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排序方式: 共有411条查询结果,搜索用时 15 毫秒
31.
Benjamin Byerly Kevin Kuhn Lisa Colletti Lynn Foster Russ Keller Elmer Lujan Alex Martinez Donivan Porterfield Dan Schwartz Khal Spencer Floyd Stanley Mariam Thomas Lisa Townsend Ning Xu Lav Tandon 《Journal of Radioanalytical and Nuclear Chemistry》2017,312(1):95-104
Thorough physical and chemical characterization of plutonium–beryllium (PuBe) neutron sources is an important capability with applications ranging from material accountancy to nuclear forensics. Characterization of PuBe sources is not trivial owing to range of existing source designs and the need for adequate infrastructure to deal with radiation and protect the analyst. This study demonstrates a method for characterization of three PuBe sources that includes physical inspection and imaging followed by controlled disassembly and destructive analysis. 相似文献
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From a Mössbauer study of an oriented single crystal of Ni0.996S (2% Fe57) at 298 K (above the metal-insulator transition at 230 K) the sign of the quadrupole splitting in Fe57 is determined to be positive; this contrasts with a negative sign found for FeS and Fe0.93S. A tentative model is presented that is consistent with these results and with magnetic anisotropy data. 相似文献
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A spin, isotopic-spin formalism for the production of pions due to decays of isobar giant resonances formed in peripheral heavy-ion collisions is presented. The projectile nucleus isobar giant resonance state is assumed to coherently form and then incoherently decay to produce the pions. Total spin and isotopic spin for the system are conserved through the concomitant excitation of the target nucleus to an isobaric analog giant resonance state. Comparisons of the predicted total pion cross sections, over a range of energies, are made with heavy-ion pion data. 相似文献
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To explore the use of methoxymethyl groups to elaborate simple benzenoid precursors to more complex polyketide-derived natural products, the reaction of phenolmetoxymethyl ether -anion was investigated with a number of electrophiles. 相似文献
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We present a locally superconformal invariant theory of supergravity which is gauge equivalent to the usual, Poincaré, supergravity. This is achieved by means of a compensating scalar supermultiplet. This shows that local superconformal symmetry can be made compatible with gravitational phenomenology. 相似文献
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A solution of the (4+n)-dimensional vacuum Einstein equations is found for which spacetime is compactified on an n-dimensional compact hyperbolic manifold (n> or =2) of time-varying volume to a flat four-dimensional Friedmann-Lemaitre-Robertson-Walker cosmology undergoing a period of accelerated expansion in the Einstein conformal frame. This shows that the "no-go" theorem forbidding acceleration in "standard" (time-independent) compactifications of string or M theory does not apply to "cosmological" (time-dependent) hyperbolic compactifications. 相似文献