August 14, 2008
Vol. 27 No. 20

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    Students garner Fermi Institute’s Sugarman Awards

    By Steve Koppes
    News Office

    Three graduate students and an undergraduate in the Physical Sciences Division at the University have received the 17th annual Nathan Sugarman Awards for Graduate and Undergraduate Student Research from the Enrico Fermi Institute.

    The graduate student recipients are Martina Hurwitz, Physics; Larry Kirby, Astronomy & Astrophysics; and Vasileios Paschalidis, Astronomy & Astrophysics. The undergraduate recipient is Jesse Marshall, a third-year in the College.

    Marshall has recently collected other honors, as well. He has been named a 2008-2009 Student Marshal, the highest honor the University bestows upon undergraduates. Marshall also has been inducted into the Phi Beta Kappa honor society and is the recipient of a Grainger undergraduate scholarship in physics.

    Marshall earned the Sugarman Award for his contributions to the TRACER research program of Dietrich Müller, Professor Emeritus in Physics and the College. TRACER (Transition Radiation Array for Cosmic Energetic Radiation) is the world’s largest balloon-borne cosmic-ray detector. Its unprecedented size and unique design allow for a direct measurement of cosmic-ray composition at energies higher than ever before, Marshall said.

    “This detector sheds light on one of the biggest mysteries in astrophysics: the origin of cosmic rays. My work has to deal with how cosmic rays are affected by their journey from their source to Earth—a trip that takes them through the galactic magnetic field and the diffuse background of particles inhabiting interstellar space,” he said.

    Results from the TRACER experiment agree well with the theory of cosmic-ray acceleration, based on ideas that Enrico Fermi put forth nearly 60 years ago. The Fermi mechanism acting in supernova remnants, the leftovers from exploding stars, is now thought to be responsible for the acceleration of most galactic cosmic rays. This mechanism also meshes well with recent gamma-ray and X-ray observations of supernova remnants.

    Kirby helped develop hardware and software for a new instrument, SHARP, to study the role of magnetism in star formation. Roger Hildebrand, the Samuel K. Allison Distinguished Service Professor Emeritus in Physics and the College, also is involved with the SHARP study, which is a multi-institutional project operated by the California Institute of Technology’s Submillimeter Observatory on Mauna Kea in Hawaii.

    SHARP measures polarized light at submillimeter wavelengths, which are invisible to the human eye. Working from Mauna Kea, Kirby has used SHARP and other instruments to map the shape and strength of the magnetic field and other characteristics of the DR21 Main star-forming region with superior precision.

    Located approximately 10,000 light years from Earth in one of the spiral arms of the Milky Way galaxy, DR21 is giving birth to some of the most massive stars ever observed. The region is “an example of a large-scale gravitational collapse where the collapse is free of major disturbances due to rotation or other effects,” Kirby said.

    Hurwitz conducts research with James Pilcher, Professor in Physics and the College, at the LHC (Large Hadron Collider), a new high-energy particle accelerator in Geneva, Switzerland, which is scheduled to begin operation later this year. She is preparing to search the LHC’s early quark data for signs of smaller structures.

    “Protons and neutrons are composed of quarks, and the question is whether quarks themselves are composed of even smaller particles,” Hurwitz said. To find out, physicists will smash two quarks together at very high energies, and then observe the resulting energy and angle of the particles emitted. “The higher the energy of the collision, the smaller the size of the particle you might be able to find,” she said.

    Hurwitz is involved in testing and commissioning the ATLAS hadronic calorimeter, a component of the detector that surrounds the point where the proton beams collide. The calorimeter measures the energy of hadrons, particles composed of quarks, a crucial aspect of the search for smaller structures.

    Paschalidis was cited for his contributions to numerical relativity, a field devoted to solving the equations of Einstein’s General Theory of Relativity using supercomputers.

    General relativity explains gravity better than any other theory, but “until very recently, all efforts to solve the Einstein equations in computers were interrupted by unexpected growth of numerical error,” Paschalidis said. These errors now can be corrected in some limited situations, but not others. “At the time, there is no universal approach to the solution of the general relativity equations,” he said.

    Paschalidis has devised a theoretical tool that is helping scientists understand why the unexpected error growth arises, and that also is leading them toward a unified solution to the problem.

    He also has proposed a new method for solving complex equations, such as the general relativity equations, which he calls “parabolization.”

    “The method is quite general, can be applied to a great number of physical theories and has thus far been very successful with the Einstein equations,” said Paschalidis, who works with Alexei Khokhlov, Professor in Astronomy & Astrophysics.

    The Sugarman awards are named for the late Nathan Sugarman, Professor Emeritus in Chemistry and the College.