-
Notifications
You must be signed in to change notification settings - Fork 8
/
calc_CosmicDoseRate.Rd
258 lines (204 loc) · 10 KB
/
calc_CosmicDoseRate.Rd
1
2
3
4
5
6
7
8
9
10
11
12
13
14
15
16
17
18
19
20
21
22
23
24
25
26
27
28
29
30
31
32
33
34
35
36
37
38
39
40
41
42
43
44
45
46
47
48
49
50
51
52
53
54
55
56
57
58
59
60
61
62
63
64
65
66
67
68
69
70
71
72
73
74
75
76
77
78
79
80
81
82
83
84
85
86
87
88
89
90
91
92
93
94
95
96
97
98
99
100
101
102
103
104
105
106
107
108
109
110
111
112
113
114
115
116
117
118
119
120
121
122
123
124
125
126
127
128
129
130
131
132
133
134
135
136
137
138
139
140
141
142
143
144
145
146
147
148
149
150
151
152
153
154
155
156
157
158
159
160
161
162
163
164
165
166
167
168
169
170
171
172
173
174
175
176
177
178
179
180
181
182
183
184
185
186
187
188
189
190
191
192
193
194
195
196
197
198
199
200
201
202
203
204
205
206
207
208
209
210
211
212
213
214
215
216
217
218
219
220
221
222
223
224
225
226
227
228
229
230
231
232
233
234
235
236
237
238
239
240
241
242
243
244
245
246
247
248
249
250
251
252
253
254
255
256
257
258
% Generated by roxygen2: do not edit by hand
% Please edit documentation in R/calc_CosmicDoseRate.R
\name{calc_CosmicDoseRate}
\alias{calc_CosmicDoseRate}
\title{Calculate the cosmic dose rate}
\usage{
calc_CosmicDoseRate(
depth,
density,
latitude,
longitude,
altitude,
corr.fieldChanges = FALSE,
est.age = NA,
half.depth = FALSE,
error = 10,
...
)
}
\arguments{
\item{depth}{\link{numeric} (\strong{required}):
depth of overburden (m). For more than one absorber use \cr
\code{c(depth_1, depth_2, ..., depth_n)}}
\item{density}{\link{numeric} (\strong{required}):
average overburden density (g/cm^3). For more than one absorber use \cr
\code{c(density_1, density_2, ..., density_n)}}
\item{latitude}{\link{numeric} (\strong{required}):
latitude (decimal degree), N positive}
\item{longitude}{\link{numeric} (\strong{required}):
longitude (decimal degree), E positive}
\item{altitude}{\link{numeric} (\strong{required}):
altitude (m above sea-level)}
\item{corr.fieldChanges}{\link{logical} (\emph{with default}):
correct for geomagnetic field changes after Prescott & Hutton (1994).
Apply only when justified by the data.}
\item{est.age}{\link{numeric} (\emph{with default}):
estimated age range (ka) for geomagnetic field change correction (0-80 ka allowed)}
\item{half.depth}{\link{logical} (\emph{with default}):
How to overcome with varying overburden thickness. If \code{TRUE} only half the
depth is used for calculation. Apply only when justified, i.e. when a constant
sedimentation rate can safely be assumed.}
\item{error}{\link{numeric} (\emph{with default}):
general error (percentage) to be implemented on corrected cosmic dose rate estimate}
\item{...}{further arguments (\code{verbose} to disable/enable console output).}
}
\value{
Returns a terminal output. In addition an
\linkS4class{RLum.Results}-object is returned containing the
following element:
\item{summary}{\link{data.frame} summary of all relevant calculation results.}
\item{args}{\link{list} used arguments}
\item{call}{\link{call} the function call}
The output should be accessed using the function \link{get_RLum}
}
\description{
This function calculates the cosmic dose rate taking into account the soft-
and hard-component of the cosmic ray flux and allows corrections for
geomagnetic latitude, altitude above sea-level and geomagnetic field
changes.
}
\details{
This function calculates the total cosmic dose rate considering both the
soft- and hard-component of the cosmic ray flux.
\strong{Internal calculation steps}
(1)
Calculate total depth of all absorber in hg/cm^2 (1 hg/cm^2 = 100 g/cm^2)
\deqn{absorber = depth_1*density_1 + depth_2*density_2 + ... + depth_n*density_n}
(2)
If \code{half.depth = TRUE}
\deqn{absorber = absorber/2}
(3)
Calculate cosmic dose rate at sea-level and 55 deg. latitude
a) If absorber is > 167 g/cm^2 (only hard-component; Allkofer et al. 1975):
apply equation given by Prescott & Hutton (1994) (c.f. Barbouti & Rastin
1983)
\deqn{D0 = C/(((absorber+d)^\alpha+a)*(absober+H))*exp(-B*absorber)}
b) If absorber is < 167 g/cm^2 (soft- and hard-component): derive D0 from
Fig. 1 in Prescott & Hutton (1988).
(4)
Calculate geomagnetic latitude (Prescott & Stephan 1982, Prescott &
Hutton 1994)
\deqn{\lambda = arcsin(0.203*cos(latitude)*cos(longitude-291)+0.979*
sin(latitude))}
(5)
Apply correction for geomagnetic latitude and altitude above sea-level.
Values for F, J and H were read from Fig. 3 shown in Prescott & Stephan
(1982) and fitted with 3-degree polynomials for lambda < 35 degree and a
linear fit for lambda > 35 degree.
\deqn{Dc = D0*(F+J*exp((altitude/1000)/H))}
(6)
Optional: Apply correction for geomagnetic field changes in the last
0-80 ka (Prescott & Hutton 1994). Correction and altitude factors are given
in Table 1 and Fig. 1 in Prescott & Hutton (1994). Values for altitude
factor were fitted with a 2-degree polynomial. The altitude factor is
operated on the decimal part of the correction factor.
\deqn{Dc' = Dc*correctionFactor}
\strong{Usage of \code{depth} and \code{density}}
(1) If only one value for depth and density is provided, the cosmic dose
rate is calculated for exactly one sample and one absorber as overburden
(i.e. \code{depth*density}).
(2) In some cases it might be useful to calculate the cosmic dose rate for a
sample that is overlain by more than one absorber, e.g. in a profile with
soil layers of different thickness and a distinct difference in density.
This can be calculated by providing a matching number of values for
\code{depth} and \code{density} (e.g. \verb{depth = c(1, 2), density = c(1.7, 2.4)})
(3) Another possibility is to calculate the cosmic dose rate for more than
one sample of the same profile. This is done by providing more than one
values for \code{depth} and only one for \code{density}. For example,
\code{depth = c(1, 2, 3)} and \code{density = 1.7} will calculate the cosmic dose rate
for three samples in 1, 2 and 3 m depth in a sediment of density 1.7 g/cm^3.
}
\note{
Despite its universal use the equation to calculate the cosmic dose
rate provided by Prescott & Hutton (1994) is falsely stated to be valid from
the surface to 10^4 hg/cm^2 of standard rock. The original expression by
Barbouti & Rastin (1983) only considers the muon flux (i.e. hard-component)
and is by their own definition only valid for depths between 10-10^4
hg/cm^2.
Thus, for near-surface samples (i.e. for depths < 167 g/cm^2) the equation
of Prescott & Hutton (1994) underestimates the total cosmic dose rate, as it
neglects the influence of the soft-component of the cosmic ray flux. For
samples at zero depth and at sea-level the underestimation can be as large
as ~0.1 Gy/ka. In a previous article, Prescott & Hutton (1988) give another
approximation of Barbouti & Rastin's equation in the form of
\deqn{D = 0.21*exp(-0.070*absorber+0.0005*absorber^2)}
which is valid for depths between 150-5000 g/cm^2. For shallower depths (<
150 g/cm^2) they provided a graph (Fig. 1) from which the dose rate can be
read.
As a result, this function employs the equation of Prescott & Hutton (1994)
only for depths > 167 g/cm^2, i.e. only for the hard-component of the cosmic
ray flux. Cosmic dose rate values for depths < 167 g/cm^2 were obtained from
the "AGE" program (Gruen 2009) and fitted with a 6-degree polynomial curve
(and hence reproduces the graph shown in Prescott & Hutton 1988). However,
these values assume an average overburden density of 2 g/cm^3.
It is currently not possible to obtain more precise cosmic dose rate values
for near-surface samples as there is no equation known to the author of this
function at the time of writing.
}
\section{Function version}{
0.5.2
}
\examples{
##(1) calculate cosmic dose rate (one absorber)
calc_CosmicDoseRate(depth = 2.78, density = 1.7,
latitude = 38.06451, longitude = 1.49646,
altitude = 364, error = 10)
##(2a) calculate cosmic dose rate (two absorber)
calc_CosmicDoseRate(depth = c(5.0, 2.78), density = c(2.65, 1.7),
latitude = 38.06451, longitude = 1.49646,
altitude = 364, error = 10)
##(2b) calculate cosmic dose rate (two absorber) and
##correct for geomagnetic field changes
calc_CosmicDoseRate(depth = c(5.0, 2.78), density = c(2.65, 1.7),
latitude = 12.04332, longitude = 4.43243,
altitude = 364, corr.fieldChanges = TRUE,
est.age = 67, error = 15)
##(3) calculate cosmic dose rate and export results to .csv file
#calculate cosmic dose rate and save to variable
results<- calc_CosmicDoseRate(depth = 2.78, density = 1.7,
latitude = 38.06451, longitude = 1.49646,
altitude = 364, error = 10)
# the results can be accessed by
get_RLum(results, "summary")
#export results to .csv file - uncomment for usage
#write.csv(results, file = "c:/users/public/results.csv")
##(4) calculate cosmic dose rate for 6 samples from the same profile
## and save to .csv file
#calculate cosmic dose rate and save to variable
results<- calc_CosmicDoseRate(depth = c(0.1, 0.5 , 2.1, 2.7, 4.2, 6.3),
density = 1.7, latitude = 38.06451,
longitude = 1.49646, altitude = 364,
error = 10)
#export results to .csv file - uncomment for usage
#write.csv(results, file = "c:/users/public/results_profile.csv")
}
\section{How to cite}{
Burow, C., 2024. calc_CosmicDoseRate(): Calculate the cosmic dose rate. Function version 0.5.2. In: Kreutzer, S., Burow, C., Dietze, M., Fuchs, M.C., Schmidt, C., Fischer, M., Friedrich, J., Mercier, N., Philippe, A., Riedesel, S., Autzen, M., Mittelstrass, D., Gray, H.J., Galharret, J., Colombo, M., 2024. Luminescence: Comprehensive Luminescence Dating Data Analysis. R package version 0.9.25. https://r-lum.github.io/Luminescence/
}
\references{
Allkofer, O.C., Carstensen, K., Dau, W.D., Jokisch, H., 1975.
Letter to the editor. The absolute cosmic ray flux at sea level. Journal of
Physics G: Nuclear and Particle Physics 1, L51-L52.
Barbouti, A.I., Rastin, B.C., 1983. A study of the absolute intensity of muons at sea level
and under various thicknesses of absorber. Journal of Physics G: Nuclear and
Particle Physics 9, 1577-1595.
Crookes, J.N., Rastin, B.C., 1972. An
investigation of the absolute intensity of muons at sea-level. Nuclear
Physics B 39, 493-508.
Gruen, R., 2009. The "AGE" program for the
calculation of luminescence age estimates. Ancient TL 27, 45-46.
Prescott, J.R., Hutton, J.T., 1988. Cosmic ray and gamma ray dosimetry for
TL and ESR. Nuclear Tracks and Radiation Measurements 14, 223-227.
Prescott, J.R., Hutton, J.T., 1994. Cosmic ray contributions to dose rates
for luminescence and ESR dating: large depths and long-term time variations.
Radiation Measurements 23, 497-500.
Prescott, J.R., Stephan, L.G., 1982. The contribution of cosmic radiation to the environmental dose for
thermoluminescence dating. Latitude, altitude and depth dependences. PACT 6, 17-25.
}
\seealso{
\link{BaseDataSet.CosmicDoseRate}
}
\author{
Christoph Burow, University of Cologne (Germany)
, RLum Developer Team}