【摘要】 β射线面密度测量仪广泛应用于锂电池涂布工序中极片面密度的在线测量。研究发现，当β源与探测器距离固定时，源与薄膜间距的变化会显著影响面密度测量精度。通过Geant4蒙特卡罗模拟发现，该影响主要源于薄膜对β射线的散射作用。模拟比较了三种准直器几何模型（探测器侧单准直器、源侧单准直器、源探测器双侧准直器）下源与薄膜间距变化1 mm时面密度测量的平均偏差，结果表明源侧单准直器几何模型下的偏差最小。并根据模拟结果进行了实验验证，改进装置后，源与薄膜间距变化1 mm导致的面密度最大测量偏差从约13.3%降至3.5%。研究结果为降低锂电池极片在线测量误差提供了参考。更多还原

【Abstract】 [Background] The β-ray surface density measurement instrument is widely used for the online measurement of the surface density of electrode sheets in the coating process of lithium batteries. A significant measurement error was observed when the source-to-film distance(SFD) varied under fixed source-to-detector distance(SDD). [Purpose] This study aims to investigate and minimize the impact of SFD variations on the accuracy of β-ray surface density measurements. [Methods] Firstly, experimental tests were conducted using the β-ray surface density measurement device with a fixed SDD to quantify the influence of SFD changes(4～8 mm) on copper film surface density measurements. Then, Geant4 Monte Carlo simulations were performed to model β-ray scattering effects under three collimator configurations: detector-side single collimator, source-side single collimator, and dual collimators. Finally, the optimized source-side single collimator geometry was experimentally validated by reproducing SFD variations and recalculating measurement deviations. [Results] Initial experimental results reveal that 1 mm SFD variation causes a maximum measurement deviation of 13.3% in surface density values. Monte Carlo simulation results demonstrate that the source-side single collimator configuration minimizes scattering effects,showing the smallest mean deviation among all three geometries tested. Experimental validation confirms this improvement with the maximum deviation decreasing from 13.3% to 3.5% after device optimization. [Conclusions]Results of this study show a 73.7% reduction in measurement error caused by SFD variations is achieved by adopting a source-side single collimator, providing a practical solution for enhancing online surface density measurement accuracy in lithium battery production.更多还原