Additional file 1 of Sample size and the limits to precision in Pb-isotopic dating by ID-TIMS

Additional file 1. Table S1. Variations of calculated Pb isotopic ratios in the reference material EarlyTime 1x with assumed blank parameters. Table S2. Johnson-Nyquist noise at 24°C as a function of feedback resistance and integration time. Table S3. Comparison of amplifier noise in select mass spectrometers with theoretical (Johnson-Nyquist) noise of 1011 Ohm resistor at 24°C. Table S4. Precision of measurements of the 207Pb/206Pb by TIMS as a function of sample size, ion yield, baseline noise, and measurement conditions (integration times for signal and baseline).

附加文件1：表S1。参考物质EarlyTime 1x中计算所得铅（Pb）同位素比值随假设空白参数的变化情况。表S2：24℃下约翰逊-奈奎斯特噪声随反馈电阻与积分时间的变化关系。表S3：部分选定质谱仪的放大器噪声与24℃下10¹¹欧姆电阻的理论（约翰逊-奈奎斯特）噪声对比。表S4：采用热电离质谱（TIMS）测得的²⁰⁷Pb/²⁰⁶Pb比值测量精度随样品量、离子产率、本底噪声及测量条件（信号与本底积分时间）的变化规律。