numOSL (version 1.8)

analyst: Equivalent dose determination

Description

Calculating an equivalent dose using a data set 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,
        weight = TRUE, plot = TRUE, model = NULL, origin = NULL)

Arguments

Sigdata

matrix(required): a series of decay curves stored column by column

Redose

vector(required): 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

double(with default): measurement errror

disb

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

typ

character(with default): type of an OSL decay curve, only CW-OSL decay curve can be analyzed currently

nstart

integer(with default): maximum number of trials used for initializing parameters of a non-linear growth curve, see function fitGrowth for details

upb

double(with default): upper limit on b value (i.e., the reciprocal of the saturating dose), see function fitGrowth for details

ErrorMethod

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

nsim

integer(with default): maximum number of simulations if a Monte Carlo method is applied to assessing the standard error of an equivalent dose

weight

logical(with default): fit the growth curve using a weighted or an un-weighted procedure, see function fitGrowth for details

plot

logical(with default): draw a plot or not

model

character (optional): model used for fitting the growth curve, see function fitGrowth for available models. The procedure will find an optimal model between "line" an

origin

logical(optional): force the growth curve to pass the origin or not. The procedure will choose whether pass the origin or not automatically if origin=NULL

Value

• Return a list containing the following elements:
• Curvedata
  data used for constructing the growth curve
• Ltx
  sensitivity-corrected natural OSL and its standard error
• model
  fitting model of the growth curve
• LMpars
  optimized parameters of the growth curve
• value
  minimized objective of the growth curve
• ED
  equivalent dose and its standard error
• RecyclingRatio
  recycling ratio
• Recuperation
  recuperation

Details

Function analyst is used for estimating an equivalent dose using a SAR data set. It works in a manner similar to software Analyst written by Duller (2007). See function fitGrowth and calED for more details concerning growth curve fitting and equivalent dose calculation.

References

Galbraith R, 2002. A note on the variance of a backround-corrected OSL count. Ancient TL, 20(2): 49-51.

Duller, G., 2007. Software Analyst, user mannual. Freely 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(1): 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(9): 746-751.

See Also

calED; fastED; fitGrowth

Examples

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