Bulletin of the American Physical Society
2015 Fall Meeting of the APS Division of Nuclear Physics
Volume 60, Number 13
Wednesday–Saturday, October 28–31, 2015; Santa Fe, New Mexico
Session HG: Electromagnetic Interactions |
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Chair: Harut Avagyan, Thomas Jefferson National Accelerator Facility Room: Peralta |
Friday, October 30, 2015 8:30AM - 8:42AM |
HG.00001: Quasielastic Transverse and Longitudinal Response Functions in the range 0.55 GeV/c$\leq \mid \overrightarrow{q}\mid\leq$1.0 GeV/c Hamza Atac In order to determine the Coulomb sum in nuclei, a precision measurement of inclusive electron scattering cross sections in the quasi-elastic region was performed at Jefferson Lab. Incident electrons with energies ranging from 0.4 GeV to 4 GeV scattered from $^{4}He$,$^{12}C$,$^{56}Fe$ and $^{208}Pb$ nuclei at four scattering angles ($15^{\circ},60^{\circ},90^{\circ},120^{\circ}$) and scattered energies ranging from 0.1 GeV to 4 GeV. A Rosenbluth separation method is performed to extract the transverse and longitudinal response functions at three-momentum transfers in the range 0.55 GeV/c$\leq \mid \overrightarrow{q}\mid\leq$1.0 GeV/c. The Coulomb Sum is obtained for $^{56}Fe$ and $^{12}C$ ,and compared to predictions. We will present the results and discuss their impact in regard to short range nucleon-nucleon correlations and as well as the possible modification of the nucleon electromagnetic properties in the nuclear medium. [Preview Abstract] |
Friday, October 30, 2015 8:42AM - 8:54AM |
HG.00002: Boost Effects in the (e,e') Transverse Response of $^3$He Edward Tomusiak, Victor Efros, Winfried Leidemann, Giuseppina Orlandini, Luping Yuan In an earlier paper Efros {\it et al} [1] investigated frame dependence in calculations of the transverse (e,e') response function of $^3$He. These calculations were non-relativistic but did incorporate relativistic corrections in the electromagnetic operators. Those corrections, taken from the work of Ritz et al [2] are of order M$^{-3}$ and represent kinematical effects. It was found that in the region of the quasi-elastic peak, with one proviso, frame dependence held to a good approximation up to q=700 MeV/c. The one proviso was that we not include one of the corrections - the so-called $\omega$-dependent term. Although this term vanishes in one of the frames (the ANB frame) the question arises as to whether or not another correction exists which might nearly restore frame independence. This work investigates the possibility that Boost effects may provide an explanation. We report on our progress in this regard.\\[4pt] [1] Victor. D. Efros, Winfried Leidemann, Giuseppina Orlandini, Edward Tomusiak, Phys.Rev.{\bf C 83}, 057001 (2011).\\[0pt] [2] F. Ritz, H. G\"oller, T. Wilbois, and H. Arenh\"ovel, Phys.Rev.{\bf C55}, 2214 (1997). [Preview Abstract] |
Friday, October 30, 2015 8:54AM - 9:06AM |
HG.00003: Elastic Compton Scattering from the Deuteron Near 100 MeV Michael Kovash, Khayrullo Shoniyozov Differential cross sections for elastic Compton scattering from targets of carbon and deuterium have been measured from 86 to 113 MeV using a tagged bremsstrahlung beam at the MAX 1 electron storage ring in Lund, Sweden. Photon spectra were collected in 2009 and 2010 at scattering angles of 60, 120 and 150 degrees using three very large, high efficiency NaI spectrometers, each with a FWHM resolution of approximately 2 MeV. The deuterium target consisted of a cryogenic liquid cell of 17 cm length. Improvements made to the running conditions of previous MAX-lab data sets include the use of multi-hit time digitizers, and reduced instantaneous counting rates in both the tagging and the NaI detectors. GEANT4 simulations have been used to determine the photon detector response and efficiency, as well as the photon losses in the targets. The overall accuracy of this procedure is verified by comparing the current carbon results with previous data. The new deuterium cross sections will be presented and compared with the earlier results from this collaboration. The combined data set will be compared with recent Chiral Effective Field Theory calculations to determine the values of the neutron polarizabilities, $\alpha_n$ and $\beta_n$. [Preview Abstract] |
Friday, October 30, 2015 9:06AM - 9:18AM |
HG.00004: Momentum Distributions for $^2H(e,e'p)$ Sabine Jeschonnek, William P. Ford, J.W. Van Orden A primary goal of deuteron electro-disintegration is the possibility of extracting the deuteron momentum distribution. This extraction is inherently fraught with difficulty, as the momentum distribution is not an observable and the extraction relies on theoretical models dependent on other models as input. We present a new method for extracting the momentum distribution which takes into account a wide variety of model inputs thus providing a theoretical uncertainty due to the various model constituents. To test the extraction, pseudo-data was generated, and the extracted ``experimental'' distribution, which has theoretical uncertainty accounted by this extraction method, can be compared to the theoretical distribution. The calculations presented here are using a Bethe-Salpeter like formalism with a wide variety of bound state wave functions, form factors, and final state interactions. Our method takes into account the theoretical uncertainty from the various model constituents entering the calculation. In the examples we compared, the original distribution was typically within the error band of the extracted distribution. The input wave functions do contain some outliers which are discussed in the talk. [Preview Abstract] |
Friday, October 30, 2015 9:18AM - 9:30AM |
HG.00005: The spectral function of $^{40}$Ar through the $\mathbf{(e,e^{\prime p})}$ reaction Donal Day Accelerator based neutrino-oscillation measurements, where neutrinos interact predominantly with nucleons bound in nuclei, demand an accurate description of the cross sections. Nuclear effects play a decisive role and are considered one of the main sources of systematic uncertainties. An effort is underway to develop theoretical models capable of a fully quantitative description of the neutrino-nucleus cross sections. An approach based on many body theory has proven successful in explaining electron-nucleus cross sections. The application of this approach to the analysis of neutrino interactions will require accurate models of the spectral functions for the nuclei in neutrino detectors. Of paramount importance is $^{40}$Ar, to be used in the Deep Underground Neutrino Experiment (DUNE, formerly LBNE). A $^{40}Ar(e,e^{\prime} p)$ experiment which will prove indispensable for the construction of the argon spectral function has been approved at Jefferson Lab. The $(e,e^{\prime p})$ data, in addition, will advance theoretical developments, including the description of final-state interactions, unavoidable in neutrino experiments. The motivation, goals, experimental details and plans for the execution of this measurement will be discussed. [Preview Abstract] |
Friday, October 30, 2015 9:30AM - 9:42AM |
HG.00006: Measurement of the Response Function of a BC501A Neutron Detector J. Miller, D. Alexander, A. Daniel, E.V. Hungerford, M.W. Ahmed, M. Sikora A 5'' X 2'' BC501A neutron detector was used to measure proton recoil spectra at a number of mono-energetic incident neutron energies between 2 and 6 MeV at the Triangle Universities Nuclear Laboratory. The goal of the experiment was to characterize the response function for a variety of known neutron energies so that an unknown neutron spectrum can be obtained by unfolding the detector response to the incident spectrum. We discuss calibration, optimization of the neutron-gamma discrimination, and the progress of the analysis. [Preview Abstract] |
Friday, October 30, 2015 9:42AM - 9:54AM |
HG.00007: Quark distributions at $x>1$ Nadia Fomin Inclusive lepton scattering has been used to measure nuclear structure functions from a Q$^2$ of a few to 200 GeV$^2$. We have previously used target-mass corrections to remove scaling violations for finite Q$^2$, yielding excellent agreement between almost all existing data sets. We will present our recent analysis of nuclear structure functions at high $x$ in terms of QCD and discuss possible sources of remaining disagreement as well as upcoming measurements. [Preview Abstract] |
Friday, October 30, 2015 9:54AM - 10:06AM |
HG.00008: Fermion Mass Renormalization Using Time-dependent Relativistic Quantum Mechanics Timothy Kutnink, Amelia Santrach, Sarah Hocket, Scott Barcus, Athanasios Petridis The time-dependent electromagnetically self-coupled Dirac equation is solved numerically by means of the staggered-leap-frog algorithm with refcecting boundary conditions. The stability region of the method versus the interaction strength and the spatial-grid size over time-step ratio is established. The expectation values of several dynamic operators are then evaluated as functions of time. These include the fermion and electromagnetic energies and the fermion dynamic mass, as the self-interacting spinors are no longer mass-eigenfunctions. There is a characteristic, non-exponential, oscillatory dependence leading to asymptotic constants of these expectation values. In the case of the fermion mass this amounts to renormalization. The dependence of the expectation values on the spatial-grid size is evaluated in detail. Statistical regularization is proposed to remove the grid-size dependence. [Preview Abstract] |
Friday, October 30, 2015 10:06AM - 10:18AM |
HG.00009: Negative Entropy of Life Shantilal Goradia We modify Newtonian gravity to probabilistic quantum mechanical gravity to derive strong coupling. If this approach is valid, we should be able to extend it to the physical body (life) as follows. Using Boltzmann equation, we get the entropy of the universe (137) as if its reciprocal, the fine structure constant (ALPHA), is the hidden candidate representing the negative entropy of the universe which is indicative of the binary information as its basis (http://www.arXiv.org/pdf/physics0210040v5). Since ALPHA relates to cosmology, it must relate to molecular biology too, with the binary system as the fundamental source of information for the nucleotides of the DNA as implicit in the book by the author: ``Quantum Consciousness - The Road to Reality.'' We debate claims of anthropic principle based on the negligible variation of ALPHA and throw light on thermodynamics. We question constancy of G in multiple ways. [Preview Abstract] |
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