howmuchC14: Amount of C14 particles in a sample

In rice: Radiocarbon Equations

Amount of C14 particles in a sample

Description

Calculate the expected amount of remaining C14 atoms in a sample, given its weight and age.

Usage

howmuchC14(
  age,
  wght = 1,
  use.cc = TRUE,
  Av = 6.02214076e+23,
  C14.1950 = 1.176e-12,
  current = 2.5e-05,
  format = "g",
  cc = 1,
  postbomb = FALSE,
  cc.dir = NULL,
  thiscurve = NULL,
  talk = TRUE,
  decimals = 3
)

Arguments

age	The age of the sample (in cal BP per default, or in C14 BP is use.cc=FALSE).
wght	The weight of the sample (in mg). Defaults to 1 mg.
use.cc	Whether or not to use the calibration curve. If set to use.cc=FALSE, then we assume that the age is the radiocarbon age (this enables ages beyond the reach of the calibration curves to be used).
Av	Avogadro's number, used to calculate the number of carbon atoms in the sample.
C14.1950	The standard 14C/C ratio back in AD 1950 (1.176e-12, so around 1 in 1 trillion carbon atoms was a 14C atom at that moment in time.
current	The current of 12C+ ions arriving at the Faraday counter. Defaults to current=25e-6, 25 micro-Ampere.
format	The format of the printed numbers. Defaults to either scientific (for large numbers) or as fixed-point, depending on the size of the number.
cc	calibration curve for C14 (see caldist()).
postbomb	Whether or not to use a postbomb curve (see caldist()).
cc.dir	Directory of the calibration curves. Defaults to where the package's files are stored (system.file), but can be set to, e.g., cc.dir="curves".
thiscurve	As an alternative to providing cc and/or postbomb, the data of a specific curve can be provided (3 columns: cal BP, C14 age, error).
talk	Whether or not to provide feedback (defaults to TRUE).
decimals	Number of decimals to be returned for F and atom counts.

Details

The number of carbon atoms in the sample is estimated. Given the known C14/C ratio at F=1, and given the sample's age, we can estimate the number of remaining C14 atoms. Given a 12C current at the detector end of an AMS, we can then also calculate how many 14C ions would be counted per second and minute. Note that backgrounds are not modelled (but could be investigated by e.g. typing howmuchC14(45e3) which gives as c. 1 background count per second).

Value

The estimated number of C14 atoms.

Author(s)

Maarten Blaauw

Examples

  howmuchC14(0) # recent sample
  howmuchC14(55e3) # at dating limit
  howmuchC14(145e3) # way beyond the dating limit, 1 C14 atom per mg remains

rice documentation built on Jan. 8, 2026, 9:07 a.m.