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Fall 2003

Schedule Fall 2003

September 16, 2003
3:00 pm (Tuesday)

Dr. Allan J. Zuckerwar
NASA Langley Research Center

Speed of Sound in Planetary Atmospheres

There are two parts to the problem of predicting the speed of sound in a planetary atmosphere: first, to characterize the physical and chemical properties of the atmosphere (temperature, pressure, and composition); and secondly, to utilize this information to predict the real speed of sound (including specific heat, virial, and relaxation corrections). The sound speed profile is closely related to the temperature profile. In some cases there is a substantial dispersion, that is, a frequency dependence of the sound speed due to molecular relaxation. Results are shown for the inner planets having atmospheres (Venus, Earth, and Mars), the outer planets (Jupiter, Saturn, Uranus, and Neptune), and a satellite of Saturn (Titan).

September 30, 2003
3:00 pm (Tuesday)

Prof. Claudio Rebbi
Center for Computational Science, Boston University

Lattice QCD

I will illustrate the basic principles of the lattice regularization of a quantum gauge field theory and explain why this regularization, coupled to computer simulations, offers such a powerful tool for studying the low energy properties of Quantum Chromodynamics (QCD).

I will briefly review the progress made through two decades of investigations in numerical lattice QCD and the present state of affairs. I will also offer a preview of what the near future may offer as new technology for lattice computations.

October 7, 2003
3:00 pm (Tuesday)

Prof. David J. Ernst
Vanderbilt University

Neutrino Oscillations: What are the Data Telling Us?

The concept of neutrino oscillations and the world's data are reviewed. This includes reactor data, beam stop data, atmospheric data, and solar data. Arguments which lead one to conclude that the data is not consistent with the standard three neutrino mixing matrix will be presented. A simple model of each of the experiments is developed. The results of an analysis, within the model, is performed and results which are indeed consistent with all of the data, including the Los Alamos LSND data, are presented.

October 16, 2003
3:00 pm (Thursday)

Note unusual date

Dr. Zheng-Tian Lu
Physics Division, Argonne National Laboratory

Atom Trap, Krypton-81, and Egypt

Please note unusual room

Since radio-carbon dating was first demonstrated in 1949, the field of trace analyses of long-lived radioactive isotopes has seen steady growth on both analytical methods and applicable isotopes. The impact of such analyses has reached a wide range of scientific and technological areas. A new method, named Atom Trap Trace Analysis (ATTA), was developed by our group and used to analyze 81Kr (t1/2 = 2.3´105 years, isotopic abundance ~ 1´10-12) in environmental samples. In this method, individual 81Kr atoms are selectively captured and detected with a laser-based atom trap. 81Kr is produced in the upper atmosphere by cosmic-ray induced spallation and neutron activation of stable krypton isotopes. It is the ideal tracer for dating ice and groundwater in the age range of 104-106 years. As the first real-world application of ATTA, we have determined the mean residence time of the old groundwater in the Nubian Aquifer located underneath the Western Desert of Egypt.

November 4, 2003
3:00 pm (Tuesday)

Prof. David DeMille
Yale University

Fundamental physics with diatomic molecules: from CP violation to quantum computation

Our group is applying the techniques of precision measurement and quantum control that are common in atomic physics, to the more complex system of diatomic molecules. This is enabling unique types of leverage on a variety of problems of fundamental interest, ranging from tests of symmetry violations to the manipulation of complex many-body states of interest in condensed-matter physics. I will describe in detail two of our experiments. The first is a search for the CP-violating electric dipole moment of the electron, which is expected to reach an unprecedented level of sensitivity. The second centers around the production of ultracold polar molecules, with possible applications in large-scale quantum computing and other areas.

November 11, 2003
3:00 pm (Tuesday)

Dr. Michael Kuss
Institute for Nuclear Physics (INFN), Pisa, Italy

GLAST and the Gamma-Ray Sky

GLAST (gamma-ray large area space telescope) is a next-generation high-energy space-borne telescope, to be launched in 2006. It will detect gamma-rays in the energy range between 10 keV and 300 GeV, overlapping with the energy range covered by ground-based Cerenkov telescopes. It is a follow-on to the very successful EGRET instrument on the Compton Gamma-Ray Observatory, which took data from 1991 to 1996, but with vastly improved technology that will result in a factor of 30 or more in sensitivity. This will enable the detection of several thousands of new high-energy sources, making a major step in the study of such exciting objects like gamma-ray bursts, blazars, pulsars, supernova remnants, the search for dark matter, diffuse galactic radiation, and unidentified high-energy sources.

November 18, 2003
3:00 pm (Tuesday)

Dr. Warren Funk
Director, Institute for Superconducting RF Science & Technology, Jefferson Laboratory

Jefferson Lab and the Past, Present and Future of Microwave Superconductivity

In recent months, Jefferson Lab has been making the news with some striking nuclear physics results: form factors for the neutron and deuteron, and most recently with confirmation of the discovery of the pentaquark. The nuclear physics program at JLab is enabled by the world's largest installation of superconducting radio frequency (SRF) systems. This talk will focus on the application of SRF to the Continuous Electron Beam Accelerator Facility and the role of the Institute in its creation, maintenance and upgrade. The exciting future for SRF science and technology will be clear from a review of projects, both under construction and proposed. The talk will touch on what are perceived as the fundamental limits of niobium in this application and where current research interest is centered.