c14_units: Radiocarbon unit calculations
In joeroe/c14: Tidy Radiocarbon Data

c14_units

R Documentation

Radiocarbon unit calculations

Description

\loadmathjax

Functions for calculating basic units used in radiocarbon measurements.

c14_age() calculates the conventional radiocarbon age (CRA) from a fraction modern measurement.

c14_f14c() reverse-calculates the fractionation-corrected fraction modern value (\mjeqnF^14CF14C or \mjeqnpMpM) of a radiocarbon age.

Usage

c14_age(x, decay = c14::c14_decay_libby)

c14_f14c(x, decay = c14::c14_decay_libby)

Arguments

`x`	For `c14_age()`, a vector of fraction modern (\mjeqnF^14CF14C) measurements. For `c14_f14c()`, a vector of conventional radiocarbon ages.
`decay`	Decay constant. The default is the Libby constant (`c14_decay_libby`), which is the standard for calculating conventional radiocarbon ages. Use `c14_decay_cambridge` for the Cambridge constant, or a single numeric for other values.

Details

c14_age() calculates the conventional radiocarbon age, \mjeqntt, as defined by \insertCiteStuiver1977;textualc14:

\mjdeqn

t = -\frac1\lambda\lnF^14Ct = -1/l * ln(F^14C)

c14_f14c() implements the inverse of this function:

\mjdeqn

F^14C = e^-\lambda tF14C = e^(-lt)

The decay constant conventionally used for calculating radiocarbon ages is the Libby decay constant, \mjeqn\lambda_L=8033^-1lL = 1/8033. An alternative is the Cambridge decay constant, \mjeqn\lambda_C=8267^-1lC = 1/8267 \insertCiteStenstrom2011c14.

Reported radiocarbon ages are usually rounded based on the magnitude of the error \insertCiteStuiver1977c14. For this reason, reverse-calculating fraction modern from a radiocarbon age is unlikely to return the precise original measurement of the sample.

Where available, fraction modern is the recommended measurement for calibration \insertCiteBronk_Ramsey2008c14.