William "Billy" Robbins
Sydney Institute for Astronomy (SIfA), School of Physics
2014 (Submitted) PhD, The Univ. Sydney
2008 MS, The Pennsylvania State Univ.
2006 BA, Univ. of California at Berkeley
The shocks left behind by the explosions of stars are detectable for tens of thousands of years. The shocks, commonly referred to as supernova remnants (SNRs), are observed throughout the electromagentic spectrum -- from radio waves to gamma-rays. A composite of infrared (red; NASA/JPL- Caltech/Steward/O. Krause et al.), optical (yellow; NASA/STScI), and X-ray (blue and green; NASA/CXC/SAO) images of the Cassiopeia A SNR is displayed here:
Most SNRs emit radio (synchrtron) emission and are often detected in (thermal or synchrotron) X-rays. An X-ray image of the field of SNR G296.7-0.9 is shown below with contours of radio surface brightness. (The more interior the contour, the brighter the radio emission.) The numbered X-ray sources (5 and 6) are unrelated emission along the line-of-sight -- most probably stars within the Milky Way or galaxies in the background.
Why is this important to you? The nuclear fusion that powers stars and the nuclear reactions that occur during explosive destruction are probably the dominant source of heavy elements in the Universe. For example, the thermonuclear explosion of a white dwarf star (a type Ia supernova) and its SNR distribute an amount of iron comparable to the mass of the Sun. (The Sun constitutes about 3/4 of all the mass of our solar system -- it's heavier than all the planets combined!) Anemia is a deficiency of iron in our blood; in a round-about way, we need star dust to survive. Studying the rates and products of supernovae and their remnants allow us consider the chemical evolution of the Milky Way. Some of the cosmic rays that are accelerated by SNRs bombard the Earth's atmosphere creating Carbon-14, which allows humans to date ancient artifacts. Did I mention that they're freakin' cool??· High-Energy Cosmic Rays
I've spent a good fraction of my research life working on electronics and data analysis for the IceCube Neutrino Observatory. The Observatory is essentially a lattice of cameras (digital optical modules; DOMs) embedded in the Antarctic ice. Neutrinos travel at speeds comparable to the speed of light. As neutrinos travel through the ice in the IceCube detector, they emit (Cherenkov) radiation, which is used to model their path, energy, and interactions with the ice.
While at Berkeley Lab (Go Bears!), I was a member of a team that tested the electronics of the DOMs. I was also involved in an effort by the Penn. State group to use the LEDs mounted on each DOM to measure the ice properties (that affect the progation of light emitted by neutrinos) within the Observatory. The following plot is an example: a measure of the average distance a photon travels within the detector (propagation length) versus a measure of depth (DOM number). The blue '*' are LED measurements and are plotted in comparison to other measures (see Kurt Woschnagg's paper, for example). The light blue vertical band indicates a known layer of dust that was created by volcanic activity.· Low-Frequency Radio Antenna Design
I was fortunate to have been involved with the development of the Long Wavelength Array in New Mexico, USA. In essence, this radio telescope is a collection of geographically scattered radio antennas working in concert. Pairs of antennas that are close together measure large-scale emission on the sky. More distant pairs of antennas provide the higher resolution, but filter out large scale emission. The images prodced by any radio interferometer are a weighted average of measurements with short and long antenna spacings.
While at the US Naval Research Laboratory, I simulated the response of a single antenna element to changes in the environment (like rain) and various design choices (like the size of ground screen reflector beneath the antennas). I also had the opporunity to perform field tests of the antenna protoypes. Here's a picture of Joe Craig and some student volunteers assembling an LWA antenna (with the Janksy Very Large Array in the background): Thanks to the Office of Naval Reserach for providing the funding for this project!· Illumination Engineering
I spent a little more than a year as a research technician in the Lighting Group at Berkeley Lab -- again, Go Bears! -- that has since spurred the California Lighting Technology Center. The primary objective of the group is to create low-cost, high-quality, energy-efficient and marketable lighting systems. While there, I developed an effective, low-cost method for heat regulation by the control electronics for residential down-lighting systems. Part of this work was funded by the US Department of Energy's SULI program.· Plasma Physics
I spent a few months in the P-24 group at Los Alamos building a plasma probe for a project to simulate cosmic accretion in a laboratory. This work was funded by the great folks at the Princeton Plasma Physics Lab.
I am very fortunate to be an Astronomy Guide at the amazing Sydney Observatory. Evening tours can include star gazing through a modern telescope and the oldest operating telescope in Australia. The tours also include an introduction to the historical significance of the Observatory and are open to the public. Additionally, the Observatory hosts special outreach events and school tours and the Observatory staff have a sweet blog.
I also have the pleasure of being involved in undergraduate education at the University of Sydney. Links to feedback pages for current students are below.
Music of the heart
Flow-rate versus radius
Group B: drag-force v. fluid viscocity
Group H: impulse v. fluid behavior
Group I: viscosity variations of fluids
Here are some quotes that I liked.
Sometimes I read things.