Bulletin of the American Physical Society
Fall 2009 Meeting of the Four Corners Section of the APS
Volume 54, Number 14
Friday–Saturday, October 23–24, 2009; Golden, Colorado
Session K8: Nuclear Physics |
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Chair: Cynthia Galovich, University of Northern Colorado Room: Hill Hall 209 |
Saturday, October 24, 2009 1:50PM - 2:02PM |
K8.00001: Importance truncation in the No-Core Shell Model Michael Kruse, Petr Navratil, Bruce Barrett The No-Core Shell Model is an ab-initio technique, capable of calculating observable quantities of light nuclei (A $<$= 12) very accurately. However, for heavier nuclei, the computational requirements become unfeasible. The problem lies in the massive size of the basis space employed. Importance truncation allows us to make a good a priori guess of which basis states might be relevant for certain observables. We are thus able to dramatically reduce the size of the required basis, opening up the possibility to perform structure calculations of heavier nuclei and also astrophysical reactions. [Preview Abstract] |
Saturday, October 24, 2009 2:02PM - 2:14PM |
K8.00002: Effective three-body monopole interaction in the valence cluster approximation for the p-shell Sybil de Clark, Alexander Lisetskiy, Bruce Barrett, Michael Kruse No-core shell model calculations of binding energies using the two-body cluster approximation can omit higher-body correlations in small model spaces. To try and remedy this, we include higher-body correlations up to six nucleons in a two-body effective hamiltonian suitable for standard shell model (SSM) calculations, by performing two successive unitary transformations. The obtained effective hamiltonian contains a core, one-body and two-body pieces (due respectively to interactions among the core nucleons, between a valence and core nucleons and between two valence nucleons). We investigated the size of these interactions as a function of isospin for nuclei with A = 8 to 16 and compared the ab-initio results with the SSM results. The differences grow larger with A, indicating the need for three- and higher-body terms in the effective hamiltonian with increasing A. Taking the effective three-body monopole interaction into account for A$>$7, we found greatly improved results. [Preview Abstract] |
Saturday, October 24, 2009 2:14PM - 2:26PM |
K8.00003: A Quadrupole Band-Pass Filter for a White Proton Source Jonathon Morrow, Jerry Peterson The LANSCE facility at Los Alamos National Laboratory uses a beam of 800 MeV protons as a source of continuous (white) beams of neutrons, used for a wide range of basic and applied science. The same source also provides a white source of protons, which would be very useful for research, if some degree of energy resolution were available. We are designing a quadrupole magnet system that will provide such energy resolution by focusing only the desired momentum onto a sample, with protons of more or less momentum more widely diffused. Results will be given for designs based on simple thin lens optics to understand the criteria and general trends. A full design will require use of magnetic beam transport codes and a specific magnet system. [Preview Abstract] |
Saturday, October 24, 2009 2:26PM - 2:38PM |
K8.00004: Liquid Lithium Pendant Droplet for Laboratory Nuclear Astrophysics Beam Experiments Mark Calton, John Ellsworth Exposing and maintaining a clean surface of a small quantity of lithium metal in vacuum may be accomplished by a liquid lithium hanging droplet. Finding little literature on the subject, I have been experimenting to test this idea and will report on my efforts. [Preview Abstract] |
Saturday, October 24, 2009 2:38PM - 2:50PM |
K8.00005: Lithium Gadolinium Borate Scintillator for Low Flux Neutron Detection in Laboratory Nuclear Astrophysics Jacob A.J. Siebach, John E. Ellsworth, Lawrence B. Rees Lithium gadolinium borate crystal embedded in a plastic scintillator promises to enhance low flux neutron detection through paired pulse scintillation. The signal from this detector contains an energy pulse and a capture gate pulse. We report here efforts to develop a method to recognize the neutron gate signal, extract energy information, and calibrate this new scintillator. [Preview Abstract] |
Saturday, October 24, 2009 2:50PM - 3:02PM |
K8.00006: Using X-ray Fluorescence to Date Petroglyphs James McNeil Petroglyphs were created by ancient peoples of the Colorado Plateau who pecked figures of cultural or religious significance into the desert varnish, the ubiquitous dark patina covering the rock surfaces of the region. Manganese (Mn) is a significant elemental component of desert varnish that is often at trace levels in the substrate rock. As such, F. Lytle has shown that under certain conditions, it may be possible to estimate the age of petroglpyhs using Mn levels. In this work we use x-ray fluorescence to measure Mn levels in the desert varnish of petroglyphs and then use dated graffiti to attempt to calibrate the Mn level with age. Preliminary results from petroglyph panels in eastern Utah will be presented. [Preview Abstract] |
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