Bulletin of the American Physical Society
2005 2nd Joint Meeting of the Nuclear Physics Divisions of the APS and The Physical Society of Japan
Sunday–Thursday, September 18–22, 2005; Maui, Hawaii
Session JL: Applications of Nuclear Physics |
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Sponsoring Units: DNP JPS Chair: Jennifer Church, Lawrence Livermore National Laboratory Room: Ritz-Carlton Hotel Oahu |
Thursday, September 22, 2005 9:00AM - 9:15AM |
JL.00001: Examples for low energy nuclear physics simulations using GEANT4 L. Erikson, K. Chipps, U. Greife, F. Sarazin, J. Blackmon General purpose software libraries such as the latest version of the Geometry and Tracking toolkit (GEANT4) continue to gain favor in the physics community. The advancements offered in GEANT4 are considerable but utilization isn't trivial. One possible approach is to extend GEANT4 with a flexible software package designed to simulate and analyze commonly used detectors in this field. Such a package could be used with a number of projects allowing for greater focus on physics over software. This talk describes the use of such a library to study a variety of applications, including: a cosmic ray veto, experiments with radioactive nuclear beams, and a neutrino detector. [Preview Abstract] |
Thursday, September 22, 2005 9:15AM - 9:30AM |
JL.00002: Geant4-based Simulation of Cosmic Ray Shower Development in the Earth's Atmosphere Xiaochun He, Hakmana Sanjeewa, Christopher Cleven Geant simulation package has been widely used for decades in high energy nuclear and particle physics experiment for studying detector performance. The newest version of this simulation toolkit, Geant4, is constructed with objected oriented technology and implemented in C++. Its application areas now expend to medical, accelerator and space physics studies. We report here our implementation of Geant4 simulation for studying cosmic ray shower development in the atmosphere with a realistic geomagnetic field and air density distribution. This study will provide significant detailed information about secondary cosmic ray shower particles and their distributions as a function of the altitude, the geomagnetic locations and the air density variations. The simulated results are important for understanding the measurement of primary cosmic ray spectra. [Preview Abstract] |
Thursday, September 22, 2005 9:30AM - 9:45AM |
JL.00003: Initial search for triggered energy release from $^{177m}$Lu James Carroll Nuclear isomers like $^{178m2}$Hf and $^{180m}$Ta store large energy densities for long times and most often release that energy via beta, gamma or electron capture decay. These qualities have led to suggestions that isomers could serve in a wide variety of applications and, of course, such metastable states provide a fertile basis for studies of nuclear structure. The demonstration that real photons could induce, or trigger, the depopulation of $^{180m}$Ta has provided a first step in understanding the underlying physics. Likewise, the failed search for low-energy triggering of $^{178m2}$Hf has emphasized the need to connect the body of level data to investigations of energy-release mechanisms. This talk will discuss, in this context, initial tests of triggering of the 160-day isomer of $^{177m}$Lu by real photons. [Preview Abstract] |
Thursday, September 22, 2005 9:45AM - 10:00AM |
JL.00004: The Effect of X-Ray Lasers on the Strategic Defense Initiative (SDI) and the Resulting Government Changes Thomas A. Boster Strong and intense monochromatic x-ray emission lines were found experimentally in the mid to late 1970's.$^{1-4}$ These findings resulted in the theoretical search for an x-ray laser system. These proposed systems for a ``Star Wars'' approach were made known to the highest levels of the United States Government.$^{5}$ Details will be discussed and examples given. \newline \newline $^{1 }$T. A. Boster, et al., Bull. Am. Phys. Soc., \underline {22} 1240 (1977). \newline $^{2 }$T. A. Boster, et al., Bull. Am. Phys. Soc., \underline {23} 549 (1978). \newline $^{3 }$T. A. Boster, et al., Bull. Am. Phys. Soc., \underline {24} 507 (1979). \newline $^{4 }$T. A. Boster, et al., Bull. Am. Phys. Soc., \underline {32} 1060 (1987). \newline $^{5 }$Personal communication from Dr. Edward Teller. [Preview Abstract] |
Thursday, September 22, 2005 10:00AM - 10:15AM |
JL.00005: Real-time Measurements of Carbon Partitioning in Plants Using $^{11}$CO$_2$ M.R. Kiser, C.R. Howell, A.S. Crowell, C.D. Reid Understanding the effects that increased levels of atmospheric carbon dioxide (CO$_2$) can have on plants is of global importance. Of particular concern is the effect on crop yield and plant growth, as well as the potential of long-term carbon sequestration via natural processes. To better understand plant response to increased CO$_2$ levels, we use a short half-life radioisotope labelling process to trace the dynamics of carbon allocation and translocation within the plant. Using the positron-emitter carbon-11, which is produced at Triangle Universities Nuclear Laboratory via the reaction $^{14}$N(p, $\alpha$)$^{11}$C, we are able to introduce $^{11}$CO$_2$ to plants grown at current and projected CO$_2$ concentrations at the Duke University Phytotron. Positron emission imaging techniques are then used to trace the transport and distribution of carbon throughout the plant. Results from collimated, single-detector measurements and a low spatial resolution ($\sim$1cm) planar positron emission imager will be presented, as well as plans for $^{13}$N studies and the construction of a high spatial resolution ($\sim$3mm) planar imager. [Preview Abstract] |
Thursday, September 22, 2005 10:15AM - 10:30AM |
JL.00006: Modeling neutron reactions on actinides Mark Chadwick, Philip Young, Robert MacFarlane, Toshihiko Kawano, Patrick Talou I will describe statistical model calculations of neutron reactions on isotopes of uranium, plutonium, and americium. This work uses Hauser-Feshbach, direct, preequilibrium, and fission theories to calculate neutron cross sections from 1 keV to 20 MeV. A particular challenge is the prediction of cross sections such as fission, capture, and (n,2n) for unstable target nuclei few measurements have been made. I will describe how systematical properties of reactions on isotope chains helps constrain predictions for such nuclei. I will also describe integral simulation comparisons to measurements made at LANL critical assembly facility, that provide an important validation of these results. The new cross sections are the basis of a new ENDF/B-VII cross section library that will be released by the US nuclear data community at the end of 2005. These data are valuable for use in radiation transport simulations in a number of applications, including stockpile stewardship, advanced fuel cycles, and nonproliferation. [Preview Abstract] |
Thursday, September 22, 2005 10:30AM - 10:45AM |
JL.00007: High Resolution Measurement of Atmospheric Radiation During Thunderstorms Miho Ishigaki, Mark Greenfield, Mike Kubo, Kazuhisa Kumora Atmospheric $\gamma $ radiation was continuously observed in Utsunomiya and Shishiku highland, Japan, both of which have frequent seasonal lightning. Using a Ge detector, this observation ranging from 100 keV to 3000 keV was aimed at examining the characteristic $\gamma $ rays from atmospheric radioisotopes and 511 keV annihilation $\gamma $ rays with higher resolution during thunderstorms. Previous work proposed that excess $\gamma $ rays might be from radioisotopes such as $^{39}$Cl or $^{38}$Cl produced via nuclear reactions on atmospheric elements from bombardment of energetic protons or photons inside thunderclouds. Although these gamma ray energies have not yet been observed, the number of 511 keV annihilation $\gamma $ rays was slightly more than that observed during storms without lightning. Anomalous increases in the ratio of $^{214}$Bi to $^{214}$Pb (radon progeny) had also been observed during thunderstorms. Studies using an air filter near the Ge detector, increasing the observable volume of air exposed during thunderstorms, are in progress in order to elucidate the cause of this lightning enhanced radiation. [Preview Abstract] |
Thursday, September 22, 2005 10:45AM - 11:00AM |
JL.00008: Atmospheric $\gamma $ Radiation Associated with Lightning Mark Greenfield, Miho Ishigaki, Mike Kubo, Kazuhisa Komura, Geoff Austin, David Krofcheck, Margaret Peace, Paul Barker, Paul Ruscher, William Cottrill Increases in atmospheric $\gamma $ ray rates, GRR, during thunderstorms have been observed in Mitaka, Utsunomiya and Sishiku, \textbf{Japan}. Increased GRR associated with lightning persisted for a few hours and subsequently decayed with $\tau _{1/2}$=50 min. In the summer of 2003 a Ge detector with 2 keV resolution positioned near the rocket launch site at the lightning research center in Starke, Fla, \textbf{USA} was used to observe increases in integrated GRR following five rocket triggers up to five times pre-trigger background which subsequently decayed with about $\tau _{1/2}$=50 min. Recent data from \textbf{Japan} presented in the previous paper as well as data from Auckland, \textbf{New Zealand,} using high resolution Ge detectors, verify the previously observed correlations of GRR with precipitation, but additional gamma rays following lightning strikes, with energies other than those from anomalous increases in radon progeny and positrons, have yet to be observed. [Preview Abstract] |
Thursday, September 22, 2005 11:00AM - 11:15AM |
JL.00009: Neutron-Induced Partial Gamma-Ray Cross-Section Measurements on Uranium Using a Monoenergetic and Pulsed Beam at TUNL A. Hutcheson, A.S. Crowell, B. Fallin, C.R. Howell, J. Kelley, M. Kiser, A.P. Tonchev, W. Tornow, R.S. Pedroni, G.J. Weisel, J.A. Becker, D. Dashdor, R.A. Macri, N. Fotiades, R.O. Nelson An experimental program is being carried out at TUNL to study (n,2n) excitation functions on actinide nuclei using monoenergetic neutrons with the goal of improving the partial cross-section data for the NNSA Stockpile Stewardship Program. Measurements have been performed on $^{235,238}$U targets in the TUNL shielded neutron source area using a pulsed neutron beam with incident neutron energies between 5 and 18 MeV. The resultant emitted gamma rays are measured using different types of HPGe detectors. More than thirty (n,n') and (n,2n) partial cross-sections have been measured in this energy range, and experimental results will be compared with the Hauser-Feshbach model. A more in-depth explanation of the experimental techniques and analysis will be presented. [Preview Abstract] |
Thursday, September 22, 2005 11:15AM - 11:30AM |
JL.00010: Nuclear Interaction Cross Sections for NASA's New Vision Ram Tripathi, J. W. Wilson NASA has a new vision for space exploration in the 21$^{st}$ Century encompassing a broad range of human and robotic missions including missions to Moon, Mars and beyond. As a result, there is a focus on long duration space missions. Protection from the hazards of severe space radiation in deep space long duration is of paramount importance for the new vision. Accurate risk assessments critically depend on the accuracy of the input nuclear cross sections of the interaction of ions with materials, electronics and tissues. A huge amount of essential experimental information for all the ions in space, across the periodic table, for a wide range of energies of several (up to a Trillion) orders of magnitude are needed for the radiation protection engineering for space missions that is simply not available (due to the high costs) and probably never will be. Therefore, there is a compelling need to develop reliable accurate models of nuclear reactions and structures that form the basic input ingredients. State-of-the-art nuclear cross sections models have been developed at the NASA Langley Research Center. However a considerable number of interaction methodologies need to be developed to alleviate the situation. [Preview Abstract] |
Thursday, September 22, 2005 11:30AM - 11:45AM |
JL.00011: An Outreach Initiative to Improve High School Physics Nouredine Zettili We want to discuss our outreach initiative at Jacksonville State University designed to help improve the teaching of physics at a number of high schools in Northeast Alabama. This initiative is part of Project IMPACTSEED (IMproving Physics And Chemistry Teaching in SEcondary Education), a No-Child Left Behind grant funded by the Alabama Commission on Higher Education. This project is motivated by a major pressing local need: A large number of high school physics teachers teach out of field. IMPACTSEED is designed to achieve a double aim: (a) to make physics and chemistry understandable and fun to learn within a hands-on, inquiry-based setting; (b) to overcome the fear-factor for physics and chemistry among students. Through a two-week long summer institute, a series of weekend workshops designed to help bring technology into physics classrooms, and onsite support, we have been providing year-round support to the physics/chemistry teachers in this area. IMPACTSEED aims at providing our students with a physics/chemistry education that enjoys a great deal of continuity and consistency from high school to college. [Preview Abstract] |
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