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N. D. Stalnaker B. T. Kenna M. Kahn 《Journal of Radioanalytical and Nuclear Chemistry》1973,14(2):395-400
A sample preparation method has been developed which produces both standard and unknown samples of the same size, shape, composition
and density (a necessary condition for minimum error). A solution of standard or unknown material was pipetted onto graphite
wetted with acetone, the material was dried and mixed with additional graphite to give a homogeneous mixture containing≥99%
graphite. Portions of the mixture were pressed into uniform cylindrical pellets. Application of the method to the activation
analysis of several copper compounds gave results which generally agreed with analysis by thiosulfate titration of liberated
iodine to within less than 1%.
This work was supported by the United States Atomic Energy Commission. 相似文献
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B. F. Smith R. R. Gibson G. D. Jarvinen T. W. Robison N. C. Schroeder N. D. Stalnaker 《Journal of Radioanalytical and Nuclear Chemistry》1998,234(1-2):225-229
A preconcentration approach to assist in the measurement of low levels of americium and plutonium in waste waters has been
developed based on the concept of using water-soluble metal-binding polymers in combination with ultrafiltration. The method
has been optimized to give over 90% recovery and accountability from actual waste water. 相似文献
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L. Lorini N. Ashby A. Brusch S. Diddams R. Drullinger E. Eason T. Fortier P. Hastings T. Heavner D. Hume W. Itano S. Jefferts N. Newbury T. Parker T. Rosenband J. Stalnaker W. Swann D. Wineland J. Bergquist 《The European physical journal. Special topics》2008,163(1):19-35
The record of atomic clock frequency comparisons at NIST over the past half-decade provides one of the tightest constraints
of any present-day temporal variations of the fundamental constants. Notably, the 6-year record of increasingly precise measurements
of the absolute frequency of the Hg+ single-ion optical clock (using the cesium primary frequency standard NIST-F1) constrains the temporal variation of the fine
structure constant α to less than 2 · 10−6yr−1 and offers a Local Position Invariance test in the framework of General Relativity. The most recent measurement of the frequency
ratio of the Al+ and Hg+ optical clocks is reported with a fractional frequency uncertainty of ±5.2 · 10−17. The record of such measurements over the last year sensitively tests for a temporal variation of α and constrains , consistent with zero. 相似文献
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Optical lattice induced light shifts in an yb atomic clock 总被引:1,自引:0,他引:1
Barber ZW Stalnaker JE Lemke ND Poli N Oates CW Fortier TM Diddams SA Hollberg L Hoyt CW Taichenachev AV Yudin VI 《Physical review letters》2008,100(10):103002
We present an experimental study of the lattice-induced light shifts on the (1)S(0) --> (3)P(0) optical clock transition (nu(clock) approximately 518 THz) in neutral ytterbium. The "magic" frequency nu(magic) for the 174Yb isotope was determined to be 394 799 475(35) MHz, which leads to a first order light shift uncertainty of 0.38 Hz. We also investigated the hyperpolarizability shifts due to the nearby 6s6p(3)P(0) --> 6s8p(3)P(0), 6s8p(3)P(2), and 6s5f(3)F(2) two-photon resonances at 759.708, 754.23, and 764.95 nm, respectively. By measuring the corresponding clock transition shifts near these two-photon resonances, the hyperpolarizability shift was estimated to be 170(33) mHz for a linear polarized, 50 microK deep, lattice at the magic wavelength. These results indicate that the differential polarizability and hyperpolarizability frequency shift uncertainties in a Yb lattice clock could be held to well below 10(-17). 相似文献
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A method has been developed for the preparation of irradiation samples which ensures that both standard and unknown samples
are of the same size, shape, density and composition. Powdered standard and unknown samples were diluted with graphite to
give homogeneous mixtures containing ≥80% graphite; these mixtures were pressed into cylindrical pellets. This method of sample
preparation has been applied to the determination of nitrogen in organic and polymeric compounds. The results generally agree
with Kjeldahl analyses within 5%.
This work was supported by the United States Atomic Energy Commission. 相似文献
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B. F. Smith R. R. Gibson G. D. Jarvinen M. M. Jones M. T. Lu T. W. Robison N. C. Schroeder N. Stalnaker 《Journal of Radioanalytical and Nuclear Chemistry》1998,234(1-2):219-223
Water-soluble metal-binding polymers in combination with ultrafiltration are shown to be an effective method for selectively
removing dilute actimide ions from acidic solutions of high ionic strength. The actinide-binding properties of commercially
available water-soluble polymers and several polymers which have been reported in the literature were evaluated. The functional
groups incorporated in the polymers were pyrrolidone, amine, oxime, and carboxylic, phosphonic, or sulfonic acid. The polymer
containing phosphonic acid groups gave the best results with high distribution coefficients and concentration factors for241Am(III) and238Pu(III)/(IV) at pH 4 to 6 and ionic strengths of 0.1 to 4. 相似文献