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121.
The diffusion of 59Fe and 60Co has been measured in pure CoO and dilute iron-doped CoO, (Co1?cFecO, as a function of temperature (1000–1400°C) and oxygen partial pressure Po2), (10?7 ≦ Po2 ≦ 0 21 atm) The enhancement factors for the diffusivities of iron and cobalt are nearly identical, which suggests that the primary cause of the enhancement is the increased concentration of charge-compensating cation vacancies with the addition of iron. The Fe ions dissolved in CoO appear to exist as a mixture of Fe2+ and Fe3+ ions, the fraction of iron ions in the three-plus state decreases with decreasing Po2 The simultaneous diffusion of 52Fe and 59Fe has been measured as a function of (itpo; at 1200°C The correlation factor for Fe impurity diffusion determined from the isotope-effect measurements is about the same as that for self-diffusion in CoO at high (itPo2 (2 × 10?3 ≦ po2 ≦ 0 21 atm), but increases slightly with decreasing pO2 Both the enhancement-effect and isotope-effect experiments suggest that the nearestneighbor interactions between Fe ions and vacancies is small, and that the dissolved Fe ions do not have strongly bound electron holes. 相似文献
122.
123.
M.R. Jane P. Grannis B.D. Jones N.H. Lipman D.P. Owen V.Z. Peterson W.T. Toner E.H. Bellamy M.G. Green J. Kirkby C.M. Solomonides J.A. Strong D.H. Thomas 《Physics letters. [Part B]》1975,59(1):99-102
We have looked for the decay η → π0e+e? in an optical spark chamber experiment at the Rutherford Laboratory. Our observations are consistent with no events being seen and give an upper limit rate (η → π0e+e?)/ rate (η → all) < 4.5 × 10?5 (90% C.L.). 相似文献
124.
125.
M.R. Jane P. Grannis B.D. Jones N.H. Lipman D.P. Owen V.Z. Peterson W.T. Toner E.H. Bellamy M.G. Green J. Kirkby C. Solomonides J.A. Strong D.H. Thomas 《Physics letters. [Part B]》1975,59(1):103-105
In an optical spark chamber experiment we have obtained a sample of 80 eta Dalitz decays (η → e+e?γ) and have measured the eta electromagnetic form factor to be F(X) = 1.0?(0.22 ±0.45)X, where X=Mee2/Mη2, and the branching ratio (η→e+e?γ/(η→π+π?π0)= (0.0082 ± 0.0020). 相似文献
126.
S. A. Dickey J. J. Kraushaar R. J. Peterson 《Zeitschrift für Physik A Hadrons and Nuclei》1985,320(4):649-654
Inelastic scattering of 35 MeV alpha particles from7Li was used to induce the five known inelastic excitations. A collective coupled channel analysis yielded deformations for each transition and isoscalar quadrupole reduced transition rates were determined for each. The strong-coupling rotational model was found to agree closely with the results for the states associated with the ground state band, but the higher states are excited mainly by a two-step mechanism. 相似文献
127.
Diffusion of 54Mn in Mn1?δO single crystals has been measured by a serial sectioning technique as a function of temperature (1000–1500°C) and deviation from stoichiometry (0.00003 < δ < 0.12). The value of m in the expression varies from about 6 at low Po2 at all temperatures to a value approacing 2 at high Po2 and high temperatures, thus suggesting that diffusion occurs by doubly charged vacancies at low Po2 with increasing contributions from singly charged and neutral vacancies as Po2 (and vacancy concentration) increases. For δ near 0.1, the values of D fall below the values extrapolated from smaller defect concentrations. The isotope effect for cation self-diffusion was measured by simultaneous diffusion of 52Mn and 54Mn in Mn1?δO (0.0004 < δ < 0.116) at 1300 and 1500°C. The measured values of fΔK are independent of temperature within experimental error, and decrease from a value of 0.70 at low defect concentrations to 0.37 for large values of δ. The isotope-effect results suggest that diffusion occurs by single non-interacting vacancies at low defect concentrations; defect-defect interactions become important for δ ? 0.01. The defect-defect interactions may involve essentially individual defects or may result in defect clusters; the similarity between the present isotope-effect results and those for Fe1?δ0 suggests that defect clustering plays a significant role in mass transport in Mn1?δO at large values of δ. 相似文献
128.
129.
F.E. Cecil J.R. Shepard R.R. Sercely R.J. Peterson N.S.P. King 《Physics letters. [Part B]》1976,64(4):411-413
We have measured the differential cross sections for the reactions 12C(τ, τ′)12C(17.77 MeV 0+T=1) and 12C(τ, t)12N(2.43 MeV) at Eτ=44 MeV. The similar shapes of the angular distributions and the relative magnitudes of the cross sections suggest that the 12N 2.43 MeV level is the 0+T=1 analog to the q12C 17.77 MeV level. We have also studied the reaction 14N(p,t) 12N(2.43 MeV) at Ep=52 MeV. The strength with which this level is excited in this reaction is consistent with reasonable two-step calculations assuming the 2.43 MeV level to have Jπ=0+. 相似文献
130.