Bulletin of the American Physical Society
2007 APS April Meeting
Volume 52, Number 3
Saturday–Tuesday, April 14–17, 2007; Jacksonville, Florida
Session C15: Nuclear Physics Studies with Light Nuclei |
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Sponsoring Units: DNP Chair: Betty Tsang, Michigan State University Room: Hyatt Regency Jacksonville Riverfront City Terrace 11 |
Saturday, April 14, 2007 1:30PM - 1:42PM |
C15.00001: ABSTRACT WITHDRAWN |
Saturday, April 14, 2007 1:42PM - 1:54PM |
C15.00002: Spectroscopic factors of excited states for sd shell nuclei Jenny Lee, Betty Tsang, Bill Lynch, Shi Chun Su Numerous experiments have been performed to extract spectroscopic factors (SFs) in the last 40 years. However, the criteria used to extract SFs differ from experiments to experiments, making comparison of experimental SFs to theoretical calculations difficult. Recently, a consistent criterion has been adopted to analyze the neutron ground state SFs from a wide range of nuclei from Z=3-24 [1]. We have extended this method to analyze the neutron SF from excited states for sd shell nuclei as well as for Ni and Sn isotopes. Preliminary results suggest that the systematic agreement between the experimental SF and shell model predictions may be used to confirm the spin of some excited states when there are ambiguities in the spin assignments. Comparisons of the results with shell model calculations with different residual interactions will be presented. Reference: [1] M.B. Tsang et al., Phys. Rev. Lett. 95 (2005) 222501 [Preview Abstract] |
Saturday, April 14, 2007 1:54PM - 2:06PM |
C15.00003: Short Range correlations in 3He(e,e$'$pp)n Hovhannes Baghdasaryan Nucleon-Nucleon (NN) Short Range Correlations (SRC) represent a valuable part of the nuclear wave function. The better knowledge of SRC will give us better understanding of nuclear matter and nuclear interactions in extreme conditions. A study of the effects of short-range correlations over the 3He(e,e$'$pp)n reaction measured at Jefferson Lab is presented. Two different approaches selected to in investigate correlation effect in nuclear matter. Looking at the reaction, we can extract the kinematic regions where the NN SRC is an almost non interacting spectator pair. We have measured the relative and total momentum distributions of spectator (pp) and (pn) pairs up to 600 MeV/c. We will compare results with various theories. [Preview Abstract] |
Saturday, April 14, 2007 2:06PM - 2:18PM |
C15.00004: Numerical Estimates of \mbox{$^3 \textrm{He} (e,e'pp)n$} Reaction at High $Q^2 $ Tigran Abrahamyan Final state interactions in high-energy electrodisintegration of $^3\textrm{He}$ described in the Generalized Eikonal Approximation which allows one to account for the internal motion of the target nucleons otherwise neglected in the conventional Glauber approximation. Numerical calculations of the residual system's total and relative momentum distribution performed within the formalism of decay function, which represents a generalization of the conventional spectral function. Theoretical calculations successfully compared with the 4.4 GeV electron beam data of \mbox{$^3 \textrm{He} (e,e'pp)n$} experiment performed in Jefferson Lab Hall B using nearly 4$\pi$ CLAS magnetic spectrometer. [Preview Abstract] |
Saturday, April 14, 2007 2:18PM - 2:30PM |
C15.00005: Spectroscopic Study of $\Lambda $ Hypernuclei using the (e,e'K$^{+})$ Reaction Leon Cole The ``Spectroscopic Study of $\Lambda $ Hypernuclei up to the Medium-Heavy Mass Region Through the (e,e'K$^{+})$ Reaction'' (HKS Experiment) was successfully completed during the summer of 2005 at Jefferson Laboratory. It utilized a new High Resolution Kaon Spectrometer (HKS) and a ``Tilt Method'' to the electron arm aiming to achieve the best ever resolution and the highest possible production yield of $\Lambda $Hypernuclei. The goal of the experiment is to investigate $\Lambda $ hypernuclear structures with precise measurements of the mass spectra from light to medium-heavy mass region. Such precise spectroscopy will provide valuable information on the single-particle behavior of $\Lambda $ hyperon in a nuclear medium, gain knowledge on the effective $\Lambda $-N interaction, and nuclear structure probed by the $\Lambda $ hyperon. An overview of HKS experiment will be presented and preliminary results of the excitation spectra from various targets will be showcased. [Preview Abstract] |
Saturday, April 14, 2007 2:30PM - 2:42PM |
C15.00006: JLab E05-115: hypernuclear spectroscopy in a wider mass region Lulin Yuan The ability of electroproduction in obtaining high resolution hypernuclear spectroscopy by using high precision electron beam has been demonstrated by recent results of hypernuclear spectra of $^{12}_\Lambda$B, $^{16}_\Lambda$N, $^{28}_\Lambda$Al, etc. from Jefferson Lab. JLAB E05-115, a newly approved and upgraded experiment currently under preparation in JLab Hall C, will expand hypernuclear spectroscopy to a wider mass region (A=6$\sim$52). High resolution hypernuclear spectroscopy for medium heavy to heavy hypernuclei will enable us to extract the spin dependent $\Lambda$-N interaction beyond p-shell and help to understand the role of strangeness in dense nuclear matter. In the light mass region, hypernuclear spectroscopy by electroproduction can produce neutron rich and mirror hypernuclei that helps us to understand the effect of Charge Symmetry Breaking and reveal new nuclear structure aspects induced by strangeness. Experimental setup of E05-115 is optimized based on the experiences learned from two previous Hall C hypernuclear experiments. It will replace the electron spectrometer of the previous HKS experiment by a large acceptance, high resolution HES spectrometer. The physics motivation, experimental setup and current status of E05-115 will be presented. [Preview Abstract] |
Saturday, April 14, 2007 2:42PM - 2:54PM |
C15.00007: New Cross Section Data for the $^{10}B(d,n_0)^{11}C$ Reaction Below 160 keV S. Stave, M.W. Ahmed, M.A. Blackston, A.S. Crowell, S.S. Henshaw, C.R. Howell, P. Kingsberry, B.A. Perdue, H.R. Weller, B.L. Doyle, P. Rossi, A.J. Antolak, R.M. Prior, M.C. Spraker New data were taken recently at TUNL to investigate the plausibility of using low energy deuterons and the $^{10}B(d,n)^{11}C$ reaction as a source of 6.3 MeV neutrons. A preliminary analysis of the data at and below incident deuteron energies of 160 keV indicates an $n_0$ neutron cross section that is lower than previous estimates by at least two orders of magnitude. In separate runs, deuterons with three different energies (160, 140 and 120 keV) impinged on a thin layer of $^{10}B$ and were stopped in the target. The resulting 6.3 MeV $n_0$ neutrons were detected at 8 angles between 0$^{\circ}$ and 150$^{\circ}$. The angle integrated yields were used to determine the astrophysical $S$ factor for this reaction assuming a constant value for the $S$ factor. The reported cross sections below 160 keV are calculated using the extracted value of the $S$ factor. [Preview Abstract] |
Saturday, April 14, 2007 2:54PM - 3:06PM |
C15.00008: Evidence for New Structures in $^{17}$O A.M. Crisp, K.W. Kemper, O. Momotyuk, B.T. Roeder, N. Keeley In an effort to confirm that certain strongly excited states in $^{17}$O are selectively populated by four and five-particle reactions and are the result of direct, single-step transfer, spectra and angular distributions have been obtained for the reactions $^{16}$O(d,p)$^{17}$O, $^{13}$C($^{6}$Li,d)$^{17}$O, $^{12}$C($^{7}$Li,d)$^{17}$O, and $^{12}$C($^{6}$Li,p)$^{17}$O$^{2}$. Strong states seen in the five particle transfer reactions at 11.82, 12.00, 12.22 and 12.42 MeV are very weakly populated in $^{16}$O(d,p) showing that they have very little single particle strength. Excitation functions were also measured for $^{12}$C($^{7}$Li,d) in the energy range 32-35 MeV and for $^{12}$C($^{6}$Li,p) in the energy range 26-32 MeV. The same strong states were observed at each energy. These data were collected using the FSU Tandem/LINAC accelerator. The angular distributions for the strong states are well described by DWBA calculations yielding further support for five-particle single-step transfer. $^{2}$M.J. Smithson, D.L. Watson, and H.T. Fortune, J.Phys.G, Nucl. Phys. 12 (1986) 985. [Preview Abstract] |
Saturday, April 14, 2007 3:06PM - 3:18PM |
C15.00009: Coupled SU(3) models of rotational states in nuclei and quasi-dynamical symmetry Gabriela Thiamova, David J. Rowe This contribution reports a first step towards the development of a model of low-lying nuclear collective states based on the progression from weak to strong coupling of a combination of systems in multiple SU(3) irreps. The motivation for such a model comes partly from the remarkable persistence of rotational structure observed experimentally and in many model calculations. This work considers the spectra obtainable by coupling just two SU(3) irreps via a quadrupole-quadrupole interaction. For a particular value of this interaction, the two irreps combine to form strongly-coupled irreps while for zero interaction the weakly-coupled results are mixtures of many such strongly-coupled irreps. A notable result is the persistence of the rotor character of the low-energy states for a wide range of the interaction strength. Also notable is the fact that, for very weak interaction strengths, the energy levels of the yrast band resemble those of a vibrational sequence while the B(E2) transition strengths remain close to those of an axially symmetric rotor, as observed in many nuclei. An application to shape coexistence in $^{16}$O is considered to show that the model gives a qualitative indication of which \textit{np-nh} states are likely to contribute to the low-energy states of nuclei. [Preview Abstract] |
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