Bulletin of the American Physical Society
2014 Annual Meeting of the Far West Section of the APS
Volume 59, Number 14
Friday–Saturday, October 24–25, 2014; Reno, Nevada
Session D1: Poster Session |
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Room: JCSU 320 |
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D1.00001: Literary Analysis of Titan's Atmosphere in Particular Tholin Formation Brandon Leets Saturn's moon, Titan, has been an intriguing area of study to the astronomical community since its discovery. Titan has a thick atmosphere unlike any other moon in the solar system. One of the biggest discoveries in Titan's atmosphere was the presence of large particles known as Tholins. The production of these larger particles begins in the upper atmosphere and as they accumulate mass they descend down to the surface of Titan. This precipitation causes a haze layer to form over the moon, making it difficult to see and understand the surface. This process is believed to be similar to what may have happened in Earth's early atmosphere. This haze layer has a greenhouse and anti-greenhouse effect. It has been found that seasonal changes in wind and temperature affects the rate of production and type of Tholins. Also strong winds along the equator prevent molecules from mixing in the polar regions of Titan. These winds can reach upwards of 70 m/s and occur mostly during seasonal changes. By carefully adjusting models to include current knowledge regarding C/N ratios. Pressure, temperature, and ignition sources it will be possible to gain a better understanding of Titan's atmosphere and in turn the evolution of Earth's atmosphere. [Preview Abstract] |
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D1.00002: Mechanical Manipulation of Atomic Spin Jose Valencia, Cris Montoya, Andrew Geraci The atomic spin of cold atoms can be measured and manipulated through micro-mechanical resonators, e.g cantilevers. This method could allow single-spin sensitivity and sub-micron spatial resolution enabling new studies of decoherence and quantum control. We describe our experiment that manipulates the spin of trapped, cold Rb atoms using magnetic material on a cantilever. [Preview Abstract] |
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D1.00003: Design of Superconducting Magnetic Shielding for an Axion Detector Jordan Dargert, Suyesh Koyu, Andrew Geraci A new experiment has recently been proposed [1] that can detect the Peccei-Quinn (PQ) axion, a hypothetical particle whose detection could explain Dark Matter's existence and the smallness of the neutron electric dipole moment. ~Using a new form of Nuclear Magnetic Resonance, the method can probe well into the PQ axion decay range. Additionally it does not rely on cosmological assumptions. In this poster, I will discuss the design of a superconducting magnetic shield that is required for reducing background magnetic fields in the experiment. \\[4pt] [1] A. Arvanitaki and A. A. Geraci, arxiv: 1403.1290, Phys. Rev. Lett. (accepted) 2014. [Preview Abstract] |
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D1.00004: Investigation of shock damage from x-pinch wire loads Ben Hammel, Tim Darling In x-pinch experiments on the Nevada Terawatt Facility's 1-MA pulsed power machine (Zebra), significant damage of the anode has been observed. Post shot analysis shows scabbing at the free-surface as well as multiple spall layers. This damage is a result of a strong shock - generated by several factors: (1) a rapid deposition of energy from ballistic electrons impacting the sample, resulting in ablation of material; (2) ablation from the impact of a high Mach-number plasma jet - formed from the implosion of the x- pinch wire array; (3) magnetic pressure resulting from the electrical current flowing across the surface of our target, perpendicular to the induced magnetic field. We are currently preforming experiments to characterize the mechanisms responsible for this shock generation, and investigating the material state as a result of shock-compression of this type. Free-surface velocities as high as 2 km/s in 2, 3, and 4-mm-thick Copper targets have been recorded using a Line-VISAR (Velocity Interferometer System for Any reflector). The time-profile of the drive is characterized by the hard x-ray (100 keV -1 MeV) emission resulting from the bremsstrahlung radiation due to the impact of electrons with the target. We see that damage is a strong function of x-pinch wire material, and not correlated to the linear mass of the x-pinch load. The feasibility of using this drive type as a method for shock-physics experiments is also discussed. [Preview Abstract] |
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D1.00005: Introduction of a novel method for manufacturing ultrathin silicon ribbon Hyung Woo Choi, Mohammed Danyan, Dhanesh Chandra, Ghassan Jabbour We report on a new and quick (ca. 1 hour!) route for fabricating ultrathin silicon substrate directly from \textit{in-situ} molten silicon by an inductor heater spin-melt based technique. Structural and compositional properties of silicon substrate indicate a pure (without SiO$_{2}$, SiC formation) and polycrystalline nature of the fabricated ribbon. Compared to conventional methods for manufacturing thin silicon substrates, including edge stabilized growth (ESG), edge-defined film-fed growth (EFG), ribbon growth on substrate (RGS), etc., our development shows significant thickness reduction. In this regard, we were able to obtain unprecedented 20 $\mu$m thick samples, without any supporting carrier. We anticipate our high-speed low cost fabrication approach of silicon substrates to have a great potential in photovoltaic and semiconductor industry. [Preview Abstract] |
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D1.00006: SiN thin films for fabrication of flexible organic solar cell with enhanced stability Hyung Woo Choi, Barry O'Brian, Yong Kyun Lee, Jeayoung Choi, Ghassan Jabbour We demonstrate an enhanced stability of organic solar cells (OSC) through the incorporation of a thin silicon nitride (SiN) layer (ca. 300 nm) as a diffusion barrier of oxygen and water. Chemical vapor deposition (CVD) at 150 $^{\circ}$C was used to deposit the SiN on flexible substrates of polyethylene naphthalate (PEN) and polyethylene terephthalate (PET). Upon device testing, OSCs with silicon nitride barrier layer showed three orders of magnitude improved performance when exposed to water vapor, as compared to OSCs without SiN. Un-encapsulated devices with SiN film showed only a 20{\%} decrease in power conversion efficiency after exposure to air for more than a month! On the other hand, OSCs without the SiN layer failed upon exposure to air for 15 days. Detailed fabrication, testing and characterization of engineered devices will be given. [Preview Abstract] |
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D1.00007: Observation of long-lived room temperature phosphorescence from exciplex in organic metal-free materials Tianlei Zhou, Yue Wang, Ghassan Jabbour Long-lived room temperature phosphorescence (RTP) from metal-free organic material system is very rare because the intersystem crossing rate in organic molecules is very small, and long-lived excited triplet states are easily quenched by oxygen and thermal perturbations. This research presents an intense long-lived RTP from exciplex formation, for a given organic materials system, in the absence of phosphorescence protector or stabilizer. Our experimental observation indicates that such exciplex is resistant to oxygen quenching and can be obtained easily by grinding the powders of given materials. Our approach demonstrates, for the first time to our knowledge, a low cost and efficient route to obtaining long-lived RTP in organic materials. [Preview Abstract] |
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D1.00008: Laser Produced Neutrons and Isotope Activation at the Nevada Terawatt Facility Zephyr McCormick, Oleksandr Chalyy, Timothy Darling, Benjamin Hammel, Jeremy Iratcabal, Erik McKee, Piotr Wiewor, Aaron Covington Preliminary feasibility studies of pulsed-power based neutron and isotope production is underway at the Nevada Terawatt Facility. Both the Leopard Laser and Zebra Z-pinch systems have been utilized for neutron and isotope production studies. Preliminary experiments on Leopard have successfully produced $\sim$10$^{6}$ neutrons per laser shot using 5 $\mu$m Au foil targets with 6 mm of LiF as a converter material. Alternate materials for both thin foil targets and converters are being investigated, along with modifications to laser targets, in an effort to improve neutron and isotope yields from NTF systems Preliminary experiments on Zebra Z-pinch have successfully produced radioactive isotopes that decay via the $\beta$+ pathway. It is believe that the parent isotopes originate in the shot hardware (Type 304 SST) used to support deuterium treated Pd wire loads. The radioactive decay of the daughter isotopes is measured using a standard nuclear coincidence detection technique. Follow on experiments are being designed to increase yields in laser and Z-pinch shots and further explore the mechanisms governing isotope production in Z-pinch shots. [Preview Abstract] |
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D1.00009: Spectroscopic Analysis of K- and L-Shell Radiation from Gas-Puff Jet Experiments on the UNR Leopard Laser E.E. Petkov, A.S. Safronova, V.L. Kantsyrev, J.J. Moschella, P. Wiewior, V.V. Shlyapsteva, M.C. Cooper, M.E. Weller, I.K. Shrestha, A. Stafford, K.A. Schultz The study of cluster formation in gas-puff jet experiments and the x-ray emission from them under fs and ns laser impulses is of interest as there are many applications in physics (x-ray backlighting, lithography, high-harmonic generation, etc.) We present spectroscopic analysis of K- and L-shell radiation from Ar and Kr gas-puff jet experiments performed on the high-power Leopard Laser at UNR. To enhance our theoretical understanding of this radiation, and to help with identification of spectral lines, non-local thermodynamic equilibrium (non-LTE) kinetic models of Ar and Kr have been developed. Approximate temperature and density parameters have been identified in experiments with pure Kr, pure Ar, and Kr/Ar mixtures. Further work is discussed. [Preview Abstract] |
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D1.00010: Spatial distribution of Ti-tracer in OMEGA implosions T. Joshi, R. Mancini, D. Mayes, T. Nagayama, R. Tommasini, J. Delettrez, S. Regan, S. Hsu, J. Cobble, J. Baumgaertel, P. Bradley We discuss the observation and analysis of implosion core spectrally-resolved image data from Ti-doped, deuterium-filled OMEGA direct-drive implosions. The targets were spherical plastic shells of varying thicknesses and gas pressures with a thin Ti-doped tracer layer at the fuel-shell interface. The spectral features from the tracer are primarily observed at the collapse of the implosion and recorded with three identical gated, multi-monochromatic x-ray imager (MMI) instruments fielded along quasi-orthogonal lines-of-sight. The gated data show simultaneous emission and absorption features associated with Ti K-shell line transitions. The spectrally-resolved images recorded with MMI were processed to obtain narrow-band images\footnote{T. Nagayama, et. al, J. App. Phys. 109, 093303, (2011).} and spatially-resolved spectra characteristics of annular regions on the image\footnote{T. Nagayama, et al, Phys. Plasmas 19, 082705, (2012)} Detailed spectroscopic analysis of the spatially-resolved line spectra yields electron temperature and density of the plasma in the core. An Abel inversion of the image's intensity profiles and a complementary analysis method of the spatially-resolved Ti x-ray lines reveal the spatial distribution of the Ti in the core, and provide information on the symmetry and hydrodynamic stability of the implosion. [Preview Abstract] |
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D1.00011: Multi-Parameter Characterization of Laser Ablation Plasmas Jeremy Iratcabal, Timothy Darling, Paul Neill, Aaron Covington The laser ablation of solid targets results in the formation of complex plasma plumes. The theoretical description of these plumes is challenging and requires multi-physics simulations bounded by accurate data on all aspects of ablation phenomena. To meet this challenge, a new experimental platform has been developed to characterize the spatial and temporal evolution of laser ablation plumes. This system records a variety of diagnostics that can be synchronized to a common master-clock. The common clock allows each ablation plume to be described in event-mode, where a careful examination of energy and momentum partitioning can be made for each ablation plume. The experimental system has been designed to survey a wide variety of target materials and geometries using laser intensities ranging from 10\textsuperscript{6} to 10\textsuperscript{19} W/cm\textsuperscript{2}. Physical parameters of the plumes are being measured with a powerful array of spectroscopic instruments, optical laser probes, charged particle analyzers, and nuclear instruments. A careful and accurate characterization of laser ablation plumes containing neutral and ionized atomic and molecular species provides measurements useful in high energy density physics, astrophysics, and technological fields. [Preview Abstract] |
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D1.00012: Photoionized Neon Plasma Experiments at Z: Data Processing and Analysis Development D. Mayes, T. Lockard, T. Durmaz, R. Mancini, J. Bailey, G. Rochau, G. Loisel, R. Heeter, D. Liedahl We discuss an experimental effort to study the atomic kinetics in photoionized plasmas via K-shell line absorption spectroscopy. The experiment employs the intense x-ray flux emitted by the collapse of a Z-pinch to heat and backlight a neon photoionized plasma contained within a cm-scale gas cell placed at various distances from the Z-pinch and filled with neon gas. High-resolution spectra show absorption by several ionization stages of neon, including Be-, Li-, He-, and H-like ions. Analysis of these spectra yields ion areal-densities and charge state distributions, which can be used to benchmark atomic kinetics codes. In addition, the electron temperature is extracted from level population ratios of Li- and Be-like ions, which can be used to test heating models of photoionized plasmas. We will also discuss improvements made to the processing and analysis methods, as well as trends that are visible in the analysis results. [Preview Abstract] |
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D1.00013: Spectroscopic Analysis of Radiation from New Planar Wire Array Experiments on the LTD Generator at U Michigan M.Y. Lorance, A. Stafford, M.E. Weller, A.S. Safronova, V.L. Kantsyrev, I. Shrestha, V.V. Shlyaptseva, M.C. Cooper, E.E. Petkov, N.M. Jordan, S.G. Patel, A.M. Steiner, D.A. Yager-Elorriaga, R.M. Gilgenbach Recently experiments of planar wire arrays (PWAs) were carried out on the MAIZE Linear Transformer Driver (LTD) generator at the University of Michigan (UM) for the first time. Specifically, Al 5056 (95{\%} Al, 5{\%} Mg) double planar wire arrays (DPWAs) comprised of two planes of six wires with various interplanar and interwire gaps were imploded. Spectra were gathered with an x-ray time-integrated spatially resolved spectrometer capable of measuring approximately between 4 -- 16 {\AA}. This presentation focuses on using non-local thermodynamic equilibrium (non-LTE) kinetic models of K-shell Al and Mg to estimate the plasma conditions of the experiments, such as electron temperature ($T_{e})$ and density ($n_{e})$. The DPWAs with different wire diameters were used to create masses of 41 or 25 $\mu $g and modeling indicates a higher $T_{e}$ for the less massive loads with a maximum $T_{e}$ of approximately 550 eV for K-shell Al. The importance of studying radiation and spectra from planar wire arrays on LTD devices are discussed. [Preview Abstract] |
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D1.00014: Investigation of the 3D Structure of the Z-Pinch Using UV Laser Probing Austin Anderson, Vladimir Ivanov The 3D structure of Z-pinches was investigated using four 266 nm beams. These beams were evenly spaced at 45 degrees with respect to each other, allowing a full view of pinch. The laser pulse duration is 150 ps, with a $\sim$ 100 ps temporal accuracy between the 4 channels. Strong asymmetry was found in Z pinches produced by implosion of asymmetrical wire array loads. Studying the asymmetry of Z-pinches is important for understanding the 3D structure of Z-pinches and the effectiveness of using Abel inversion, which requires cylindrical symmetry. Results and a discussion are presented. [Preview Abstract] |
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D1.00015: Neutron production using deuterited palladium wires Erik McKee, Tim Darling, Ben Hammel The Zebra 1-MA/100ns rise time pulse power generator (HDZP-II) was initially designed to pinch single extruded wires of frozen deuterium in an effort to achieve fusion ignition [1], however solid thin-wire loads are now the main target. In general, the load for production of neutrons is a 4-wire, 20$\mu$m palladium wire in X-pinch configuration treated with deuterium gas. The generation of neutrons on Zebra are not from realization of Lawson's criterion [2], but rather are produced through beam-like collisions in MHD sausage-like instabilities with large and local electric fields. This project builds on the wire-array knowledge accumulated at NTF and we report on a reproducible, pulsed neutron source with yields exceeding 10$^{9}$.\\[4pt] [1] J. S. Schlacter, ``Solid D2 fiber experiments on HDZP-II.'' Plasma Phys. Control Fusion 32:1073, 1990.\\[0pt] [2] Anderson, O. A., Baker, W. R., Colgate, S. A., Ise, J., Pyle, R. V., 1958, ``Neutron Production in Linear Deuterium Pinches,'' Phys. Rev. 45, pp 1375-1387 [Preview Abstract] |
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D1.00016: Developing Software to Analyze Plasma Expansion Jeffrey Mei Shadowgrams are used to analyze the expansion speed of plasma. However, it is difficult to define the border of the plasma in a shadowgram because the border is turbulent and contains laser speckle. Prior techniques to define the edge of a rod were done partly by eye. However, by adding the subjective human element in the procedure, the results are less likely to be reproducible. In addition, for low resolution images, even a pixel difference may significantly change the measured expansion rate. Therefore, the computer program LengthAnalysis was developed as a way to obtain robust measurements of shadowgram plasma width. The edge of a shadowgram is defined by the largest change in contrast. LengthAnalysis utilizes the gray values obtained from the plot profile tool from the image processing program, ImageJ, to identify the areas of greatest change in contrast. Since the regions of greatest contrast change identify an edge, the difference between the two greatest regions of contrast yields the width. Though the idea is simple, laser speckle and the alignment of the target may alter the measurement of width. Laser speckle can move the regions of greatest contrast, while the slant of the target spreads out these regions in the plot profile. [Preview Abstract] |
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D1.00017: The ignition of the HB11 fusion reaction in a heterogeneous mutual impact configuration Friedwardt Winterberg It was shown that the cross section-velocity product of a thermonuclear reaction averaged over a Maxwellian can be substantially increased in a mutual colliding impact configuration [1]. While the cross-section velocity product for the neutron-less hydrogen-boron11 reaction can thereby be increased by about 40\%, the heterogeneous separation of the boron from the hydrogen in a lattice leads to an almost 50\% reduction of the bremsstrahlungs- losses. Taken together, this leads to an approximately two-fold gain, sufficient to ignite the hydrogen-boron11 thermonuclear reaction [2].\\[4pt] [1] F. Winterberg, Physics of Plasmas 21, 092708 (2014.)\\[0pt] [2] F. Winterberg, ``The Release of Thermonuclear Energy by Inertial Confinement,'' World Scientific, 2010, p. 134. [Preview Abstract] |
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D1.00018: Progress towards measuring gravity on the micrometer length scale with optically levitated silica microsperes David Atherton, Gambhir Ranjit, Jordan Stutz, Mark Cunningham, Andrew Geraci Discrepancies between the strength of gravity and other Standard Model forces suggest corrections to Newtonian gravity at the sub-millimeter length scale. In this poster, we present progress towards the realization of a system capable of measuring gravity at micrometer length scales. In ultra-high vacuum, optically-trapped and cooled microspheres show great promise as force sensors. They are completely decoupled mechanically from their environment and can have high Q factors. We are developing an apparatus to trap and cool spheres in a combined optical dipole-cavity trap. Ultimately, with a sphere trapped in an anti-node close to an end-mirror of the cavity, Non-Newtonian gravity-like forces will be tested by monitoring the displacement of the sphere as a mass is brought behind the cavity mirror. [Preview Abstract] |
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D1.00019: Modeling Sodium Nanowire's With Monte Carlo Simulated Annealing Pereyra Carlos Building upon a Monte Carlo Simulated Annealing (\textbf{MCSA}) program, simulations were conducted on sodium nanowire's to determine and analyze how atoms arrange themselves in equilibrium. Previous calculations based on the quantum motion of conduction electrons have shown that only wires with ``magic'' radii are stable [3]. ``Magic'' conductance values 1, 3, 6, 12, 17, were modeled and the radial and pair distance distributions of these structures were analyzed. Radial distribution results show that structures form discrete shells, or radial regions, where atoms tend to reside, while pair distance distributions give information about the periodic arrangements of the atoms.Finding the optimal set of parameters in the program that allowed for structures with minimal amount of disorder while keeping the computation time reasonable was the objective of this project. This has proved sometimes closer to an art form than a systematic search. This has worked well for the smaller wires, but larger wires still remain rather disordered regardless of these changes. [Preview Abstract] |
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D1.00020: Ground-based and Satellite Retrieved Aerosol Properties Downwind of the 2013 California Rim Fire U.S.A. Dambar Air, William Arnott, James Barnard, Madhu Gyawali Wildfires are a common feature of western U.S. ecology. This presentation describes the radiative properties of the Rim Fire plume as it passed over Reno, NV in August 2013 and clear sky days for comparison. Aerosol physical and optical properties were obtained from ground based instruments, the Multifilter Rotating Shadowband Radiometer (MFRSR) and the CIMEL sun photometer operated as part of the NASA AERONET, MODIS satellite instruments, and in-situ measurements from photoacoustic (PA) instruments. Optical properties retrieved with the MFRSR show excellent agreement with those obtained with the CIMEL. However, satellite measurements indicate significant departure from the ground based measurements. The MFRSR retrieved single scattering albedo (SSA) of the Rim fire decreases with wavelength, from 0.91 at 415 nm to 0.86 at 870 nm. It was noteworthy that the SSA values from PA measurements and from the MFRSR retrievals were in agreement during the Rim fire; in contrast, they were very different for clean day. This presentation provides useful assessment of satellite retrieved AOD and determination of the aerosol optical and physical properties for the Rim Fire. [Preview Abstract] |
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D1.00021: Low Cost Preparation of Nano-cellulose Ultrathin Transparent Paper Tianlei Zhou, Hyung Woo Choi, Ghassan Jabbour We will present a low cost fabrication approach to ultrathin transparent paper based on blade coating of nano-cellulose. Depending on experimental and process conditions, an unprecedented thickness of 800 nm fully transparent paper (visible range) can be made. By tuning the process parameters, the optical transparency can be manipulated to suit a given application. For example, the substrate can be made with high haze which is suitable for certain lighting and display applications. Impact and other potential application of our approach will be highlighted as well. [Preview Abstract] |
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D1.00022: Short Range Tests of Gravity Michael Ross, Crystal Cardenas, Marika Leitner, Kolby Bell, C.D. Hoyle Gravity was the first force to be described mathematically, yet it is the only fundamental force not well understood. The Standard Model of quantum mechanics describes interactions between the fundamental strong, weak and electromagnetic forces while Einstein's theory of General Relativity (GR) describes the fundamental force of gravity. There is yet to be a theory that unifies inconsistencies between GR and quantum mechanics. Scenarios of String Theory predicting more than three spatial dimensions also predict physical effects of gravity at sub-millimeter levels that would alter the gravitational inverse-square law. The Weak Equivalence Principle (WEP), a central feature of GR, states that all objects are accelerated at the same rate in a gravitational field independent of their composition. A violation of the WEP at any length would be evidence that current models of gravity are incorrect. At the Humboldt State University Gravitational Research Laboratory, an experiment is being developed to observe gravitational interactions below the 50-micron distance scale. The experiment measures the twist of a parallel-plate torsion pendulum as an attractor mass is oscillated within 50 microns of the pendulum, providing time varying gravitational torque on the pendulum. The size and distance dependence of the torque amplitude provide means to determine deviations from accepted models of gravity on untested distance scales. [Preview Abstract] |
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