[en] Electron induced two nucleon knockout reactions (e,e'pp) and (e,e'np) were performed for ³He, ⁴He, and ¹²C nuclei with incident energies of 2.261 GeV and 4.461 GeV using the CLAS detector at Jefferson Lab. Events with missing momenta lower than the Fermi level and missing energies smaller than the pion threshold were studied. The residual system was assumed to be a spectator and the process was considered as a quasi-free knockout of an NN pair. The data showed that the initial momentum extends up to 800 MeV/c with considerable strength. The cross sections for ³He(e,e'pp)n were compared to the calculations of J.M. Laget. It was found that the final state interactions (FSI) and the meson exchange currents (MEC) dominate the cross sections and the short range properties of the NN pair were substantially undermined. However, the node of the S state wave function of the pp pair at around 400 MeV/c initial momentum starts to be recognizable in the 4.461 GeV data. The data and the theory suggest that with higher momentum transfers, especially in the region x_Bj > 1, the competing processes such as FSI and MEC will be less important and the detailed study of the short-range properties of nucleons inside nuclei will be more desirable

[en] We use the self-consistent mean-field theory method to study the ground states of the quantum ferrimagnetic chain. This one-dimensional chain can be described by the Hamiltonian: H=Σ_i [(S_i·s_j)_λ+(s_i·S_j)_λ], where (S_i·s_j)_λ=λ(S_i^xs_j^x+S_i^ys_j^y)+S_i^zs_j^z. At the Heisenberg point (λ=1), we observe two branches of the low lying excitation. We calculate the gap between the two excitation branches, the spin reduction and the spin fluctuation at T=0 K. We also give the correlation length at T=0 K. These results agree with the established numerical results quite well. We also calculate the ground-state energy and the excitation gap varying with the Ising anisotropy λ. It agrees quite well with quantum Monte Carlo approaches and fourth-order perturbation approaches

No abstract available

[en] Reliability and technique centered maintenance (RtCM) is a systematic engineering method used to determine the preventive maintenance requirement of equipment assets and optimizing the maintenance system. This paper has introduced the process and technological innovation of RtCM method through a practical example of RtCM application in the moisture separator reheater system in a nuclear power plant. Besides, the economic benefit resulting from RtCM application was evaluated. The results indicate that RtCM method, into which the maintenance templates, technical characteristic analysis, equipment identification and quantitative analysis technique were introduced, is a more efficient and more advanced method in the maintenance the optimization field and plays an important role in improving the equipment reliability. (authors)

[en] The geometry of 1,2,4-triazole is similar to those of pyrazoles and imidazoles, which is a six-electron aromatic system of five-membered ring. Compared with pyrazoles and imidazoles, the bonding of the 1,2,4-triazole ring with metal complexes has one link more, thus resulting in more rich coordination modes. The triazole ring tends to adopt bidentate (bridging) or tridentate for trizolate anions to construct polynuclear or extending structures. Therefore, mononuclear metal-triazole complexes are rare especially for first-row transition metals. To our knowledge, there exist only a few papers about mononuclear metal-triazole complexes. Besides the coordination chemistry, triazoles have other applications in the wide fields, such as photography, agriculture, medicine and industry. As a readily available and inexpensive resource, 1,2,4-triazole is also a good candidate to synthesize suitable nitrenium ion precursors, and synthetic applications and implication as 'ultimate carcinogens' from aromatic amines. In view of coordination character of 1,2,4-triazole, herein two mononuclear coordination compounds, [Cd(HCOOH)(ptr)I₂]·H₂NCH₂NH₂ and [ZnCl₂(ptr)₂]·H₂O (ptr = m-phenol-1,2,4-triazole), were synthesized and the crystal structures and properties of fluorescence and diffuse reflectance spectrum were characterized

[en] The method of ion assisted vapour deposition (IAD or IVD) for preparing thin films is described. The comparison of the Ag/Si thin film prepared by IVD with those prepared by conventional vacuum vapour deposition has been made. The interface ion mixing of Ag/Si, and the surface microstructure of the Ag/Si thin films are measured by RBS, TEM, SEM etc

[en] B₄C pellets with different B/C ratio and nuclear purity grade sodium were put into a stainless steel cladding tubes and the out-of-pile tests were carried out at 550, 650 and 750 degree C. The test period is 82 d. After compatibility test, the appearance of B₄C pellets is integral, and crack or break are not found. However, the surfaces become rough and original metal luster is lost. The chemical reaction product NaB₅O₈ deposits and adheres to the surface of B₄C pellets. This results in the volume increasing of B₄C pellets. No considerable change in microstructure and grain size of B₄C pellets are observed. There are B, Na and C penetrate into cladding inner surface. The amount of B and Na penetration increases with the temperature and B/C ratio increasing, but C penetration is opposite. The chemical reaction products among Na, impurities in sodium, B₄C and cladding are NaBO₂ , Cr₂B, Fe₂B and Ni₃B. The formation of the borides made increasing considerably in microhardness at the cladding inner surface

[en] A prototype device was proposed to detect latent explosives based on neutron back scattering and activation methods. Monte-Carlo simulation was made, and the results indicate that the back scattering neutron and the gamma ray counts increase corresponding to carbon, oxygen and nitrogen. This increase can be used to determine the exist of latent explosive. (authors)

[en] The compatibility tests for the forging tungsten with coolants are performed in sodium at 500, 600 and 700 degree C, and in water at 100 degree C. The results show: a compact W_xO_y film is formed at the surface of the tungsten, its thickness is about 1 - 2 μm. There are also corrosion product Na_xWO_y on the surface of the specimens, the amount of Na_xWO_y dependents on the temperature and the oxygen content in the sodium. After test for more than 400 h, the matrix of tungsten is not attacked further by sodium and oxygen resulting from the protection of the W_xO_y film, the thickness of W_xO_y film and the weight loss become a constant; for the corrosion of the tungsten in water, a W_xO_y film at the specimen surface is formed at the beginning of the test, its thickness is about 0.8 μm; This film is porous and loose, and they peels off after test for more than 100 h. The new oxide film does not form again because of the lack of the oxygen, the weight loss of the specimens is near a constant

[en] In order to research the damages of plutonium to the human body in the nuclear accident conditions, ²³⁹PuO₂ particles deposition location and deposition rate in the lung bronchium were simulated with computational fluid dynamic method in the paper. The results show that inhaled ²³⁹PuO₂ particles deposit mostly in the first and the second bifurcation of the lung airway. The research can give references to the nuclear measurement concerned in the plutonium and uranium nuclide deposited in the human's lung airway under nuclear accident conditions. (authors)