Bulletin of the American Physical Society
75th Annual Meeting of the Southeastern Section of APS
Volume 53, Number 13
Thursday–Saturday, October 30–November 1 2008; Raleigh, North Carolina
Session NB: Astrophysics, Nuclear Astrophysics, and Some Particle Physics |
Hide Abstracts |
Chair: Liliana Caballero, North Carolina State University Room: Holiday Inn Brownstone Washington |
Saturday, November 1, 2008 8:15AM - 8:27AM |
NB.00001: The DEAP/CLEAN dark matter search Michael Akashi-Ronquest The DEAP/CLEAN collaboration is constructing the latest generation of a series of single-phase Noble-liquid dark matter experiments. The Mini-CLEAN-360 detector will be the next of these experiments to be brought on-line in 2009, and is expected to obtain a sensitivity to the spin-independent WIMP-nucleon cross-section in the neighborhood of $10^{-45} \mathrm{cm}^{2}$ for $M_{\mathrm{WIMP}}$ $\approx$ $100 \mathrm{GeV}$. The DEAP/CLEAN detectors observe only the scintillation light from the liquid target, removing the need for TPCs which can lower the light yield and make larger scale experiments a challenge. The ratio of the amount of prompt to total scintillation light provides an excellent statistic with which to discriminate background electron from signal nuclear recoils. The MiniCLEAN-360 experiment will have the ability to utilize LAr or LNe as a target, which in the event of a positive signal will allow the expected $A^{2}$ dependence in cross section to be probed, as well as produce very different intrinsic background characteristics. In addition to the status of the MiniCLEAN-360 detector, data from the smaller R\&D detectors MicroCLEAN and DEAP-1 will be presented, including their demonstrated background rejection power. Finally, the schedule and design for a ton-scale detector, DEAP/CLEAN-3600, will be reviewed. [Preview Abstract] |
Saturday, November 1, 2008 8:27AM - 8:39AM |
NB.00002: Search for Friendly Mini Black Holes in the Laboratory Romulus Godang, C.M. Jenkins, Marco Cavaglia, Lucien Cremaldi, Roy Arunava, Don Summers Black holes are among the most intriguing objects in the universe. Massive astronomical black holes are now believed to exist with masses as large as a billion times the mass of Sun. In this paper we discuss the possibility of how to find observational evidence for friendly mini-black holes in the laboratory if they exist in nature. We study the mini-black holes using our Monte Carlo generator called ``CATFISH'' (Collider grAviTational FIeld Simulator for black Holes). We are investigating the signatures of mini black hole production in the proton-proton collisions at the CMS experiment (Compact Muon Solenoid) at CERN (European Organization for Nuclear Research) near Geneva, Switzerland. [Preview Abstract] |
Saturday, November 1, 2008 8:39AM - 8:51AM |
NB.00003: Enhanced LIGO Update Katherine Dooley A series of upgrades on the Initial LIGO (Laser Interferometer Gravitational-Wave Observatory) detectors is almost complete and will result in an improved configuration called Enhanced LIGO with a two to three time increase in sensitivity above 100Hz. Changes include increased laser power, new Input Optics (Faraday Isolator and Electro-optic modulators), DC readout, an Output Mode Cleaner, in-vacuum readout hardware, a new Thermal Compensation System, and an advanced seismic isolation table. It is expected that Enhanced LIGO will be operational by spring 2009, marking the commencement of a sixth science run which will last until the interferometers are decommissioned for building the Advanced LIGO system. I will briefly describe the improvements and present the status of the upgrade. [Preview Abstract] |
Saturday, November 1, 2008 8:51AM - 9:03AM |
NB.00004: Magnetic Field Amplification in Nonlinear Diffusive Shock Acceleration - a Monte Carlo Model Andrey E. Vladimirov, Donald C. Ellison, Andrei M. Bykov Recent observations indicating very high values of magnetic fields in collisionless shocks of supernova remnants have triggered extensive research in magnetic field amplification (MFA) by diffusive shock acceleration (DSA). The problem is essentially nonlinear -- that is, magnetic turbulence and accelerated particles produced in the process of DSA carry enough energy to feed back on the structure of the collisionless shock that determines the regime of DSA. Although many aspects of MFA and of dynamics of charged particles in the amplified fields are unknown, the structure of shocks can be studied from the standpoint of fundamental conservation laws. We present the outline and some results of a Monte Carlo model of nonlinearly modified shocks with efficient acceleration of particles and generation of strong stochastic magnetic fields. The model provides insight on the complex connections between components of strong collisionless shocks and makes predictions applicable in various astrophysical problems ranging from structure formation in the Universe to supernova remnant evolution and the origin of cosmic rays. [Preview Abstract] |
Saturday, November 1, 2008 9:03AM - 9:15AM |
NB.00005: Measurement of the Total Cross-Section for the $^{9}$Be($\gamma $,n$\alpha )\alpha $ reaction C.W. Arnold, T.B. Clegg, H.J. Karwowski, C.R. Howell, A.P. Tonchev, G. Rusev The $^{9}$Be($\gamma $,n$\alpha )\alpha $ cross section is key to understanding isotopic abundances of nuclei produced during the r-process. The inverse reaction bridges the unstable mass gaps at A=5 and 8 leading to $\alpha (\alpha $n,$\gamma )^{9}$Be($\alpha $,n)$^{12}$C and so on, producing seed nuclei for the r-process and setting the neutron-to-seed nucleus ratio that drives universal isotopic abundance predictions [Ref 1,2]. In order to make high precision measurements ($\pm $ 5{\%}) of the $^{9}$Be($\gamma $,n$\alpha )\alpha $ cross-section which includes narrow resonances, tunable gamma ray beam with small $\Delta $E/E is required along with gamma and neutron detectors whose efficiencies are well known. We used TUNL's high intensity gamma ray source (HI$\gamma $S) to measure the cross sections for $^{9}$Be($\gamma $,n) in the energy range of 1.55 to 5.0 MeV with beam energy resolutions between 14 and 150 keV as determined by large Ge detector. The neutrons were detected using $^{3}$He proportional counter. Experimental details will be discussed and the results as well as their astrophysical consequences will be presented. [Ref 1] B. Meyer \textit{et al.}, Astro J., \textbf{399} 656-664 (1992). [Ref 2] T. Kajino \textit{et al.}, Nuc. Phys. A, \textbf{704}, 165c-178c (2002) [Preview Abstract] |
Saturday, November 1, 2008 9:15AM - 9:27AM |
NB.00006: Study of Stellar Helium Burning with O-TPC at TUNL/HI$\gamma $S P.-N. Seo, A.H. Young, W.R. Zimmerman, M. Gai, M.W. Ahmed, E.R. Clinton, S.S. Henshaw, C.R. Howell, B.A. Perdue, S.C. Stave, C. Sun, H.R. Weller, Y. Wu, P.P. Martel, B. Bromberger, V. Dangendrof, K. Tittermeier, A. Breskin The Optical-readout Timing Projection Chamber (O-TPC), operating with a CO$_{2}$(80{\%})+N$_{2}$(20{\%}) gas mixure at 150 Torr, has been successfully commissioned at TUNL/HI$\gamma $S with alpha-particles from a $^{148}$Gd standard source. The O-TPC will be used to study the $^{16}$O($\gamma $,$\alpha )^{12}$C reaction, the time-reversed reaction of the oxygen formation in stellar helium burning. This reaction is considered to be of major importance since it determines the C/O ratio that in turn determines the final state of a supernova (black hole or neutron star). While we studied this reaction at 9.55 MeV, on the 1$^{-}$ resonance of $^{16}$O, we also took an advantage of the powerful detection system to investigate the $^{16}$O($\gamma $,3$\alpha )$ reaction at 10.53, 10.84, and 11.16 MeV gamma energy from HI$\gamma $S, spanning the 1$^{-}$ resonance of $^{12}$C located at 10.84 MeV which may or may not contribute to carbon formation during stellar helium burning. We will describe these two recent experiment and preliminary results from our data analysis that is in progress both at Yale and TUNL/Duke University. [Preview Abstract] |
Saturday, November 1, 2008 9:27AM - 9:39AM |
NB.00007: The Influence of Neutron Capture Rates in the Rare Earth Region on the r-Process Matthew Mumpower, Gail McLaughlin, Rebecca Surman The r-process has long been known to be an integral component of heavy element nucleosynthesis. We study the sensitivity of the r-process to neutron capture rates along the rare earth peak. We identify important neutron capture rates in this region and show how these rates influence specific sectors of the abundance pattern. [Preview Abstract] |
Saturday, November 1, 2008 9:39AM - 9:51AM |
NB.00008: Simplicial Matter for Simplicial Spacetimes Jonathan McDonald, Warner Miller If spacetime is indeed discrete at a fundamental level, then it is imperative that we develop a description of matter consistent with discrete spacetimes. Here we develop a method of coupling of non-gravitational sources to lattice spacetimes by utilizing the inherent properties of the simplicial structure. The contracted Bianchi identities are used as a guide to identifying how one incorporates matter fields into the lattice. We then use this guiding principle to define the fields using the inherent structure of the lattice. We also discuss the subtle properties of the lattice that become important when simplicial spacetimes are extended beyond the vacuum theory. This understanding of the coupling between lattice geometry and matter fields becomes useful to the kinematic states of spin foams, the emergent theory of Causal Dynamical Triangulations, and to path integral formulations of Regge Calculus. [Preview Abstract] |
Saturday, November 1, 2008 9:51AM - 10:03AM |
NB.00009: On a Latent Structure of Lepton Universality Rasulkhozha Sharafiddinov The mass of an electroweakly charged lepton consists of the two components of the electric and weak nature and regardless of the difference in masses, all leptons have an equal charge with his radius as well as an identical magnetic moment. Between these currents there appear the most diverse connections, for example, at their interactions with an electroweak field of spinless nuclei. We derive the united equations which relate the mass and its structural parts to charge, charge radius and magnetic moment of each lepton as a consequence of the ideas of flavor symmetry laws. Thereby, they require the verification of lepton universality from the point of view of a constancy of the size implied from the multiplication of a weak mass of lepton by its all the rest mass. Such a principle gives the possibility to define the lepton weak masses. If this picture is not changed, leptons universally interact not only with photon or weak neutral boson but also with any of gauge fields. [Preview Abstract] |
Saturday, November 1, 2008 10:03AM - 10:15AM |
NB.00010: New Covariant Constraints for New Forces of Nature Jeffrey Tithof, Yuri Kamyshkov, Mikhail Vysotsky Four fundamental interactions exist (strong, weak, electromagnetic, and gravity) which are well modeled by modern physics, but can additional interactions exist in nature? I will present results from our work in reanalyzing data from the previously published neutron-proton scattering experiment ``Measurement of np Elastic Scattering at High Energies and Very Small Momentum Transfers'' (Nuclear Physics, B232 (1984) 365-397). The 4-momentum transfer distribution for scattered neutrons is fit by taking into account a strong interaction Regge-like term, a Schwinger scattering term (which is the scattering of the magnetic moment of the neutron on the proton and electron electric charges), and a term describing the new force in a covariant form. Constraints on the new force were obtained from a statistical chi-square analysis of the theoretical fit to the experimental data. New constraints were analyzed for the new forces described by covariant amplitudes, corresponding to scalar, pseudoscalar, vector, or axial vector exchange particles. Findings are that new vector and axial vector light particle exchanges are strongly bounded by high energy data and the analogous bound for a scalar particle is weaker. For a pseudoscalar exchange, bounds cannot be set from present data. Our limits are compared with similar searches in several other experiments. [Preview Abstract] |
Follow Us |
Engage
Become an APS Member |
My APS
Renew Membership |
Information for |
About APSThe American Physical Society (APS) is a non-profit membership organization working to advance the knowledge of physics. |
© 2024 American Physical Society
| All rights reserved | Terms of Use
| Contact Us
Headquarters
1 Physics Ellipse, College Park, MD 20740-3844
(301) 209-3200
Editorial Office
100 Motor Pkwy, Suite 110, Hauppauge, NY 11788
(631) 591-4000
Office of Public Affairs
529 14th St NW, Suite 1050, Washington, D.C. 20045-2001
(202) 662-8700