93 research outputs found

    Coulomb Distortion Effects for Electron or Positron Induced (e,e′)(e,e') Reactions in the Quasielastic Region

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    In response to recent experimental studies we investigate Coulomb distortion effects on (e,e′)(e,e') reactions from medium and heavy nuclei for the case of electrons and positrons. We extend our previously reported full DWBA treatment of Coulomb distortions to the case of positrons for the 208Pb(e,e′)^{208}Pb(e,e') reaction in the quasielastic region for a particular nuclear model. In addition, we use previously reported successful approaches to treating Coulomb corrections in an approximate way to calculate the Coulomb distortion effects for (e,e′)(e,e') reactions for both electrons and positrons for the case of a simple nuclear model for quasielastic knock-out of nucleons. With these results in hand we develop a simple {\em ad-hoc} approximation for use in analyzing experiments, and discuss methods of extracting the ``longitudinal structure function" which enters into evaluation of the Coulomb sum rule. These techniques are generally valid for lepton induced reactions on nuclei with momentum transfers greater than approximately 300 MeV/cMeV/c.Comment: 18 pages, 6 figure

    Nuclear Shell Model Calculations of Neutralino-Nucleus Cross Sections for Silicon 29 and Germanium 73

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    We present the results of detailed nuclear shell model calculations of the spin-dependent elastic cross section for neutralinos scattering from \si29 and \ge73. The calculations were performed in large model spaces which adequately describe the configuration mixing in these two nuclei. As tests of the computed nuclear wave functions, we have calculated several nuclear observables and compared them with the measured values and found good agreement. In the limit of zero momentum transfer, we find scattering matrix elements in agreement with previous estimates for \si29 but significantly different than previous work for \ge73. A modest quenching, in accord with shell model studies of other heavy nuclei, has been included to bring agreement between the measured and calculated values of the magnetic moment for \ge73. Even with this quenching, the calculated scattering rate is roughly a factor of 2 higher than the best previous estimates; without quenching, the rate is a factor of 4 higher. This implies a higher sensitivity for germanium dark matter detectors. We also investigate the role of finite momentum transfer upon the scattering response for both nuclei and find that this can significantly change the expected rates. We close with a brief discussion of the effects of some of the non-nuclear uncertainties upon the matrix elements.Comment: 31 pages, figures avaiable on request, UCRL-JC-11408

    Thermal properties of Fe-54

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    We study the thermal properties of Fe-54 with the Brown-Richter interaction in the complete 1p0f model space. Monte Carlo calculations show a peak in the heat capacity and rapid increases in both the moment of inertia and M1 strength near a temperature of 1.1 MeV that are associated with the vanishing of proton-proton and neutron-neutron monopole pair correlations; neutron-proton correlations persist to higher temperatures. Our results are consistent with a Fermi gas level density whose back-shift vanishes with increasing temperature.Comment: 10 pages (RevTeX) and 2 figures (uuencoded postscript). Caltech preprint MAP-171 (originally submitted May 1994

    Overview of the PALM model system 6.0

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    In this paper, we describe the PALM model system 6.0. PALM (formerly an abbreviation for Parallelized Largeeddy Simulation Model and now an independent name) is a Fortran-based code and has been applied for studying a variety of atmospheric and oceanic boundary layers for about 20 years. The model is optimized for use on massively parallel computer architectures. This is a follow-up paper to the PALM 4.0 model description in Maronga et al. (2015). During the last years, PALM has been significantly improved and now offers a variety of new components. In particular, much effort was made to enhance the model with components needed for applications in urban environments, like fully interactive land surface and radiation schemes, chemistry, and an indoor model. This paper serves as an overview paper of the PALM 6.0 model system and we describe its current model core. The individual components for urban applications, case studies, validation runs, and issues with suitable input data are presented and discussed in a series of companion papers in this special issue

    COX-1 (PTGS1) and COX-2 (PTGS2) polymorphisms, NSAID interactions, and risk of colon and rectal cancers in two independent populations

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    Nonsteroidal anti-inflammatory drugs (NSAIDs) target the prostaglandin H synthase enzymes, cyclooxygenase (COX)-1 and -2, and reduce colorectal cancer risk. Genetic variation in the genes encoding these enzymes may be associated with changes in colon and rectal cancer risk and in NSAID efficacy

    Theory of thin airfoils in fluids of high electrical conductivity

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    Regenerative Thermomagnetic Power

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    Magneto-gasdynamic channel flow

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