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The Chemistry os Spent Nuclear Fuel From X-Ray Absorption Spectroscopy
Present and future nuclear fuel cycles will require an understanding of the complex chemistry of trace fission products and transuranium actinides in spent nuclear fuel (SNF). Because of the unique analytical challenges presented by SNF to the materials scientist, many of its fundamental physical and chemical properties remain poorly understood, especially on the microscopic scale. Such an understanding of the chemical states of radionuclides in SNF would benefit development of technologies for fuel monitoring, fuel performance improvement and modeling, fuel reprocessing, and spent fuel storage and disposal. We have recently demonstrated the use of synchrotron x-ray absorption spectroscopy (XAS) to examine crystal chemical properties of actinides and fission products in extracted specimens of SNF. Information obtained includes oxidation state, chemical bond coordination, and quantitative elemental concentration and distribution. We have also used XAS in a scanning mode to obtain x-ray spectral micrographs with resolution approaching 1 micron. A brief overview of the technique will be presented, along with findings on uranium, plutonium, neptunium, technetium, and molybdenum in commercial PWR SNF specimens
Improved W boson mass measurement with the D0 detector
We have measured the W boson mass using the D0 detector and a data sample of
82 pb^-1 from the Tevatron collider. This measurement used W -> e nu decays,
where the electron is close to a boundary of a central electromagnetic
calorimeter module. Such 'edge' electrons have not been used in any previous D0
analysis, and represent a 14% increase in the W boson sample size. For these
electrons, new response and resolution parameters are determined, and revised
backgrounds and underlying event energy flow measurements are made. When the
current measurement is combined with previous D0 W boson mass measurements, we
obtain M_W = 80.483 +/- 0.084 GeV. The 8% improvement from the previous D0
measurement is primarily due to the improved determination of the response
parameters for non-edge electrons using the sample of Z bosons with non-edge
and edge electrons.Comment: submitted to Phys. Rev. D; 20 pages, 18 figures, 9 table
Limits on Anomalous WWgamma and WWZ Couplings from WW/WZ->enujj Production
Limits on anomalous WWgamma and WWZ couplings are presented from a study of
WW/WZ->enujj events in ppbar collisions at sqrt{s}=1.8 TeV. Results from the
analysis of data collected using the D0 detector during the 1993-1995 Tevatron
collider run at Fermilab are combined with those of an earlier study from the
1992-1993 run. A fit to the transverse momentum spectrum of the W boson yields
direct limits on anomalous WWgamma and WWZ couplings. With the assumption that
the WWgamma and WWZ couplings are equal, we obtain -0.34< lambda < 0.36 (with
Delta kappa=0) and -0.43< Delta kappa < 0.59 (with lambda=0) at the 95
confidence level for a form-factor scale Lambda=2.0 TeV.Comment: 37 pages, 13 figures, submitted to Phys. Rev.
Multiple jet production at low transverse energies in PP¯ collisions at sqrt[s]=1.8 TeV.
We present data on multiple production of jets with transverse energies near 20 GeV in pp̅ collisions at sqrt[s]=1.8 TeV. QCD calculations in the parton-shower approximation of pythia and herwig and the next-to-leading order approximation of jetrad are compared to the data for one, two, three, and four jet inclusive production. Transverse energy spectra and multiple jet angular and summed transverse-energy distributions are adequately described by the shower approximation while next-to-leading order calculations describe the data poorly