RLum.OSL_decomposition {OSLdecomposition}

Separate CW-OSL components in RLum.Analysis data sets

Description

Calculates the CW-OSL signal component intensities for each CW-OSL measurement under the requirement that the decay rates are already given. The signal decomposition process uses an analytical approach described in detail in Mittelstrass (2019) and Mittelstrass et al. (in preparation). This function processes RLum.Analysis data sets created within the Luminescence-package (Kreutzer et al. 2012).

Usage

RLum.OSL_decomposition(
  object,
  record_type = "OSL",
  K = 3,
  decay_rates = NULL,
  report = FALSE,
  report_dir = NULL,
  image_format = "pdf",
  open_report = TRUE,
  rmd_path = NULL,
  verbose = TRUE
)

Arguments

object

RLum.Analysis or list of RLum.Analysis (required): Data set of one or multiple CW-OSL measured aliquots. The data set must either contain a list element ⁠$OSL_COMPONENTS⁠ or the parameter decay_rates must be defined.

record_type

character (with default): Type of records, selected by the RLum.Analysis attribute ⁠@recordType⁠. Common are: "OSL","SGOSL" or "IRSL".

K

numeric (with default): Number of components. Selects the according result table in the ⁠$OSL_COMPONENTS⁠ list item of the data set object.

decay_rates

numeric vector or data.frame (optional): User-defined component decay rates. If this parameter is defined, the parameter K will ignored. If the input object is a data.frame, then the decay rates must be stored in the column ⁠$lambda⁠.

report

logical (with default): Creates a html report, saves it in the report_dir directory. The report contains the results and detailed information on the data processing.

report_dir

character (optional): Path of output directory if report = TRUE. If report_dir = NULL (default), a temporary folder is used which is deleted when the R session is closed. File paths are also allowed as parameter, then a new directory named after the OSL data file will be created.

image_format

character (with default): Image format of the automatically saved graphs if report = TRUE and report_dir is set. Allowed are .pdf, .eps, .svg (vector graphics), .jpg, .png, .bmp (pixel graphics) and more, see ggplot2::ggsave. The images are saved in the report_dir subfolder ⁠/report_figures⁠. Set image_format = NULL if no images shall be saved.

open_report

logical (with default): If set to TRUE a browser window displaying the report will be opened automatically.

rmd_path

character (with default): For advanced users: File path to the rmarkdown source code file of the report. This allows to execute a manipulated version of the report.

verbose

logical (with default): Enables console text output.

Details

The workflow of this function is as follows:

1. optimise_OSLintervals: Approximates the optimal integration intervals. Uses the global average curve as time axis template. If none global average curve is given, one is automatically created using sum_OSLcurves.

2. decompose_OSLcurve: Calculates component intensities for all record_type measurements. Uses the "det" algorithm if a background correction was performed with RLum.OSL_correction or the "det+nls" algorithm if no background correction was performed. For error estimation, the "empiric" approach is used.

3. Creates a html report to summarize the results (optional).

Data sets must be formatted as RLum.Analysis objects and should have been processed with RLum.OSL_correction and RLum.OSL_global_fitting beforehand. Output objects are also RLum.Analysis objects and are meant for equivalent dose determination with Luminescence::analyse_SAR.CWOSL.

If report = TRUE, a html report of the results is rendered by the rmarkdown-package and saved in the working directory, which is usually the directory of the data file. This report can be displayed, shared and published online without any requirements regarding the operation system or installed software. However, an internet connection is needed to display the MathJax encoded equations and special characters. The Rmarkdown source code of the report can be found with the following command:

system.file("rmd", "report_Step2.Rmd", package = "OSLdecomposition")

Value

The input object, a list of RLum.Analysis objects is returned but with a new list element object[["DECOMPOSITION"]], containing:

• ⁠$decompositon.input⁠ data.frame: Set of input components. Relevant is just the column ⁠$lambda⁠

• ⁠$results⁠ data.frame: Overview table of decomposition

• ⁠$parameters⁠ list: Input and algorithm parameters

The RLum.Data.Curve attribute ⁠@info⁠ of each CW-OSL record contains the new entry ⁠$COMPONENTS⁠ with the curve-individual signal component parameters. It can be read for example by:

object[[i]]@records[[j]]@info[["COMPONENTS"]]

Last updates

2022-05-02, DM: Added new parameter open_report to give control over automatic browser opening

Author(s)

Dirk Mittelstrass, [e-mail]

Please cite the package the following way:

Mittelstraß, D., Schmidt, C., Beyer, J., Heitmann, J. and Straessner, A.: R package OSLdecomposition: Automated identification and separation of quartz CW-OSL signal components, in preparation.

References

Kreutzer, S., Schmidt, C., Fuchs, M.C., Dietze, M., Fischer, M., Fuchs, M., 2012. Introducing an R package for luminescence dating analysis. Ancient TL, 30 (1), 1-8.

Mittelstraß, D., 2019. Decomposition of weak optically stimulated luminescence signals and its application in retrospective dosimetry at quartz (Master thesis). TU Dresden, Dresden.

See Also

RLum.OSL_global_fitting, decompose_OSLcurve, optimise_OSLintervals, Luminescence::analyse_SAR.CWOSL

Examples

#'FB_10Gy' is a dose recovery test with the Fontainebleau quartz
# measured in a lexsyg research with green LED stimulation
data_path <- system.file("examples", "FB_10Gy_SAR.bin", package = "OSLdecomposition")
data_set <- Luminescence::read_BIN2R(data_path, fastForward = TRUE)

# Separate components
data_set_decomposed <- RLum.OSL_decomposition(
data_set, decay_rates = c(0.8, 0.05))