Bulletin of the American Physical Society
78th Annual Meeting of the Southeastern Section of the APS
Volume 56, Number 9
Wednesday–Saturday, October 19–22, 2011; Roanoke, Virginia
Session CA: Recent Progress in Nuclear Astrophysics |
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Chair: Jonathan Link, Virginia Polytechnic Institute and State University Room: Crystal Ballroom A |
Thursday, October 20, 2011 10:45AM - 11:15AM |
CA.00001: Progress towards Low Energy Neutrino Spectroscopy (LENS) Invited Speaker: The Low-Energy Neutrino Spectroscopy (LENS) experiment will precisely measure the energy spectrum of low-energy solar neutrinos via charged-current neutrino reactions on indium. LENS will test solar physics through the fundamental equality of the neutrino fluxes and the precisely known solar luminosity in photons, will probe the metallicity of the solar core through the CNO neutrino fluxes, and will test for the existence of mass-varying neutrinos. The LENS detector concept applies indium-loaded scintillator in an optically-segmented lattice geometry to achieve precise time and spatial resolution and unprecedented sensitivity for low-energy neutrino events. The LENS collaboration is currently developing a prototype, miniLENS, in the Kimballton Underground Research Facility (KURF). The miniLENS program aims to demonstrate the performance and selectivity of the technology and to benchmark Monte Carlo simulations that will guide scaling to the full LENS instrument. We will present the motivation and concept for LENS and will provide an overview of the R\&D efforts currently centered around miniLENS at KURF. [Preview Abstract] |
Thursday, October 20, 2011 11:15AM - 11:45AM |
CA.00002: Borexino--A Breakthrough in Spectroscopy of Low Energy Neutrinos from the Sun Invited Speaker: Low energy ($<1$ MeV) solar neutrinos account for 99$+$\% of the emitted flux providing the essential window on energy production in the sun. For many decades of solar neutrino research, these could not be directly measured because of the formidable background barrier below 3 MeV. This constraint was broken by the Borexino experiment which has now measured the flux of 0.862 MeV neutrinos from the decay of 7Be in the sun. Indeed, this result is the most precise ($<$5\%) solar neutrino flux known today. A strong push is being made for results on other solar neutrinos. These results arising from extraordinary technical achievements, far exceed initial goals set for this project some 20 years ago. I will trace the development and brief history of this project, describe the salient features of the detector, point out the principal technical achievements and present the most recent results and their impact on our understanding of energy production in the sun via the proton-proton chain as well as the CNO cycle. The results bear vitally on neutrino phenomenology as well. In addition to the sun, Borexino has also measured neutrinos from the interior of the earth. Future directions and plans being discussed presently for Borexino will be indicated. [Preview Abstract] |
Thursday, October 20, 2011 11:45AM - 12:15PM |
CA.00003: Exploring the Cosmos from the Ground: Nuclear Astrophysics at UNC/TUNL Invited Speaker: Nuclear astrophysics is an inherently interdisciplinary field encompassing observational astronomy, astrophysical modeling, and measurements of thermonuclear reaction rates. In general, a group studies only one of these branches in depth; however, the unique nuclear astrophysics group at University of North Carolina--Chapel Hill and Triangle Universities Nuclear Laboratory (TUNL) incorporates both theoretical and experimental research. Currently focusing on nuclear reaction measurements involved in thermonuclear explosions and heavy-element synthesis, the Laboratory for Experimental Nuclear Astrophysics (LENA) utilizes two accelerators with an energy range of $\sim50-1000$ keV and current up to $\sim$1.5 mA to measure proton fusion with various targets. Recent and on-going measurements include $^{23}$Na$(p,\gamma)^{24}$Mg, $^{14}$N$(p,\gamma)^{15}$O, and $^{17,18}$O$(p,\gamma)^{18,19}$F. Our group has also formulated a new Monte Carlo method for calculating thermonuclear reaction rates from experimental results (such as resonance strengths), in which a rigorous statistical definition of uncertainties arises naturally. These rates provide a backbone for a new type of stellar reaction rate library currently in preparation, STARLIB. This library attempts to bridge the gap between experimental nuclear physics data and stellar modelers by providing a convenient tabular format with reliable uncertainties for use in simulating astrophysical phenomena. We expect to submit STARLIB for publication by year's end, which will coincide with the unveiling of a webpage for ease of dissemination and updating. Finally, our group uses this library to run simplified models of astrophysical events, such as novae or AGB stars, via network calculations. The results from these models indicate which reactions significantly influence various isotopic abundances, thus providing motivation for new reactions to measure at LENA and other laboratories. [Preview Abstract] |
Thursday, October 20, 2011 12:15PM - 12:45PM |
CA.00004: DIANA - An Underground Accelerator Facility for Nuclear Astrophysics Invited Speaker: Measuring nuclear reactions of astrophysical interest at {\em stellar} energies is usually a daunting task because the cross sections are very small and background rates can be comparatively large. Often, cosmic-ray interactions set the limit on experimental sensitivity, but can be reduced to an insignificant level by placing an accelerator underground -- as has been demonstrated by the LUNA accelerators in the Gran Sasso underground laboratory. The Dual Ion Accelerator facility for Nuclear Astrophysics (DIANA) is a proposed next-generation underground accelerator facility, which would be constructed at the 4850 ft level of the Homestake Mine in Lead, SD. This talk will describe DIANA and the questions in nuclear astrophysics that can be explored at such a laboratory. [Preview Abstract] |
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