Seminar: Spring 2006

Seminars are held on Tuesdays, 3:45-4:45pm in SB110, unless otherwise noted. Meet at 3:30 in SB157 for refreshments (refreshments are available even on Tuesdays with no seminar!). See Calvin's Visitor Resources for maps and directions to the Science Building.

Schedules from previous semesters: Fall 2005, Spring 2005, Fall 2004, Spring 2004, Fall 2003, Spring 2003, Fall 2002, Spring 2002, Fall 2001, Spring 2001, Fall 2000, Spring 2000, Fall 1999.

Feb 7: On the road to Dushanbe (or what passes for roads in Central Asian republics) Phil Ammar '04
Humanitarian aid work is never easy, and combined that with the challenge of living in an unstable, former Soviet republic, life is rarely uneventful. I will share some of the highlights of the past half year and some hopes for the future.

Feb 14: Providing the monitoring needed to clean tomorrow's air: A proposal for a regional network to study ozone
Prof. Gary Morris, Valparaiso University
Ozone is an important trace gas in the Earth's atmosphere. Without the ozone layer, life at the surface would be very different indeed. However, ozone produced at the surface destroys crops and negatively impacts human health. Surface monitors inform the public when local air quality is unhealthy. Satellite monitors can help track large pollution events related to large emission events such as forest fires.
But neither of these technologies is able to fully gauge the scope of the pollution problem since neither is capable of measuring the vertical distribution of ozone in the troposphere. To provide these important vertical measurements, we use instruments attached to weather balloons known as ozonesondes. In this talk, I provide an overview of the technology, our motivations for studying ozone, and a proposal to establish a network of ozonesonde stations at colleges in the Great Lakes Region.

Mar 15: Discovering New Planets with ET, the Exoplanet Tracker
Andrew Vanden Heuvel '04, University of Florida
As a graduate student in astronomy, I participate in surveys for new
extrasolar planets using a novel instrument, the Exoplanet Tracker (ET).
ET combines an interferometer with a spectrograph to measure very small
changes in radial velocity that indicate the presence of Jupiter-like
planets orbiting nearby stars. I will provide an overview of the
state-of-the-art in exoplanet detection, a decription of how our
particular instrument works, the results of our recent surveys, and our
future plans for an all-sky survey for extrasolar planets.

Mar 29: Calculating the emitted gravitational radiation of binary neutron stars
Reese Haywood, Notre Dame
Directly detecting the gravitational wave signal is one goal of the gravitational wave detectors, LIGO, VIRGO and others. However, terrestrial background noise prevents detection as the expected signal strength is below the background level. This makes it necessary to provide a theoretical template which may be used to cross correlate with the data. In this talk I describe the conformal and flat approximation for binary neutron systems and how it is used in calculating a gravitational wave template.

Apr 11: Photoreflectance Characterization and Research in Multi-Layer Device Structures
Dr. P.L. Stephan Thamban, University of Texas
In this presentation, a modulation spectroscopy experiment, photoreflectance (PR), associated to optical characterization of semiconductors will be described. An approach (beyond band gap approach), yet to be exploited in PR characterization, that enables one to characterize specific layers in multilayer device structures will be presented. PR results from PHEMT (pseudomorphic high electron mobility transistor) device structures and PIN photodiodes will be discussed. (PIN diodes have P-type / Intrinsic / N-type semiconductor layers for enhanced speed and bandwidth.)

Apr 27: The Deep Impact Mission to Comet Temple I: a Smashing Success
Dr. Harold Reitsema '72, Ball Aerospace
Comets are believed to contain the most pristine material left over from the formation of the solar system. The surfaces of comets have been altered by long term exposure to the vacuum of space and the ultraviolet radiation from the sun. To study the pristine material, scientists must either remove the altered surface layers or obtain samples from deep within the nucleus. Lander missions are complex and expensive, so NASA chose instead to excavate below the surface through a high energy impact by a spacecraft. The Deep Impact mission used a small spacecraft to create an impact crater on the comet Temple I on July 4, 2005 that was observed by a second spacecraft and from the ground. Studies of the resulting crater and material ejected from the comet nucleus have given new insights into the composition and structure of comets

May 2: Entangled Photons and Local Realism
Prof. David Van Baak, Calvin College
This seminar will discuss the meaning of 'entanglement' in quantum mechanics, and how it typifies what Einstein called 'spooky action at a distance.' It will display cases of the 'Bell inequalities', which reveal that quantum mechanics makes predictions which disagree with the consequences of the attractively plausible notion of 'local realism'. And it will introduce the Calvin College version of an entangled-photon apparatus, in which measurements can be made which test whether real world properties agree with local realism, or with the glamorous but outrageous predictions of quantum mechanics.

May 4: Observing Star Formation at Cosmic Dawn: Looking Forward to ALMA
Dr. Paul Vanden Bout '61, National Radio Astronomy Observatory
Our understanding of the evolution of galaxies is dependent on our understanding of the formation of stars, a process which traces spiral structure and galaxy mergers. While much is known about star formation in the Milky Way and nearby galaxies, little is known about the formation and evolution of the first galaxies in the Universe. Clues to their nature can be gleaned from a handful of galaxies in the early Universe that are observable with present telescopes. A new facility under construction, the Atacama Large Millimeter Array (ALMA), will enable studies of many thousands of early Universe galaxies. The status of the ALMA project is presented following a background discussion of star formation - the topic that forms one of the prime motivations for its construction.