Bulletin of the American Physical Society
Joint Fall 2011 Meeting of the Texas Sections of the APS, AAPT, and Zone 13 of the SPS
Volume 56, Number 7
Thursday–Saturday, October 6–8, 2011; Commerce, Texas
Session N2: Atomic, Molecular, and Optical Physics II |
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Chair: Harry Downing, Stephen F. Austin State University Room: Sam Rayburn Center Second Floor, Room Innovations B |
Saturday, October 8, 2011 12:05PM - 12:17PM |
N2.00001: Solution of the photon propagation paradox Amy West, Adam Houk, Charles Regan, Ayrton Bernussi, Louis Grave de Peralta We present an experimental study on the formation of surface plasmon polariton (SPP) standing waves. We demonstrate that SPP tomography in a quantum eraser arrangement permits the detection of the photons passing through the dark fringes of the observed interference pattern. We present a comprehensive explanation of how photons could pass undetected across the regions occupied by the dark fringes. [Preview Abstract] |
Saturday, October 8, 2011 12:17PM - 12:29PM |
N2.00002: Common-path spectral phase microscopy Nelson Cardenas, Samarendra Mohanty Quantitative phase microscopy is an emerging non-contact method for quantifying physical properties (refractive index, thickness) of materials. The high spatial resolution achieved with millisecond-scale resolution using this non-staining method over a wide-field of view is highly advantageous for mapping dynamic changes in the sample properties due to temperature, pressure and molecular interactions. Since refractive index dispersion is intrinsic to a material, he spectral measurement of refractive index changes will allow characterization and analytical quantification of material. Here, we introduce common-path spectral phase microscopic (CP-SPM) imaging of microscopic objects. CP-SPM is based on a common path interferometer with a tunable laser beam With this method, we are able to characterize both the refractive index of particles over a continuous wavelength band, and also the characteristics of several types of particles simultaneously. [Preview Abstract] |
Saturday, October 8, 2011 12:29PM - 12:41PM |
N2.00003: Temperature dependence of the depolarization rates of Ne$^{\ast }$(2p$_{i}$ [J=1]) atoms induced by helium atom collisions Cristian Bahrim, Vaibhav Khadilkar, Hiraku Matsukuma, Masahiro Hasuo Theoretical depolarization rates for disalignment, disorientation, and alignment destruction of the Ne$^{\ast }$(2p$_{i}$ [J=1]) atoms at temperatures between 10 K and 3000 K are compared with measurements done in Ne-He glow discharges. We perform quantum close-coupling many-channel calculations using a molecular approach for the interaction between Ne$^{\ast }$(2p$_{i}$ [J=1]) and He atoms [1]. Excellent agreement between our calculations and experimental data above 77 K [1, 2] is found for all the J = 1 states. For the 2p$_{5}$ and 2p$_{7}$ states this agreement is found even down to 20K. The temperature dependence of the depolarization rates can be explained using the anisotropy of the molecular channels [2]. However for the Ne$^{\ast }$(2p$_{10}$ [J=1]) atoms, our disalignment rate coefficients are larger than the measurements recently reported in [3] after the radiation re-absorption is subtracted from the disalignment rates. In this paper we carefully address this issue. \\[0pt] [1] Bahrim C, and Khadilkar V 2009 \textit{Phys Rev A} \textbf{79} 042715. [2] Khadilkar V, and Bahrim C 2010 \textit{J Phys B }\textbf{43 }235209. [3] Matsukuma H, Shikama T, and Hasuo M 2011 \textit{J Phys B} \textbf{44 }075206. [Preview Abstract] |
Saturday, October 8, 2011 12:41PM - 12:53PM |
N2.00004: Laser wakefield-accelerated multi-GeV electrons using the Texas Petawatt Laser Neil Fazel, Rafal Zgadzaj, Xiaoming Wang, Watson Henderson, Peng Dong, Richard Korzekwa, Yen-Yu Chang, Hai-En Tsai, Austin Yi, Vladimir Khudik, Serguei Kalmykov, Gillis Dyer, Erhard Gaul, Aaron Bernstein, Mikael Martinez, Ted Borger, Franki Aymond, Doug Hammond, R. Escamilla, Srdjan Marijanovic, Gennady Shvets, Todd Ditmire, Michael Downer Interaction of intense laser pulse and underdense plasma is a promising source for generating multi-GeV electrons beams within the compact confines of the lab. The quality of the electron beam, stability of the electron generation, and scalability to higher energies, are some of the challenges that are being met. We report on a laser wakefield acceleration experiment taking advantage of the powerful Texas Petawatt laser, and using relatively low plasma density together with ionization induced injection, to accelerate electrons. Self-focusing and self-guiding of the laser beam, self-injection and trapping of electrons, and some approaches to diagnostics of accelerated electrons are discussed. [Preview Abstract] |
Saturday, October 8, 2011 12:53PM - 1:05PM |
N2.00005: Visualization of evolving laser-generated structures by frequency domain tomography Yenyu Chang, Zhengyan Li, Xiaoming Wang, Rafal Zgadzaj, Michael Downer We introduce frequency domain tomography (FDT) for single-shot visualization of time-evolving refractive index structures (e.g. laser wakefields, nonlinear index structures) moving at light-speed. Previous researchers demonstrated single-shot frequency domain holography (FDH), in which a probe-reference pulse pair co- propagates with the laser-generated structure, to obtain snapshot-like images. However, in FDH, information about the structure's evolution is averaged. To visualize an evolving structure, we use several frequency domain streak cameras (FDSCs), in each of which a probe-reference pulse pair propagates at an angle to the propagation direction of the laser-generated structure. The combination of several FDSCs constitutes the FDT system. We will present experimental results for a 4-probe FDT system that has imaged the whole-beam self-focusing of a pump pulse propagating through glass in a single laser shot. Combining temporal and angle multiplexing methods, we successfully processed data from four probe pulses in one spectrometer in a single-shot. The output of data processing is a multi-frame movie of the self- focusing pulse. Our results promise the possibility of visualizing evolving laser wakefield structures that underlie laser-plasma accelerators used for multi-GeV electron acceleration. [Preview Abstract] |
Saturday, October 8, 2011 1:05PM - 1:17PM |
N2.00006: Lasing without Inversion in He-like Boron: Transient Response Eyob Sete, Anatoly Svidzinsky, Yuri Rostovtsev, Hichem Eleuch, Pankaj Jha, Szymon Suckewer, Marlan Scully Lasing without population is more attractive in short wavelength spectral regimes, as traditional lasing condition are difficult to achieve due to fast spontaneous life time for shorter spectral domain. We thus here propose a scheme for demonstration of lasing without inversion in short wavelength regime. Using Helium-like Boron as our gain medium, we show that it is possible to have transient lasing with out inversion at 6.1nm. [Preview Abstract] |
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