Bulletin of the American Physical Society
2019 Annual Meeting of the APS Four Corners Section
Volume 64, Number 16
Friday–Saturday, October 11–12, 2019; Prescott, Arizona
Session E06: Industrial and Applied Physics |
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Chair: Ben Ferguson, Raytheon Room: AC1 107 |
Friday, October 11, 2019 2:48PM - 3:12PM |
E06.00001: Compact X-ray Free-electron Laser with Nano-patterned Electron Beams Invited Speaker: William Graves We are pursuing development of a very compact XFEL based on inverse Compton scattering (ICS) from a nanopatterned electron beam. CXFEL depends on a novel method to produce transform-limited x-ray output in all dimensions, i.e., with all photons in a single degenerate quantum state. This method avoids the noise amplification of SASE by imprinting a well-defined coherent modulation on the electrons via diffraction in a thin crystal grating. We will present experimental results demonstrating the first steps in this method. The spatial pattern in the diffracted electrons is converted to a temporal pattern using sophisticated electron optics that exchange the transverse and temporal phase space dimensions. The result is a nano-patterned electron beam that can be tuned for wide range of applications. The method allows for coherent control of the phase, frequency, bandwidth, pulse length and amplitude of the x-ray pulses, and enables a variety of multi-color experiments with precisely tunable femtosecond delays for pump-probe experiments, and perhaps even sub-cycle phase-locking of the multiple colors. The output will cover the photon energy range from 100 eV to 8 keV. The CXFEL pulse energy is expected to be tens of nJ due to its small size and low beam energy. For experiments that require higher pulse energies or harder photons, CXFEL presents an excellent seed source that can transfer its unique phase control to large XFELs. [Preview Abstract] |
Friday, October 11, 2019 3:12PM - 3:36PM |
E06.00002: 2S-8S/D spectroscopy with a cryogenic hydrogen beam Invited Speaker: Dylan Yost Hydrogen is the most abundant element in the universe, and the most important element for the development of modern physics -- an attribute that can be traced back to its simplicity as an effective two-body system. Currently, precision hydrogen spectroscopy remains an exciting field which determines the Rydberg constant and stringently tests QED. In addition, spectroscopy of the 2S-8S/D transitions, in conjunction with the precisely measured 1S-2S transition, can be used to determine the proton charge radius. However, previous measurements of these transitions do not agree with more recent determinations of the proton radius in both hydrogen and muonic hydrogen spectroscopy. In this talk, we will present preliminary spectroscopy of the 2S-8S/D transitions with a new experimental setup. A 5 K atomic hydrogen beam is optically excited to the 2S state via two-photon absorption. The 2S-8S/D transitions are then excited by two-photon absorption at 778 nm. This method could result in a more precise measurement due to the reduction of velocity effects, and greater metastable flux. \\ \\ In Collaboration with: Adam Brandt, Samuel Cooper, Cory Rasor, Jordan Smith, Zak Burkley, Colorado State University [Preview Abstract] |
Friday, October 11, 2019 3:36PM - 4:00PM |
E06.00003: Using X-ray Vision to Understand How Things Break: Coherent X-ray Diffraction Imaging of Materials In Extreme Conditions Invited Speaker: Richard Sandberg Two recent advances are radically changing the way we study materials. First, revolutions in x-ray sources are providing thousands to millions of times brighter x-ray beams. These sources (i.e. upgraded synchrotron storage rings and x-ray free electron lasers) are enabling scientists to probe materials at ever faster temporal and spatial length scales. Second, rapidly advancing coherent x-ray imaging techniques are taking advantage of these increases to perform nanometer scale and ultrafast imaging of materials. Furthermore, the possibility of improvement in the majority of our current technological capabilities is limited by material properties. There is a need to understand how materials behave under extreme conditions and how they ultimately fail across many industries and applications in order to improve current materials. In this talk, I will review how we are taking advantage of these revolutions to study material failure using a lensless imaging technique known as `x-ray coherent diffraction imaging.' I will introduce the principles of x-ray coherent diffraction imaging and describe several applications to study metal damage and failure under extreme conditions. [Preview Abstract] |
Friday, October 11, 2019 4:00PM - 4:12PM |
E06.00004: Multi-Beam Plasma Generation of Terahertz: Order, Dissonance, and Their Advantages Clayton D. Moss, Shayne A. Sorenson, Jeremy A. Johnson Terahertz (THz) radiation is a useful spectroscopic tool for studying nonlinear structural and electronic dynamics in a variety of systems. Often, nonlinear effects are only observed at high field strengths---which requires a source of intense THz pulses. Two-color laser-induced plasmas are an attractive THz source; our previous experimental work has shown that adding a third color can enhance THz output. Using numerical simulations based on the photocurrent model of coherent THz emission from laser-induced plasma we explore multi-beam THz generation that can be achieved in a tabletop environment. The scheme consists of three beams: an IR fundamental (1100-1800 nm), its second harmonic, and a third 800 nm pulse that in certain configurations can improve THz output. Considering experimental fixed-phase and random-phase THz generation schemes reveals that when order can be achieved throughout the setup it can be advantageous to use commensurate, ordered wavelengths. However, when phase stability cannot be achieved between the IR and 800 nm beams, using the natural dissonance of incommensurate color combinations can overcome this phase instability to still produce amplified, coherent THz pulses. [Preview Abstract] |
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