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Production of Light Nuclei from 36Ar and 40Ar Fragmentation at About 60 MeV/Nucleon
FANG De-Qing, SHEN Wen-Qing, FENG Jun, CAI Xiang-Zhou, MA Yu-Gang, ZHANG Hu-Yong, HU Peng-Yun, ZHAN Wen-Long, GUO Zhong-Yan, XIAO Guo-Qing, LI Jia-Xing, WANG Meng, WANG Jian-Feng, NING Zhen-Jiang, WANG Jin-Chuan, WANG Jian-Song, WANG Quan-Jin, CHEN Zhi-Qiang
Chin. Phys. Lett. 2001, 18 (6):
753-755
.
Fragments produced in the reactions of 69 MeV/nucleon 36Ar and 55 MeV/nucleon 40Ar on a Be target have been measured experimentally. The isotopic distributions from fragmentation reaction for both projectiles are reproduced by using a modified statistical abrasion-ablation model. Strong isospin effect exhibits in the isotopic distributions produced in 36Ar and 40Ar fragmentation. Experimental evidence is seen for the disappearance of the isospin effect in fragmentation reaction.
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Directed and Elliptic Flow in 112Sn+112Sn Collisions
ZHANG Hu-Yong, MA Yu-Gang, YU Li-Ping, SHEN Wen-Qing, CAI Xiang-Zhou, FANG De-Qing, ZHONG Chen, HAN Ding-Ding
Chin. Phys. Lett. 2001, 18 (6):
756-758
.
The directed and elliptic flow in collisions of 112Sn+112Sn at energies from 35 to 90 MeV/nucleon are studied in an isospin-dependent quantum molecule dynamics model. With increasing incident energy, the directed flow rises from negative to positive. Its magnitude depends on the nuclear equation of state (EOS). However, the elliptic flow decreases with increasing incident energy and its magnitude is not very sensible to EOS. Systematic studies of the impact parameter dependence and the cluster mass dependence are also performed. The study of directed flow at intermediate energies thus provides a means of extracting the information on the nuclear equation of state.
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Application of Laser Magnetic Resonance Spectroscopy to the
Measurement of Electric Dipole Moment of Free Radicals
LIU Yu-Yan, , GUO Yuan-Qing, HUANG Guang-Ming, LIN Jie-Li, DUAN Chuan-Xi, LI Feng-Yan, LI Jin-Rui
Chin. Phys. Lett. 2001, 18 (6):
774-775
.
An intracavity CO laser magnetic resonance spectrometer with homogeneous dc electric field applied via a pair of parallel Stark plates in the absorption cell is used to measure the electric dipole moments of free radicals. Taking advantage of high sensitivity and high resolution of this technique and the Stark effect, highly-resolved saturated absorption spectra of v = 1-0 transition of 15N16O in the ground state X2II3/2 have been successfully observed in the presence of a low electric field. The electric dipole moment of NO in the electronic ground state is determined as μ = 0.1566 ± 14 D (Debye) from the analysis of the observed spectra, confirming that, combined with the Stark field, the laser magnetic resonance technique can be an effective and reliable approach for the precise measurement of electric dipole moments of free radicals, especially the unstable ones.
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Self-Organized Criticality Properties of the Turbulence-Induced
Particle Flux at the Plasma Edge of the HT-6M Tokamak
WANG Wen-Hao, YU Chang-Xuan, WEN Yi-Zhi, XU Yu-Hong, LING Bi-Li, GONG Xian-Zu, LIU Bao-Hua, WAN Bao-Nian
Chin. Phys. Lett. 2001, 18 (6):
793-795
.
Power spectrum and the probability distribution function (PDF) of the turbulence-induced particle flux Γ in the velocity shear layer of the HT-6M edge region have been measured and analysed. Three regions of frequency dependence (f0, f-1, f-4) have been observed in the spectrum of the flux. The PDF of the flux displays a Γ-1 scaling over one decade in Γ. Using the rescaled-range statistical technique, we find that the degree of the self-similarity (Hurst exponent) of the particle flux in the measured region ranges from 0.64 to 0.83. All of these results may mean that the plasma transport is in a state characterized by the self-organized criticality.
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Void Evolution in α-Al2O3 Irradiated by En ≥1 MeV Neutrons of 3 x 1020cm-2
XU Yong-Jun, FAN Zhi-Guo, LUO Qi, WANG Rong, ZHU Jia-Zheng, T. Iwata, T. Minamisono, K. Matsuta, M. Fukuda, M. Mihara, ZHU Sheng-Yun
Chin. Phys. Lett. 2001, 18 (6):
808-809
.
The void evolution in α-Al2O3 irradiated by En ≥1 MeV neutrons of 3 x 1020cm-2 and post-annealed from 100°C to 1050°C has been studied by a positron annihilation lifetime technique. The void nucleation starts at 500°C. In the annealing temperature region from 550°C to 750°C, the radius of created voids keeps constant at a value of about 0.29 nm and the number of voids increases with increasing temperature. Afterwards,the radius of voids increases rapidly with the increasing annealing temperature and reaches 1.21nm at 1050°C.
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Strong Quantum Fluctuation of Vortices in Bulk Samples of the New Superconductor MgB2
WEN Hai-Hu, LI Shi-Liang, ZHAO Zhi-Wen, NI Yong-Ming, REN Zhi-An, CHE Guang-Can, YANG Hai-Peng, LIU Zhi-Yong, ZHAO Zhong-Xian
Chin. Phys. Lett. 2001, 18 (6):
816-819
.
By using transport and magnetic measurement, the upper critical field Hc2(T) and the irreversibility line Hirr(T) has been determined. A big separation between Hc2(0) and Hirr(0) has been found showing the existence of a quantum vortex liquid state induced by quantum fluctuation of vortices in the new superconductor MgB2. Further investigation on the magnetic relaxation shows that both the quantum tunneling and the thermally activated flux creep depends weakly on temperature. However, when the melting field Hirr is approached, a drastic rise of the relaxation rate is observed. This may indicate that the melting of the vortex matter at a finite temperature is also induced by the quantum fluctuation of vortices.
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Low Temperature Specific Heat of Superconducting MgB2
LUO Jian-Lin, ZHANG Jie, CHEN Zhao-Jia, BAI Hai-Yang, WANG Yu-Peng, MENG Ji-Bao, JIN Duo, REN Zhi-An, CHE Guang-Can, ZHAO Zhong-Xian
Chin. Phys. Lett. 2001, 18 (6):
820-822
.
The specific heat of the recently discovered superconductor MgB2 has been measured at temperatures ranging from 4.5 to 80 K. Superconducting anomaly ΔC at Tc is clearly observed. The total specific heat in normal state can be well fitted by electronic and phonon contributions. The Debye temperature θD is obtained to be 737 K, much larger than other intermetallic superconductors. Normal state electronic specific heat coefficient γ is found to be 2.48 ± 0.5 mJ/mol.K2 and ΔC/γTc is between 1.41 and 2.15.
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Upper Critical Field and Irreversibility Line Determined by
Transport Measurement of the New Superconductor MgB2
JIN Hao, WEN Hai-Hu, LI Shi-Liang, ZHAO Zhi-Wen, NI Yong-Ming, REN Zhi-An, CHE Guang-Can, YANG Hai-Peng, LIU Zhi-Yong, ZHENG Dong-Ning, ZHAO Zhong-Xian
Chin. Phys. Lett. 2001, 18 (6):
823-825
.
Resistive transitions of the new superconductor MgB2 are carried out under magnetic fields from 0 to 8 T. It is found that the irreversibility field Hirr(T) and the upper critical field Hc2(T) obtained are very close to those determined in the magnetic measurement. By using the Arrhenius activation law ρ = ρ0exp(-U/kBT), the activation barrier U has been determined by the low dissipation part of R(T) curves. It is found that U kBT manifests a very weak thermal activation and thermal fluctuation effect. This may further indicate that the flux dynamics near Hirr(T) is induced by strong quantum fluctuation and tunneling of vortices.
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Energy Transfer in Cubic PbF2:Gd Crystals
ZHANG Guo-Bin, SHI Jun-Yan, ZHANG Zeng-Ming, HAN Zheng-Fu, SHI Chao-Shu, ZHANG Xin-Yi, G. Zimmerer, M. Kirm, SHEN Ding-Zhong
Chin. Phys. Lett. 2001, 18 (6):
829-830
.
The emission and excitation spectra of cubic PbF2:Gd were measured. Compared with pure crystals, the emissions from Gd3+ were observed upon cation exciton excitation in lattices, while the emission from intrinsic self-trapped exciton was quenched. It indicates the energy transfer from exciton to the 4f state of Gd3+.
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Compound Derived from Anthracene and Pyrazol for a Light-Emitting Diode
WANG Ming-Liang, ZHANG Jun-Xiang, LIU Ju-Zheng XU Chun-Xiang
Chin. Phys. Lett. 2001, 18 (6):
831-833
.
A new compound, 5-(9-anthryl)-1,3-diphenyl-1H-pyrazol (ADPP), with an anthryl moiety as an emissive group and a diphenylpyrazoline moiety as a charge transporting group is designed and synthesized. The absorption, photoluminescence, electroluminescence, and electrochemistry are measured. Absorption of ADPP is similar to that of anthracene in the vibonic structure but shows slight red shifts because anthryl moiety twists strongly with respect to pyrazol moiety although delocalization still exists between the two moieties. Light emitting devices fabricated with ADPP show a bright blue emission at 470 nm. The turn-on voltage is 12 V and the light emission follows the current closely, indicating an efficient charge injection and transport for both electrons and holes.
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43 articles
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