Bulletin of the American Physical Society
12th Annual Meeting of the Northwest Section of the APS
Volume 55, Number 6
Friday–Saturday, October 1–2, 2010; Walla Walla, Washington
Session C1: Particle and Nuclear Physics |
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Chair: Harry Miley, Pacific Northwest National Laboratory, and Mary Alberg, Seattle University Room: Science 276 |
Friday, October 1, 2010 1:30PM - 2:06PM |
C1.00001: The hunt for Low Mass Dark Matter with CoGeNT Invited Speaker: The past year has revealed tantalizing hints of potential direct detection of Dark Matter. I will report on recent results from the CoGeNT collaboration using innovative P-Type Point Contact Germanium detectors deployed at Soudan, MN. The ultra-low energy threshold of the detector and excellent energy resolution allow CoGeNT to push into the previously unexplored low-mass region. I will present technological highlights, the most recent results from the search and place them in the broader context of the experimental Dark Matter field. [Preview Abstract] |
Friday, October 1, 2010 2:06PM - 2:42PM |
C1.00002: In a muon's lifetime: From Fermi's constant to ``calibrating" the sun Invited Speaker: This presentation will cover three experiments at the Paul Scherrer Institute, Switzerland, all measuring the muon lifetime with high precision. The MuLan experiment [2] uses a simple soccer-ball like scintillator array to detect the positrons from the decay of positive muons. We collected twice 10$^{12}$ muon decays in two different target materials to obtain the final precision of 1 ppm for the lifetime. This determines the Fermi constant G$_{F}$ to 0.5 ppm precision [1]. The muon capture experiment MuCap uses a negative muon beam stopped in a time projection chamber as an active target filled with ultra-pure hydrogen gas. The elementary capture process $\mu ^{-}$+p $\to $ n+$\nu $ offers a rare (0.15{\%}) additional disappearance channel. The measured difference of the positive and negative muon's lifetime determines the rate of the capture process to a final precision of 1{\%}. This can be used to derive an improved value of the proton's pseudoscalar form factor g$_{P}$ to 7{\%} precision. A first result g$_{P}$ = 7.3 $\pm $ 1.1 has been published [3]. This is a first precise, unambigous determination of g$_{P}$ and an important test of QCD symmetries. Recently, we started a new experiment, MuSun [4] to measure the $\mu ^{-}$+d $\to $ n+n+$\nu $ doublet capture rate. This measurement will provide a benchmark of the understanding of weak processes in the two nucleon-system. It was shown, that other weak reactions involving the two nucleon system (pp $\to $ de$^{+}\nu $ or $\nu $+d reactions) are related to the same low-energy constant, characterizing the two nucleon system at short distances. This constant is not well constrained and therefore the MuSun experiment comes closest to calibrating these basic astrophysical reactions under terrestrial conditions. \\[4pt] [1] In preparation for publication\\[0pt] [2] Phys. Rev. Lett. 99, 032001 (2007)\\[0pt] [3] Phys. Rev. Lett. 99, 032002 (2007)\\[0pt] [4] http://www.npl.uiuc.edu/exp/musun/documents/prop07.pdf [Preview Abstract] |
Friday, October 1, 2010 2:42PM - 3:18PM |
C1.00003: Lattice QCD Study on Hadron Interactions Invited Speaker: To understand the nature of matter from the everyday nuclei of atoms on Earth to the exotic matter in dense stellar environments, we must study the strong interactions between hadrons. In this talk, I will review recent progress on calculating hadron interactions directly from quantum chromodynamics (QCD) using integration over discrete four-dimensional spacetime lattices. I will cover selected scattering processes within the light-hadron sector and also some including charmed mesons and charmonia. Finally, I will sketch out the effort to perform few-body calculations and discuss the prospects for future developments. [Preview Abstract] |
Friday, October 1, 2010 3:18PM - 3:33PM |
C1.00004: BREAK
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Friday, October 1, 2010 3:33PM - 3:45PM |
C1.00005: Study of Nuclear Resonance Spacing for Spherical Nuclei A.N. Behkami Neutron resonance data are the most extensive source of information on nuclear level densities. In this type of experiment the nuclear energy levels are observed at about neutron binding energy, and the number of levels is obtained by counting the resonance in a particular neutron energy intervals. Level spacing information has been obtained from slow neutron resonances (s-wave) data for nuclei with A-values across the whole periodic table. A number of authors have analyzed the neutron resonance data with a Bethe type formula. Although several of these comparisons were reasonably successful, the degree of their success depends in large part on adjustable parameters. In the present study we have made a comparison of the nuclear level spacing calculated with a microscopic theory of interacting fermions. In particular we have investigated the A (mass number) dependence of the level density at essentially constant excitation energy, normally the neutron binding energy. The ratio D$_{Theo}$/D$_{Exp }$for more than hundred nuclei has been determined. It is found the average value of D$_{Theo}$/D$_{Exp}$ depends on the magnitude of nuclear pairing and shell. The effect of nuclear pairing and shell will be presented and discussed. [Preview Abstract] |
Friday, October 1, 2010 3:45PM - 3:57PM |
C1.00006: Mirnov Coil Analysis by Singular Value Decomposition Method in IR-T1 Tokamak Mohammad K. Salemi, Shervin Saadat, Mahmoud Ghoranneviss, Alireza Tabadar The spatial and temporal structures of magnetic signal in the tokamak is analyzed using recently developed singular value decomposition (SVD) technique to determine the structure of current perturbation as the discharge progresses. In this work we use SVD technique for that purpose in IR-T1 tokamak.\footnote{C. Nardonet, ``Multichannel Fluctuation Data Analysis By The Singular Value Decomposition Method Application To MHD Modes In Jet,'' Plasma Physics {\&} Controlled Fusion, V. 34, No. 9, 1992, 1447-1465} [Preview Abstract] |
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