Abstract: Abstract: The passage of ultrasonic sound through a fluid leads to pulsations of an entrained bubble that are so nonlinear that acoustic energy density is concentrated by 12 orders of magnitude to generate picosecond flashes of ultraviolet light. The spectrum, for xeonon bubbles, matches an 8,000K ideal Planck blackbody even though the micron radius of the bubble is small compared to the photon mean free path. To probe the formation of a blackbody we have weakened sonoluminescence by generating it with a water hammer. Time resolved spectroscopy of these 1.μs flashes; allow one to follow the transition from transparent to opaque emission. These states can also exist simultaneously as segregated regions. A simple interpretation in terms of a phase transition driven by Debye screening and quantum hybridization will be presented.
Bio: Seth Putterman is a professor of Physics at UCLA. His PhD advisor was George Uhlenbeck. Seth is interested in Superfuid Helium, Nonlinear Processes, Single Ion Traps, Energy Focusing Effects and Thermodynamics.
Time: 4:00pm – 5:30pm
Location: Physics and Astrophysics Conference Room 102/103
Light refreshments available 4:00pm; Presentation begins 4:15pm.
Open to All