Bulletin of the American Physical Society
Joint Fall 2011 Meeting of the Texas Sections of the APS, AAPT, and Zone 13 of the SPS
Volume 56, Number 7
Thursday–Saturday, October 6–8, 2011; Commerce, Texas
Session F1: Nuclear Physics II |
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Chair: Bao-An Li, Texas A&M University--Commerce Room: Sam Rayburn Center Second Floor, Room Innovations A |
Friday, October 7, 2011 3:40PM - 3:52PM |
F1.00001: Neutron-Proton pairing and the Symmetry Energy in Nuclear Matter Yuan Tian, Bao-An Li, Zhong-Yu Ma The effect of neutron-proton(n-p) pairing in symmetry energy is studied in the symmetric matter. A separable n-p pairing interaction has been introduced by adjusting the pairing properties of the bare nucleon-nucleon interaction in the symmetric matter. The isospin triplet channel $T=1$ n-p pairing has small effect on the symmetry energy, but the effects of isospin singlet channel $T=0$ n-p pairing is significant especially at very low densities. [Preview Abstract] |
Friday, October 7, 2011 3:52PM - 4:04PM |
F1.00002: Magnetic effects in heavy-ion collisions at intermediate energies Li Ou, Bao-An Li The time-evolution and space-distribution of internal electromagnetic fields in heavy-ion reactions at beam energies between 0.2 to 2 AGeV are studied within IBUU11 model. While the magnetic field can be significantly higher than the estimated surface magnetic field of magnetars, it has almost no effect on nucleon observables as the Lorentz force is normally much weaker than the nuclear force. Very interestingly, however, the magnetic field generated by the projectile-like (target-like) spectator has a strong focusing/diverging effect on $\pi^+/\pi^-$ at forward (backward) rapidities. Consequently, the differential $\pi^-/\pi^+$ ratio as a function of rapidity is significantly altered by the magnetic field while the total multiplicities of both positive and negative pions remain about the same. At beam energies above about 1 AGeV, the differential $\pi^-/\pi^+$ ratio is sensitive to the density dependence of nuclear symmetry energy $E_{\rm{sym}}(\rho)$. So magnetic effects should be carefully considered in future studies of using the differential $\pi^-/\pi^+$ ratio as a probe of the $E_{\rm{sym}}(\rho)$ at supra-saturation densities. [Preview Abstract] |
Friday, October 7, 2011 4:04PM - 4:16PM |
F1.00003: Observational effects of nuclear pasta in neutron stars Michael Gearheart Neutron stars (NSs) provide us with an excellent laboratory for examining nuclear theory under conditions not obtainable here on Earth. In the solid inner crust of the NS near the transition to the liquid core, nuclei can form cylindrical, slab and bubble structures (so-called pasta phases). Some NSs are observed to undergo gamma ray flares which have oscillations in the X-ray tail of their lightcurve. These oscillations are thought to be caused by torsional oscillations in the crust which depends on the shear modulus (rigidity) of the crust. We present a study of the lower and upper bound observational effects of the pasta regime on the frequency of the torsional modes and the maximum quadrupole ellipticity sustainable by the crust. [Preview Abstract] |
Friday, October 7, 2011 4:16PM - 4:28PM |
F1.00004: Statistical Tests on Neutron Star Glitches Joshua Hooker Glitches in pulsars are occasional, sudden increases in their rotation frequency as the pulsar otherwise steadily spins down. Using a set of neutron star equations of state which span the experimentally constrained range of asymmetric nuclear matter properties, we calculate the crustal moment of inertia, which relates to the size of a glitch in a broad class of glitch models in which the sudden spin-ups are due to angular momentum transfer between some of the superfluid neutrons in the star and the crust. We present a statistical test to compare the observational data to compare with our theoretical results. [Preview Abstract] |
Friday, October 7, 2011 4:28PM - 4:40PM |
F1.00005: Accelerator-Driven Subcritical Fission in a Molten Salt Core: Green Nuclear Power for the New Millennium Peter McIntyre Scientists at Texas A{\&}M University, Brookhaven National Lab, and Idaho National Lab are developing a design for accelerator-drive subcritical fission in a molten salt core (ADSMS). Three high-power proton beams are delivered to spallation targets in a molten salt core, where they provide $\sim $3{\%} of the fast neutrons required to sustain 600 MW of fission. The proton beams are produced by a flux-coupled stack of superconducting strong-focusing cyclotrons. The fuel consists of a eutectic of sodium chloride with either spent nuclear fuel from a conventional U power reactor (ADSMS-U) or thorium (ADSMS-Th). The subcritical core cannot go critical under any failure mode. The core cannot melt down even if all power is suddenly lost to the facility for a prolonged period. The ultra-fast neutronics of the core makes it possible to operate in an isobreeding mode, in which neutron capture breeds the fertile nuclide into a fissile nuclide at the same rate that fission burns the fissile nuclide, and consumes 90{\%} of the fertile inventory instead of the 5{\%} consumed in the original use in a conventional power plant. The ultra-fast neutronics produces a very low equilibrium inventory of the long-lived minor actinides, $\sim $10$^{4}$ less than what is produced in conventional power plants. ADSMS offers a method to safely produce the energy needs for all mankind for the next 3000 years. [Preview Abstract] |
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