numOSL (version 2.4)

calDA: Annual dose rate (age) calculation

Description

Calculating the annual dose rate and burial age.

Usage

calDA(dose, minGrainSize, maxGrainSize, Ucontent, Thcontent, 
      Kcontent, Wct, depth, altitude, latitude, longitude, 
      bulkDensity = 2.5, alphaValue = 0.03, nsim = 10000, 
      rdcf = 0.05, rba = 0.05, plot = TRUE)

Arguments

dose

vector(required): equivalent dose and associated measurement error (unit, Gy)

minGrainSize

numeric(required): lower limit on grain size (unit, um)

maxGrainSize

numeric(required): upper limit on grain size (unit, um)

Ucontent

vector(required): uranium content and its measurement error (unit, ppm)

Thcontent

vector(required): thorium content and its measurement error (unit, ppm)

Kcontent

vector(required): potassium content and its measurement error (unit, 1 percent)

Wct

vector(required): water content and its measurement error (unit, 1 percent)

depth

numeric(required): sampling depth (unit, m)

altitude

numeric(required): altitude of the sampling site (unit, m above sea level)

latitude

numeric(required): latitude of the sampling site (unit, decimal degree)

longitude

numeric(required): longitude of the sampling site (unit, decimal degree)

bulkDensity

numeric(with default): average density of bulk sample (unit, g/cm^3)

alphaValue

numeric(with default): average alpha efficiency

nsim

integer(with default): number of Monte Carlo iterations

rdcf

numeric(with default): constant relative standard error for dose-rate conversion factors (unit, 1 percent)

rba

numeric(with default): constant relative standard error for beta dose absorption fraction (unit, 1 percent)

plot

logical(with default): draw a plot or not

Value

Return a matrix that contains calculated annual dose rate and age

Details

Function calDA is used for calculating the annual dose rate and burial age using concentrations of radioactive nuclides (uranium, thorium, potassium) obtained from Neutron Activation Analysis (NAA), grain size, water content, average sample density, geographical parameters (depth, altitude, latitude, longitude), and an equivalent dose value. The elemental concentrations are converted into annual dose rate according to dose-rate conversion factors (Adamiec and Aitken, 1998). Beta dose absorded fractions are calculated through linear interpolation using published data (Fain et al., 1999). The cosmic ray dose rate is estimated as a function of depth, altitude and geomagnetic latitude (Prescott and Hutton, 1994). The standard error of an annual dose rate is estimated by a "parametric bootstrap" method. To perform the simulation, dose-rate conversion factors and beta dose absorption factor are assumed to have constant relative standard errors. Arguments such as dose, Ucontent, Thcontent, Kcontent, wct should be two-element vectors with the form c(value,sd), as their measurement uncertainties are major error sources. Arguments such as depth, altitude, latitude, longitude, bulkDensity, alphaValue can be either a scalar of a two-element vector. This means that uncertainties from these quantities can be either ignored or taken into account during the simulation.

References

Adamiec G, Aitken M, 1998. Dose-rate conversion factors: update. Ancient TL, 16(2): 37-49.

Fain J, Soumana S, Montret M, Miallier D, Pilleyre T, Sanzelle S, 1999. Luminescence and ESR dating Beta-dose attenuation for various grain shapes calculated by a Monte-Carlo method. Quaternary Science Reviews, 18(2): 231-234.

Prescott JR, Hutton JT, 1994. Cosmic ray contributions to dose rates for Luminescence and Esr dating: large depths and long-term time variations. Radiation Measurements, 23(2-3): 497-500.

Examples

# NOT RUN {
calDA(dose=c(25.04,0.68), minGrainSize=90,
      maxGrainSize=180, Ucontent=c(2.86,0.19),
      Thcontent=c(8.63,0.34), Kcontent=c(2.00,0.11),
      Wct=c(0.05,0.05), depth=c(1.1,0.05), altitude=c(1170,58.5), 
      latitude=c(37.64,1.88), longitude=c(103.16,5.16),
      bulkDensity=c(2.5,0.1), nsim=10000, rdcf=0.05, rba=0.05) 
# }