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Volume 7 Issue 5
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Original Articles
TRAILS ON A REGULAR DIFFUSION-LIMITED AGGREGATION FRACTAL
WANG Xiaomin ZHENG Dafang LIN Zhifang, TAO Ruibao*
Chin. Phys. Lett. 1990, 7 (5): 193-196 .  
Abstract   PDF(pc) (46KB) ( 329 )
By an exact renormalization method the trail problem on a regular fractal for the diffusion-limited aggregation is considered, and the mean square end-toend distance critical exponent v is obtained. It is indicated that self-avoiding trails and self-avoiding walks are in different universality classes on this irreversible kinetic growth fractal.


FRACTAL BORDER OF DIFFUSION-LIMITED AGGREGATION CLUSTER
BI Lingsong
Chin. Phys. Lett. 1990, 7 (5): 197-199 .  
Abstract   PDF(pc) (34KB) ( 360 )
Both the similarities existing between diffusion-limited aggregation (DLA) cluster border and Brownian motion and the perimeter-area relation have revealed that the fractal dimension of DLA cluster border is about 2.0.

HEAT KERNEL REGULARIZATION IN SUPERSYMMETRY
LI Jiangnan, YAN Jun, HU Shike
Chin. Phys. Lett. 1990, 7 (5): 200-203 .  
Abstract   PDF(pc) (48KB) ( 340 )
By borrowed operators, the heat kernel regularization method is applicable in supersymmetry. The anomalies of supersymmetry Yang-Mills current and spinor current are derived by this method.

LOGARITHMIC MOMENTS AS NEW CHARACTERISTICS FOR LARGE MULTIPLICITY FLUCTUATIONS IN SMALL RAPIDITY WINDOWS
Igor M.Dremin*, WU Yuanfang, LIU Lianshou,
Chin. Phys. Lett. 1990, 7 (5): 204-207 .  
Abstract   PDF(pc) (50KB) ( 370 )
The behavior of logarithmic moments of particle distributions in different rapidity windows is discussed for pp and PA collisions at high energies. The special role of those events, having no-particle in the rapidity window, is stressed.
TWO-LEVEL CONVOLUTlON FORMULA FOR NUCLEAR STRUCTURE FUNCTION
MA Boqiang
Chin. Phys. Lett. 1990, 7 (5): 208-211 .  
Abstract   PDF(pc) (48KB) ( 410 )
A two-level convolution formula for the nuclear structure function is derived in considering the nucleus as a composite system of baryon-mesons which are also composite systems of quark-gluons again. The results show that the European Muon Colaboration effect can not be explained by the nuclear effects as nucleon Fermi motion and nuclear binding contributions.
THE POSSIBILITY OF A NEW RESONANCE OF THREE-BODY LINEAR CHAIN STRUCTURE IN THE REACTION 12C+16O AT Ec.m≈33.5MeV
KONG Xiangjing*, P.L.Li*, J.J.Kolata, A.Morsad, L.Goetting, R.A.Kryger, S.Dixit, R.Tighe, W.Chune
Chin. Phys. Lett. 1990, 7 (5): 212-215 .  
Abstract   PDF(pc) (53KB) ( 341 )
There is a peak in the excitation function of total cross section of low energy α-particles in the reaction 12C+16O at Ec.m≈33.5MeV. The experimental distribution of α-particle emitted event has been obtained. The result of theoretical calculation roughly agrees with experimental data, gives an orientation where three-body resonances can be expected, and the information on internal structure of three-body linear chain molecule.
THEORETICAL XUV SPECTRA FROM CARBON-LIKE COBALT IONS BY RELATIVISTIC CONFIGURATION INTERACTION CALCULATION
ZOU Yu, LI Jiaming*
Chin. Phys. Lett. 1990, 7 (5): 216-218 .  
Abstract   PDF(pc) (36KB) ( 398 )
Allowed Δn = 0 transitions of highly ionized metal atoms, which may appear in the solar spectra as well as in spectra from the high-temperature tokamak plasmas, lie in the extreme vacuum UV (XUV) region, 100Å≤ λ ≤ 200Å . Here we report our theoretical calculation of the Δn = 0 transitions of C-like cobalt ions; it is in good agreement with the experimental measurement. Such theoretical calculations of the transition wave lengths and their oscillator strengths should be very helpful to identify the XUV spectra.

A NEW DERIVATION OF KELDYSHS FORMULA
CHEN Baozhen
Chin. Phys. Lett. 1990, 7 (5): 219-221 .  
Abstract   PDF(pc) (34KB) ( 556 )
In this letter, a new derivation of Keldysh's formula is presented and a brief discussion about the comparison between the new derivation and the original one is given.
EXACT FORMULAS OF NON-LINEAR STANDING WAVES
MAA Dahyou (MA Dayou)
Chin. Phys. Lett. 1990, 7 (5): 222-225 .  
Abstract   PDF(pc) (37KB) ( 502 )
On the basis of hydrodynamic equations, an exact theory of non-linear standing sound waves is proposed, avoiding the unaccountable results of earlier theories.
STOPPING POWER OF PROTON IN MONOCRYSTALLINE, POLYCRYSTALLINE AND AMORPHOUS SILICON
MA zhongquan*, LIU Jiarui, ZHU Peiran
Chin. Phys. Lett. 1990, 7 (5): 226-229 .  
Abstract   PDF(pc) (55KB) ( 314 )
The allotropic effect on the electronic topping power of protons in solids was systematically determined by the nuclear resonance reaction 27Al (p ,γ) 28Si at Ep =774 and 992ke V in an silicon on sapphire (SOS) sample of epitaxial Si on sapphire. Details of the experimental technique are described. The experimental error is less than3 %.
LATTICE DYNAMICS OF STRAINED Si/Ge SUPERLATTICES
ZI Jian, ZHANG Kaiming, XIE Xide
Chin. Phys. Lett. 1990, 7 (5): 230-233 .  
Abstract   PDF(pc) (54KB) ( 397 )
Lattice dynamics of strained (Si)4/(Ge)4 superlattice grown pseudomorphically on (001)-oriented Si1-xGex (0 ≤ x ≤ 1) substrate is investigated. In the present calculations, the effects of strain and substrate are discussed.
STUDY OF PHASE BOUNDARIES FOR SITE-BOND PERCOLATION
LIU Yunpeng, ZHENG Maosheng
Chin. Phys. Lett. 1990, 7 (5): 234-236 .  
Abstract   PDF(pc) (35KB) ( 374 )
Relations of phase boundaries and phase region for site-bond percolation are given. It can be seen from the simulation of Monte Carlo that the relations describe the site-bond percolation process much better than others practically.
INFLUENCE OF OXYGEN CONTENT ON SUPERCONDUCTIVITY OF Bi-SYSTEM MATERIAL
WANG Shunxi, XIA Jianshen, ZHANG Qirui, CHEN Xianhui, CHEN Zuyao, LIU Xianming, JI Mingrong
Chin. Phys. Lett. 1990, 7 (5): 237-240 .  
Abstract   PDF(pc) (55KB) ( 436 )
The sample with nominal composition Bi1.8Pb0.35Sr2Ca2Cu3Oy was prepared by solid state reaction method. Through the measurements of resistivity, dc. susceptibility, and the analysis of X-ray diffraction and Energy Dispersive X-ray (EDX) microanalysis, we found that: (1) there is only one superconducting transition with transition temperature near 110K, its zero-resistance temperature (Tce) is as high as 106.5K, the diffraction pattern is similar to that of 2223 single phase (110K), but the cation ratio of Bi:Pb:Sr:Ca:Cu is near 25.8:5.74:18.43:19.53:30.50, i.e., Bi2.5Pb0.5Sr2Ca2Cu3.We suppose that the 3223 phase is caused by intergrowth in the sample; (2) like the 1-2-3 phase material, the superconductivity of Bi-system is sensitive to oxygen content. We suppose that different oxygen content in the same crystal structure leads to the change of electronic structure, and so to great difference in the superconductivity.
13 articles