Reference_Data {RCarb}

Reference data

Description

Reference data and correction factors for beta and gamma radiation used for internal calculations. These values are used instead of the correction factors given in Aitken (1985) for the carbonate model.

Format

Reference_Data: list

NAME	TYPE	DIM	DESCRIPTION
DATAek	matrix	4 x 4	correction factors for electrons for water and carbonate to sediment mass ratio for K
DATAet	matrix	4 x 4	correction factors for electrons for water and carbonate to sediment mass ratio for Th
DATAet230	matrix	4 x 4	correction factors for electrons for water and carbonate to sediment mass ratio for Th-230
DATAeu	matrix	4 x 4	correction factors for electrons for water and carbonate to sediment mass ratio for U
DATAeu234	matrix	4 x 4	correction factors for electrons for water and carbonate to sediment mass ratio for U-234
DATAeu238	matrix	4 x 4	correction factors for electrons for water and carbonate to sediment mass ratio for U-238
DATApk	matrix	4 x 4	correction factors for photons for water and carbonate to sediment mass ratio for K
DATApt	matrix	4 x 4	correction factors for photons for water and carbonate to sediment mass ratio for T
DATApt230	matrix	4 x 4	correction factors for photons for water and carbonate to sediment mass ratio for Th-230
DATApu	matrix	4 x 4	correction factors for photons for water and carbonate to sediment mass ratio for U
DATApu234	matrix	4 x 4	correction factors for photons for water and carbonate to sediment mass ratio for U-234
DATApu238	matrix	4 x 4	correction factors for photons for water and carbonate to sediment mass ratio for U-238
mejdahl	data.frame	36 x 4	beta-dose attenuation values for quartz grains according to Mejdahl (1979)
DR_conv_factors	data.frame	4 x 13	beta and gamma dose rate conversion factors used internally (see details)

Details

The reference values are used internally to account for: (1) grain size depend beta-attenuation factors (Mejdahl, 1979) and (2) to correct nuclide dependent beta and gamma radiation for water/carbonate proportions. The latter values are given as matrix and precise values are interpolated during the modelling process.

Additionally 'RCarb' provides and own set of dose rate conversion factors to convert concentrations of U, Th, and K to dose rate values. Historically Carb (and thus 'RCarb') as its own dose rate conversion factors, which differ slightly from other published values. To provide a consistent calculation approach by default the 'old' Carb values are used, but the user can further switch (see model_DoseRate) to values provided by Adamiec & Aitken (1998), Guérin et al. (2011) or Liritzis et al (2013).

Different values quoted for U-238 and U-234 accounts for different activity ratios. For further details on the origin of these data we refer to Nathan & Mauz (2008) and Nathan (2010).

Nuclear data origin according to Nathan & Mauz (2008)

The gamma primary energy spectra of uranium, thorium and potassium are drawn from Evaluated Nuclear Structure Data File (ENSDF) database at http://www.nndc.bnl.gov (2002-01-16) and the beta primary energy spectra was derived from ENSDF end-point energies using a Fermi beta decay model (Evans, 1955) modified by Behrens & Szybisz (1976). For the simulations of the collisional mass stopping powers for quartz the software ESTAR (Berger et al., 2000) was used. The mass energy-absorption coefficients for quartz were tabulated by Hubbell & Seltzer (2004).

For further details and references please read Nathan & Mauz (2008)

Version

0.2.0

References

Adamiec, G., Aitken, M.J., 1998. Dose-rate conversion factors: update. Ancient TL 16, 37–50. http://ancienttl.org/ATL_16-2_1998/ATL_16-2_Adamiec_p37-50.pdf

Guérin, G., Mercier, N., Adamiec, G., 2011. Dose-rate conversion factors: update. Ancient TL 29, 5–9. http://ancienttl.org/ATL_29-1_2011/ATL_29-1_Guerin_p5-8.pdf

Liritzis, I., Stamoulis, K., Papachristodoulou, C., Ioannides, K., 2013. A Re-Evaluation of Radiation Dose-Rate Conversion Factors. Mediterranean Archaeology and Archaeometry 12, 1–15. http://maajournal.com/Issues/2012/pdf/FullTextLiritzis.pdf

Mejdahl, V., 1979. Thermoluminescence dating: beta-dose attenuation in quartz grains. Archaeometry 21, 61-72. http://ancienttl.org/ATL_32-2_2014/ATL_32-2_Mauz_p24-32.pdf

Nathan, R.P., Mauz, B., 2008. On the dose-rate estimate of carbonate-rich sediments for trapped charge dating. Radiation Measurements 43, 14-25. doi:10.1016/j.radmeas.2007.12.012

Nathan, R.P., 2010. Numerical modelling of environmental dose rate and its application to trapped-charge dating. DPhil thesis, St Hugh's College, Oxford. https://ora.ox.ac.uk/objects/ora:6421

Further reading

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

Berger, M.J., Coursey, J.S., Zucker, M.A., 2000. ESTAR, PSTAR, and ASTAR: Computer Programs for Calculating Stopping-Power and Range Tables for Electrons, Protons, and Helium Ions (version 1.2.2). http://physics.nist.gov/Star (2005-08-09). National Institute of Standards and Technology, Gaithersburg, MD.

Behrens, H., Szybisz, L., 1976. Shapes of beta spectra. Physics Data 6-1, Zentralstelle fuer Atomkernenergie-Dokumentation (ZAED), Germany.

Evans, R.D., 1955. The Atomic Nucleus. McGraw-Hill, NY.

Hubbell, J.H., Seltzer, S.M., 2004. Tables of X-Ray Mass Attenuation Coefficients and Mass Energy-Absorption Coefficients (version 1.4). http://physics.nist.gov/xaamdi (2005-08-09). National Institute of Standards and Technology, Gaithersburg, MD.

Examples

data(Reference_Data, envir = environment())
str(Reference_Data)
Reference_Data$DATAek