Applying the extreme low-level γ-ray spectroscopic analysis the environmental neutron flux is measured using different moderator construction and environment through the reaction 197Au (n, γ) 198Au. The contribution...Applying the extreme low-level γ-ray spectroscopic analysis the environmental neutron flux is measured using different moderator construction and environment through the reaction 197Au (n, γ) 198Au. The contribution of thermal and resonance neutrons is separated using the cadmium difference technique, while fast neutrons are measured by the paraffin moderator. The results of altitude dependence of the neutron flux are discussed. The thermal neutron flux near the surface of sea water is less than its value at 100 cm over ground near sea water, while the value over the surfaces of fresh water is higher than that near the surface of sea water. Also the thermal neutron flux at 5 cm soil depth increases, then decreases to its original value at 10 cm depth and still constant until 25 cm, then decreases rapidly to reach 27% of its original value at 60 cm depth. The soil compositions, corresponding neutron temperatures and effective absorption cross sections of earth are the most effective factors on the equilibrium region of thermal neutrons in the ground.展开更多
The conjecture that ultra-high-energy cosmic rays (UHECRS) are actually strangelets is discussed. Besides the reason that strangelets can do as cosmic rays beyond the Greisen-Zatsepin-Kuzmin-cutoff, another argument t...The conjecture that ultra-high-energy cosmic rays (UHECRS) are actually strangelets is discussed. Besides the reason that strangelets can do as cosmic rays beyond the Greisen-Zatsepin-Kuzmin-cutoff, another argument to bombarding bare strange stars. It is proposed that the exotic quark surface of a bare strange star could be an effective astro-laboratory in the investigations of the extra dimensions and of the detection of ultra-high-energy neutrino fluxes. The flux of neutrinos (and other point-like particles) with energy larger than 2.3×10^20 eV could be expected to be smaller than 10^-26 cm^-2 s^-1 if there are two extra spatial dimensions.展开更多
An improvement for application of Dancoff factor is developed. It combines Stamm'ler's two-term method for resonance integral calculation with neutron current method for Dancoff factor calculation. Stamm'l...An improvement for application of Dancoff factor is developed. It combines Stamm'ler's two-term method for resonance integral calculation with neutron current method for Dancoff factor calculation. Stamm'ler's formulation, which is originally derived for the infinite lattice geometry, can be easily revised to contain the Dancoff factor explicitly, while the neutron current method can easily calculate the Dancoff factor for general irregular assembly geometry. For the resonance interference effects the resonance interference factor table is built in pairs of nuclides, only for the interference between 238 U and other resonance nuclides, spanning over a range of background cross-section and number density ratio of the pairing nuclides. A series of verification calculations have been carried out for problems of infinite lattice and single assembly geometry, with two or multiple resonance absorbers. For these verification calculations, our improvement on Dancoff factor application and resonance interference give good results.展开更多
TN941.1 95010544提高彩电图像分辨率的研讨=Development onincreasing resolution factor of color television[刊,中]/张秀屏,刘锡国,丛玉良(吉林工业大学电子系.吉林,长春(130022))//光学精密工程.—1994,2(2).—89—93介绍利用计算...TN941.1 95010544提高彩电图像分辨率的研讨=Development onincreasing resolution factor of color television[刊,中]/张秀屏,刘锡国,丛玉良(吉林工业大学电子系.吉林,长春(130022))//光学精密工程.—1994,2(2).—89—93介绍利用计算机辅助分析程序作工具,研究与分析亮度通道电路,从而提高彩电图像的分辨率。图7表1参2(任延同)展开更多
With the construction of the neutron wall for the external target experiment at CSR, it will be possible to detect high energy neutrons. A BUU model (Li Baoan, Phys. Rev. Lett. , 88, 19(2002)192 701.) is applied to si...With the construction of the neutron wall for the external target experiment at CSR, it will be possible to detect high energy neutrons. A BUU model (Li Baoan, Phys. Rev. Lett. , 88, 19(2002)192 701.) is applied to simulate the. neutron flow in both symmetric (Ni+Ni,Pb+Pb) and asymmetric (Pb + Ni) systems.It is shown that, at the energy above iseveral hundreds of,MeV/u, the flow signals are very obvi-展开更多
文摘Applying the extreme low-level γ-ray spectroscopic analysis the environmental neutron flux is measured using different moderator construction and environment through the reaction 197Au (n, γ) 198Au. The contribution of thermal and resonance neutrons is separated using the cadmium difference technique, while fast neutrons are measured by the paraffin moderator. The results of altitude dependence of the neutron flux are discussed. The thermal neutron flux near the surface of sea water is less than its value at 100 cm over ground near sea water, while the value over the surfaces of fresh water is higher than that near the surface of sea water. Also the thermal neutron flux at 5 cm soil depth increases, then decreases to its original value at 10 cm depth and still constant until 25 cm, then decreases rapidly to reach 27% of its original value at 60 cm depth. The soil compositions, corresponding neutron temperatures and effective absorption cross sections of earth are the most effective factors on the equilibrium region of thermal neutrons in the ground.
基金Supported by the National Natural Science Foundation of China under Grants Nos 10235020 and 10235030, and the Major State Basic Research Development Programme under Grant No G200007400.
文摘中子流动模型预言中子开始在 s = 在来临的原子核 Fe-58 和 Pb-208 之间自由地流动 3 fm，这些原子核的有效表面是 3 fm 的在长度分开。由于中子流动， N/Z 价值很快到达平衡分布。同时系统，原来在熔化山谷，被注入不对称的分裂山谷。在不对称的分裂山谷的合成原子核的动态过程与一个二参数的 Smoluchowski 方程被对待。克服不对称的分裂障碍并且完成的概率加重原子核配置，这被显示出，因此熔化十字节显然由于 isospinequilibrium 的效果被压制。
文摘The conjecture that ultra-high-energy cosmic rays (UHECRS) are actually strangelets is discussed. Besides the reason that strangelets can do as cosmic rays beyond the Greisen-Zatsepin-Kuzmin-cutoff, another argument to bombarding bare strange stars. It is proposed that the exotic quark surface of a bare strange star could be an effective astro-laboratory in the investigations of the extra dimensions and of the detection of ultra-high-energy neutrino fluxes. The flux of neutrinos (and other point-like particles) with energy larger than 2.3×10^20 eV could be expected to be smaller than 10^-26 cm^-2 s^-1 if there are two extra spatial dimensions.
文摘An improvement for application of Dancoff factor is developed. It combines Stamm'ler's two-term method for resonance integral calculation with neutron current method for Dancoff factor calculation. Stamm'ler's formulation, which is originally derived for the infinite lattice geometry, can be easily revised to contain the Dancoff factor explicitly, while the neutron current method can easily calculate the Dancoff factor for general irregular assembly geometry. For the resonance interference effects the resonance interference factor table is built in pairs of nuclides, only for the interference between 238 U and other resonance nuclides, spanning over a range of background cross-section and number density ratio of the pairing nuclides. A series of verification calculations have been carried out for problems of infinite lattice and single assembly geometry, with two or multiple resonance absorbers. For these verification calculations, our improvement on Dancoff factor application and resonance interference give good results.
文摘TN941.1 95010544提高彩电图像分辨率的研讨=Development onincreasing resolution factor of color television[刊,中]/张秀屏,刘锡国,丛玉良(吉林工业大学电子系.吉林,长春(130022))//光学精密工程.—1994,2(2).—89—93介绍利用计算机辅助分析程序作工具,研究与分析亮度通道电路,从而提高彩电图像的分辨率。图7表1参2(任延同)
文摘With the construction of the neutron wall for the external target experiment at CSR, it will be possible to detect high energy neutrons. A BUU model (Li Baoan, Phys. Rev. Lett. , 88, 19(2002)192 701.) is applied to simulate the. neutron flow in both symmetric (Ni+Ni,Pb+Pb) and asymmetric (Pb + Ni) systems.It is shown that, at the energy above iseveral hundreds of,MeV/u, the flow signals are very obvi-
