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Volume 6 Issue 5
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Original Articles
COMPARISON OF CHARGED PARTICLE MULTIPLICITIES IN THREE-JET AND TWO-JET EVENTS FROM e+e- ANNIHILATION AT HIGH ENERGIES
LIU Ximing
Chin. Phys. Lett. 1989, 6 (5): 193-196 .  
Abstract   PDF(pc) (42KB) ( 419 )
The charged particle multiplicity < n3j> in the three-jet events in e+e- annihilation is considered. The comparison of < n3j> with < n2j> is presented. The prediction of the multiplicity agrees well with experiments. Moreover, some predictions for high energy range are made.












GENERATION OF STIMULATED EMISSION BY VISIBLE MULTIPHOTON DISSOCIATION OF PbCl2 MOLECULES
CHENG Bingying, ZHAO Lizeng, ZHANG Daozhong, YANG Yongwu, ZHAO Yuying
Chin. Phys. Lett. 1989, 6 (5): 197-200 .  
Abstract   PDF(pc) (50KB) ( 382 )
Stimulated emission was generated at the 722.9nm line of neutral lead atoms by multiphoton dissociation of PbCl2 molecules with a DPS dye laser. Anti-Stokes Raman scattering around 283.3nm was also observed. The effects of the heat-pipe oven temperature and pump laser energy on the 722.9nm radiation was studied. The energy conversion efficiency of the 722.9nm laser is about 5%. It provides a way for frequency conversion by multiphoton dissociation of simple molecules with a visible laser.
INVESTIGATION OF LINEAR ION BERNSTEIN WAVE IN KT-5B TOKAMAK
LIU Wandong, WEN Yizhi, WAN Shude, YU Changxuan
Chin. Phys. Lett. 1989, 6 (5): 201-204 .  
Abstract   PDF(pc) (53KB) ( 365 )
Linear ion Bernstein waves have been successfully excited in KT-5B tokamak by a toroidal current antenna. Ion Bernstain waves were detected by two rf Langmuir probes and identified by their exciting region and their dispersion relation. The ion temperature profile in the tokamak has been obtained from the dispersion relation of ion Bernstein wave in agreement with the measuring by an electrostatic ion probe.
CALCULATIONS OF NUCLEAR STOPPING POWERS AND RANGES IN THE LOW-ENERGY REGION
ZHANG Jianhua, LIU Jiarui, LIYi*
Chin. Phys. Lett. 1989, 6 (5): 205-208 .  
Abstract   PDF(pc) (48KB) ( 448 )
The interactions between incident particles and solids in ion implantation have been discussed, basing on the generalized Langevin theory. Considering anharmonic effects of interactions among lattice atoms, we calculated numerically the nuclear stopping power and the distribution of projected ranges, which are in agreement with the results of the program TRIM-88 in the low-energy limit.
ROLE OF ALTER LAYER IN DEPTH PROFILE OF INTERFACE
ZHANG Qiangji, LU Ming, FEI Lu
Chin. Phys. Lett. 1989, 6 (5): 209-212 .  
Abstract   PDF(pc) (53KB) ( 391 )
A new model based on the alter layer induced by ion bombardment has been proposed, which can explain the depth profile of interface of Ta2O5/Ta quite well. In contradiction with the generally accepted point of view the depth profile does not follow the shape of the error function. The dcminant factor for resolution is the thickness of the alter layer (δ) rather than the electron mean free path (λ). The Ta2O5/Ta sample was prepared by the method of anodic oxidation with thickness of 500Å. All the surface analyses were performed by using scanning Auger micro probe (model PHI-590) at room temperature.
RENORMALIZATION GROUP METHOD FOR CALCULATING THE LOCALIZATION LENGTH OF COUPLED DISORDERED CHAINS
TAN Weichao*, YANG Chuliang
Chin. Phys. Lett. 1989, 6 (5): 213-216 .  
Abstract   PDF(pc) (47KB) ( 381 )
A renormalization group method for calculating the localization length of coupled disordered chains is presented. By using this method, we can determine the localization length of coupled chains accurately.
PECULIAR PROPERTY OF SINGLE PHASE Bi3PbCa3Sr3Cu4Oy
XIA Jiansheng, CHEN Zuyao*, CAO Liezhao, HE Zhenhui FANG Minghu, CHEN Xianhui*, QIAN Yitai*, ZHANG Qirui
Chin. Phys. Lett. 1989, 6 (5): 217-220 .  
Abstract   PDF(pc) (0KB) ( 208 )
The R(H) and Jc (T) of single phase material Bi3PbCa3Sr3Cu4Oy were investigated. As the temperature belows 65K, the sample likely shows the characteristics of homogeneous superconductors. Very high critical current density and no negative magnetoresistance are observed. This distinct property distinguishes the new material from other ceramic superconductors.

MAGNETIC PROPERTIES OF HEAT TREATED Nd3Fe81B16 ALLOY
GU Benxi, ZHAI Hongru, SHEN Baogen, S.Methfessel
Chin. Phys. Lett. 1989, 6 (5): 221-224 .  
Abstract   PDF(pc) (49KB) ( 337 )
The hysteresis loop and Mössbauer spectrum of the heat treated Nd3Fe81B16 alloy ribbons annealing at 660°C for 10min. have been measured. A coercive field of about 2kOe and an energy product of about 8MGOe are obtained at room temperature. X-ray diffraction and Mössbauer spectrum analyses show that the high coercivity may originate from the Fe3B phase containing Nd. The value of remanence and energy product in this alloy are much higher than those of anisotropic BaFe12O19 ferrite, It may be used as a cheap permanent magnet.
OBSERVATION OF RAMAN SCATTERING AND FLUORESCENT SPECTRA OF KTiOPO4 ( KTP ) CRYSTAL
XU Liwen, CHANG Dawei, NIU Hongda, JIA Shouquan
Chin. Phys. Lett. 1989, 6 (5): 225-228 .  
Abstract   PDF(pc) (56KB) ( 530 )
By measuring Raman scattering spectra of KTiOPO4(KTP) crystal with several configurations, we found the orientation of polarizability tensor in flux-grown KTP (KTPF) was perpendicular to the orientation of polarizability tensor in hydrothermally grown KTP (KTPH). Fluorescent and Raman spectra of KTP were measured from room temperature to 4.2K. The appearance of peaks at 135cm-1 and 800cm-1 at 77K and the temperature dependence of Raman spectrum lines are discussed.
FORMATION OF AMORPHOUS Cu60Zr40 AND Ni50Zr50 POWDERS BY MECHANICAL ALLOYING
DONG Yuanda, XIAO Keqin, LIU Lin, WU Ziqiang, WANG Weihua, HE Yizhen
Chin. Phys. Lett. 1989, 6 (5): 229-232 .  
Abstract   PDF(pc) (48KB) ( 493 )
Amorphization of Cu-Zr and Ni-Zr systems by mechanical alloying(MA) was studied by X-ray diffraction. The results show that the amorphization is not merely a simple interdiffusion by thermal activation; in addition, the strain induced by MA also accelerates this process.
GEOMETRICAL OPTICS IN AN INHOMOGENEOUS UNIVERSI
FANG Lizhi, WU Xiangping
Chin. Phys. Lett. 1989, 6 (5): 233-236 .  
Abstract   PDF(pc) (43KB) ( 357 )
In comparison with a homogeneous universe, a clumpy universe possess two types of effects on geometrical optics: 1. the convergence due to the gravititational-lens effects of the clumps; 2. the divergence due to the less mass density outside the clumps. On the other hand, thermodynamics requires that the total effects are double offset. This give us an effective method to judge the rationality of various calculations of the lensing effect in a clumpy universe.
AN AUTOMATIC CONTROL SYSTEM FOR MOLECULAR BEAM EPITAXY GROWTH EQUIPMENT
GAO Zongren, XIONG Xiuzhong
Chin. Phys. Lett. 1989, 6 (5): 237-240 .  
Abstract   PDF(pc) (34KB) ( 359 )
12 articles