910 resultados para Microregião do Seridó - NE - Brasil


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报道Arq + +Ne(q =8,9,11,12 )碰撞体系中多电子转移过程 ,得到了多组实验测量电荷交换截面数据 ,讨论入射离子电荷交换截面、反冲离子产生截面与入射离子电荷态、能量以及散射离子电荷态的关系 ,并且将实验结果与Arq + +Ar碰撞体系进行对比研究。在修正分子库仑过垒模型的基础上 ,对实验现象做了合理的解释

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采用符合关联实验技术进行的Ar~(q+)+Ne(q=8,9,11,12)碰撞体系中多电子转移过程的研究。在实验上鉴别了反应中各种电子转移过程,并测量了转移电离截面。研究了转移电离截面与反冲离子电荷态的关系,并利用修正后的分子过垒模型计算结果与实验结果进行了对比分析,计算结果较合理地描述了实验现象。

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介绍了用透射法测量中能区2 0 Ne打9Be靶碎裂产生的次级束与Si靶作用的核反应总截面的方法 ,以及实验的探测器布局、实验过程和实验结果 .并对理论上预言有奇异结构的核1 2 N ,1 7Ne和1 7F的实验结果与其相邻核进行了比较

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采用逆运动学方法对放射性核束17F和18Ne与质子进行弹性散射实验 ,得到了实验测量微分截面 .用较准确描述放射性核素性质的CH89参数化的光学势为初始光学势 ,用扭曲波玻恩近似的理论计算程序DWUCK4和自动参数搜索程序ABOD对实验数据进行光学势参数理论拟合 ,得到了与实验数据相符合的光学势参数 .将得到的光学势参数进行分析 ,得到了17F和18Ne实势相互作用均方根半径分别为 3 2 3 9fm和 3 3 1 7fm .

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讨论了目前16O(α ,γ) 2 0 Ne反应的实验研究工作 ,并对2 0 Na β+—→2 0 N →16O +α的β+ 缓发衰变α能谱的相对强度值同文献进行了比较 ,讨论了低能激发能级、共振强度及其对共振截面的贡献、S因子的理论研究 .

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用半经典模型考虑20Na+208Pb→p+19Ne+208Pb的Coulomb解离过程。用MonteCarlo方法计算前角放置的望远镜阵列对Coulomb解离碎片的探测效率。讨论了天体环境下p+19Ne→20Na俘获反应道的低能级共振截面测量的可行性。

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An investigation of a commercial oxide dispersion-strengthened steel (MA9561) irradiated with high energy Ne-ions to high doses at elevated temperatures is presented. Specimens of MA956 oxide dispersion strengthened steel together with a 9% Cr ferritic/martensitic steel, e.g., Grade 92 steel were irradiated simultaneously with 20Ne-ions (with 122 MeV) to successively increasing damage levels of 1, 5 and 10 dpa at the damage peak at 440 C and 570 C, respectively. Cross-sectional microstructures of the specimens were investigated with transmission electron microscopy. MA956 oxide dispersion strengthened steel showed a higher resistance to void swelling especially to void growth at the grain boundaries than the ferritic/martensitic steel, e.g., Grade 92 steel did, and thus exhibited a prominence for an application in the situation of a high He production at high temperatures. The suppression of the growth of voids especially at the grain boundaries in MA956 is ascribed to an enhanced recombination of the point defects and a trapping of Ne atoms at the interfaces of the yttrium–aluminum oxide particles and the matrix.

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In this work the void swelling behavior of a 9Cr ferritic/martensitic steel irradiated with energetic Ne-ions is studied. Specimens of Grade 92 steel (a 9%Cr ferritic/martensitic steel) were subjected to an irradiation of Ne-20-ions (with 122 MeV) to successively increasing damage levels of 1, 5 and 10 dpa at a damage peak at 440 and 570 degrees C, respectively. And another specimen was irradiated at a temperature ramp condition (high flux condition) with the temperature increasing from 440 up to 630 degrees C during the irradiation. Cross-sectional microstructures were investigated with a transmission electron microscopy (TEM). A high concentration of cavities was observed in the peak damage region in the Grade 92 steel irradiated to 5 dpa, and higher doses. The concentration and mean size of the cavities showed a strong dependence on the dose and irradiation temperature. Enhanced growth of the cavities at the grain boundaries, especially at the grain boundary junctions, was observed. The void swelling behavior in similar 9Cr steels irradiated at different conditions are discussed by using a classic void formation theory. (c) 2008 Elsevier B.V. All rights reserved.

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The L-shell ionization processes of a Ne gas target associated with single-electron capture by bombardment of Cq+ and Oq+ (q=2,3) are investigated using the projectile-recoil-ion coincidence method in the energy range from 80 to 400 keV/u (v(p)=1.8-4 a.u.). The cross-section ratios (R-k1) of k-fold ionization to single capture are compared with the results for He2+-Ne collisions by Dubois [Phys. Rev. A 36, 2585 (1987)]. All the velocity dependences are quite similar. The ratios increase as the projectile energy increases in the lower-energy region, reach the maxima for projectile energies around E-max=160q(1/2) keV/u, and then decrease at higher energies. These results qualitatively agree with our calculations in terms of the Bohr-Lindhard model within the independent-electron approximation.

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In the present work specimens of mono-crystalline silicon carbide (4H polytype) were irradiated to three successively increasing ion fluences ranging from 7.2 x 10(14) to 6.0 x 10(16) ions/cm(2) (corresponding to the peak displacement damage of 1, 4 and 13 dpa) with Ne and Xe ions respectively with the energy of 2.3 MeV/amu. The irradiated specimens were subsequently annealed at temperatures of 1173 and 1273 K. Defect structure was investigated with transmission electron microscopy (TEM) using a cross-sectional specimen preparation technique. The typical microstructures of the annealed specimens irradiated with Ne or Xe ions to high fluences are characterized by small gas bubbles in high concentration in the peak damage region and black dots and dislocation loops (located in the basal plane) in a shallower and broader depth region. Larger dislocation loops were observed in the Xe-ion irradiated specimen than in the Ne-ion irradiated specimen at the same peak damage level. The enhanced formation of dislocation loops in the case of Xe-ion irradiation is understandable by assuming stronger inclination of heavier inert-gas atoms to occupy substitute site in the peak damage region.