Bulletin of the American Physical Society
2010 Fall Meeting of the APS Division of Nuclear Physics
Volume 55, Number 14
Tuesday–Saturday, November 2–6, 2010; Santa Fe, New Mexico
Session NF: Post-deadline Session |
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Chair: Peter Moller, Los Alamos National Laboratory Room: Kearney |
Saturday, November 6, 2010 10:30AM - 10:42AM |
NF.00001: $\pi $N P$_{11}$ Revival Igor Strakovsky We discuss some difficulties associated with resonance identification in $\pi$N elastic and other two-body reactions, in particular the Roper and higher P$_{11}$ states. [Preview Abstract] |
Saturday, November 6, 2010 10:42AM - 10:54AM |
NF.00002: Quantum Statistics and Astrophysical Photodisintegration Rates Grant Mathews, Yamac Pehlivan, Toshitaka Kajino, Baha Balantekin Tabulated rates for astrophysical photodisintegration reactions make use of Boltzmann statistics for the photons as well as the interacting nuclei. Here we derive analytic corrections for the Planck-spectrum quantum statistics of the photon energy distribution. These are deduced directly from the detailed-balance condition without the assumption of equilibrium. We show that these corrections affect not only the photodisintegration rates but also modify the conditions of nuclear statistical equilibrium. We deduce new analytic corrections to the classical Maxwell- Boltzmann statistics which can easily be added to existing reaction network tabulations. We show that the effects of quantum statistics, though generally small, always tend to speed up photodisintegration rates and become significant for nuclei and environments for which $Q/kT \la 5$. We examine possible effects of these corrections on the $r$-process, the $rp$-process, the $\gamma$-process, and big bang nucleosynthesis. We find that, although in most cases one is justified in neglecting these corrections, several cases arise for which significant corrections could occur. These include an $r$-process with very high neutron density, or an $rp$- process with reactions dominated by a low-lying resonances and low proton separation energies. [Preview Abstract] |
Saturday, November 6, 2010 10:54AM - 11:06AM |
NF.00003: Measurement of 26Al(d,p)27Al to constrain the 26Al(p,gamma) reaction rate Steven Pain, D.W. Bardayan, J.C. Blackmon, K.Y. Chae, K.A. Chipps, J.A. Cizewski, K.L. Jones, R.W. Kavanagh, R.L. Kozub, J.F. Liang, C. Matei, M. Matos, C.D. Nesaraja, P.D. O'Malley, W.A. Peters, S.T. Pittman, K.T. Schmitt, J.F. Shriner, M.S. Smith, G.L. Wilson The galactic mapping of the 1809-keV $\gamma$ ray from the beta decay of $^{26}$Al has provided an insight into ongoing galactic nucleosynthesis. Understanding the abundance of $^{26}$Al requires knowledge of rate of destruction of $^{26}$Al, partially via the $^{26}$Al(p,$\gamma$)$^{27}$Si reaction, which is determined by states near the proton threshold in $^{27}$Si. Due to the difficulty of measuring these resonances directly, an alternative is to measure mirror states in $^{27}$Al to inform the $^{27}$Si structure. The spectroscopic strengths of a few known mirror states are the dominant sources uncertainty in the $^{26}$Al(p,$\gamma$)$^{27}$Si reaction rate. The $^{26}$Al(d,p)$^{27}$Al reaction has been measured in inverse kinematics at the HRIBF. A beam of $\sim$5 million $^{26}$Al per second impinged on a $\sim$150 $\mu$g/cm$^2$ CD$_2$ target. Proton ejectiles were detected in the SIDAR and ORRUBA silicon detector arrays. Details of the experimental setup and data analysis will be presented. [Preview Abstract] |
Saturday, November 6, 2010 11:06AM - 11:18AM |
NF.00004: Many body effects in neutron star crusts and connection with observables Rishi Sharma Neutron star crusts are relatively clean condensed matter systems where nuclei coexist with electrons and -- below neutron drip -- neutrons in a superfluid state. Collective effects in this many body system sometimes play important roles in the calculation of properties like heat transport, and charge screening. I will describe the calculation of these properties. They directly effect observables like the profile of surface temperature of a neutron star, and frequencies of oscillations in giant flares. [Preview Abstract] |
Saturday, November 6, 2010 11:18AM - 11:30AM |
NF.00005: Dark matter, neutron stars and strange quark matter M. Angeles Perez-Garcia, Jirina Stone, Joseph Silk The energy release due to neutralino WIMP self-annihilation in the thermalization volume inside a compact object is shown to be comparable to the energy needed to create a long-lived lump of strange quark matter, or strangelet, for WIMP masses above a few GeV. Since strange matter is the most stable state of matter, accretion of self-annihilating dark matter onto neutron stars provides a mechanism to seed compact objects with lumps of strange quark matter and this effect may trigger a conversion of most of the star into a strange star. Using an energy estimate based on the Fermi gas model combined with the MIT bag model for the long-lived strangelet, a new limit on the possible values of the WIMP mass can be set that is competitive with those from direct searches. Our limit is especially important for subdominant species of massive neutralinos. [Preview Abstract] |
Saturday, November 6, 2010 11:30AM - 11:42AM |
NF.00006: Project X: A High Intensity Proton Source at Fermilab Stephen Holmes As the Fermilab Tevatron Collider program draws to a close a strategy has emerged of an experimental program built around the high intensity frontier. The centerpiece of this program is a superconducting H- linac that will support world leading programs in long baseline neutrino experimentation and the study of rare processes, with potential applications in nuclear physics and nuclear energy. Project X will provide multi-MW beams from the Main Injector over the energy range 60-120 GeV, simultaneous with mult-MW beams at 3 GeV. Shared technology development with ILC and the Muon Collider will establish a bridge to future facilities at the energy frontier. This talk will describe the currently favored accelerator configuration, associated performance projections, status of the accelerator R{\&}D program, and the strategy for moving forward. [Preview Abstract] |
Saturday, November 6, 2010 11:42AM - 11:54AM |
NF.00007: The Fermilab Project-X Research Program Robert Tschirhart Fermilab has been working with the international particle physics and nuclear physics communities to explore and develop research programs possible with a new high intensity proton source known as ``Project-X.'' Project X will provide multi-megawatt proton beams from the Fermilab Main Injector over the energy range 60-120 GeV, simultaneous with multi-megawatt protons beams at 3 GeV with very flexible beam-timing characteristics. The Project-X research program includes world leading sensitivity in long-baseline neutrino experiments, neutrino scattering experiments, a rich program of ultra-rare muon and kaon decays, opportunities for next-generation electric dipole moment experiments and other nuclear/particle physics probes that reach far beyond the Standard Model of particle physics. The sensitivity and future prospects of these lines of research will be presented and discussed. [Preview Abstract] |
Saturday, November 6, 2010 11:54AM - 12:06PM |
NF.00008: An alternate view of nuclear structure Aran David Stubbs This is a brief description of an alternate theory of the structure of atomic nuclei. It derives from the alternate theory of fundamental particles (also at this conference), but is separate from it. In this theory, atomic nuclei are comprised of up/down diquarks plus individual up quarks and down quarks (monoquarks). The count of monoquarks and diquarks is identical. Each diquark binds to 1 to 6 monoquarks, and each monoquark binds to 1 to 6 diquarks, in the standard body-centered-cubic structure. The surface is typically octahedral (which is the minimum surface for the bcc structure), except that some small nuclei have simpler structures - such as the cube of the Helium 4 nucleus. All interior monoquarks are downs, as are a few surface monoquarks. Analysis of minimum surface and statistical comparisons to actual nuclei are included, as are many illustrations. [Preview Abstract] |
Saturday, November 6, 2010 12:06PM - 12:18PM |
NF.00009: Harmonic-Oscillator-Based Effective Theory (HOBET): Effective Interactions without a Potential Satoru Inoue, Wick Haxton, Cory Schillaci HOBET is a treatment of the few-body nuclear problem in which an expansion around an intermediate momentum scale -- defined by the oscillator parameter and the number of shells in the P space -- provides the separation of scales necessary for a successful effective theory. This leads to a bound-state theory with both infrared and ultraviolet corrections: the former depends sensitively on binding energy and can be summed to all orders by a Green's function technique, while the latter can be replaced by a rapidly converging contact-gradient expansion with energy-independent strong-interaction coefficients. Here we demonstrate that the scattering (Lippmann-Schwinger) equation can be reorganized in precisely the same way, so that these coefficients (the effective interaction) can be determined directly from phase shifts, eliminating the need for a Q-space potential. [Preview Abstract] |
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