu, Barry C Walker Spectroscopy techniques, such as time-of-flight, revolutionized measurements of laser matter interactions. Terawatt and petawatt laser systems can create focused intensities exceeding 1020 W/cm2. Traditional experimental techniques are unable to quantify the > 100 keV photoelectrons from the interaction of these intensities with atoms and molecules. A new generation of spectrometers and sample preparation is required. At this time, a ‘breakthrough’ technology for measuring the interaction of atoms and molecules in ultrastrong fields has not emerged. We present a magnetic deflection spectrometer for ultrastrong field laser experiments in a focused geometry with atoms and molecules. Beta decay samples 14C, 137Cs and 204Tl are used to calibrate the spectrometer over its energy range from 20 keV to 2 MeV. The UHV spectrometer employs a rotatable magnet analyzer in vacuum to measure photoelectrons emitted into polar angles from 10 to 100 degrees from the laser wave vector k. Recent spectra for noble gases and chloromethane will be presented. |
Saturday, November 10, 2018 4:48PM - 5:00PM |
G05.00003: High-Density Gas Jet Characterization for Laser-Plasma Interaction Abdurrahman Younis, Robert Schwartz, Linus Feder, Howard Michael Milchberg To understand laser-plasma interaction and make use of plasma wakefield acceleration, we focus an intense laser pulse into a vacuum chamber and release high-density bursts of gas into the beam path. There exists a critical density of electrons beyond which an electromagnetic wave does not propagate. While the behavior of the plasma wave in the over- and under-dense regime is well established, densities in the vicinity of the critical value remain unexplored. In order to attain sufficiently high peak gas densities with short rise-time, we developed a method of injecting high-pressure gas from sub-millimeter gas jet nozzles, and designed and built a high-voltage pulse driver to control a state-of-the-art solenoid valve. We have demonstrated that near-critical density gas with sub-millisecond rise-times is producible, so it is a viable target for high-intensity laser wakefield acceleration experiments. |
Saturday, November 10, 2018 5:00PM - 5:36PM |
G05.00004: Collective effects in Casimir-Polder forces Invited Speaker: Kanupriya Sinha Fluctuation forces between neutral objects due to the quantum fluctuations of the electromagnetic field are a fascinating feature of quantum electrodynamics. When considering atom-surface interactions at nanoscales, such forces become an imperative element of consideration in understanding nanophotonic systems. It is then an important question whether and how these forces can be tailored to achieve better control and coherence of quantum systems interacting at nanoscales. In this talk we introduce the use of collective effects as a means to tailor Casimir-Polder (CP) forces. |
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