Bulletin of the American Physical Society
Joint Fall 2009 Meeting of the Ohio Sections of the APS and AAPT
Volume 54, Number 9
Friday–Saturday, October 9–10, 2009; Delaware, Ohio
Session C4: Nuclear, High-Energy, Biophysics |
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Chair: Robert Kaye, Ohio Wesleyan University Room: Conrades-Wetherell Science Center 151 |
Saturday, October 10, 2009 8:00AM - 8:12AM |
C4.00001: Collective behavior in $^{71}$As R.A. Kaye, C.J. Drover, S.R. Arora, N.R. Baker, S.L. Tabor, T.A. Hinners, C.R. Hoffman, S. Lee, Y. Sun, Y.-C. Yang, J. D{\"o}ring, J.K. Bruckman High-spin states in $^{71}$As were studied using the $^{54}$Fe($^{23}$Na, $\alpha 2 p$) reaction at 80 MeV provided by the John D. Fox superconducting accelerator at Florida State University. Prompt $\gamma$-$\gamma$ coincidences were measured using an array of 10 Compton-suppressed Ge detectors. The yrast band based on the $\pi g_{9/2}$ intrinsic configuration was extended up to a $(\frac{37}{2}^+)$ state and now shows evidence of a band crossing near $\hbar \omega = 0.7$ MeV. Lifetimes of 17 excited states were measured using the Doppler-shift attenuation method applied to the experimental line shapes of decays in three known rotational bands. Transition quadrupole moments $Q_t$ inferred from the lifetimes indicate that moderate to high collective behavior persists to the highest observed spins in the lowest positive- and negative-parity bands. The band suggested to be based on the $\pi f_{7/2}$ orbital shows similar collectivity and large intraband $B(M1)$ strengths, but the associated $Q_t$ values are somewhat smaller than expected from cranked Woods-Saxon calculations. These results will also be compared with the predictions of the projected shell model. [Preview Abstract] |
Saturday, October 10, 2009 8:12AM - 8:24AM |
C4.00002: ABSTRACT WITHDRAWN |
Saturday, October 10, 2009 8:24AM - 8:36AM |
C4.00003: A Simple Model and Unified Theory of Elementary Particles and Interactions (UTOEPI) Ashok Sinha This paper introduces a new paradigm involving the concept of a three-dimensional time (3-D T) which, together with the usual three-dimensional space (3-D S), forms a six-dimensional space-time (6-D ST) continuum for describing super-high energy (Planck scale) elementary particle and cosmological phenomena. The inevitability of introducing such a view of the relativistic space-time continuum is highlighted for an arbitrary relative velocity between any two frames of reference. For a spherically symmetric system, this leads to the notion of a 5- sphere topology. In this framework, a heuristic model and a simple theory of elementary particles and the four basic interactions (strong, weak, electromagnetic and gravitational) is developed, including a simplistic parametric representation of the elementary particle masses in terms of the basic parameters of these interactions, in linear and quadratic approximations. The questions of supersymmetry and the Higgs field are briefly discussed as self-consistent extensions of the model. Development of a statistical theory (Maxwell-Boltzmann Equation) of a relativistic ensemble of quark-gluon type plasma in the conventional manifestly 4-covariant and the new manifestly 6-covariant frameworks is also formulated to indicate the interrelations among the four interactions in a simple manner. [Preview Abstract] |
Saturday, October 10, 2009 8:36AM - 8:48AM |
C4.00004: The Weak Mixing Matrix Vic Dannon, Robert Levine We show that the Weak Mixing Matrix, $ \left( {\begin{array}{*{20}c} {U_{ud} } & {U_{us} } & {U_{ub} } \\ {U_{cd} } & {U_{cs} } & {U_{cb} } \\ {U_{td} } & {U_{ts} } & {U_{tb} } \\ \end{array}} \right)$ , is not equal to the product of rotations, and in particular, it is not equal to the KM, or the PDG Matrices. \par \noindent At most, we may find an approximating matrix for the Weak Mixing Matrix that is based on the rotation matrices. \par \noindent We show that one such approximating matrix for the Real part of the Weak Mixing Matrix is $$\left( {\begin{array}{*{20}c} {\cos \theta _C \cos \theta _C^3 } & {\sin \theta _C \cos \theta _C^3 } & {\sin ^3 \theta _C \cos \theta _C^2 } \\ { - \sin \theta _C \cos \theta _C^2 } & {\cos \theta _C \cos \theta _C^2 } & {\sin ^2 \theta _C } \\ { - \cos \theta _C \sin ^3 \theta _C } & { - \cos \theta _C \cos \theta _C^3 \sin ^2 \theta _C } & {\cos \theta _C^2 \cos \theta _C^3 } \\ \end{array}} \right),$$ where $\theta _C $ is the Cabbibo angle. \par \noindent The approximating matrix depends on $\theta _C $ alone, and predicts the Real part of the Weak Mixing Matrix to a high degree of accuracy. \par \noindent We establish, with a Chi-Squared Goodness-of- Fitness-Test, that our approximating matrix can be used with extremely high level of statistical confidence. [Preview Abstract] |
Saturday, October 10, 2009 8:48AM - 9:00AM |
C4.00005: All-or-none protein-like folding of a homopolymer chain Mark Taylor, Wolfgang Paul, Kurt Binder Many small proteins fold via a first-order ``all-or-none'' transition directly from an expanded coil to a compact native state. Here we report an analogous direct freezing transition from an expanded coil to a compact crystallite for a simple flexible homopolymer. Wang-Landau sampling is used to construct the complete density of states for square-well chains up to length 256. Analysis within both the microcanonical and canonical ensembles shows that, for a chain with sufficiently short-range interactions, the usual polymer collapse transition is preempted by a direct freezing transition. Despite the non-unique homopolymer ground state, the thermodynamics of this direct freezing transition are identical to the thermodynamics of two-state protein folding. A free energy barrier separates a high entropy ensemble of unfolded states from a low entropy set of crystallite states and the transition proceeds via the formation of a transition-state folding nucleus. An Arrhenius analysis of the folding/unfolding free energy barrier yields a Chevron plot characteristic of proteins and the model chain satisfies the van't Hoff calorimetric criterion for two-state folding. [Preview Abstract] |
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