numOSL (version 1.6)

analyst: Analysing equivalent dose values.

Description

Calculating an equivalent dose value and estimating its standard error using dataset from a SAR sequence.

Usage

analyst(Sigdata, Redose, sig.channel = NULL, back.channel = NULL, 
        mr = 0.01, disb = c("p","op"), typ = "cw", nstart = 100,
        upb = 0.5, ErrorMethod = c("mc","sp"), nsim = 1000,
        plot = TRUE, 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)

sig.channel

vector(with default): channels used for signal integration, default sig.channel=1:4

back.channel

vector(with default): channels used for background counts subtraction, default back.channel is set equal to the last 20 channels

mr

numeric(with default): the measurement errror

disb

character(with default): the assumed distribution of background counts, "p" means Possion, and "op" means over-Possion

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

nsim

numeric(with default): the allowed maximum number of simulations when applying a Monte Carlo method to assess the standard error of an equivalent dose

plot

logical(with default): draw a plot or not

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:
• Curvedata
  data used to construct the growth curve
• Ltx
  the natural 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 equivalent dose and its standard error
• RecyclingRatio
  the recycling ratio
• Recuperation
  the recuperation

Details

Function analyst is used for estimating an equivalent dose and assessing its standard error using a SAR dataset. It analyses an ED value in a manner similar to software Analyst by Duller (2007). See function fitGrowth for more details.

References

Galbraith R, 2002. A note on the variance of a backround-corrected OSL count. Ancient TL, 20: 49-51.

Duller, G., 2007. Analyst. Use mannual. Available at http://www.nutech.dtu.dk/english/Products-and-Services/Dosimetry/Radiation-Measurement-Instruments/TL_OSL_reader/Software.

Further reading

Li B, 2007. A note on estimating the error when subtracting background counts from weak OSL signals. Ancient TL, 25: 9-14.

Adamiec G, Heer AJ, Bluszcz A, 2012. Statistics of count numbers from a photomultiplier tube and its implications for error estimation. Radiation Measurements, 47: 746-751.

See Also

calED; fastED; fitGrowth

Examples

# load package "numOSL".
 library(numOSL)
 # load data.
 data(Signaldata)
 # Early background subtraction.
 analyst(Signaldata[[1]], Redose=c(80,160,240,320,0,80)*0.13,
         sig.channel=1:2, back.channel=3:8)