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Volume 4 Issue 1
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Original Articles
SEARCH FOR AXIONS IN ORTHOPOSITRONIUM DECAY
TANG Xiaowei
Chin. Phys. Lett. 1987, 4 (1): 1-4 .  
Abstract   PDF(pc) (41KB) ( 449 )
Monoenergetic peaks have been searched in the inclusive gamma ray spectrum from oPs decay. For axion mass 60keV to 970keV the 90% confidence level limits on the rabtio R of single gamma ray to three gamma ray decay from oPs 6 x10-4 to 6x10-5 without the assumption of the penetrating axions.

THE FORMATION OF HEAVY ELECTRONS IN A MAGNETICALLY ORDERED MATERIAL
CHEN Changfeng, ZHANG Liyuan
Chin. Phys. Lett. 1987, 4 (1): 5-8 .  
Abstract   PDF(pc) (41KB) ( 370 )
The necessary conditions for the presence of heavy electrons in metals and compounds, which contain local f electrons, are analyzed with an emphasis on the magnetically ordered materials. A self-consistent treatment on the Periodic Anderson Hamiltonian shows that there is a sharp change in the effective mass (therefore the density of states) while the virtual bound level crosses the Fermi level; meantime a transition between magnetic and nonmagnetic or/and between different magnetic states may concomitantly occur. Numerical calculation has been carried out and some typical results are shown.

THE HYDROGEN-DISLOCATION INTERACTION IN Fe-0.5wt%Ti ALLOY
MAO Ou, DU Jiaju
Chin. Phys. Lett. 1987, 4 (1): 9-12 .  
Abstract   PDF(pc) (51KB) ( 448 )
Internal friction measurement on hydrogen-induced cold work peak in Fe-0.5wt%Ti alloy is reported. The character of the peak is determined and compared with that in pure iron. The activation energy for the peak has been obtained. The binding energy between hydrogen atoms and dislocations is estimated from the result of isothermal aging experiment.
COLORED STATES IN QUASI-CONFINEMENT MODELS
DING Yibing*, ZHAO Guangda, QIN Danhua
Chin. Phys. Lett. 1987, 4 (1): 13-16 .  
Abstract   PDF(pc) (42KB) ( 421 )
It is assumed in this paper that the interquark (or gluon) forces are dominated by color octet exchange, which leads to the attractive forces to form colored bound states. The mass spectrum of colored states is discussed in two quasi- confinement models. A qualitative prediction of the experimental signature on the colored bound states is included.
EXPERIMENTAL STUDIES ON GROWTH KINETICS OF SALOL CRYSTALS FROM THE MELT
JIN Weiqing*, Hiroshi Komatsu
Chin. Phys. Lett. 1987, 4 (1): 17-20 .  
Abstract   PDF(pc) (57KB) ( 502 )
In situ observation method has been carried out to investigate the growth kinetics of salol from the melt. The temperature-dependence of growth rate of salol crystals in a supercooling range of 0 to 3°C for (102) and (012) faces are studied. The lateral (two dimensional nucleation) –to-continuous growth transition has been obtained. The free energy of step ε, the radius of the critical nucleus r*, and the excess free energy of a critical nucleus ΔG* are measured for (102) and (012) faces.
SUB-NATURAL LINEWIDTH OPTICAL-PUMPING DIPS IN A HOMOGENEOUSLY BROADENED SPECTRAL LINE
LI Mengyang, FU Jishi
Chin. Phys. Lett. 1987, 4 (1): 21-24 .  
Abstract   PDF(pc) (53KB) ( 406 )
Sub-natural linewidth optical-pumping dips have been observed in a homogeneously broadened. fluorescence line in Na atomic beam spectroscopy. To our knowledge, this is the first observation of sub-natural linewidth dip by optical pumping. A theoretic explanation is given.

REMANENCE DIRECTION OF Nd2Fe14B PERMASENT MAGNET AT 77K AS A FUNCTION OF OBLIQUELY APPLIED MAGNETIC FIELD
JIN Hanmin, CHEN Huinan, CHEN Guanmian*
Chin. Phys. Lett. 1987, 4 (1): 25-28 .  
Abstract   PDF(pc) (58KB) ( 394 )
The remanence direction of Nd2Fe14B permanent magnet at 77K, initially at saturated remanence along the grain oriented direction, as a function of magnetic field applied along a direction making 70°with the initial remanence direction is calculated neglecting the magnetic interaction between the crystallites. The results are very different from the experimental results obtained by using torque method.
A BETHE-LATTICE APPROACH TO THE SPIN WAVE EXCITATIONS NEAR THE INTERFACE OF TWO FERROMAGNETIC INSULATORS
WANG Xiaofei, LIN Zonghan(Tsung-han Lin )
Chin. Phys. Lett. 1987, 4 (1): 29-32 .  
Abstract   PDF(pc) (52KB) ( 355 )
The property of spin wave spectra near the interface of two ferromagnetic insulators is studied. Starting from Heisenberg model and using Bethe -lattice approximation and Green's function technique, the local density of magnon states (LDOMS) is calculated for different parameters. A gap in the LDOMS is found in certain parameter region.
A NEW MODEL FOR THE MIXED VALENCE COMPOUNDS
ZHENG Hang
Chin. Phys. Lett. 1987, 4 (1): 33-36 .  
Abstract   PDF(pc) (45KB) ( 361 )
The ground-state properties of the Sm-based mixed valence compounds are discussed by means of introducing an indirect on-site hybridization mediated by phonons, for the direct on-site hybridization is forbidden by inversion symmetry. A self-consistent field approximation is used, and a nonzero energy gap and a fluctuating valence state are given. The results obtained can be used to explain the small energy gap and the valence fluctuation phenomena observed in SmB6 and SmS.
THEORETICAL AND EXPERIMENTAL STUDIES ON THE DOUBLE-FREQUENCY MODE-LOCKED Ar+ LASER
BAO Xiaoyi, WU Cunkai
Chin. Phys. Lett. 1987, 4 (1): 37-40 .  
Abstract   PDF(pc) (50KB) ( 381 )
The principle and characteristics of the double-frequency mode-locked Ar+ laser are described. There are two light pulses in the Ar+ laser cavity at any time, and the mode spacing is doubled at about 210MHz. This leads to a factor of about two in average output power of the Ar+ laser. A theoretical explanation for the experimental phenomenon is given.
CALCULATION OF THE a3 COEFFICIENT FOR SPINOR FIELD BY PROPER TIME EXPANSION METHOD
XU Dianyan
Chin. Phys. Lett. 1987, 4 (1): 41-43 .  
Abstract   PDF(pc) (30KB) ( 409 )
The a3 coefficient is an important and useful quantity from which one can evaluate the vacuum polarization energy-momentum tensors and revise Einstein's classical gravitational field equation to a semiclassical level. The a3 coefficient of spinor field is calculated by proper time expansion method in this article.
HIGH PRESSURE SYNTHESIS OF HIGH Tc A15 Nb3Si
WANG Yaoji, WANG Wenkui, HE Shouan, H. Iwasaki
Chin. Phys. Lett. 1987, 4 (1): 44-46 .  
Abstract   PDF(pc) (34KB) ( 374 )
The A15 Nb3Si with a smaller lattice parameter (a=0.5093nm) has been synthesized from the amorphous Nb77Si23 alloy under high pressure by using Bridgman anvils apparatus. Superconductivity measurements shoued that the A15 phase produced from Nb77Si23 has the highest Tc(19.1K) among all that can be obtained from Nb-Si alloys.
12 articles