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Volume 13 Issue 7
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Original Articles
Effect of the Boundary on the Dynamics of Solitary Waves
WANG Jun-yi, WANG Wei, WANG Ben-ren, WEI Rong-jue
Chin. Phys. Lett. 1996, 13 (7): 481-484 .  
Abstract   PDF(pc) (185KB) ( 550 )
The effect of the boundary on the dynamics of solitary waves has been studied. The inverse scattering transformation for the solitary wave equation with boundary condition is treated by the reduction group theory. The effective potential of interaction between the solitary wave and the boundary is found to be same as the Morse potential. The physical mechanism of the soliton oscillation could be interpreted by our results.
Semi-unitary Transformation Induced Supersymmetric Partner Hulthen System
ZHANG Jiu-an, MA Gui-rong, ZHANG Jian-zu
Chin. Phys. Lett. 1996, 13 (7): 485-488 .  
Abstract   PDF(pc) (143KB) ( 387 )
The supersymmetric partner system of Hulthen system in the s state is obtained by using a semi-unitary transformation. The physical foundation of applications of semi-unitary transformation to supersymmetric quantum mechanics is explored.
Weyl Representation of the Space-Time of the Vacuum C Metric when m =0
WANG Yong-cheng
Chin. Phys. Lett. 1996, 13 (7): 486-491 .  
Abstract   PDF(pc) (104KB) ( 673 )
By using the imaginary Weyl coordinate method, the whole space-time of the vacuum C metric when m = 0 can be represented by the Weyl coordinate system. In addition, a revised transformation relation between Weyl and Minkowski coordinates has been introduced, and the whole space-time obtained by the Minkowski form of the metric can also be represented by Weyl coordinate system.

Compensate Effect Under Time-Scale Transformation in Vaidya-Bonner Space-Time
MA Yong, ZHAO Zheng
Chin. Phys. Lett. 1996, 13 (7): 492-495 .  
Abstract   PDF(pc) (123KB) ( 582 )
The Hawking effect in the Vaidya-Bonner space-time can be considered as a compensate effect of the scale transformation of coordinate time. The gauge potential is the contraction of the affine connection. It is found that the rate of change of temperature can be obtained as the pure gauge potential of the compensate field, in addition to the Hawking temperature which was known from the stationary black holes.

Monte Carlo Simulations of Classical O(2) Model on Nice Tree and Bethe Lattice
GUO Wen-an, YANG Zhan-ru
Chin. Phys. Lett. 1996, 13 (7): 496-499 .  
Abstract   PDF(pc) (209KB) ( 510 )
The Metropolis Monte Carlo algorithm is applied to a classical O(2) model on nice tree and Bethe lattice. Finite-size scaling theory is applied to estimate the critical temperature. The results show that the continuous symmetry may not be spontaneously broken even if df ≥ dw + 1 where df and dw are the fractal dimension and the dimension of the random walk on the structure respectively or even if the random walk on the structure is transient.

Liquid-Gas Transition in the Ionic System
DING Guo-hui, XU Bo-wei
Chin. Phys. Lett. 1996, 13 (7): 500-503 .  
Abstract   PDF(pc) (134KB) ( 379 )
The phase transition in the ionic system in dimension d = 3 is studied in the formulation of quantum sine-Gordon field theory. By a variational method the phase diagram is investigated, and the critical point terminating the coexistence of conducting liquid and conducting gas is obtained.
Yrast Bands Calculation for Odd-Odd Nuclei 160Ho, 162Tm and 164Tm
ZHU Shun-quan, ZHENG Ren-rong
Chin. Phys. Lett. 1996, 13 (7): 504-507 .  
Abstract   PDF(pc) (167KB) ( 607 )
In this paper, the axial symmetry rotor plus quasiparticle model is generalized from odd nuclei to odd-odd nuclei. Energy spectra of yrast bands for nuclei 160Ho, 162Tm and 164Tm are calculated by using the method. Signature inversions in these three nuclei are reproduced, and one possible signature inversion mechanism connected with the calculation is also discussed.
Nuclear Parton Distribution
XUE Da-li, LI Guang-lie,
Chin. Phys. Lett. 1996, 13 (7): 508-511 .  
Abstract   PDF(pc) (166KB) ( 362 )
The quark and gluon distributions in nuclei are investigated by a parton model, where the common partons of several nucleons and the non-nucleonic components are considered. The comparisons of this model with the data for F2A1(x)/F2A2(x) and the recent data for GSn(x)/GC(x) are also present.

J/ψ and γ Photoproduction in Pb-Pb Collisions at Large Hadron Collider
LIU Lian-shou, LI Yun-de
Chin. Phys. Lett. 1996, 13 (7): 512-515 .  
Abstract   PDF(pc) (195KB) ( 403 )
Hard photoproduction of J/ψ and γ at large hadron collider Pb-Pb collisions with center of mass energy 6300AGeV is discussed in the process Pb + Pb → Pb + J/ψ(Γ) + X with three types of equivalent photon spectrum function. It turns out that in hard photoproduction the J/ψ cross section is dominated by the gluon and heavy quark fragmentation, especially the gluon fragmentation is very important at large pt, while the γ cross section is dominated by the leading order process. It may be conclude from the result that the hard photoproduction processes can be used to test several important problems such as the gluon distribution in the nucleus, gluon and heavy quark fragmentation of J/ψ, and so on. In addition the process also provide a new way of testing the EMC effects.

Alpha-Chain Structure of 12C
XIE Wen-fang*, BAO Cheng-guang
Chin. Phys. Lett. 1996, 13 (7): 516-519 .  
Abstract   PDF(pc) (172KB) ( 500 )
Alpha-chain states in 12C are studied via an analysis of underlying quantum mechanical symmetry. It is pointed out that the linear chain band exists undoubting in 12C. However, the pure linear chain structure does not exist in 12C. All possible linear chain states are mixture with triangle structures.
Energy Loss and Straggling of 4He Ions in Havar
LU Xi-ting, JIN Chang-wen, WU Ze-qing, XIA Zong-huang
Chin. Phys. Lett. 1996, 13 (7): 520-523 .  
Abstract   PDF(pc) (130KB) ( 526 )
The energy loss and energy straggling of 4He ions in Havar foil were measured with the transmission geometry. The present result of energy loss has good agreements with that of the previous experiment and the semi-empirical predictions, while for the energy straggling data significant deviation was found at lower energies compared with the predictions of Bohr theory.
Origin of Self-pumped Phase Conjugate Waves in KNSBN Crystals
ZHANG Liang-min, ZHANG Jing-wen, SHAO Zong-shu, MU Xiao-dong, CHEN Huan-chu, JIANG Min-hua
Chin. Phys. Lett. 1996, 13 (7): 523-526 .  
Abstract   PDF(pc) (213KB) ( 465 )
A multistage four-wave mixing interaction region model resulting in self-pumped phase conjugation output of the incident beam is suggested to explain the experimental observations. The competition between forward and backward two-wave mixing is demonstrated and used to explain the formation of the mechanism. The backscattering beams from random noise beams may be amplified by contradirectional two-wave mixing selectively and act as pumped beams from our experimental observations under a laser entering the negative c face of copper-doped potassium sodium strontium barium niobate crystal. The phase conjugation reflectivity of as high as 33% is measured.

Formation of Endohedral Complexes in Collisions of H2 and D2 with C60
XING Yue-lin, XIA Yue-yuan, MEI Liang-mo
Chin. Phys. Lett. 1996, 13 (7): 527-530 .  
Abstract   PDF(pc) (248KB) ( 519 )
Formations of endohedral complexes in collisions of H2 and D2 with C60 molecules have been studied using a molecular dynamics simulation method. H@ C60 complex is produced when a H2 molecule collides with a C60 molecule dong the direction from the center of a hexagonal ring into the center of the C60 at collision energy E0 = 40 eV. At the same collision condition, a D2 molecule colliding with a C60 molecule forms a D2@ C60 complex.

Partial Disordering of GaAs/AlGaAs Quantum Well by Rapid Thermal Annealing
WANG Jian-hua, YU Guang-rui, JIN Feng, LI De-jie
Chin. Phys. Lett. 1996, 13 (7): 531-533 .  
Abstract   PDF(pc) (175KB) ( 469 )
The partial disordering of GaAs/AlGaAs quantum well (QW) material has been obtained by rapid thermal annealing with SO2 dielectric capping film. In this case, the absorption edge of QW material was shifted apparently. A laser and a modulator were integrated on a same chip by partial disordering process on the select4d area of QW wafer which was grown by molecular beam epitaxy.
Pressure-Induced Amorphous Transition of Li2Ge7O15 Crystal
CHEN Liang-chen, GU Hui-cheng, WANG Li-jun, LI Feng-ying, CHE Rong-zheng, ZHOU Lei, XIU Li-song, LAN Guo-xiang
Chin. Phys. Lett. 1996, 13 (7): 534-536 .  
Abstract   PDF(pc) (165KB) ( 484 )
Pressure-induced amorphous transition of Li2Ge7O15 (LGO) crystal has been investigated by using in situ high pressure energy dispersive x-ray diffraction with synchrotron radiation at the pressure up to 21.6 GPa. Diamond anvils were used to generate high pressure. Pressure was measured in terms of the diffraction of Pt as an internal pressure standard. The crystal structure of LGO is an orthorhombic lattice at atmospheric pressure. According to the high pressure x-ray diffraction results, new diffraction lines begin to appear and LGO undergoes an intermediate phase transition at the pressure of 12.9 GPa. But, the diffraction lines disappear wholly and LGO becomes an amorphous phase at the pressure of above 14.8 GPa. This amorphous transition is irreversible.
Structural Changes in Nitrogen-Doped a C:H Films
LIU Yi-chun, KONG Xiang-gui, YU Ji-qi, FAN Xi-wu, Tagliaferro Alberto
Chin. Phys. Lett. 1996, 13 (7): 537-540 .  
Abstract   PDF(pc) (249KB) ( 453 )
The influence of nitrogen on the microstructure of a-C:H film is investigated by infrared, photoluminescence (PL), and transmittance-reflectance spectra. It is indicated that nitrogen incorporation into a-C:H network will weaken some C-H bonds, which is confirmed by differential scanning calorimeter experimental results. It is also demonstrated that nitrogen entering into a-C:H film can raise luminescence intensity. On the other hand, nitrogenation will reduce PL thermal stability.

Electrical Characteristics of Metal Contacts to Boron Doped Polycrystalline Semiconducting Diamond Thin Films
LIU Xing-zhao, YANG Bang-chao, JIA Yu-min, LI Yan-rong
Chin. Phys. Lett. 1996, 13 (7): 541-544 .  
Abstract   PDF(pc) (200KB) ( 687 )
Low resistance ohmic contacts have been fabricated on chemical vapor deposition grown polycrystalline B doped semiconducting diamond thin films by thermally activated solid state reaction process. A bilayer metallization of Ti/Au was employed. After annealing at 820°C for 10min in Ar atmosphere, the specific contact resistance of 2 x 10-4 Ω.cm2 has been obtained. The properties of the diamond/Ti interfaces have been characterized by using x-rays diffraction and scanning electron microscopy. The performance of semiconducting diamond thin film thermistors has been reported.
Thermoelectric Effect of YBa2Cu3O7-δ Films with Risetime of 0.6 Nanosecond
ZHANG Lian-fang, TANG Bo, HUANG He-sheng, ZHANG Hui-yun, LIU Meng-lin, WU Zhen-yi, ZHOU Yue-liang*
Chin. Phys. Lett. 1996, 13 (7): 545-548 .  
Abstract   PDF(pc) (179KB) ( 313 )
Voltage pulses of 90 V have been observed in YBa2Cu3O7-δ films with a tilted orientation when they are illuminated by pulsed laser at room temperature. The signals result from the anisotropy of thermoelectricity in the films. The thermoelectric signals related to the tilted angle are linear to the laser power and wavelength-independent. It is shown that the response of films to the mode-locked laser has a risetime less than 1ns and width less than 20 ns. The films with the superconducting transition temperature of 90K were prepared by laser ablation.

A Cluster Algorithm for the 2-D SU(3) x SU(3) Chiral Model
JI Da-ren, ZHANG Jian-bo
Chin. Phys. Lett. 1996, 13 (7): 549-552 .  
Abstract   PDF(pc) (196KB) ( 452 )
To extend the cluster algorithm to SU(N) x SU(N) chiral models, a variant version of Wolff's cluster algorithm is proposed and tested for the 2-dimensional SU(3) x SU(3) chiral model. The results show that the new method can reduce the critical slowing down in SU(3) x SU(3) chiral model.

Electrical Properties of Semi-insulating GaAs Grown from the Melt Under Microgravity Conditions
WANG Zhan-guo, LIN Lan-ying, LI Cheng-ji, ZHONG Xing-ru, LI Yun-yan, WAN Shou-ke, SUN Hong
Chin. Phys. Lett. 1996, 13 (7): 553-556 .  
Abstract   PDF(pc) (227KB) ( 466 )
A technologically important undoped semi-insulating (SI) GaAs single crystal was successfully grown in the Chinese recoverable satellite as far as we know for the first time by using a similar growth configuration described previously. The experimental results proved that the space SI GaAs crystals have a lower density of defects and defect-impurity complexes as well as a better uniformity.
Nucleation Mechanism of Polycrystalline Diamond Film Deposited on Ceramic Alumina by Microwave Plasma Chemical Vapor Deposition
XIA Yi-ben, MO Yao-wu, WANG Yu, HUANG Xiao-qin, CHEN Da-ming, WANG Hong
Chin. Phys. Lett. 1996, 13 (7): 557-560 .  
Abstract   PDF(pc) (233KB) ( 493 )
Polycrystalline diamond films have been deposited on ceramic alumina substrates by microwave plasma chemical vapor deposition method. Variation of the emission spectra in the microwave plasma with the microwave power and the vapor pressure in the reaction chamber is studied, respectively. Relationships between the hydrogen atomic spectra and the average energy of the electrons in the plasma, as well as the mechanism of diamond film deposition on ceramic alumina are discussed.

21 articles