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931.
Carolyn E. M. Morris A. E. Alexander A. G. Parts 《Journal of polymer science. Part A, Polymer chemistry》1966,4(5):985-995
The polymerization of methyl acrylate in water and in dilute, aqueous, soap solutions, initiated by potassium peroxydisulfate, has been investigated, a dilatometric method being used to follow the conversion. It has been shown that small amounts of an anionic soap increase the rate of reaction while a cationic soap has the reverse effect. The change of molecular weight with conversion has also been examined as well as the effect of the exclusion of oxygen from the system. 相似文献
932.
The application of a dissipative Galerkin scheme to the numerical solution of the Korteweg de Vries (KdV) and Regularised Long Wave (RLW) equations, is investigated. The accuracy and stability of the proposed schemes is derived using a localised Fourier analysis. With cubic splines as basis functions, the errors in the numerical solutions of the KdV equation for different mesh-sizes and different amounts of dissipation is determined. It is shown that the Galerkin scheme for the RLW equation gives rise to much smaller errors (for a given mesh-size), and allows larger steps to be taken for the integrations in time (for a specified error tolerance). Also, the interaction of two solitons is compared for the KdV and RLW equations, and several differences in their behaviour are found. 相似文献
933.
The reorientation effect in Coulomb excitation has been used to measure the following static quadrupole moments: . Interference effects from higher excited states have been included in the analysis, with the signs of the E2 matrix elements taken from an anharmonic model. The value obtained for is in disagreement with two previous measurements. We attribute the discrepancy to the smaller internucleon separation distances involved in the previous experiments, which can cause deviations from Coulomb excitation cross sections. The other quadrupole moments have not been measured previously. The B (E2: 0+ → 2+) measured were: . From the angular distribution of the de-excitation γ-rays of the Pb nuclei following recoil into vacuum, we have determined the following (two standard deviations), . Our value of is in agreement with a previous measurement. 相似文献
934.
Mean lifetimes of levels in 22Ne have been measured by the Doppler-shift attenuation method using the inverse reaction 4He(19F, pγ)22Ne. The Doppler-broadened lineshapes observed at 0° were analyzed using scaled experimental stopping powers and give the following results for each of the following levels (energy in keV and lifetime in fs): 4457 ( < 15), 5147 (1300 ± 500), 5522 (27 ± 4), 5641 ( < 20), 6311 (70 ± 10), 6345 ( < 15), 6636 ( < 20) and 6817 ( < 15). The lifetime of the 6311 keV 6+ level is particularly interesting for testing model predictions. The large basis shell model calculations of Preedom and Wildenthal are in good agreement with the experimental B(E2) values for the 2+, 4+ and 6+ members of the ground-state band. 相似文献
935.
936.
The production of ?0 and f mesons in πN→π+π?N reactions in the momentum range 4 to 17 GeV/c is investigated in a model-independent way by imposing in full the positivity of the density matrix. The results so obtained are used in order to determine the effective Regge trajectories for unnatural and natural parity exchanges and are compared to results obtained in different analyses. 相似文献
937.
938.
S. Alexander 《Solid State Communications》1974,14(11):1069-1071
It is demonstrated that phase transitions predicted to be first order by the Landau symmetry arguments can be continuous for a finite range of the physical parameters. For transitions with a rank-two tensor order parameter it is shown that fluctuations in a phase associated with the anisotropy of the tensor result in a renormalization of the cubic term. This leads to continuous transitions when the coefficient of the bare cubic term is small compared to the coefficient of the quartic term. It is shown that the argument can be extended to more general cases when the order parameter belongs to a multidimensional representation of the broken symmetry group. 相似文献
939.
Pionic atom data are refitted in terms of conventional π? nuclear optical potentials, modified to allow for finite range in the underlying p-wave πN interaction. We find that level shifts and widths in light and medium-weight nuclei cannot distinguish between the various ranges tested. In heavy nuclei, and for reasonable choices of neutron radii, the data tend to exclude ranges of order 0.5 fm and larger. 相似文献
940.
G. Alexander L. Criegee H.C. Dehne K. Derikum R. Devenish G. Flügge G. Franke Ch. Gerke E. Hackmack P. Harms G. Horlitz Th. Kahl G. Knies E. Lehmann R. Schmitz U. Timm P. Waloschek K. Wacker 《Physics letters. [Part B]》1978,78(1):162-166
The decay of the heavy lepton τ into πv has been established using the magnetic detector PLUTO. The branching ratio is determined to be BR(τ→πv)=(9.0 ± 2.9)% with an additional systematic uncertainty of 2.5%. This value is in good agreement with the theoretical prediction. 相似文献