[en] This document describes a neutrino oscillation experiment performed at the Los Alamos Meson Physics Facility. The oscillation mode searched for is /bar /nu///sub μ/ → /bar /nu///sub e/. The first chapter is a review of the known properties of the neutrino and a description of the phenomenon of neutrino oscillation. Previous experimental limits on this unobserved phenomenon are also given. The second chapter describes the experimental apparatus used by the E645 experiment to detect neutrinos produced in the LAMPF beam stop. The salient features of the detector are its large mass (20 tons of CH₂), its fine segmentation (to allow good particle tracking), good energy resolution, its recording of the history both before and after tracks appear in the detector, an active cosmic-ray anticoincidence shield, and 2000 gm/cm² of passive cosmic-ray shielding. It is located 26.8 m from the neutrino source, which has a mean neutrino energy of 40 MeV. The third chapter details the reduction of the 1.3 million event data sample to a 49 event sample of neutrino candidates. Principle backgrounds are Michel electrons from stopping cosmic-ray muons and protons from np elastic scattering by cosmic-ray neutrons. The fourth chapter explains how background levels from neutrino-nuclear scattering are predicted. The result of a maximum-likelihood analysis reveals no evidence for oscillation. 90% confidence levels are set at δm² = .10 eV² for large mixing and sin²(2θ) = .014 for large δm². 82 refs., 18 figs., 55 tabs

[en] This document describes a neutrino oscillation experiment performed at the Los Alamos Meson Physics Facility. The oscillation model searched for is bar ν_μ → bar ν_e. The first chapter is a review of the known properties of the neutrino and a description of the phenomenon of neutrino oscillation. Previous experimental limits on this unobserved phenomenon are also given. The second chapter describes the experimental apparatus used by the E645 experiment to detect neutrinos produced in the LAMPF beam stop. The salient features of the detector are its large mass (20 tons of CH₂), its fine segmentation (to allow good particle tracking), good energy resolution, its recording of the history both before and after tracks appear in the detector, an active cosmic-ray anticoincidence shield, and 2000 gm/cm² of passive cosmic-ray shielding. It is located 26.8 m from the neutrino source, which has a mean neutrino energy of 40 MeV. The third chapter details the reduction of the 1,3 million event data sample to a 49 event sample of neutrino candidates. Principle backgrounds are Michel electrons from stopping cosmic-ray muons and protons from np elastic scattering by cosmic-ray neutrons. The fourth chapter explains how background levels from neutrino-nuclear scattering are predicted. The result of maximum-likelihood analysis reveals no evidence for oscillation. 90% confidence levels are set at δm² = .10 eV² for large mixing and sin²(2θ) = .014 for large δm²

[en] Materials either doped with traces of boron or containing this element as a matrix component have important technological and research applications. For most applications in technology, semiconductor doping, chemical vapor deposition of glass films, and optical waveguide fiber manufacture, boron levels or distribution must be controlled precisely. Thus, methods for quantitation of boron are needed, and its analytical chemistry still receives considerable study. Several nondestructive nuclear methods are described in this paper that have unique capabilities for quantitative analyses of boron at the trace and macro levels. Excellent high-sensitivity determinations are based on alpha track counting. For micro- and macroanalyses, the nuclear track technique using the ¹⁰B(n,α)⁷ Li reaction has been applied to map qualitatively the distribution of boron in borosilicate glass and in optical waveguide glass and fibers. Boron in the 1.59 to 7.75% range is determinable in silicate glasses. Similar information has also been obtained by prompt gamma neutron activation. Neuron depth profiling of boron in glass has been performed also. Results for several of these methods are reported

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[en] A procedure is described in which substoichiometric separations can be performed by solvent extraction so that quantitative determinations by neutron activation are free from the influence of most chemical interferences that would normally cause an error. The extraction system, tri-n-octylphosphine oxide-cyclohexane-hydrochloric acid, in which gallium and gold are simultaneously extracted, was used as an example to demonstrate the advantages of the interference-free procedure. Trace of gold in the presence of gallium have been quantitatively determined in silicon dioxide by neutron activation and substoichiometric separation. Replicate determination of gold in the presence of different amounts of gallium were highly precise, 26.6+-0.3 ng. Samples and standards were irradiated for 30 min with a flux of 1x10¹³n cm^-2s^-1. Irradiation were timed such that a 4- to 5-hour decay period had expired before postirradiation processing was begun to measure the γ-activity of ¹⁹⁸Au. (T.I.)

[en] The detection limits of many nonnuclear methods for ultratrace (<=0.1 μg/g) elemental determinations lie well below the level at which precise and accurate practical analysis can be executed routinely. Advances in analytical methodologies (chemical methods, instrumental methods and nuclear techniques) which are rapidly eroding such disparities are reviewed. The controlled environments for trace analysis, the reagent purification methods and routine analytical operations are described. The applications of X-ray fluorescence, atomic absorption, stable isotope dilution mass spectrometry, and laser intracavity absorption spectrophotometry to ultratrace analyses not amenable to solution by nuclear methods are discussed. (author)

[en] The decays of stopped pions in the LAMPF beam stop present a unique opportunity to probe neutrino oscillations in the mass region of deltam² approx.0.1eV² and mixing parameters as low was sin²2THETA approx.10^-3. The appearance of anti nu/sub e/ will be measured with high sensitivity by Experiment 645 during the run cycle that begins in the summer of 1986

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