| Physics at the University of Virginia | ||||||
| Academics | People | Research | Announcements | Facilities | Administration | Classes |
| Tuesday, September 21, 1999 | R. Workman [Host: Hans Weber] | |
| 3:30 PM, Room 204 | George Washington University | |
| Physics Building | “Topics in N* Resonance Analysis” |
| Tuesday, October 5, 1999 | Norm Kolb [Host: Blaine Norum] | |
| 3:30 PM, Room 204 | University of Saskachewan | |
| Physics Building | “Probing Chiral Symmetry with Photonuclear Reactions” |
| Chiral Perturbation Theory (ChPT) is an effective field theory in which the spontaneous breaking of the Quantum Chromodynamic (QCD) chiral symmetry is exploited to make predictions for many low-energy processes. Nuclear Compton scattering and near-threshold pion photoproduction are two of the phenomena that can be used to test the chiral dynamics of QCD via ChPT. Compton scattering can be used to extract the electric and magnetic polarizabilites of the nucleon, which are fundamental structure constants. Pion photoproduction close to threshold determines the fundamental pion-nucleon amplitudes in a model-independent way. The proton polarizabilities and pion-proton threshold amplitude are in reasonable agreement with predictions. The situation for the neutron is not nearly so good, both on an experimental as well as theoretical basis. Experimental results from these programs at the Saskatchewan Accelerator Laboratory will be reviewed. |
| Tuesday, October 19, 1999 | Xiaotong Song | |
| 3:30 PM, Room 204 | University of Virginia - Physics Dept | |
| Physics Building | “Substructure of the Nucleon” |
| Tuesday, October 26, 1999 | Wally Melintchouk [Host: S. Luiti] | |
| 3:30 PM, Room 204 | University of Aolelaisle/Jefferson Lab | |
| Physics Building | “Mirror nuclei, the neutron and quark-hadron duality” |
| Tuesday, December 14, 1999 | Dr. William Junkin [Host: Stephen Thornton] | |
| 3:30 PM, Room 203 | Erskine College | |
| Physics Building | “Web-based Software to Enhance Instructor-Student Interaction” |
| Web-based (HTML) software will be introduced which enhances student learning by increasing student involvement and instructor-student interaction. Most of these interactive or polling software and templates, some of which I have developed, are free. They are used in "Peer Instruction" developed by Eric Mazur (Harvard University) and "JiTT" (Just-in-Time Teaching) developed by Novak and Garvin (IUPUI), Patterson (Air Force Academy), and Christian (Davidson). These recent pedagogies have been used effectively in physics and other disciplines at the high school and undergraduate level. Preliminary results of using some of this software with traditional introductory physics labs are especially promising. This session will demonstrate these materials, make them available to those that are interested, explain how to make them work on your platform or network, explain how to combine them with other web-based materials, and mention results from using them. The session is designed for anyone, novice web-surfer to experienced web-master. |
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Thursday, January 27, 2000 Note Special Day |
Helmut Haberzettl [Host: Hans Weber] | |
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3:00 PM, Room 313 Note Special Time |
George Washington University | |
| Physics Building | “Theoretical issues of interacting mesons, baryons and photons” |
| Tuesday, February 29, 2000 | Dustin McNulty [Host: Don Crabb] | |
| 3:30 PM, Room 204 | University of Virginia | |
| Physics Building | “A Precise Measurement of the g2 Structure Function of the Proton and Deuteron” |
| Tuesday, March 7, 2000 | Larry Cardman [Host: Blaine Norum] | |
| 3:30 PM, Room 204 | Jefferson Laboratory, Newport News, VA | |
| Physics Building | “CEBAF @ Jefferson Lab: A New Microscope for Nuclear Physics” |
| Tuesday, March 14, 2000 | Frank Wesselmann [Host: Donal Day] | |
| 3:30 PM, Room 204 | Old Dominion University | |
| Physics Building | “Precision Measurement of the Spin Structure of the Proton and the Deuteron” |
| Over the past decade, many experiments have measured the nucleon spin structure functions using polarized deep inelastic scattering, both in the US and in Europe. After a brief survey of these efforts, the results from SLAC experiments E155 and E155x will be presented. This pair of experiments has measured g1 and g2 of the proton and the deuteron with high precision and over a large kinematic range, providing the best measurements available. In the discussion of these measurements, special attention will be given to the radiative corrections, which have a significant impact on the measured results and also on statistical and on systematic errors. |
| Tuesday, March 21, 2000 | Sabine Jeschonnek [Host: Simonetta Liuti] | |
| 3:30 PM, Room 204 | Jefferson Lab | |
| Physics Building | “Search for the Origin of Duality” |
| Tuesday, April 4, 2000 | Xiatong Song [Host: Hans J. Weber] | |
| 3:30 PM, Room 204 | University of Virginia | |
| Physics Building | “Spin Structure Function g2” |
| Tuesday, April 11, 2000 | C V K Baba [Host: P. K. Kabir] | |
| 3:30 PM, Room 204 | Tata Institute of Fundamental Research, Bombay | |
| Physics Building | “A Search for Color van der Waals Interaction” |
| Tuesday, April 18, 2000 | Gwyn Williams [Host: Robert Jones] | |
| 3:30 PM, Room 204 | JLAB | |
| Physics Building | “Surface Dynamics Using Synchrotron Radiation” |
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Thursday, April 27, 2000 Note Special Day |
Stephen Thornton/Robert Watkins [Host: Physics Department] | |
|
6:30 PM, Room 203 Note Special Time |
University of Virginia | |
| Physics Building | “The Sixth Annual National Physics Day Show” |
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Monday, September 25, 2000 Note Special Day |
I. Sick [Host: Donal Day] | |
| 3:30 PM, Room 313 | Univ. Basel | |
| Physics Building | “Many Body Theory Interpretation of Deep Inelastic Scattering” |
| Tuesday, October 3, 2000 | H. P. Wirtz [Host: D. Pocanic] | |
| 3:30 PM, Room 204 | Paul Scherrer Institute | |
| Physics Building | “Waveform Digitization with the Domino Sampling Chip in the PIBETA Experiment” |
| Tuesday, October 10, 2000 | Emil Frlez [Host: Dinko Pocanic] | |
| 3:30 PM, Room 204 | University of Virginia | |
| Physics Building | “Is There A Tensor Admixture To V-A Interaction In The Radiative Pion Decay?” |
| The PIBETA experiment at PSI has been taking data for over a year. Acquired statistics of rare pion and muon decays exceeds now the previous world total by up to an order of magnitude. In this talk I will examine the pi+ --> e+ gamma events collected so far, especially in the part of the phase space sensitive to deviations from the canonical V-A interaction. As the PIBETA detector is running with 12 simultaneous physics triggers, the cross-normalization of different decay channels enables us to extract the absolute pi+ --> e+ nu gamma branching ratio in a simple way and compare it with a straightforward theoretical calculation. |
| Tuesday, October 17, 2000 | Mark Strikman [Host: Donal Day] | |
| 3:30 PM, Room 204 | Penn State University | |
| Physics Building | “Perspectives of using high-energy electron scattering for probing microscopic nuclear structure” |
| Tuesday, October 24, 2000 | Gordon Cates (POSTPONED) | |
| 3:30 PM, Room 204 | UVA- Physics Department | |
| Physics Building | “TBA” |
| Tuesday, November 21, 2000 | Qwar Benhar [Host: S. Liuti] | |
| 3:30 PM, Room 204 | INFN, Rome | |
| Physics Building | “The Imprint Of The Equation of State on the Acial W- Modes of Oscillating Neutron Stars” |
| Tuesday, December 5, 2000 | Haiyan Gao [Host: Simonetta Liuti] | |
| 3:30 PM, Room 204 | MIT | |
| Physics Building | “JLab experiment E95-001: quasielastic scattering of polarized electrons from Polarized 3He nuclei” |
| Tuesday, December 12, 2000 | Raju Venugopalan (POSTPONED) [Host: Simonetta Liuti] | |
| 3:30 PM, Room 204 | BNL | |
| Physics Building | “TBA” |
| Tuesday, February 13, 2001 | Yelena Prok [Host: Dinko Pocanic] | |
| 3:30 PM, Room 204 | University of Virginia - Physics Dept. | |
| Physics Building | “The measurement of the spin structure function g1 in the resonance region” |
| Tuesday, March 20, 2001 | Ashot Gasparian [Host: Gordon Cates] | |
| 3:30 PM, Room 204 | Jefferson Lab | |
| Physics Building | “The Chiral Anomaly and Neutral Pion Lifetime” |
| The system of the three light neutral mesons, pi-zero, eta eta-prime, contains fundamental information about chiral symmetry breaking in low energy QCD. In particular, SU(3)and isospin breaking by the light quark masses lead to important mixing effects among the mesons. Because of the small mass of the pion, the prediction of the chiral anomaly for the pi-zero To gamma - gamma decay width is more accurate and exact in the limit of massless quarks. In this limit the predicted decay width depends only on two fundamental constants: the number of colors in QCD,and the pion decay constant.The “PrimEx ” collaboration at Jefferson Lab will perform a high precision measurement of the neutral pion lifetime using the small angle coherent photoproduction of pi-zero's in the Coulomb field of a nucleus,i.e., the Primakoff effect. After giving a general overview of chiral symmetry breaking and the appearance of the chiral anomaly at low energies,this talk will present previous measurements and focus on the current experiment at JLab. The experimental program for the more massive eta and eta-prime mesons with the 12 GeV JLab energy upgrade will also be discussed. |
| Tuesday, April 3, 2001 | Kent Pashke [Host: Ralph Minehart] | |
| 3:30 PM, Room 204 | Carnegie Mellon | |
| Physics Building | “Probing the Spin Structure of Strangeness Production: ” |
| Tuesday, April 10, 2001 | Ioana Niculescu [Host: D. Pocanic] | |
| 3:30 PM, Room 204 | Jefferson Lab | |
| Physics Building | “Exploring Quark-Hadron Duality at Medium Energies” |
| Quark-hadron duality reflects the relationship between the quark and hadron descriptions of hadronic processes and is related to the nature of the transition from non-perturbative to perturbative QCD. The phenomenon of duality can be studied in a variety of processes, such as e+e- annihilation, deep inelastic scattering, heavy quark decays, etc. Recent data on inclusive electron-proton and electron-deuteron inelastic scattering obtained at Jefferson Lab were utilized for precision tests of quark-hadron duality. These results will be presented, together with future plans of testing/expanding the concept of quark-hadron duality at Jefferson Lab. |
| Tuesday, April 17, 2001 | Larry Weinstein [Host: Ralph Minehart] | |
| 3:30 PM, Room 204 | ODU | |
| Physics Building | “N N Corelations in 3He(e,e'pp) n' ” |
| Tuesday, May 1, 2001 | Yongsoo Yoon [Host: Thomas Gallagher] | |
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4:00 PM, Room 204 Note Special Time |
Univ. of California | |
| Physics Building | “Probing Quantum Phase Transitions with NanoCalorimeter” |
| Tuesday, September 18, 2001 | Scott Wilburn [Host: Dinko Pocanic] | |
| 3:30 PM, Room 204 | LANL | |
| Physics Building | “Measurement of Neutron Beta Decay Parameters with a Polarized Pulsed Cold Neutron Beam” |
| Tuesday, September 25, 2001 | B. Borosoy [Host: Blaine Norum] | |
| 3:30 PM, Room 204 | Technical University | |
| Physics Building | “Chiral Dynamics of the eta-prime meson” |
| The lowest-lying nonet of pseudoscalar mesons consists of the Goldstone boson octet of pions, kaons and the eta, which become massless in the chiral limit of zero quark masses, and the corresponding singlet state, the eta-prime, which, on the other hand, remains a massive state in the chiral limit due to the axial U(1) anomaly. In order to describe the interactions of the eta-prime with the Goldstone boson octet at low energies, the conventional chiral effective Lagrangian is extended to include the eta-prime. The results presented in this talk include (eta)-(eta-prime) mixing and the dominant decay mode of the eta-prime into (eta bion pion). Furthermore, we conbine the chiral Lagrangian approach with a coupled channel analysis, in order to investigate eta-prime electroproduction off the nucleons. The investigation of the eta-prime may offer new insights into the role of the axial U(1) anomaly in chiral dynamics. |
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Thursday, September 27, 2001 Note Special Day |
Patrick Hautle [Host: Donald Crabb] | |
| 3:30 PM, Room 204 | PSI | |
| Physics Building | “Polarized Scintillating Targets for Spin Physics” |
| Tuesday, October 9, 2001 | Rocco Schiavilla [Host: H. J. Weber] | |
| 3:30 PM, Room 204 | JLAB | |
| Physics Building | “A Random Walk in the Physics of Light Nuclei” |
| In this talk I will discuss our current understanding, based on realistic nuclear Hamiltonians and currents, of a number of disparate issues generally relating to the structure and dynamics of light nuclei. These include: energy spectra of light nuclei with A up to 10, the determination of GEn from d(e,e')d data, longitudinal and transverse strength in the quasi-elastic (e,e') response of nuclei, the determination of parity-violating components of the NN interaction from pp elastic scattering, and finally (time permitting) an update on hep neutrinos from SuperK. |
| Tuesday, October 23, 2001 | Renee Fatemi [Host: H. Weber] | |
| 3:30 PM, Room 204 | UVA | |
| Physics Building | “The Spin Structure of the Proton in the Resonance Region” |
| Inclusive double spin asymmetries p(e,e') measured in Hall-B at Jefferson Lab show that the resonance region contributes significantly to the low Q2 (0.15-1.2 GeV2) evolution of the structure function gp1(x,Q2) and its first moment. These results have important implications for the limits of current pQCD predictions as well as for the expected low Q2 convergence to the Gerasimov-Drell-Hearn Sum Rule. |
| Tuesday, November 13, 2001 | X. Ji [Host: Xiatong Song] | |
| 3:30 PM, Room 204 | University of Maryland | |
| Physics Building | “GDH Sum Rule” |
| Tuesday, December 4, 2001 | Sergey Kulagin [Host: S. Liuti] | |
| 3:30 PM, Room 204 | Institute for Nuclear REsearch, Moscow | |
| Physics Building | “Nuclear Physics of Parton Distributions” |
| Tuesday, January 15, 2002 | Stefen Bass [Host: S. Liuti] | |
| 3:30 PM, Room 204 | Department of Physics, Duke University & RIKEN-BNL Research Center Fellow | |
| Physics Building | “ Quark-Gluon-Plasma Theory: Overview of status and perspectives” |
| It is believed that shortly after the creation of the universe in the Big Bang all matter was in a state called the Quark Gluon Plasma (QGP). Due to the rapid expansion of the Universe, this plasma went through a phase transition to form hadrons and nuclear matter as we know it today. The investigation of QGP properties will yield important novel insights into the development of the early universe and the behavior of QCD under extreme conditions. It is sought to recreate this highly excited state of primordial matter under controlled laboratory conditions using relativistic heavy ion collisions, e.g. at the Super-Proton-Synchrotron (SPS) at CERN and at the Relativistic Heavy-Ion Collider (RHIC) at Brookhaven National Laboratory. SPS and first RHIC data have yielded many interesting and sometimes surprising results which have not yet been fully evaluated or understood by theory. I will review the current status of QGP theory - main emphasis will be put on what we have learned at the SPS and at RHIC and what the most pressing challenges are for the near future. |
| Tuesday, February 26, 2002 | Markus Diehl [Host: G. Cates] | |
| 3:30 PM, Room 204 | DESY | |
| Physics Building | “Generalized parton distributions and their ramifications” |
| Tuesday, April 30, 2002 | Vina Punjabi [Host: S. Liuti] | |
| 3:30 PM, Room 204 | Norfolk State University | |
| Physics Building | “Measurement of the Ratio G_Ep/G_Mp at large Q^2 at Jefferson Lab” |
| Tuesday, October 22, 2002 | Mike Clark [Host: George Gillies] | |
| 3:30 PM, Room 204 | NRPB - England | |
| Physics Building | “Radiation and Gravity” |
| The standard phenomenological model for the interaction for ionising radiation with matter, originally formulated by Bethe and widely used to calculate the transfer of energy, can also be used to model the quantum exchange processes that mediate forces. Such models are shown to be compatible with Newtonian gravitation and with the principle of weak equivalence. The gravitational constant G (kg –1 m3 s –2) can be related to Planck’s constant h, the speed of light c, the atomic mass unit u, and a dimensionless coupling constant ag. The applications and implications of the derived formulation will be examined. This formulation for G gives a new interpretation of Planck quantities, and a prediction emerges for experimental values of G to increase with increasing temperature of the attracting mass. Finally, gravitational shielding is predicted to occur but at vanishingly small proportions both in the laboratory and in the cosmos. * M J Clark is at the National Radiological Protection Board, Chilton, Didcot, OX11 0RQ, UK (e-mail mike.clark@nrpb.org.uk). |
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Monday, November 25, 2002 Note Special Day |
Charles Earl Hyde-Wright [Host: Donal Day] | |
| 3:30 PM, Room 204 | Old Dominion University | |
| Physics Building | “'Peering deeply into the proton: Deeply Virtual Compton Scattering and Generalized Parton Distributions” |
| Tuesday, January 14, 2003 | Alexandra Fantoni [Host: Simonetti Liuti] | |
| 3:30 PM, Room 204 | INFN, Laboratorio Nazionale di Frascati | |
| Physics Building | “Quark-Hadron Duality Studies in Polarised Structure Functions” |
| Tuesday, February 18, 2003 | Prof. Murray Peshkin [Host: Xiaotong] | |
| 3:30 PM, Room 204 | Argonne National Laboratory | |
| Physics Building | “Spin and Statistics in Nonrelativistic Quantum Mechanics''” |
| The connection between spin and statistics is usually proved by using the full machinery of relativistic quantum field theory, providing little insight into what physics actually underlies it or whether there can be exceptional cases. I will show, using elementary methods of ordinary nonrelativistic quantum mechanics that identical zero-spin particles must obey symmetric statistics. The key assumption is that no dynamical variable in the theory distinguishes among identical spin-zero particles. Whether this approach can be extended to identical particles with nonvanishing spin is currently uncertain. |
| Tuesday, February 25, 2003 | Dr. Senho Choi [Host: Nilanga Liyanage] | |
| 3:30 PM, Room 204 | Temple University | |
| Physics Building | “Study of the Porized Structure Functions of the Neutron at Low Q2 with Polarized 3He ” |
| Tuesday, March 11, 2003 | Prof. Stanly J. Brodsky [Host: Xiaotong Song] | |
| 3:30 PM, Room 204 | SLAC | |
| Physics Building | “The Unexpected Effects of Final-State Interactions in QCD” |
| It is usually assumed that the structure functions measured in deep inelastic lepton-proton scattering are the probability distributions for finding quarks and gluons in the target nucleon. In fact, gluon exchange between the fast, outgoing partons and the target spectators, which is usually assumed to be an irrelevant gauge artifact, affects the leading-twist structure functions in a profound way, leading to diffractive leptoproduction processes, shadowing of nuclear structure functions, and target spin asymmetries. In particular, final-state interactions from gluon exchange leads to single-spin asymmetries in semi-inclusive deep inelastic lepton-proton scattering which are not power-law suppressed at large photon virtuality Q^2 at fixed x_{bj}. |
| Tuesday, April 15, 2003 | Maxim Bychkov [Host: Dinko Pocanic] | |
| 3:30 PM, Room 204 | UVA | |
| Physics Building | “PIBETA experiment: overview and preliminary results” |
| Tuesday, April 22, 2003 | Ying Wang [Host: Dinko Pocanic] | |
| 3:30 PM, Room 204 | UVA | |
| Physics Building | “PIBETA experiment: PIBETA Detector Waveform Digitizing System” |
| Tuesday, April 29, 2003 | Brent A. VanDevender [Host: Dinko Pocanic] | |
| 3:30 PM, Room 204 | UVA | |
| Physics Building | “Achieving Proposed Accuracy in the PIBETA Experiment -- It's About Time!” |
| In order for PIBETA to attain its proposed accuracy it is imperative that all electronic artifacts be removed from the timing scheme in offline analysis. Some progress has been made but it is evident that attepts to extend these improvements with traditional ADC/TDC methods will be impossible. The efforts can be salvaged however by studying digitized waveforms and developing new timing algorithms which exploit the raw signals. |
| Tuesday, May 6, 2003 | Brad Sawatzky [Host: Norum] | |
| 3:30 PM, Room 313 | UVA | |
| Physics Building | “A Measurement of the Neutron Asymmetry in Near-Threshold DeuteriumPhoto-Disintegration ” |
| Tuesday, May 13, 2003 | Alexander Stolin [Host: Mark Williams] | |
| 3:30 PM, Room 313 | UVA | |
| Physics Building | “Development of CT-SPECT scanner for small animal imaging” |
| Tuesday, May 20, 2003 | Kebin Wang [Host: Blaine Norum] | |
| 3:30 PM, Room 313 | UVA | |
| Physics Building | “Hadronization in Nucleus by Deep Inelastic Scattering” |
| Tuesday, September 30, 2003 | Paul Kingsberry [Host: Donal Day] | |
| 3:30 PM, Room 204 | Department of Physics and Astronomy, University of New Mexico | |
| Physics Building | “P+PBAR -> LAMBDA+LAMBDABAR WITH A POLARIZED TARGET” |
| The reaction p+pbar -> lambda+lambdabar was examined by CERN experiment PS185/3 at the Low-Energy Antiproton Ring (LEAR) with beam momenta of 1.525 GeV/c and 1.640 GeV/c. The proton target was transversely polarized to enable measurements of the depolarization and spin transfer, which quantify the transfer of the transverse spin of the target proton to that of the outgoing lambda and lambdabar, respectively. Theoretical calculations of Dnn, the component of the depolarization normal to the production plane, differ greatly according to whether quark-gluon or meson-exchange models are utilized. Final results for the measured depolarization Dnn and spin transfer Knn will be presented for both beam momenta. These results appear to be inconsistent with the specific angular distributions predicted under the assumptions of both production scenarios. |
| Tuesday, November 11, 2003 | Pibero Djawotho | |
| 3:30 PM, Room 204 | College of William & Mary | |
| Physics Building | “Measurement of the Neutron (3He) Spin Structure Functions at Low Q2; a Connection between the Bjorken and Gerasimov-Drell-Hearn Sum Rule” |
| This talk presents results of experiment E94-010 performed at JLAB (simply known as JLab) in Hall A. The experiment aimed to measure the low Q2 evolution of the Gerasimov-Drell-Hearn(GDH) integral from Q2 = 0.1 to 0.9 GeV2. The GDH sum rule at the real photon point provides an important test of Quantum Chromodynamics (QCD) radiative rections. The low Q2 evolutions of the GDH integral contests various resonance models. Chiral Perturbation Theory and lattice QCD calculations, but more importantly, it helps us understand the transition between partonic and hadronic degrees of freedom. At high Q2, beyond 1 GeV2, the difference of the GDH integrals for the proton and the neutron is related to the Bjorken sum rule, another fundamental test of QCD radiative corrections. In addition, results of the measurements for the spin structure functions g1 and g2 cross sections, and asymmetries are presented. E94-010 was the first experiment of its kind at JLAB. It used a high-pressure, polarized 3He target with a gas pressure of 10 atm and average target polarization of 38%. For the first time, the polarized electron source delivered an average beam plarization of 70% with a beam current of 15 µa; The limit on the beam current was only imposed by the target. The experiment required six different beam energies from 0.86 to 5.1 GeV. This was the first time the accelerator ever reached 5.1 GeV. Both High-Resolution Spectrometers of Hall A, used in singles mode, were positioned at 15.5 degree; each. |
| Tuesday, December 9, 2003 | Karl Slifer [Host: Donal Day] | |
| 3:30 PM, Room 313 | Temple University | |
| Physics Building | “Neutron Spin Structure at Low Q2 Using a Polarized 3He Target” |
| We have measured the spin dependent longitudinal and transverse 3He(e,e,) cross sections for 0.1 |
| Tuesday, February 3, 2004 | Sergey Alekhin [Host: Simonetta Liuti] | |
| 3:30 PM, Room 204 | Institute for HEP, Serpukhov | |
| Physics Building | “The latest global analyses of parton distribution functions” |
| Tuesday, February 24, 2004 | Bodo Reitz [Host: Nilanga Liyanage] | |
| 3:30 PM, Room 204 | Jefferson Lab | |
| Physics Building | “Studies of Short-Range Correlations and Reaction Dynamic Effects in the 4He(e,e'p) Reaction” |
| Studying few-body nuclear targets in the (e,e'p) reaction is a powerful method to investigate specific aspects of the nucleus. The 4He nucleus is an especially interesting target since it has many of the ingredients of a complex, heavy nucleus, while as an A=4 system, microscopic calculations are still feasible. Making use of the high luminosity electron beam at Jefferson Lab together with the high resolution spectrometers in Hall A, Jefferson Lab Hall A experiment E97-111 has measured the 4He(e,e'p)3He cross section at recoil momenta up to~500 MeV/c in various kinematics. In plane-wave impulse approximation, many calculations predict a sharp minimum in the cross section for recoil momenta around 450~MeV/c and show that its location is sensitive to the short-range part of the internucleon potential. However, reaction dynamic effects such as final-state interactions and meson-exchange currents can obscure such a minimum. Measuring this cross section at various kinematical settings over the same recoil-momentum range gives the possibility to study these reaction dynamics effects. Preliminary results of this experiment will be presented, and will be compared to recent theoretical predictions. |
| Tuesday, March 2, 2004 | Simonetta Liuti [Host: Gordan Cates] | |
| 3:30 PM, Room 204 | UVA | |
| Physics Building | “Subatomic Journal Club” |
| Tuesday, March 30, 2004 | Dave Gaskell [Host: Donal Day] | |
| 3:30 PM, Room 204 | Jefferson Laboratory | |
| Physics Building | “Transverse Target Asymmetry in Exclusive Pi+ Production” |
| Tuesday, April 20, 2004 | Scott Rohrbaugh ( Biological Physics) [Host: Gordon Cates] | |
| 3:30 PM, Room 204 | UVA | |
| Physics Building | “Spin relazation of 129Xe from paramagnetic impurities” |
| Tuesday, April 20, 2004 | Gerald Miller [Host: Simonetta Liuti] | |
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2:00 PM, Room 313 Note Special Time |
University of Washington | |
| Physics Building | “The Proton Form Factor and the Shape of the Proton” |
| Tuesday, April 27, 2004 | Karapet Oganessyan [Host: Simonetta Liuti] | |
| 3:30 PM, Room 204 | DESY | |
| Physics Building | “Novel Transversity Properties in Semi-Inclusive Deep Inelastic Scattering” |
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Wednesday, June 23, 2004 Note Special Day |
Shigeyuki Tajima [Host: Donal Day] | |
| 3:30 PM, Room 204 | Duke University | |
| Physics Building | “Measurements of the Electric Form Factor of the Neutron” |
| Precise measurements of the electric form factor of the neutron, Gen, over a wide range of the square of the four-momentum transfer, Q^2, are important for understanding nucleon and nuclear electromagnetic structure. The Jefferson Laboratory E93-038 collaboration recently reported the first measurements of Gen using polarization techniques at Q^2 > 1 (GeV/c)^2. The collaboration measured the ratio of the electric form factor to magnetic form factors of the neutron, g = Gen/Gmn, at three Q^2 values (0.45, 1.13 and 1.45 (GeV/c)^2) using the quasi-elastic 2H(\vec e,e'\vec n)1H reaction. The value for g was determined from the measured ratio of the sideways and longitudinal components of the neutron polarization vector. A polarimeter based on np scattering was used to analyze the polarization of the recoil neutrons. In this talk, the data analyses and our results for g and Gen at Q^2=0.45 and 1.13 (GeV/c)^2 will be given. |
| Tuesday, November 9, 2004 | Kebin Wang [Host: Blaine Norum] | |
| 3:30 PM, Room 204 | UVA | |
| “Proposed Measurement of Pion Polarizabilities in JLab-Hall B” |
| Tuesday, November 30, 2004 | Gail Dodge [Host: Simonetta Liuti] | |
| 3:30 PM, Room 204 | Old Dominion University | |
| Physics Building | “Spin Structure Functions: A Window into the Structure of Hadrons” |
| Tuesday, March 29, 2005 | Ryan Snyder [Host: Gordon Cates] | |
| 3:30 PM, Room 204 | UVA | |
| Physics Building | “HAPPEX: Using Parity Violation to Probe Nucleon Strangeness” |
| Tuesday, April 5, 2005 | Nadia Fomin | |
| 3:30 PM, Room 204 | UVA | |
| Physics Building | “Inclusive Scattering From Nuclei at x>1 and High Q^2 with a 5.75 GeV Beam” |
| Tuesday, April 12, 2005 | Swadhin Taneja [Host: Gordon Cates] | |
| 3:30 PM, Room 204 | UVA | |
| Physics Building | “Study of Bound Nucleons Using Generalized Parton Distributions” |
| Tuesday, April 19, 2005 | Saul Perlmutter [Host: Brad Cox] | |
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7:30 PM, Room 402 Note Special Time |
University of California - Berkeley | |
| Chemistry Building Auditorium | “Supernovae, Dark Energy, and the Accelerating Universe” |
| This constant acted as a sort of anti-gravity to counteract the force of gravity that would otherwise be pulling the masses of the universe together. When astronomers such as Hubble and others subsequently observed the red shifts of far distant stars and galaxies, they discovered that the universe is not static but, indeed, is expanding. Therefore, it no longer seemed necessary to have a counter balance to gravity. It is said that Einstein, when he heard of the expansion of the universe, characterized his use of a cosmological constant his greatest mistake. Indeed, for the better part of 100 years the standard view of the universe was that its expansion rate was gradually slowing down under the influence of the gravity of its components. The question of the future of the universe was posed in terms of, depending on the total mass of the universe, whether the universe would come to a stop and fall back in on itself, come to a halt at infinite time, or continue to expand forever. Professor Perlmutter and his colleagues, using Supernovas Type Ia as “standard candles” because of their great brightness, have measured the expansion rate of the universe at much large distances than previously possible. In doing so, they have made the remarkable discovery that the expansion of the universe is actually accelerating. There appears to be a previously undetected force of nature that acts like antigravity, dominating the gravitational force and causing the universe to expand faster and faster with time. So the better part of a century after the cosmological constant was abandoned, it seems that it must be re-employed to describe this new phenomenon which has been labeled dark energy. Perhaps Einstein was right after all! |
| Tuesday, April 19, 2005 | Josh Pierce [Host: Don Crabb] | |
| 3:30 PM, Room 204 | UVA | |
| Physics Building | “Measurements of the Extended GDH Sum Rule at J-Lab” |
| Tuesday, April 26, 2005 | Jaideep Singh [Host: Gordon Cates] | |
| 3:30 PM, Room 204 | UVA | |
| Physics Building | “The GDH Sum Rule, the Spin Structure of Helium-3 and the Neutron using Nearly Real Photons” |
| Tuesday, August 30, 2005 | AVAILABLE | |
| 3:30 PM, Room 204 | ||
| Physics Building |
| Tuesday, September 20, 2005 | Stephen Bueltmann [Host: Donal Day] | |
| 3:30 PM, Room 204 | Old Dominion University | |
| Physics Building | “The BoNuS Experiment at Jefferson Lab” |
| Unlike the structure of the proton, our understanding of the structure of the neutron to date is limited by the unavailability of free neutrons. The BoNuS collaboration at Jefferson Lab is preparing an experiment to augement the CLAS detector in Hall B with a recoil detector to measure the momentum of recoiling protons in electron scattering on a deuterium target. The detection of very low momentum spectator protons at very backward scattering angles selects electron scattering events on almost free neutrons inside the deuteron. The newly developed recoil detector and gas target system has to be built out of lightweight materials to not absorb the very low momentum spectator protons before being detected. The experiment is scheduled to start data taking in the middle of Octber 2005 and results from an engineering run in June 2005 are presented. |
| Tuesday, September 27, 2005 | Andrei Afanasev [Host: Donal Day] | |
| 3:30 PM, Room 204 | Jefferson Lab | |
| Physics Building | “Higher-Order QED for Precision Studies of Electron Scattering” |
| High precision of electron scattering experiments on nucleons and nuclei requires precise methods to include electromagnetic radiative corrections. Using an example of elastic electron-nucleon scattering, I will describe an important role of higher-order Quantum Electrodynamic techniques for the studies of hadronic structure with electron beams. |
| Tuesday, October 4, 2005 | David Armstrong [Host: Donal Day] | |
| 3:30 PM, Room 204 | College of William and Mary | |
| Physics Building | “Strangeness in the Proportion: Parity-Violating Electron Scattering and the Structure of the Nucleon” |
| The fleeting existence of quark-antiquark pairs within the proton (or neutron) is a well-established consequence of quantum chromodyamics. It is, however, still a largely open question as to whether this sea of quark-antiquark pairs, which contains contributions from all the quark flavors (up, down, strange, etc.), has any effect on the properties of the nucleon. In particular, the contribution of the sea to the magnetic moment and the charge distribution of the proton has been a topic of considerable interest. A series of experiments, using parity-violating electron scattering to probe of the sea, have been conducted at various labs in recent years. The results of these experiments, in particular the G0 and HAPPEX experiments at Jefferson Lab, will be reviewed, and possible interpretations of the results will be presented. |
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Thursday, October 20, 2005 Note Special Day |
Leonard Gamberg [Host: Simonetta Liuti] | |
| 3:30 PM, Room 205 | Penn State | |
| Physics Building | “Transversity Properties of Quarks and Hadrons Through Hard Scattering in QCD” |
| Tuesday, October 25, 2005 | Elton Smith [Host: Donal Day] | |
| 3:30 PM, Room 204 | Jefferson Lab | |
| Physics Building | “Search for Gluonic Excitations at Jefferson Lab” |
| One of the great mysteries of modern physics is the mechanism that confines quarks into hadrons. Quarks are bound together due to the strong interaction of gluons which themselves carry color charge. Although the theory of quantum chromodynamics (QCD) describes the interaction, the solutions can only be approximated at low energies. Nevertheless colored gluons are expected to bind to each other and form flux tubes, which lattice QCD predicts will be observable in the particle spectrum as new excitations called hybrid mesons. We will describe the plans at Jefferson Lab to double the energy of the machine to 12 GeV, which will allow access these gluonic excitations experimentally, and describe the apparatus in the new Hall D which will be used to search for them. |
| Tuesday, November 1, 2005 | Stepan Stepanyan [Host: Donal Day] | |
| 3:30 PM, Room 204 | Jefferson Lab | |
| Physics Building | “Hunting the Pentaquark” |
| In the past two years more than 13 experiments have reported observation of a narrow exotic S=+1 baryon state in the mass range from 1.525 to 1.55 GeV/c2. The minimal quark content of this state, now called the Θ+, is uudds. In contrast to almost fully exclusive experiments at low energies that have reported evidence for the Θ+, there have been a number of reports of non-observation of this state, mostly in high energy inclusive experiments. The main criticisms of the reported Θ+ signals are insufficient statistics, and variation in mass. Evidence for the doubly strange, Φ-- (known as Ξ--),and for the charmed, Θc, pentaquarks have been presented only in the single experiments. The CLAS Collaboration at Jefferson Laboratory has published two papers on the experimental evidence for the Θ+ and Ξ--. These data now represent the world's largest data sets for photoproduction on hydrogen and deuterium. In this talk an overview of the experimental situation on the pentaquarks and the preliminary results of high statistics CLAS experiments will be presented. |
| Tuesday, November 8, 2005 | John Ralston [Host: Simonetta Liuti] | |
| 3:30 PM, Room 204 | University of Kansas | |
| Physics Building | “Mixing Color and Spin” |
| Tuesday, November 22, 2005 | ****THANKSGIVING BREAK**** | |
| 3:30 PM, Room 204 | ||
| Physics Building |
| Tuesday, November 29, 2005 | Pasi Huovinen [Host: Donal Day] | |
| 3:30 PM, Room 204 | UVa and University of Jyväskylä, Finland | |
| Physics Building | “Studying the QCD Equation of State with Hydrodynamics” |
| The lattice QCD calculations predict a phase transition from hadronic matter to matter where the basic degrees of freedom are partons instead of hadrons around 170 MeV temperature. It is hoped that this phase transition could be experimentally observed in the heavy ion collision experiments at BNL's RHIC collider. In this talk I will discuss how one can compare the lattice QCD predictions to experimental results by using hydrodynamics to describe the expansion stage of the collision process. The data favor a scenario with a phase transition, but surprisingly the order of the phase transition seems to be different from the QCD prediction. |
| Tuesday, December 6, 2005 | Richard Arndt [Host: Donal Day] | |
| 3:30 PM, Room 204 | Virginia Tech | |
| Physics Building | “Partial-Wave Analysis of Scattering Reactions” |
| Tuesday, February 28, 2006 | Dan Pirjol [Host: Peter Arnold] | |
| 3:30 PM, Room 204 | MIT | |
| Physics Building | “Factorization in B decays from the Soft-Collinear Effective Theory” |
| Tuesday, March 7, 2006 | ****SPRING RECESS**** | |
| 3:30 PM, Room 204 | ||
| Physics Building |
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Monday, March 13, 2006 Note Special Day |
Anna Stasto [Host: Peter Arnold] | |
| 3:30 PM, Room 204 | Brookhaven National Laboratory | |
| Physics Building | “High Energy Limit and Parton Saturation in QCD” |
| High energy limit of QCD is the area of major theoretical interest. One of its prediction is the so called perturbative BFKL Pomeron which manifests itself as a rapid growth of the gluon density with increasing center-of-mass energy. Although the rise of this density is indeed observed in the deep inelastic experiments at small values of Bjorken x, it is not compatible quantitatively with the prediction of the BFKL Pomeron. This lead to the intensive investigation of the possible corrections to the BFKL Pomeron such as higher order and the high density corrections. In this talk I will give an introduction to the high energy limit of QCD and discuss the idea of the parton saturation, an effect that is expected to occur when the gluon density is very high. I will describe the nonlinear evolution equation (Balitsky-Kovchegov equation) for the gluon density which takes into account high density corrections and present its solution. The concept of the saturation scale and the geometrical scaling at small Bjorken x will be also introduced as well as the interesting link between parton saturation in QCD and the statistical physics. Finally, I discuss some phenomenological signatures of parton saturation and outline recent theoretical progress in developing theory with so-called Pomeron loops, corrections which go beyond the Balitsky-Kovchegov equation. |
| Tuesday, March 21, 2006 | Oscar Rondon-Aramayo [Host: Donal Day] | |
| 3:30 PM, Room 204 | UVA | |
| Physics Building | “Nucleon Spin Physics Program in JLab's Hall C” |
| The Hall C facility at Jefferson Lab is carrying out an extensive program of studies on nucleon spin physics, taking advantage of the CEBAF polarized electron beam and the versatile UVa polarized target. The program started in 2002 with a measurement of the longitudinal and transverse spin structure of the nucleon resonances in experiment 01-006 (Resonances Spin Structure - RSS) on proton and deuteron targets. This work is nearing publication of the final results for the proton, which will be presented. Preliminary results for the deuteron are available, too. The Spin Asymmetries on the Nucleon Experiment - SANE (E-03-109) is in preparation to extend the measurements of RSS and other experiments on the proton to higher momentum transfers. Going beyond inclusive polarized scattering, the Semi-SANE experiment (E-04-113) will detect scattered electrons and hadrons in coincidence, to determine the decomposition of the nucleon spin into its quark flavor components. Both SANE and Semi-SANE are scheduled to take data in 2008." |
| Tuesday, April 4, 2006 | Dipangkar Dutta [Host: Donal Day] | |
| 3:30 PM, Room 204 | Duke University | |
| Physics Building | “Search for a Permanent Electric Dipole Moment (EDM) of the Neutron” |
| The search for a non-zero neutron EDM is a direct search for time reversal symmetry violation. Recently, a new experiment has been proposed to search for the neutron electric dipole moment (nEDM) with about two orders of magnitude improved sensitivity compared to the current experimental limit. One of the critical new ideas, which helps achieve the improved sensitivity, is the use of polarized Helium-3 as a co-magnetometer. Polarized He-3 is a key new component of this proposed experiment and thus maintaining its polarization under the true experimental conditions is essential for the success of the experiment. Following an overview of the past searches for the neutron EDM, I will describe the new experiment and the effort underway at Duke to study the relaxation of polarized He-3 under the conditions of the new proposed experiment. |
| Tuesday, April 11, 2006 | Joe Pole [Host: Donal Day] | |
| 3:30 PM, Room 204 | UVA | |
| Physics Building | “Detector Physics in a Small Animal CT-SPECT Scanner” |
| Tuesday, April 18, 2006 | Chad Materniak [Host: Donal Day] | |
| 3:30 PM, Room 204 | UVA | |
| Physics Building | “Search for CP Violation in Hyperon Decays” |
| Tuesday, April 25, 2006 | RESERVED [Host: Nilanga Liyanage] | |
| 3:30 PM, Room 204 | TBA | |
| Physics Building | “TBA” |
| Tuesday, September 26, 2006 | Inna Aznauyan [Host: Donal Day] | |
| 3:30 PM, Room 204 | Jefferson Lab | |
| Physics Building | “Q 2 Evolution of &gamma * N → N * Transition Amplitudes from Pion Electroproduction Data” |
| I will make short introduction to clarify some notations used in N * physics and to present resonances which we have investigated within N * program of Hall B (JLab). Then I will discuss goals of N * program related to the Q 2 evolution of &gamma * N &rarr N * amplitudes. Here the focus will be on the investigation of the scale of transition from nonperturbative to perturbative regime of QCD and on the nature of the Roper resonance. Further, I will discuss approaches used for the extraction of resonance contributions to the pion electroproduction and present the results obtained from JLab (mostly Hall B) data. This will be followed by the discussion of the obtained results and conclusion. |
| Tuesday, October 10, 2006 | Brandon Craver [Host: Donal Day] | |
| 3:30 PM, Room 204 | UVA | |
| Physics Building | “A High Precision Measurement of G E n High Q 2 ” |
| A precision measurement of the electric form factor of the neutron, G E n , has been carried out in Jefferson Lab's Hall A for Q 2 values of 1.2 to 3.5 (GeV/c) 2 using a highly polarized 3 He target and the quasi-elastic semi-exclusive 3 He(e,e'n) reaction. The experiment detected the ejected neutron with an array of scintillators and the scattered electron with the newly commissioned BigBite spectrometer. This new spectrometer has a large angular acceptance (80 msr), complementing the existing 6 msr high-resolution spectrometers, and enables a new generation of low-rate experiments with lower resolution requirements. A package of three multi-wire drift chambers was constructed in order to allow the spectrometer to operate under high rate conditions and achieve a spatial resolution of ~ 200 μm. The present status of the experiment will be presented as well as online results showing chamber performance at raw hit rates up to 20 MHz per plane. |
| Tuesday, October 31, 2006 | Larry Weinstein [Host: Donal Day] | |
| 3:30 PM, Room 204 | ODU | |
| Physics Building | “Positron-proton scattering and the proton charge distribution” |
| This talk will describe how to make intense identical positron and electron beams at Jefferson Lab and use them to measure two-photon exchange contributions to elastic electron-proton scattering. It will cover the results of a recent test run in CLAS where we produced about 10 pA each of electrons and positrons. The proton electric form factor describes the charge distribution of the proton. This has been measured extensively with electron scattering using Rosenbluth separations and polarization measurements. These measurements of the proton electric form factor disagree by a factor of three at Q 2 = 6 GeV 2 . Since alpha, the fine structure constant, is less than 1%, electron-proton scattering should be almost exclusively one-photon exchange. However, a two-photon exchange contribution of about 5% could explain the discrepancy between the measurements. We will determine the two-photon exchange contribution by measuring the ratio of the electron-proton and positron-proton elastic scattering cross sections to 1%. |
| Tuesday, November 14, 2006 | Kevin Giovanetti [Host: Donal Day] | |
| 3:30 PM, Room 204 | JMU | |
| Physics Building | “A precision measurement of the muon lifetime and the determination of the weak coupling constant |
| For several years the MULAN collaboration has been pursuing the ambitious goal of a 1 ppm determination of the muon lifetime. This experiment has been motivated by recent theoretical improvements in extracting the Fermi coupling constant GF, from the measured muon lifetime, τμ, which have reached the 1 ppm level in the theoretical error. The coupling constant GF is an essential parameter of the Standard Model. Its uncertainty limits the precision for Standard Model predictions and interpretations. Progress and highlights of the experiment will be discussed. |
| Tuesday, November 21, 2006 | Thanksgiving Recess [Host: N/A] | |
| 3:30 PM, Room 204 | N/A | |
| Physics Building | “N/A” |
| Tuesday, December 5, 2006 | Igor I. Strakovsky [Host: Donal Day] | |
| 3:30 PM, Room 204 | George Washington University | |
| Physics Building | “Partial-Wave Analysis and Spectroscopy in Pion-Nucleon Scattering up to W = 2.5 GeV” |
| We present results from a comprehensive partial-wave analysis of pi+-p elastic scattering and charge-exchange data, covering the region from threshold to 2.6 GeV in the lab pion kinetic energy, employing a coupled-channel formalism to simultaneously fit pi-p-->eta n data to 0.8 GeV. Our main result, solution SP06, utilizes a complete set of forward and fixed-t dispersion relation constraints applied to the piN elastic amplitude. The results of these analyses are compared with previous solutions in terms of their resonance spectra and preferred values for couplings and low-energy parameters. Details are available at nucl-th/0605082 |
| Tuesday, February 6, 2007 | Wally Melnitchouk [Host: Donal Day] | |
| 3:30 PM, Room 204 | Jefferson Lab | |
| Physics Building | “Two-photon exchange in elastic electron-nucleon scattering” |
| The ratio of the electric to magnetic proton form factors has traditionally been determined using the Rosenbluth separation method, in which the ratio is extracted from the angular dependence of the cross section at fixed momentum transfer Q 2 . Measurements at JLab using the alternative, polarization transfer technique found a dramatically different behavior of the ratio compared with the Rosenbluth results. I discuss the resolution of this discrepancy by considering the effects of two-photon exchange in elastic e-p scattering, taking particular account of the nucleon's finite size. Contributions from excited nucleon intermediate states are also considered, and estimates given of two-photon exchange corrections to the form factors of the neutron and He-3. |
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Wednesday, February 7, 2007 Note Special Day |
Swaolhin Tameja [Host: Simonetta Liuti] | |
| 3:30 PM, Room 313 | Ecole Polytechnique | |
| Physics Building | “New Developments In Generalized Parton Distributions” |
| Tuesday, February 20, 2007 | Ross Young [Host: Hank Thacker] | |
| 3:30 PM, Room 204 | JLAB | |
| Physics Building | “Latest results on the low-energy search for new physics” |
| The Standard Model has been enormously successful at predicting the outcomes of experiments in nuclear and particle physics. The search for new physical phenomena and a fundamental description of nature which goes beyond the Standard Model is driven by two complementary experimental strategies. The first is to build increasingly energetic colliders, such as the Large Hadron Collider (LHC) at CERN, which aim to excite matter into a new form. The second, more subtle approach, is to do precision measurements at moderate energies, where an observed discrepancy with the Standard Model will reveal the signature of these new forms of matter. Here we demonstrate that the latest measurements of the electroweak force severely constrain the possibility of physics beyond the Standard Model to above the TeV energy scale. |
| Tuesday, February 27, 2007 | Chris Dawson [Host: Hank Thacker] | |
| 3:30 PM, Room 204 | Brookhaven National Lab | |
| Physics Building | “The Kaon B-Parameter from Lattice QCD” |
| I will discuss the calculation of the Kaon B-parameter, a measure of indirect CP-violation in the Standard Model, using Lattice QCD. In particular, I will talk about the use of the Domain Wall Fermion formulation of Lattice QCD, a formulation which has continuum-like symmetry properties at finite lattice spacing at the expense of the introduction of an additional, fifth, dimension. |
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Thursday, March 1, 2007 Note Special Day |
Diana Vaman [Host: Hank Thacker] | |
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4:00 PM, Room 204 Note Special Time |
University of Michigan | |
| Physics Building | “Holography with backreacted flavor” |
| The gauge/string holographic duality has opened a new window into the non-perturbative regime of gauge theories. I will present the construction of supergravity duals to N=2 supersymmetric gauge theories coupled with matter (quarks) in the fundamental representation of the gauge group. The supergravity solutions are obtained by taking the decoupling limit of D3/D7 (color/flavor) brane systems. The backreaction of the flavor branes needs to be accounted for, as it allows to go beyond the quenched approximation on the dual gauge theory side. I will give the spectrum of mesons (bound states of quark-anti quark pairs) and discuss the effect of the backreacted flavor. Lastly, I will present the supergravity dual to the finite temperature gauge theory. This corresponds to a backreacted non-extremal D3/D7 system. At finite temperature, the fundamental matter undergoes a first order phase transition. I will discuss this phase transition from the perspective of the supergravity dual. |
| Tuesday, March 13, 2007 | James Osborn [Host: Hank Thacker] | |
| 3:30 PM, Room 204 | Boston University | |
| Physics Building | “Localization transition in QCD at nonzero temperature” |
| Over 20 years ago Diakanov and Petrov suggested that the chiral phase transition in QCD might be similar to a metal-insulator transition based on the instanton description of the QCD vacuum. The arguments, however, are general and can be applied to other topological objects as well. I will review the proposed connection between QCD and a disordered medium and present some recent results from lattice QCD that are consistent with a localization transition in the lowest eigenmodes of the Dirac operator. |
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Thursday, March 15, 2007 Note Special Day |
William Detmold [Host: Hank Thacker ] | |
|
4:00 PM, Room 204 Note Special Time |
INT, U. of Washington | |
| Physics Building | “External Fields in Lattice Hadron Physics” |
| Lattice QCD is a numerical method for solving the complicated dynamics of QCD in the non-perturbative, low energy regime, allowing computations of the spectrum and strong interactions of hadrons. To investigate the interactions of these hadrons with the remainder of the Standard Model (leptons and the electro-weak gauge bosons) and physics beyond the Standard Model, external operators must be included. This can be done by calculating hadron matrix elements with explicit operator insertions and generally also using external field techniques. In this second approach, the properties of hadrons are computed in an appropriate classical background field (e.g., electroweak) and their modification from the zero external field case determines the quantity of interest. I will discuss the advantages and disadvantages of this approach giving examples including the electromagnetic and spin polarisabilities of hadrons and the nuclear modification of parton distributions (the EMC effect). |
| Tuesday, March 20, 2007 | Kangkang Kovacs [Host: Donal Day] | |
| 3:30 PM, Room 204 | University of Virginia | |
| Physics Building | “Analysis on the Target Polarization for the study of the GDH Integral on the Deuteron Target” |
| The EG4 experiment at the Jefferson Lab (E12-06-109) studied the GDH (Gerasimov-Drell_Hearn) Sum Rule that relates the difference of the two photoabsorption cross-sections to the anomalous magnetic moment of the proton, deuteron and neutron in the real photon limit. In reality we try to approach the real photon limit by having the Q 2 very small. The experiment used a highly polarized electron beam and longitudinally polarized solid ammonia targets. The analysis to determine the deuteron target polarization using the data acquired from the NMR system will be shown with different analysis methods compared and further target polarization analysis via the scattering asymmetry method is also discussed. |
| Tuesday, April 10, 2007 | Stefan Baessler [Host: Blaine Norum] | |
| 3:30 PM, Room 204 | Johannes Gutenberg Universitat Mainz (Germany) | |
| Physics Building | “Investigating Parity Violation in Neutron Decay ” |
| Precision measurements in neutron decay allow to determine the coupling constants of weak interaction and to test aspects of the Standard Model of Elementary Particle Physics. This is achieved in measurements of the lifetime of the neutron and of several angular correlations in the decay. In my talk I will mainly report about the experiences and results we gained with the spectrometers PERKEO and aSPECT. |
| Tuesday, April 17, 2007 | Michael Carl [Host: Donal Day] | |
| 3:30 PM, Room 204 | University of Virginia | |
| Physics Building | “Measurement of hyperpolarized gas diffusion at very short time scales” |
| Hyperpolarized 3 He diffusion MRI is a powerful tool to probe lung microstructure at a length scale inaccessible by conventional k-space MRI. For short diffusion times, ∆, time dependent diffusion measurements are sensitive to the surface to volume ratio (S/V) of the surrounding structure. Because of the high gas diffusivity (D Xe =0.14cm 2 /s, D He =0.88cm 2 /s) and the small size of alveoli (~200μm), measurement of S/V with the traditional single bipolar diffusion technique is challenging in the lung, since only small diffusion attenuation can be imparted within the short time scale regime (~200μs). Given the significance of short time scale diffusion in the assessment of lung microstructure, we developed a new technique that proves promising to enable such measurements. |
| Tuesday, April 24, 2007 | Mitra Shabestari [Host: Donal Day] | |
| 3:30 PM, Room 204 | University of Virginia | |
| Physics Building | “A Precision Measurement to Test Chiral QCD Dynamics” |
| Experiment E04-007, in Hall A at Jefferson Lab, is a high precision measurement of the reaction P(e,e'P)π 0 from the threshold to 20MeV above, and Q 2 values between 0.04(GeV/c) 2 and 0.14(GeV/c) 2 . The near threshold cross sections are relatively small, which demand high resolution and as large acceptance as possible. Hall A, with the HRS and large acceptance BigBite spectrometer satisfies these requirements. I will talk about BigBite spectrometer, and also explain how the results of this experimen |