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Reflection Asymmetric Shapes in the Neutron-Rich 140,143Ba Isotopes
ZHU Sheng-jiang, WANG Mu-ge, J. H. Hamilton, A. V. Ramayya, B. R. S. Babu, W. C. Ma, LONG Gui-lu, DENG Jing-kang, ZHU Ling-yan, LI Ming, T. N. Ginter, J. Komicki, J. D. Cole, R. Aryaeinejadv, Y. K. Dardenne, M. W. Drigert, J. O. Rasmussen, Yu. Ts. Oganessian, M. A. Stoyer, S. Y. Chu, K. E. Gregorich, M. F. Mohar, S. G. Prussin, I. Y. Lee, N. R. Johnson, F. K. McGowan
Chin. Phys. Lett. 1997, 14 (8):
569-572
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Level schemes for the neutron-rich 140,143Ba nuclei have been determined by study of prompt γ-rays in spontaneous fission of 252Cf. The level pattern and enhanced E1 transitions between π = + and π = - bands show reflection asymmetric shapes with simplex quantum number s = +1 in 140Ba and s = ±i in 143Ba, respectively. The octupole deformation stability with spin variation has been discussed.
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Sigma-Meson from General Color Symmetry Model for Quantum Chromodynamics
LÜ, Xiao-fu, /sup>, LIU Yu-xin, ZOU Bing-song, DING Hui-ming, ZHAO En-gang
Chin. Phys. Lett. 1997, 14 (8):
573-576
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The property of σ-meson or f0 (400-1200) is studied in the general color symmetry model (GCM) for quantum chromodynamics. With recent determined values of mσ, fσ and fπ in GCM, the isoscalar ππ S-wave amplitude is calculated without any free parameter. The T-matrix pole for f0 (400-1200) is found to be 1011- i 284MeV, which is very close to the Particle Data Group value (400-1200)-i(300-500) MeV.
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Effect of Oxygen-Diffusion Possibly Involved in Perovskite Unit on Superconductivity of Various Oxygen-Doped Bi2Sr2CaCu208+y Single Crystals
ZHAO Xiao-ru, SUN Xue-feng, WU Wen-bin, JIA Yun-bo, ZHOU Gui-en, LI Xiao-guang, ZHANG Yu-heng
Chin. Phys. Lett. 1997, 14 (8):
613-616
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For a highly oriented Bi2Sr2CaCu208+y single crystal with a lower as-grown Tc of 72K, on air-annealing at 250°C for 2h, its Tc remained unchanged, while increased to 83 K after annealing for 25 h. For another crystal with a higher as-grown Tc of 86.7K and annealed under the same condition, its Tc was unchanged except for a slight improvement of ΔTc and was independent of the annealing time. X-ray diffraction showed that there were no changes of c-axis lattice parameter for the annealed crystals. If the above two crystals, after annealing at 250°C for 25 h, were further annealed at 600°C for 20 h, then Tc was increased to the same value of almost 88K and the c-axis lattice parameter showed a dramatic contraction. We suggested that the improvement of superconductivity of the sample annealed at much lower annealing temperature (250°C ) are associated with the oxygen diffusion involved in the pervoskite unit and this diffusion from the perovskite unit occurs earlier than that from Bi-O layers.
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Influence of Weak Self-Field Effect on Calculated Activation Energy for Superconducting Thin Film
XU Xiao-nong, SUN Ai-min, DING Shi-ying, JIN Xin, YAO Xi-xian, YAN Shao-lin, WEN Hai-hu
Chin. Phys. Lett. 1997, 14 (8):
617-620
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When the applied field Ba = μ0 Ha (Ha > Hp) is perpendicular to the surface of a disk-shaped superconducting thin film with the full penetrated field Hp, the radius R, and the thickness d, a quantitative relation between the average field < B > and the magnetization M is described by < B > = μ0 [Ha + (0.81 d/R) M] for R» d , where the term μ0(0.81 d/R) M also is the average self-field of the film. Combining this relation with the magnetic flux conservation equation and the Arrhenius relation, the effective activation energy is extracted from the experimental magnetization relaxation and the dynamic magnetization relaxation, respectively.
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20 articles
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