排序方式: 共有27条查询结果,搜索用时 15 毫秒
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D. Bisello G. Busetto A. Castro M. Nigro M. Penzo L. Pescara M. Posocco P. Sartori L. Stanco Z. Ajaltouni A. Falvard J. Jousset B. Michel J. C. Montret A. Antonelli R. Baldini A. Calcaterra G. Capon M. Schioppa J. -E. Augustin G. Cosme F. Couchot B. Dudelzak F. Fulda G. Grosdidier B. Jean-Marie S. Jullian D. Lalanne V. Lepeltier F. Manè C. Paulot R. Riskalla Ph. Roy G. Szklarz DM Collaboration 《Zeitschrift fur Physik C Particles and Fields》1988,39(1):13-19
Thee + e ?→K + K ? cross section has been measured from about 750 events in the energy interval \(1350 \leqq \sqrt s \leqq 2400 MeV\) with the DM2 detector at DCI. TheK ± form factor |F F ±| cannot be explained by the ρ, ω, ? and ρ′(1600). An additional resonant amplitude at 1650 MeV has to be added as suggested by a previous experiment. 相似文献
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J. -E. Augustin G. Cosme F. Couchot B. Dudelzak F. Fulda B. Grelaud G. Grosdidier B. Jean-Marie S. Jullian D. Lalanne V. Lepeltier B. Louis F. Mané C. Paulot R. Riskalla Ph. Roy F. Rumpf G. Szklarz Z. Ajaltouni A. Falvard J. Jousset B. Michel J. C. Montret R. Baldini S. Calcaterra G. Capon D. Bisello G. Busetto S. Limentani M. Nigro L. Pescara M. Posocco P. Sartori L. Stanco DM Collaboration 《Zeitschrift fur Physik C Particles and Fields》1987,36(3):369-376
The radiative decayJ/ψ → γ π+ π? has been studied using the 8.6 millionJ/ψ produced in the DM2 experiment at the DCIe +e? storage rings at Orsay. The π+ π? mass spectrum shows a cleanf 2 (1270) signal, and the possible presence of two other states at thef 2 (1720) andf 4 (2030) masses. For thef 2 (1270), the branching ratio BR(J/ψ →γf)xBR(f→π+ π?) is measured to be (7.50±0.30±1.12)×10?4, and the spin analysis prefers theJ=2 assignment, with helicity parametersx=0.83±0.06 andy=0.01±0.06. The existence of higher mass states is discussed. 相似文献
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The steady propagation of a thin smouldering front in a half-spacehas been considered. A suitable coordinate transformation hasallowed the region near the leading edge of the front to beexamined for both a maintained planar surface and with surfacecollapse due to material shrinkage. The change in the oxidizerconcentration for a small increment in the propagation speedfor large time and surface collapse has been determined. Theinfluence of two types of nonlinear diffusion on the shape ofthe smouldering front has been found; other cases can be dealtwith in a similar manner. 相似文献
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Gilliam SJ Jensen JO Banerjee A Zeroka D Kirkby SJ Merrow CN 《Spectrochimica acta. Part A, Molecular and biomolecular spectroscopy》2004,60(1-2):425-434
The first ab initio theoretical study of tetraantimony hexoxide (Sb4O6) is reported. The normal mode frequencies, intensities, and the corresponding vibrational assignments of Sb4O6 in T(d) symmetry were calculated using the GAUSSIAN 98 set of quantum chemistry codes at the Hartree-Fock (HF)/CEP-121G, M?ller-Plesset (MP2)/CEP-121G, and density functional theory (DFT)/B3LYP/CEP-121G levels of theory. By comparison to experimental data deduced by our laboratory and others, correction factors for the calculated vibrational frequencies were determined and compared. Normal modes were decomposed into three non-redundant motions (Sb-O-Sb stretch, Sb-O-Sb bend, and Sb-O-Sb wag). Percent relative errors found for the HF, DFT, and MP2 corrected frequencies when compared to experiment are 5.8, 6.1, and 5.7 cm(-1), respectively. Electron distributions for selected molecular orbitals are also considered. 相似文献
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Summary We present a simple and extremely accurate procedure for approximating initial temperature for the heat equation on the line using a discrete time and spatial sampling. The procedure is based on the sinc expansion which for functions in a particular class yields a uniform exponential error bound with exponent depending on the number of spatial sample locations chosen. Further the temperature need only be sampled at one and the same temporal value for each of the spatial sampling points. ForN spatial sample points, the approximation is reduced to solving a linear system with a (2N+1)×(2N+1) coefficient matrix. This matrix is a symmetric centrosymmetric Toeplitz matrix and hence can be determined by computing only 2N+1 values using quadratures.Supported in part by a grant from the Texas State Advanced Research ProgramSupported by NSF MONTS grant #ISP8011449Supported in part by grants from NSA, NASA and TATRP 相似文献
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G. P. Lamaze D. M. Gilliam A. P. Williams 《Journal of Radioanalytical and Nuclear Chemistry》1988,123(2):551-559
An accurate measurement of the neutron lifetime requires a determination of neutron fluence rate to an accuracy of a few tenths of a percent. The10B(n,)7 Li reaction offers the possibility of achieving this uncertainty. The thermal cross section is large and its departure from 1/v behavior is about 3 parts in 10000. The principal alpha branch is to the first excited state of7Li which then decays by emission of a 478 keV gamma ray. The measurement of the gamma branch can be made with boron samples that totally absorb thermal neutrons, allowing greater sensitivity and eliminating the uncertainty of target thickness. The absolute efficiency of the gamma detector can be determined by an alpha-gamma coincidence technique. Preliminary investigations of this method are presented with a discussion of the problems that must be overcome to achieve the desired uncertainty.Work supported in part by the Department of Energy 相似文献
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David M. Gilliam Andrew T. Yue 《Journal of Radioanalytical and Nuclear Chemistry》2014,299(2):1061-1065
In a paper presented in the Proceedings of the 19th World Conference of the INTDS, 1998, the results of a blind comparison between groups at NIST and the IRMM showed excellent agreement in characterization of actinide targets by alpha-particle counting with low solid-angle geometry. At that time the most accurate NIST results estimated an uncertainty of 0.03 % for the solid-angle determination. The NIST Neutron Physics Group now has improved the accuracy of its solid-angle determination by about a factor of 4, based on an improved aperture design, improved metrology, and comparisons among independent metrology techniques at NIST. Applications of this improved technology are expected to include improved NIST measurements of the free neutron lifetime and a recalibration of the NIST standard for neutron emission rate, NBS-I. 相似文献
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Dewey MS Gilliam DM Nico JS Wietfeldt FE Fei X Snow WM Greene GL Pauwels J Eykens R Lamberty A Van Gestel J 《Physical review letters》2003,91(15):152302
We report a new measurement of the neutron decay lifetime by the absolute counting of in-beam neutrons and their decay protons. Protons were confined in a quasi-Penning trap and counted with a silicon detector. The neutron beam fluence was measured by capture in a thin 6LiF foil detector with known absolute efficiency. The combination of these simultaneous measurements gives the neutron lifetime: tau(n)=(886.8+/-1.2[stat]+/-3.2[syst]) s. The systematic uncertainty is dominated by uncertainties in the mass of the 6LiF deposit and the 6Li(n,t) cross section. This is the most precise measurement of the neutron lifetime to date using an in-beam method. 相似文献