分类： 核科学技术 >> 裂变堆工程技术 提交时间： 2023-06-18 合作期刊: 《Nuclear Science and Techniques》
摘要： A nuclear battery consisting of a beta source, a phosphor layer and a photovoltaic device was prepared. Planar phosphor layers were synthesized through physical precipitation of ZnS:Cu, ZnS:Ag or SrAl2O4:Eu2+, Dy3+ phosphors. The radioluminescence (RL) spectra were used to analyze the RL effects of the phosphor layers under beta-particle excitation. Feasibility of using the materials as intermediate absorbers in the beta batteries was studied. The IV characteristics of beta RL nuclear batteries with different phosphor layers were tested using 63Ni or 147Pm beta sources. The output power of zinc sulfide matrix phosphor layer was better than that of rare-earth element oxides. In addition, a thin aluminum reflective layer was vacuum-evaporated on the phosphor layers to improve the efficiency of beta RL nuclear batteries, and the results were discussed.
分类： 核科学技术 >> 辐射物理与技术 提交时间： 2021-12-31
摘要： Controllable D-D neutron sources have a long service life, low cost, and non-radioactivity. There are favorable prospects for its application in geophysical well logging, since traditional chemical radioactive sources used for well logging pose potential threats to the safety of the human body and environment. This paper presents an improved method to measure formation density that employs a D-D neutron source. In addition, the lithological effect on the measured density was removed to better estimate the formation porosity. First, we investigated the spatial distribution of capture gamma rays through Monte Carlo simulations as well as the relationship between the ratio of capture gamma ray counts and formation density to establish theoretical support for the design of density logging tools and their corresponding data processing methods. Second, we obtained the far to near detector counts of captured gamma rays for an optimized tool structure, and then established its correlation with the density and porosity of three typical formations with pure quartz, calcite, and dolomite minerals. Third, we determined the values for correcting the densities of sandstone and dolomite with the same porosity using limestone data as the reference and established the equations for calculating the correction values, which lays a solid foundation for accurately calculating formation porosity. We observed that the capture gamma ray counts first increased then decreased and varied in different formations; this was especially observed in high-porosity formations. Under the same lithologic conditions (rock matrix), as the porosity increases, the peak value of gamma ray counts moves toward the neutron source. At different detector-source distances, the ratio of the capture gamma ray counts was well correlated with the formation density. An equation of the formation density conversion was established based on the ratio of capture gamma ray counts at the detector-source distances of 30 cm and 65 cm, and the calculated values were consistent with the true values. After correction, the formation density was highly consistent with the true value of the limestone density, and the mean absolute error was -0.013 g/cm3. The calculated porosity values were very close to the true values, and the mean relative error was 2.33%, highlighting the accuracy of the proposed method. These findings provide a new method for developing D-D neutron source logging tools and their well-log data processing methods.
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