numOSL (version 1.6)

fastED: Estimating a fast-component equivalent dose

Description

Estimating a fast-component equivalent dose using decay curves from a SAR sequence.

Usage

fastED(Sigdata, Redose, ncomp = 2, constant = TRUE,  
       control.args = list(), typ = "cw", nstart = 100, upb = 0.5, 
       ErrorMethod = c("mc","sp"), model = NULL, origin = NULL)

Arguments

Sigdata

data.frame(required): a number of decay curves, the first column should be the time values

Redose

vector(required): the regenerative dose values. Example, Redose=c(1,2,3,4,0,1)

ncomp

numeric(with default): the number of components to be decomposed

constant

logical(with default): subtract a constant component when fitting a decay curve or not

control.args

list(with default): arguments used by the differential evolution algorithm, see function decomp for details

typ

character(with default): the type of an OSL decay curve, only type of "CW" is available currently

nstart

numeric(with default): the maximum number of attempts of initializing the non-linear growth curve fitting, see function fitGrowth for details

upb

numeric(with default): the upper limit on b value, see function fitGrowth for details

ErrorMethod

character(with default): method used for assessing the standard error of an equivalent dose, default ErrorMethod="mc", see function calED for details

model

character(optional): a model used for fitting the growth curve, see function fitGrowth for available models. It will find a model automatically if model=NULL

origin

logical(optional): force the fitting to pass the origin or not. It will choose whether pass the origin or not automatically if origin=NULL

Value

• Return a list containing following elements:
• pars
  the decay rates and trapped electrons for a number of decay curves
• decayRateMat
  the decay rates for a number of decay curves (a matrix)
• Curvedata
  data used to construct the fast-component growth curve
• Ltx
  the natural fast-component standardised OSL and its standard error
• model
  the fitting model
• LMpars
  the parameters of the growth curve
• value
  the minimized chi-square value of the fitted growth curve
• ED
  the fast-component equivalent dose and its standard error
• RecyclingRatio
  the fast-component recycling ratio
• Recuperation
  the fast-component recuperation

Details

Function fastED is used to estimated a fast-component equivalent dose using a dataset from the SAR protocol (Murray and Wintle, 2000). The routine trys to decompose a series of decay curves to a specified number of components, then the numbers of trapped electrons from the fast-component are used to construct a growth curve to estimate a fast-component equivalent dose.

References

Li SH, Li B, 2006. Dose measurement using the fast component of LM-OSL signals from quartz. Radiation Measurements, 41: 534-541.

Murray AS, Wintle AG, 2000. Luminescence dating of quartz using improved single-aliquot regenerative-dose protocol. Radiation Measurements, 32: 57-73.

See Also

analyst; calED; decomp; fitGrowth

Examples

data(Signaldata)
 ### Use only the first two regenerative dose data. 
 fastED(Signaldata$cw[,-(8:15)],Redose=c(80,160)*0.13,
        control.args=list(factor=5),model="line",origin=TRUE)
 ### Use all regenerative dose data (except the zero-dose).
 # fastED(Signaldata$cw[,c(-12,-13)],Redose=c(80,160,240,320,80)*0.13,
 #        ncomp=3,constant=FALSE)