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Department of Physics and Astronomy
University of Mississippi


Event Information:

  • Tue

    Colloquium: Graduate Students' Talks

    4:00 pmLewis Hall 101

    Saeed Kamali
    Department of Physics and Astronoimy
    University of Mississippi

    New Physics in Inclusive B → Xc τ ντ Decays in Light of R(D*) Measurements


    Kevin Lin
    Department of Physics and Astronomy
    University of Mississippi

    Development of Vibrational Metrics for Internal Damage Scenarios of a Scaled Transnuclear-32 Dry Storage Cask for Spent Nuclear Fuel

    The assessment of the internal structural integrity of dry storage casks for used high burnup nuclear fuel assemblies is of critical importance before transporting these to permanent repositories. The large size and structural complexity of the Transnuclear-32 (TN-32) cask as well as the inability to access its interior make this a challenging task. To address these difficulties, we use an active acoustics approach to develop metrics that are sensitive to the internal configuration of these casks. A 6:1 scaled model of the TN-32 cask was constructed in order to study internal configuration of the fuel assemblies including various damage scenarios. The vibration modes were verified in Finite Element simulations. Each mock-up fuel assembly consists of bundled steel rods, and their structural failure is mimicked by steel shot of equal weight. This talk will report the amplitude- and phase-based active acoustics metrics we developed to characterize different levels of internal damage. Our studies indicate that vibrometric signatures of various internal conditions can be measured using sources and sensors mounted on the exterior shell. Our current methodology is sensitive enough to detect structural failures at the single fuel assembly level.


    Robert Lirette
    Department of Physics and Astronomy
    University of Mississippi

    Droplet Extraction and Manipulation at a Fluid Interface Using Fraxicon Modified Ultrasound

    Ultrasound focused at a fluid-fluid boundary creates an acoustic radiation pressure on the boundary that is dependent on the incident energy density and the relative density and sound speed of each fluid. For different fluid combinations this radiation pressure can either be positive or negative. For this study ultrasound propagating from water to carbon tetrachloride was used to create a negative radiation pressure at the interface. This fluid combination is impedance matched eliminating reflections and heating effects at the boundary. A fraxicon phase plate lens is a low profile analog of an axicon and generates an approximate Bessel beam in the far field. The near field exhibits a complex diffraction pattern including shadow zones capable of acoustic trapping. Starting with a planar interface, we demonstrate the extraction, capture, and manipulation of a carbon tetrachloride droplet. The negative radiation pressure draws the carbon tetrachloride surface up into the water, eventually breaking a droplet free. The trapped droplet is then transported through the water by moving the transducer.