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本文用包括平衡前发射在内的蒸发模型理论研究了(n,2n),(n,3n)反应的激发函数系统学.在对实验数据分析、拟合的基础上,得到一组较好的经验参数.利用这组参数计算得到的截面和实验结果符合较好. 相似文献
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《Superlattices and Microstructures》1986,2(4):385-389
We have investigated n+n−n+ structures of GaAs in which the length of the active n− region is comparable with the average donor separation. At low temperatures the resistance is independent of temperature and the magnetoresistance is large and anisotropic. These results are described by a simple quantitative model in which the low temperature conductivity is controlled by electrons tunnelling via shallow donors close to the mid-plane of the active layer. 相似文献
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本文报告了En~14MeV中子以~(27)Al(n,a)~(24)Na或~(93)Nb(n,2n)~(92m)Nb反应截面为中子注量标准测得的~(92)Mo(n,d~*)~(91m)Nb,~(106)Cd(n,d~*)~(105)Ag;~(54)Fe(n,t)~(25m+g)Mn,~(58)Ni(n,t)~(56)Co;~(51)V(n,n'a)~(47)Sc和~(92)Mo(n,n'a)~(88)Zr的反应截面。文中还列举了能收集蓟的数据以作比较,中子能量是用铌锆截面比法测定的。 相似文献
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V. B. Golubev S. I. Serednyakov K. Yu. Skovpen Yu. V. Usov 《Physics of Atomic Nuclei》2009,72(4):662-667
A project aimed at measuring the neutron electromagnetic form factor in the reaction e + e ? → n \(\bar n\) with the SND detector at the VEPP-2000 e + e ? collider is presented. The results obtained for the time resolution of the NaI(Tl) counter using flash-ADC are reported along with estimates of the efficiency of separation of neutron-antineutron events. 相似文献
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From isothermalM(H) curves nearT
c
, measured on polycrystalline Tl2Ba2Ca
n–1Cu
n
O2n
+4 and (Bi, Pb)2Sr2Ca
n–1Cu
n
O2n+4 (n=2,3) samples, we deduce the in-plane penetration depths ab as functions of temperature. An estimate according to the BCS weak-coupling clean-limit fit, which produces the data nearT
c
very well, yields ab(0)=3100 Å, 2320 Å 2210 Å, and 1960 Å for Bi2Sr2CaCu2O8, Bi1.6Pb0.4Sr2Ca2Cu3O10, Tl2Ba2CaCu2O8, and Tl2Ba2Ca2Cu3O10, respectively. A comparison between strong-coupling and weak coupling fitting curves clearly favours the weak-coupling temperature dependence of ab nearT
c
. 相似文献
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《Superlattices and Microstructures》1986,2(5):415-419
Magnetophonon resonance and quasi-elastic inter-Landau level scattering (QUILLS) are investigated in the transverse magnetoconductivity, σxx, of short (1 μm) n+n−n+ InP structures under conditions of space-charge-limited conduction. The damping of the magnetophonon resonance amplitudes at large E is also investigated. The electric field dependence of the QUILLS process in InP is in excellent agreement with a model that we have previously proposed to describe the process in n+nn+ GaAs layers. The observed form of the space-charge-limited current-voltage characteristics (I ∝ V2) is discussed in terms of the behaviour of electrons in short, lightly doped semiconductor layers under the influence of large, mutually perpendicular electric and magnetic fields. 相似文献
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在统计理论及考虑角动量守恒的激子模型的基础上,运用Monte Carlo方法计算(n,20)反应同质异能态截面比. 以59Co(n,2n)58Co、93Nb(n,2n)92Nb和181Ta(n,2n)180Ta的3个反应道为例,计算从其阈能到20MeV能区的同质异能态截面比,并和已有实验数据做了比较,结果符合较好. 这表明本文提供的方法是计算(n,2n)反应同质异能态截面比的一种有效方法. 相似文献
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用活化法以^27Al(n,α)^24Na反应截面为中子注量标准,对14MeV能区中子引起的^93Nb(n,2n)^92mNb反应截面进行了测量。中子能量由硅探测器法测定。 相似文献
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^132,134,136,137^Ba(n,p),^132,134^Ba(n,2n)反应截面测量 总被引:1,自引:0,他引:1
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A number of crystal-forming polyhedral clusters X
n
Y
n
from which zeolite-like covalent crystals can be constructed and synthesized through copolymerization by faces are proposed.
A series of the smallest sized crystal-forming carbon clusters C2n
(where n = 10, 12, 14, 16, 18, 24, 36, 60) and silicon carbide clusters Si
n
C
n
(where n = 12, 16, 18, 24, 36, 60) are constructed. Their optimized geometries, electronic structures, charge transfers, band gaps,
cohesive energies, and electron density maps are calculated using the spinrestricted Hartree-Fock method in the 6–31G(d) basis set. The Si12C12 and Si24C24 clusters, referred to as the fulsicenes, are used to construct possible crystals with rock salt (Si12C12), simple cubic (Si24C24), body-centered cubic (Si12C12), face-centered cubic (Si24C24), and hyperdiamond (Si12C12) lattices, which are termed fulsicenites. Their X-ray diffraction patterns are calculated. 相似文献
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M. D. Ossowska-Chruściel S. Zalewski A. Rudzki A. Filiks J. Chruściel 《Phase Transitions》2013,86(8):679-690
New results of investigations of phase polymorphism for two substances, hydrogenous (7OS5-d0) and partially deuterated (7OS5-d26) have been presented. On the basis of measurements of the integrated “elastic window” intensity (EL), quasielastic neutron scattering (QNS) spectra and results obtained with the Transmitted Light Intensity (TLI) method, the metastable character of the SmC phase, that at constant temperature always transforms to the crystalline phase Cr2, has been confirmed. Variations of the EL show a very clear hysteresis effect in the nematic and SmC phases as well as in solid phases. It was confirmed by a phase polymorphism in both investigated substances. Convergence of the EL and TLI methods was shown. The new phase situation of both hydrogenous and partly deuterated liquid crystals is presented. 相似文献
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Cross sections for some (n,d*),(n,t) and (n,n'α)reactions have been measured by using the activation method relative to cross sections of 27Al(n,α)24Na or 93Nb(n,2n)92mNb reactions in neutron energies around 14MeV.In this paper some of the published cross section data have also been listed and compared with our results.The neutron energies were determined by the method of cross section ratios for the reactions of 90Zr(n,2n) 89m+gZr and 93Nb(n,2n)92mNb. 相似文献
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采用中子n-反中子n与中性介子π0强相互作用的Lorentz不变耦合模型,对n-n重正化链图传播子作了有关物理分析及其严格解析计算,获得精确理论计算结果.进而将此结果用于n n→2π0反应的物理过程分析及其截面的计算研究中,并精确计算出n-n重正化链图传播下n n-2→2π0反应微分截面.还将此计算结果与n-n树图和重正化单圈链图传播下n n→2π0反应微分截面作了对比分析,获得了有关辐射修正的重要信息.此结果对于深入研究Lorentz不变耦合模型理论以及深入探索核物理中关于核子、反核子与介子强相互作用的粒子反应截面问题具有一定的参考价值.此外,还将对量子场论微扰理论中关于逐阶重正化计算的不同考虑方式与计算途径及其相关物理过程提供某些值得借鉴之处. 相似文献