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Volume 10 Issue 8
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Original Articles
Structure Transition of the Three-Dimensional Penrose Tiling Under Phason Strain Field
SUN Jirong
Chin. Phys. Lett. 1993, 10 (8): 449-452 .  
Abstract   PDF(pc) (201KB) ( 469 )
Possible periodic structures resulting from three-dimensional Penrose tiling (3DPT) by introducing the so-called phason strain are studied. Only two types of cubic structures, simple cubic (sc) and body centered cubic (bcc), are possible. Numbers of the unit-cells, which are the same as those of the 3DPT, within each structure matrix of the sc/bcc structure are also given.
Production of C60/C70 Ion Beams
FANG Dufei, GAO Haibin, LU Fuquan, TANG Jiayong, YANG Fujia
Chin. Phys. Lett. 1993, 10 (8): 453-455 .  
Abstract   PDF(pc) (166KB) ( 542 )
With a 30keV mini-separator at the accelerator laboratory of Fudan University, we have successfully obtained about 1 nA fullerene ion beam. Under the same conditions, we have also observed the fragment ions C+n (n=20-40). The C+60(C+70) beams will be used study collision between fullerene and electrons, atoms and photons.
NJL Mechanism and Supersymmetry Behavior at Finite Temperature
SONG Heshan, XU Guangnan, AN Ying
Chin. Phys. Lett. 1993, 10 (8): 456-459 .  
Abstract   PDF(pc) (162KB) ( 413 )
It is shown that the supersymmetry breaking can be realized dynamically by Nambu-Jona-Lasinio (NJL) mechanism. The supersymmetry behavior at finite temperature is also investigated and shown that the supersymmetry broken dynamically at zero temperature can be restored at finite temperature.
Screened Q-Q Potential and Spectrum of Heavy Quarkonium
DING Yibing, , CHAO Kuangta, , QIN Danhua,
Chin. Phys. Lett. 1993, 10 (8): 460-463 .  
Abstract   PDF(pc) (204KB) ( 509 )
Using a Q-Q poteiitia1 with the color screening effect due to the creation of light quark pairs, the spectra of bb and cc systems are calculated. An improved fit for the masses of the lightly excited states can be obtained. In particular, the ψ(4160) might be assigned as the 4.5 cc state.

An Investigation into the Total Reaction Cross Section and Production Cross Section of Energetic Particles
MA Yugang, SHEN Wenqing, FENG Jun, MA Yuqiang,
Chin. Phys. Lett. 1993, 10 (8): 464-467 .  
Abstract   PDF(pc) (193KB) ( 563 )
New calculations for the total reaction cross sections and production cross sections of the energetic particles are carried out via the nuclear transport theory. The experimental total reaction cross sections can be reproduced. In addition, the effects of some ingredients 011 the total reaction cross sections can be easily analyzed. It is found that the total reaction cross sections are sensitive to the nuclear equation of state below 100MeV/u and the in-medium nucleon-nucleon cross section in the full energy range addressed. While the π - meson production cross sections can be also calculated.
Rapidity, Transverse Mass Distributions and Nuclear Stopping in (14.6 AGeV/c) Si+Au Reactions
WANG Zhongqi, SA Benhao, LU Zhongdao, ZHANG Xiaoze, SONG Guang, ZHENG Yuming,
Chin. Phys. Lett. 1993, 10 (8): 468-471 .  
Abstract   PDF(pc) (208KB) ( 555 )
The experimental data of proton and pion rapidity distributions and proton transverse mass distribution in reaction of (14.6AGeV/c)Si + Au are compared with a simple relativistic hadronic cascade simulation. The theoretical results seem to prefer the statement of strong but incomplete nuclear stopping at AGS energy.
KNbO3: Fe Optical Frequency Discriminator
ZHANG Zhiguo, JIANG Qian, MI Xin, YU Zuhe, FU Panming, SHEN Dezhong*, MA Xiaoyan*
Chin. Phys. Lett. 1993, 10 (8): 472-475 .  
Abstract   PDF(pc) (207KB) ( 453 )
By using the feature that KNbO3 :Fe bas fast response time, we demonstrate a KNbO3 :Fe optical frequency discriminator (KOFD) which is based on the method of the-delayed laser-induced double)le gratings. This KOFD can be used to measure the frequency difference between two laser fields.
Nearly-Resonant Two-Photon Absorption of C60 Thin Film at 633nm
HAN Yanong, ZHANG Wenjun, GAO Xiaoming CUI Yiben, XIA Yuxing, GU Gang*, ZANG Wencheng*, DU Youwei*, FENG Duan*
Chin. Phys. Lett. 1993, 10 (8): 476-478 .  
Abstract   PDF(pc) (142KB) ( 586 )
We present measurements of two-photon absorption (TPA) coefficient of C60 thin film at 633nm. Large values of β~5 cm/W were determined. Nearly-resonant TPA transition around 3.76 eV absorption region was discussed.
Enhancement of Anti-Stokes Line of Stimulated Four-Photon Mixing in an Er3+ Doped Silica Fiber
SHEN Shupo, YU Zhongqiu*
Chin. Phys. Lett. 1993, 10 (8): 479-481 .  
Abstract   PDF(pc) (136KB) ( 525 )
By using a pulsed dye Laser of nanosecond level as a pomp source, we have investigated stimulated Raman scattering and stimulated four-photon mixing in Er3+ doped silica fibers. The experimental results show that all lines, including the pump radiation line, are obviously broadened and the anti-Stokes lines of stimulated four-photon mixing arc greatly enhanced, and that the enhancement effect is independent of the wavelength.
Microturbulence in HT-6M Tokamak
ZENG Lei, YU Changxuan, CAO Jinxiang, ZHU Guoliang, ZHANG Daqing*, LI Youyi*
Chin. Phys. Lett. 1993, 10 (8): 482-485 .  
Abstract   PDF(pc) (201KB) ( 486 )
The small scale density fluctuations in the interior of HT-6M Ohmic plasma have been studied by CO2 laser collective scattering system in deuterium discharges covering a range of neqa (chord-average density times safety factor at the limiter) and energy confinement time. The relative density fluctuations level in the interior is inversely proportional to the toroidal magnetic field and average density, and the energy confinement time TE decreases with the fluctuation level increasing in the region where TE linearly increases with neqa and satisfies the Goldston scaling Jaw. It is suggested that the microturbulence in the interior zone is responsible for anomalous transport in tokamaks.
Neutron Scattering Study of Sr Substitution for Ba in YBa2Cu3O7-y
DING Yongfan, LI Jizhou, YANG Jilian, ZHANG Baisheng, KANG Jian, YE Chuntang, FU Qiang*, JIN Sheng*, CUI Yujian*, HE Aisheng*, HE Yusheng*
Chin. Phys. Lett. 1993, 10 (8): 486-488 .  
Abstract   PDF(pc) (162KB) ( 477 )
Neutron diffraction and inelastic scattering were carried out on YBa2-xSrx Cu3O7-y(x=0.5, 1.0, 1.25). It was confirmed that the substitution of Sr for Ba in YBa2Cu3O7-y increases the oxygen vacancies in the Cu O chain. Moreover, the substitution strengthens the coupling between the Ba O plane the Cu O chain, and reduces the crystal stability. These are possible causes of Tc depression for Sr substituted YBa2Cu3O7-y.
Effects of Dislocations on Growth Habit in Crystal of Thallium Acid Phthalate
ZHAO Qinglan, HUANG Yisen, GUAN Tietang*, LIN Jingzhen*
Chin. Phys. Lett. 1993, 10 (8): 489-491 .  
Abstract   PDF(pc) (337KB) ( 492 )
The spiral and ordinary dislocations both running nearly perpendicular to the (001) growth surface of thallium acid phthalate, were revealed and identified by x-ray topography. They play an unexpectedly important role on that face by providing the self-perpetuating step sources so as to accelerate its growth rate or even to change its crystal morphology.

Mechanism of Piezoresistive Effect of TiC-Polyvinyl Chloride Composites
DU Weifang, TIAN Xu
Chin. Phys. Lett. 1993, 10 (8): 492-495 .  
Abstract   PDF(pc) (179KB) ( 468 )
The behaviors of piezoresistivity in a new series of composite materials composed of TiC particles in polyvinyl chloride (PVC) insulating polymer are investigated. Experimental results show a Pronounced change in resistivity with pressure, making the composite materials attractive candidates for pressure or stress sensors with sensitivities much higher than the conventional semiconductive silicon materials. Piczoresistive effect of TiC-PVC composite is related to the difference in the elastic properties of the TiC particles and PVC polymer, and to the large changes in resistivity with concentration close to 25 vol%TiC in composite.


Study of Flux Pinning in Zone-melted YBCO by SQUID
JI Helin, SHI Zhixian, ZENG Zhaoyang, JIN Xin, YAO Xixian, FAN Zhanguo, SHAN Yuqiao
Chin. Phys. Lett. 1993, 10 (8): 496-499 .  
Abstract   PDF(pc) (212KB) ( 485 )
Magnetic hysteresis loops arid magnetization relaxation of a zone-melted YBa2Cu306+x sample were measured by superconducting quantum interference device (SQUID) at temperature from 4.5 to 70 K. The logarithmic behavior of magnetic decay at 4.5 K arid the gradual deviation as the temperature is increased demonstrated important role of nonlinear current density dependence of effective flux pinning potential U( J) in high temperature superconductors.
Exact Solution for the One-D Spin Fluctuation Model
WANG Yupeng, JIN Duo*
Chin. Phys. Lett. 1993, 10 (8): 500-502 .  
Abstract   PDF(pc) (126KB) ( 425 )
The exact solutions via Bethe ansatz to the One-D spin fluctuation model for J >0 and J <0 are presented . The bound states are discussed based on the Bethe ansatz equations. It is shown that the antiferromagnetic spin fluctuation leads to bound states like Cooper pairs and ferromagnetic spin fluctuation to no bound state. Also we point out that our model is much similar to the δ–potential Fermi gas model.
Phase Transformation in the Infinite Layer Structure Compound (Sr, Nd) CuO2 and its Effect on Superconductivity
ZHOU Xingjiang, YAO Yushu, LI Jianqi. XU Wei, JIA Shunlian, ZHAO Zhongxian
Chin. Phys. Lett. 1993, 10 (8): 503-506 .  
Abstract   PDF(pc) (333KB) ( 451 )
Superconducting compound (Sr0.86Nd0.14) CuO2 with the infinite layer structure was synthesized under high pressure. This tetragonal structure a x a transforms into a superstructure 2√2a x 2√2a when the sample was in situ heated in transmission electron microscope to about 600K. An anormalous resistance change of the sample during heating in vacuum to 400°C confirmed the phase transformation. After the superlattice formation, the sample lost its superconductivity and became semiconducting.
Quantum Wormholes with Nonminimal Coupling
WANG Wenfu, TAO Caide*
Chin. Phys. Lett. 1993, 10 (8): 507-509 .  
Abstract   PDF(pc) (122KB) ( 467 )
A Robertson- Walker geometry with nonminimal coupled scalar field has been quantized by the canonical formulation for constrained Hamiltonian systems. The exact solutions have been found for corresponding Wheeler-DeWitt equation. These solutions satisfy the needs of Hawking's boundary condition for the wormhole wave function. Thus they can provide a quantum-mechanical description of wormholes in a theory with a nonminimal coupled scalar field. The characteristic scale of the ground state of the wormhole is of the order of Planck length.
An Important Improvement on Damour-Ruffini Approach Dealing with Hawking Effect
ZHU Jianyang, ZHAO Zheng
Chin. Phys. Lett. 1993, 10 (8): 510-512 .  
Abstract   PDF(pc) (0KB) ( 236 )
The second quantization is introduced to the approach proving Hawking radiation, suggested by Damour and Ruffini. A wave packet around an event horizon can be expanded by two alternative complete sets respectively. Making use of the Bogolubov transformation between the two sets of modes, Hawking effect can be shown.
18 articles