Table 2. Net counting rates of 55Fe samples and asymmetry correction factors of PMT quantum efficiency
样品编号
Sample No.
TDCR值
TDCR value
效率
Efficiency
质量
Mass / g
比活度Ao
Specific activity
Ao / kBq∙g-1
比活度Ac
Specific activity
Ac / kBq∙g-1
55Fe_1
0.383 0
0.622 7
0.057 11
94.21
94.16
55Fe_2
0.386 9
0.627 2
0.029 87
94.26
94.10
55Fe_3
0.386 0
0.626 1
0.029 81
94.37
93.96
55Fe_4
0.394 2
0.635 3
0.029 53
94.95
94.45
55Fe_5
0.393 4
0.634 4
0.029 62
94.15
94.09
平均值Mean
94.39
94.15
相对标准偏差Relative standard deviation
0.34%
0.19%
Table 3. The measurement result of specific activity of the 55Fe solution
不确定度分量
Uncertainty component
相对值Relative value / %
注解
Comments
测量变异性Measurement variability
0.18
5个样品的相对标准偏差
Relative standard deviation of five samples
本底Background
0.04
本底扣除引起的不确定度
Uncertainty due to background subtraction
称重Weighing
0.09
天平校准引起的不确定度
Uncertainty due to balance calibration
死时间Dead time
0.05
灵敏度分析,改变死时间(10~500 μs),记录活度的变化,按均匀分布估计不确定度
Sensitivity test, by adjusting the dead-time from 10 μs to 500 μs, recording the change of activity and estimating the uncertainty according to the uniform distribution
符合分辨时间Resolving-time
0.19
灵敏度分析,改变分辨时间从50~200 ns, 记录活度的变化,按均匀分布估计不确定度Sensitivity test, by adjusting the resolving-time from 50 ns to 200 ns, recording the change of activity and estimating the uncertainty according to the uniform distribution
衰变修正Decay correction
<0.01
由55Fe半衰期((2.787±0.008)a)修正引起的不确定度
Uncertainty due to55Fe half-life of (2.787±0.008) a
计数时间Counting time
<0.01
由2 ns定时精度引起的不确定度
Uncertainty due to timing accuracy of 2 ns
电离猝灭参数kB
Ionization quenching parameter kB
0.14
灵敏度分析,改变kB值(0.007~0.015 cm∙MeV-1),记录活度值的变化,按均匀分布估计不确定度Sensitivity test, by adjusting the kB value from 0.007 cm∙MeV-1 to 0.015 cm∙MeV-1, recording the change of activity and estimating the uncertainty according to the uniform distribution
衰变数据及模型Decay data and model
0.32
灵敏度分析,改变EC概率和荧光产额,记录活度值的变化,按均匀分布估计Sensitivity tests, by adjusting EC probabilities and the fluorescence yield, recording the change of activity and estimating the uncertainty according to the uniform distribution
合成相对标准不确定度
The combined relative
standard uncertainty ur
0.45
Table 4. The uncertainty components for specific activity of the 55Fe solution measured by liquid scintillation TDCR method