Bulletin of the American Physical Society
76th Annual Meeting of the Southeastern Section of APS
Volume 54, Number 16
Wednesday–Saturday, November 11–14, 2009; Atlanta, Georgia
Session NB: Intermediate and High Energy Nuclear Physics |
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Chair: Murad Sarsour, Georgia State University Room: Frankfurt |
Saturday, November 14, 2009 8:30AM - 8:42AM |
NB.00001: Probing the Short-Distance Structure of the Nucleus Vince Sulkosky, Douglas Higinbotham One of Jefferson Lab's original missions was to further our understanding of the short-distance structure of nuclei. In particular, to understand what happens when two or more nucleons within a nucleus have strongly overlapping wave-functions; a phenomena commonly referred to as short-range correlations. During this talk, I will review recent, momentum transfer greater than 1 [GeV/c]2 and Bjorken x greater than 1, (e,e') and (e,e'pN) data that have been used to probe the short-distance structure of the nucleus. In addition, the two short-range correlation experiments that are schedule to run in 2011 will be discussed. [Preview Abstract] |
Saturday, November 14, 2009 8:42AM - 8:54AM |
NB.00002: Understanding the Three-Body System via Quasi-Elastic Electron Scattering Ge Jin Understanding the dynamics of the 3He system is crucial for nuclear physics experiments that wish to use 3He as an effective neutron target: such as for the extraction of the neutron's electric form factor. Within theoretical models, the percentage of the S, S' and D states in the 3He ground-state wave-function can be calculated and have been shown to be sensitive to observable double-spin asymmetries. Jefferson Lab experiment E05-102 measured the polarized-target and polarized beam asymmetries in the quasi-elastic 3He(e,e') 3He(e,e'p), 3He(e,e'd) and 3He(e,e'n) channels. An overview experiment will be discussed and preliminary (e,e'p) asymmetries as a function of missing momentum will be presented. [Preview Abstract] |
Saturday, November 14, 2009 8:54AM - 9:06AM |
NB.00003: The Jefferson Lab Hall C Hypernuclear spectroscopy program Joerg Reinhold The Jefferson Lab HKS/HES Collaboration studies the electroproduction of $\Lambda$-hypernuclei in the (e,e'K$^+$) reaction, with a resolution of $\approx$400 keV (FWHM), a record for reaction spectroscopy. Ordinary nuclei are composed of protons and neutrons which in turn contain up and down quarks. A hypernucleus contains a hyperon, which contains a strange quark, implanted as an ``impurity'' within the nuclear medium. Precise information about the mass and excitation energies of hypernuclei allows one to infer the underlying hyperon-nucleon interaction, which is not yet well known. Further, it is believed that neutron stars might contain hyperons. Hypernuclear data will also constrain current models of neutron stars. In experiment E01-011 we obtained spectroscopic data on $^{12}C$, $^{28}$Si and a series of light targets. In Fall 2009, we will run experiment E05-115, an investigation of a medium heavy target, $^{51}$Cr. The talk will outline the experimental technique, present results from E01-011 and preliminary data from the just completed E05-115 run. [Preview Abstract] |
Saturday, November 14, 2009 9:06AM - 9:18AM |
NB.00004: Rare decays of $\Lambda_b$ baryons in a quark model Lonnie Mott, Winston Roberts The exclusive rare decays $\Lambda_b \rightarrow \Lambda^{(*)}\gamma$ and $\Lambda_b \rightarrow \Lambda^{(*)}\ell^{+}\ell^{-}$ are treated in the framework of a constituent quark model. By use of single component wavefunctions, the hadronic form factors for the vector, axial vector and tensor currents are derived analytically. The decay rates and forward-backward asymmetries are calculated with and without charmonium resonance contributions for the dileptonic decays. The branching ratios for these decays are also reported. [Preview Abstract] |
Saturday, November 14, 2009 9:18AM - 9:30AM |
NB.00005: Strong Decays of Heavy Baryons in the ${ }^3P_0 $ Model Benjamin Eakins Strong decays of heavy Lambda baryons are examined using the ${ }^3P_0 $ non-relativistic quark model. Specifically, the decay widths for the processes $\Lambda _b^\ast \to \Sigma _b \pi $ and $\Lambda _c^\ast \to \Sigma _c \pi $ are calculated. The results for the charmed Lambda decays will be compared with experiment. [Preview Abstract] |
Saturday, November 14, 2009 9:30AM - 9:42AM |
NB.00006: J/Psi Flow analysis for Au+Au data from PHENIX Abhisek Sen In 1986 Matsui and Satz predicted that $J/{\Psi}$ will be suppressed by Quark Gluon Plasma (QGP) due to color screening, which will prevent binding $c\bar{c}$ pair and lead to $J/{\Psi}$ suppression [1]. Many different experimental groups have studied the $J/{\Psi}$ production meachanisms in relativistic heavy ion collisions since then. In recent years, at Relativistic Heavy Ion Collider (RHIC), both PHENIX and STAR collaborations have reported $J/{\Psi}$ results from Au+Au and p+p collision. The elliptic flow study [2] is one of the most important tools to understand the initial state of matter created at heavy ion collisions. Recent reasults show a strong quark scaling property of $v_{2}$ from the measured baryons and mesons at RHIC. These results indicate fast initial state thermalization of the colliding nuclei. In this work, I am going to present the current status of $J/{\psi}$ flow measurement from its dimuon decay channel at forward rapidity in Au+Au collision at center of mass energy per nucleon nucleon collision $\sqrt{s}=200$ GeV. \\[4pt] [1] T. Matsui and H. Satz, Physics Letters B {\bf 178}, 4, (1986) \\[0pt] [2] A.M.Poskanzer and Voloshin, Physical Review {\bf 58}, 3, (1998)\\[0pt] [3] A. Adare, et al (PHENIX), PRL 98,232301 (2007) [Preview Abstract] |
Saturday, November 14, 2009 9:42AM - 9:54AM |
NB.00007: Particle and Anti-particle Effect to the Bound-State in Light-Front Dynamics Yukihisa Tokunaga, Chueng Ji Solving the relativistic bound-state problem is an important task in nuclear physics. Even the two-body bound-state problem has been solved only under a certain approximation due to the nonperturbative nature. The two-body Bethe-Salpeter equation in the Wick-Cutkosky model was often solved in the ladder approximation without including the cross-ladder contribution, although many different and more accurate treatments of the numerical method to solve the bound-state problem have been developed nowadays. In this presentation, we use the light-front dynamics (LFD) to solve the two-body bound-state problem and extend the light-front ladder approximation to include the cross-ladder contribution. In particular, we include the particle and antiparticle effect to the cross-ladder contribution. Using the variational principle, we present the numerical result of the binding energy versus the coupling constant and discuss the effect from the particle and antiparticle intermediate state. [Preview Abstract] |
Saturday, November 14, 2009 9:54AM - 10:06AM |
NB.00008: Electromagnetic Nucleus - Nucleus Cross Sections Using Energy Dependent Branching Ratios Anne Adamczyk, John Norbury Energy dependent branching ratios, derived from Weisskopf-Ewing theory, are presented and compared to an energy independent formalism, developed by Norbury, Townsend, and Westfall. The energy dependent branching ratio formalism is more versatile since it allows for not only neutron and proton emission, but also alpha particle, deuteron, helion, and triton emission. A new theoretical method for calculating electromagnetic dissociation (EMD) nucleus - nucleus cross sections, with energy dependent branching ratios, is introduced. Comparisons of photonuclear and nucleus - nucleus cross sections, using energy dependent and independent branching ratios, to experiment are presented. Experimental efforts, by various groups, have focused on measuring cross sections for proton and neutron emission, because proton and neutron emission is generally more probable than heavier particle emission. Consequently, comparisons of energy dependent and independent branching ratios to experiment are made for photoneutron and photoproton cross sections. EMD cross sections for single neutron, proton, and alpha particle removal are calculated and compared to experimental data for a variety of projectile, target, and energy combinations. Results indicate that using energy dependent branching ratios yields better estimates. [Preview Abstract] |
Saturday, November 14, 2009 10:06AM - 10:18AM |
NB.00009: Cosmic Ray Flux Measurements with a Muon Detector System Christopher Oakley A muon detector was used to measure the cosmic ray flux in the Natural Science Center (NSC) building on the Georgia State University campus. The detector measures the flux of cosmic ray muon as well as the energy-loss within the detector components. The detector was run on the third, fourth, and fifth floors of the building to determine if there is a significant change in muon flux. A simulation, the Mu II code, was designed to emulate the physics processes that occur in a cosmic ray shower. The goal of the Mu II code is to accurately simulate cosmic ray shower events and provide greater understanding of the physics to which they are related as well as introduce scientific inquiry and interest to students and educators. The results of the simulation are consistent with the data, showing similarities in energy loss distribution and a positive indication of shielding effects. [Preview Abstract] |
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