Converting equivalent dose values from seconds (s) to Gray (Gy)

Conversion of absorbed radiation dose in seconds (s) to the SI unit Gray (Gy) including error propagation. Normally used for equivalent dose data.

Usage

Second2Gray(data, dose.rate, error.propagation = "omit")

Arguments

data: data.frame (required): input values, structure: data (values[,1]) and data error (values [,2]) are required
dose.rate: RLum.Results, data.frame or numeric (required): RLum.Results needs to be originated from the function calc_SourceDoseRate, for vector dose rate in Gy/s and dose rate error in Gy/s
error.propagation: character (with default): error propagation method used for error calculation (omit, gaussian or absolute), see details for further information

Value

Returns a data.frame with converted values.

Details

Calculation of De values from seconds (s) to Gray (Gy)

$$De [Gy] = De [s] * Dose Rate [Gy/s])$$

Provided calculation error propagation methods for error calculation (with 'se' as the standard error and 'DR' of the dose rate of the beta-source):

(1) omit (default)

$$se(De) [Gy] = se(De) [s] * DR [Gy/s]$$

In this case the standard error of the dose rate of the beta-source is treated as systematic (i.e. non-random), it error propagation is omitted. However, the error must be considered during calculation of the final age. (cf. Aitken, 1985, pp. 242). This approach can be seen as method (2) (gaussian) for the case the (random) standard error of the beta-source calibration is 0. Which particular method is requested depends on the situation and cannot be prescriptive.

(2) gaussian error propagation

$$se(De) [Gy] = \sqrt((DR [Gy/s] * se(De) [s])^2 + (De [s] * se(DR) [Gy/s])^2)$$

Applicable under the assumption that errors of De and se are uncorrelated.

(3) absolute error propagation

$$se(De) [Gy]= abs(DR [Gy/s] * se(De) [s]) + abs(De [s] * se(DR) [Gy/s])$$

Applicable under the assumption that errors of De and se are correlated.

Note

If no or a wrong error propagation method is given, the execution of the function is stopped. Furthermore, if a data.frame is provided for the dose rate values is has to be of the same length as the data frame provided with the argument data

Function version

0.6.0

How to cite

Kreutzer, S., Dietze, M., Fuchs, M.C., 2024. Second2Gray(): Converting equivalent dose values from seconds (s) to Gray (Gy). Function version 0.6.0. In: Kreutzer, S., Burow, C., Dietze, M., Fuchs, M.C., Schmidt, C., Fischer, M., Friedrich, J., Mercier, N., Philippe, A., Riedesel, S., Autzen, M., Mittelstrass, D., Gray, H.J., Galharret, J., Colombo, M., 2024. Luminescence: Comprehensive Luminescence Dating Data Analysis. R package version 0.9.26. https://r-lum.github.io/Luminescence/

References

Aitken, M.J., 1985. Thermoluminescence dating. Academic Press.

Author

Sebastian Kreutzer, Institute of Geography, Heidelberg University (Germany)
Michael Dietze, GFZ Potsdam (Germany)
Margret C. Fuchs, HZDR, Helmholtz-Institute Freiberg for Resource Technology (Germany) , RLum Developer Team

Examples


##(A) for known source dose rate at date of measurement
## - load De data from the example data help file
data(ExampleData.DeValues, envir = environment())
## - convert De(s) to De(Gy)
Second2Gray(ExampleData.DeValues$BT998, c(0.0438,0.0019))
#>        De De.error
#> 1  151.48    5.334
#> 2  152.08    5.144
#> 3  165.80    6.805
#> 4  136.15    4.608
#> 5  144.42    4.642
#> 6  123.44    4.471
#> 7  123.64    4.227
#> 8  127.07    4.396
#> 9  125.06    4.630
#> 10 124.45    4.256
#> 11 118.60    4.049
#> 12 128.08    4.408
#> 13 110.78    3.701
#> 14 121.02    4.187
#> 15 124.09    4.129
#> 16 124.70    4.043
#> 17 123.68    4.262
#> 18 126.34    4.228
#> 19 128.59    4.254
#> 20 131.46    4.448
#> 21 127.77    4.330
#> 22 131.05    5.023
#> 23 126.34    4.317
#> 24 115.49    3.479
#> 25 119.58    3.815





##(B) for source dose rate calibration data
## - calculate source dose rate first
dose.rate <-  calc_SourceDoseRate(measurement.date = "2012-01-27",
                                  calib.date = "2014-12-19",
                                  calib.dose.rate = 0.0438,
                                  calib.error = 0.0019)
# read example data
data(ExampleData.DeValues, envir = environment())

# apply dose.rate to convert De(s) to De(Gy)
Second2Gray(ExampleData.DeValues$BT998, dose.rate)
#>        De De.error
#> 1  162.37    5.717
#> 2  163.02    5.514
#> 3  177.72    7.294
#> 4  145.94    4.939
#> 5  154.81    4.976
#> 6  132.32    4.792
#> 7  132.54    4.531
#> 8  136.21    4.712
#> 9  134.05    4.963
#> 10 133.40    4.562
#> 11 127.13    4.340
#> 12 137.29    4.725
#> 13 118.75    3.967
#> 14 129.72    4.488
#> 15 133.01    4.426
#> 16 133.67    4.334
#> 17 132.57    4.568
#> 18 135.43    4.532
#> 19 137.84    4.560
#> 20 140.91    4.768
#> 21 136.96    4.641
#> 22 140.47    5.384
#> 23 135.43    4.628
#> 24 123.79    3.729
#> 25 128.18    4.090