| Physics at the University of Virginia | ||||||
| Academics | People | Research | Announcements | Facilities | Administration | Classes |
| Friday, January 18, 2008 | Available | |
| 4:00 PM, Room 204 | ||
| Physics Building |
| Friday, January 25, 2008 | Bernard Gerstman [Host: Art Brill] | |
| 4:00 PM, Room 204 | Florida International University | |
| Physics Building | “Protein Folding: Energy, Entropy, and Prion Diseases” |
| Living systems are the epitome of self-organized complexity. The self-organization occurs on all scales, from the molecular up to the organismal level. The machines responsible for maintaining organization are protein molecules that receive energy and convert it to work. However, protein molecules themselves must self-organize into highly specific shapes. The folding of proteins is a self-organizing process in which a long chain heteropolymer in a disorganized configuration spontaneously changes its shape to a highly organized structure in milliseconds. I explain how the energy and entropy landscape of protein chains is shaped to allow self-organization. I also show how these principles can be used in molecular level investigations of protein-protein interactions that lead to both beneficial dimerization or disastrous, disease producing and potentially fatal protein aggregation. |
| Friday, February 1, 2008 | Available | |
| 4:00 PM, Room 204 | ||
| Physics Building |
| Friday, February 8, 2008 | Andrew Askew [Host: Brad Cox] | |
| 4:00 PM, Room 204 | Florida State University | |
| Physics Building | “Life, the Universe, and Electroweak Symmetry Breaking” |
| One of the largest remaining questions in particle physics is the mechanism by which the W and Z bosons gain their mass. In the Standard Model of Particle Physics, this electroweak symmetry breaking occurs via the Higgs mechanism, though this remains experimentally unverified. I will overview this question and then concentrate on how diboson production and kinematics can give us information about this symmetry breaking. Experimental studies of boson pairs produced at the Tevatron and observed at the D0 experiment will be presented, ending with prospects for further study at the LHC. |
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Wednesday, February 13, 2008 Note Special Day |
Zelimir Djurcic [Host: Brad Cox] | |
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3:30 PM, Room 204 Note Special Time |
Columbia University | |
| Physics Building | “Searching for Physics Beyond the Standard Model with Neutrinos” |
| Although there has been tremendous progress over the past decade, many basic properties of neutrinos are still unknown and the possibility of future surprises remains strong. Recent neutrino experiments have conclusively observed that neutrinos have non-zero masses and that neutrinos change from one flavor to another. The MiniBooNE experiment at Fermilab recently presented its first neutrino oscillation results, where no significant excess of events was observed at higher energies, but a sizeable excess of events was observed at lower energies. The lack of a significant excess at higher energies allowed MiniBooNE to rule out simple 2-neutrino oscillations as an explanation of the LSND signal; however, the excess at lower energies is presently unexplained. Other data sets, including the NuMI, antineutrino, and SciBooNE data, should allow the collaboration to determine whether the lower-energy excess is due to background or to new physics. |
| Friday, February 15, 2008 | Marvin Blecher [Host: Blaine Norum] | |
| 4:00 PM, Room 204 | Virginia Tech | |
| Physics Building | “A More Accurate Measurement of Pion to Positron Decay” |
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Tuesday, February 19, 2008 Note Special Day |
Sabine Lammers [Host: Brad Cox] | |
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3:30 PM, Room 204 Note Special Time |
Columbia University | |
| Physics Building | “The Quest for the SM Higgs” |
| The Standard Model predicts the existence of one final particle, the Higgs Boson, which is the physical manifestation of spontaneous symmetry breaking as a mechanism for electroweak symmetry breaking, and is responsible for the masses of the known gauge bosons. Without the Higgs, the Standard Model is certainly incorrect or at least incomplete. We are at a precipice in the study of particle physics today because the answer to the question of the existence of the Higgs is about to be revealed. Constraints from precision LEP electroweak data indicate that the Higgs is light, making it within reach of observation by modern high energy particle colliders. I will discuss the state-of-the-art searches for the Standard Model Higgs Boson at the Tevatron and the plans for searches at the LHC. In particular, I will highlight the search techniques that are relevant at each collider and how Higgs searches at the LHC can benefit from knowledge gained at the Tevatron. |
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Wednesday, February 20, 2008 Note Special Day |
Christopher Neu [Host: Brad Cox] | |
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3:30 PM, Room 204 Note Special Time |
University of Pennsylvania | |
| Physics Building | “W Bosons and b Quarks at the Tevatron: Understanding the Haystack to Help Find the Needle” |
| Particle physics is at the threshold of an exciting new era. A crucial experimental pursuit is the search for and observation of the Higgs boson, a prominent missing piece in the widely successful standard model of the fundamental world. Searches at the Tevatron proton-antiproton collider in Illinois are closing in on the Higgs, while experiments at the new Large Hadron Collider in Switzerland are scheduled to begin operations later this year. One of the main signatures for the Higgs contains a W boson and one or more b quarks. However, this signature is shared by more common electroweak and strong processes that have not been determined precisely by experiment until now. Herein I will present a new measurement by CDF of W boson and b quark production. This measurement will contribute to improvements in the theoretical models, and I will discuss how this result can be used to sharpen searches for the Higgs and for physics beyond the standard model at both the Tevatron and the Large Hadron Collider. |
| Friday, February 22, 2008 | Benjamin Kilminster [Host: Brad Cox] | |
| 4:00 PM, Room 204 | Ohio State University | |
| Physics Building | “Fermilab's race for the Higgs boson” |
| One of the most important mysteries in our understanding of the universe is how elementary particles acquire mass. Our best explanation for this requires the existence of a particle called the Higgs boson, which has not yet been directly observed. Particle physicists at Fermilab, near Chicago, are currently capable of producing and detecting Higgs bosons from collisions of matter and antimatter at very high energies. I will explain what exactly these physicists are looking for, and present the experimental challenges involved in a few particular methods for differentiating Higgs bosons from other background processes. Finally, I will discuss future prospects for Higgs boson discovery at Fermilab, as well as the discovery potential of future experiments. |
| Friday, February 29, 2008 | Available | |
| 4:00 PM, Room 204 | ||
| Physics Building |
| Friday, March 14, 2008 | Available | |
| 4:00 PM, Room 204 | ||
| Physics Building |
| Friday, March 21, 2008 | Available | |
| 4:00 PM, Room 204 | ||
| Physics Building |
| Friday, March 28, 2008 | Seonho Choi [Host: Nilanga Liyanage] | |
| 4:00 PM, Room 204 | Seoul National University | |
| Physics Building | “Probing Nucleons Inside Nucleus” |
| The interior world of the nucleus is still a mystery in nuclear physics. While it is well known that the nucleus is made of nucleons, their properties inside the nucleus are still a big puzzle. There has been a series of experiments to probe the nucleons inside the nucleus. However, the results are still controversial. One main remaining question is regarding the Coulomb Sum Rule (CSR). The colloquium will cover the basic concept of probing microscopic world with high energy electron beams, the key issues of the CSR problem and the recent, new experiment at Jefferson Lab to study the CSR problem. |
| Friday, April 4, 2008 | Available | |
| 4:00 PM, Room 204 | ||
| Physics Building |
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Monday, April 7, 2008 Note Special Day |
Ned Seeman [Host: Keith Williams] | |
| 4:00 PM, Room Atrium | NYU | |
| Wilsdorf Hall | “Nanoscale Assembly with DNA” |
| Friday, April 11, 2008 | John Arrington [Host: Nilanga Liyanage] | |
| 4:00 PM, Room 204 | Argonne National Lab | |
| Physics Building | “Nucleon Form Factors...50 Years Later” |
| The structure of the proton and neutron can be expressed in terms of the electric and magnetic form factors which can be measured from elastic electron-proton scattering. Fifty years ago, the first electron scattering measurements of the proton form factors started the process of mapping out the distribution of charge and magnetization of the proton. Four decades of measurements gave us a simple picture of the nucleon, but our understanding was severely limited by the experimental techniques and theoretical understanding. The last ten years as provided several new experimental and theoretical techniques, giving us a much clearer picture of nucleon structure, and providing a few surprises along the way. |
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Tuesday, April 15, 2008 Note Special Day |
Daniel Eisenstein [Host: Dinko Pocanic] | |
| 4:00 PM, Room 204 | University of Arizona | |
| Physics Building | “Dark Energy and Cosmic Sound” |
| I present galaxy clustering results from the Sloan Digital Sky Survey that reveal the signature of acoustic oscillations of the photon-baryon fluid in the first million years of the Universe. The scale of this feature can be computed and hence the detection in the galaxy clustering serves as a standard ruler, giving a geometric distance to a redshift of 0.35. I will discuss the implications of this measurement for the composition of the universe, including dark energy and spatial curvature. I will close with a more general discussion of SDSS-III, a new collaborative project that will feature a large redshift survey aimed at refining the acoustic oscillation distance scale to 1% as well as surveys for extrasolar planets and the structure of the Milky Way. |
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Thursday, April 17, 2008 Note Special Day |
Alan Watson [Host: Physics Department] | |
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7:30 PM, Room Chemistry Building, Room 402 Note Special Time |
University of Leeds, United Kingdom | |
| Physics Building | “The Birth of Cosmic Ray Astronomy on the Argentine Pampas” |
| Friday, April 18, 2008 | Alan Watson [Host: Brad Cox] | |
| 4:00 PM, Room 203 | Leeds University, England | |
| Physics Building | “Is the search for the origin of the highest energy cosmic rays over?” |
| This question can now be asked because of two results obtained using data recorded at the Pierre Auger Observatory. It has been established, at the 6-sigma level, that the flux of the highest energy cosmic rays is suppressed at energies beyond 5 x 10 19 eV and that above this energy an anisotropy in the arrival directions of the particles is apparent. The arrival directions appear to be associated with sources within the GZK horizon (z ~ 0.018 or 75 Mpc). From these observations it seems probable that we have observed the long-sought Greisen-Zatsepin-Kuzmin effect, demonstrating that ultra-high energy cosmic rays are of extragalactic origin. It is also probable that these particles are protons, thus offering the possibility of insights into features of particle physics at centre-of-mass energies 30 times greater than will be reached at the LHC. Preliminary conclusions from studies of detailed features of extensive air showers suggest that extrapolations from Tevatron energies may not be what have been anticipated hitherto. Much further work remains to be done. |
| Friday, April 25, 2008 | Kyungwha Park [Host: Keith Williams] | |
| 4:00 PM, Room 204 | Virginia Tech | |
| Physics Building | “Interaction between a molecular magnet monolayer and a metallic surface” |
| Over the past decade, molecular magnets or single-molecule magnets have drawn considerable attention due to observed magnetic quantum tunneling and interference and a possibility of using them for information storage or devices. There have been so far significant efforts to build and characterize thin films or monolayers of single-molecule magnets on surfaces or single-molecule magnets bridged between electrodes. However, there is need to understand changes of the properties of single-molecule magnets in those environments using atomic-scale simulations. In this regard, we simulate, within density-functional theory, a nanostructure in which prototype Mn12 molecules are adsorbed via a thiol group onto a gold surface. Based on a supercell calculation, we investigate how much charge and spin are transferred between a Mn12 molecule and the metal surface. In addition, we compare the electronic structure and magnetic properties of the nanostructure with those of an isolated Mn12 molecule in the absence and presence of spin-orbit interaction. |
To add a speaker, send an email to ek6n@Virginia.EDU. Include the seminar type (e.g. Colloquia), date, name of the speaker, title of talk, and an abstract (if available). [Please send a copy of the email to phys-seminars@Virginia.EDU.]
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