β--Decay Evaluated Data

1946RE10: 14C; measured T1/2.
1948NO02: 14C; measured T1/2.
1948YA02: 14C; measured T1/2.
1949HA52: 14C; measured T1/2.
1949JO07: 14C; measured T1/2.
1950EN59: 14C; measured T1/2.
1950MI10: 14C; measured T1/2.
1951LI26: 14C.
1951MA30: 14C; measured T1/2.
1954CA41: 14C.
1957LI51: 14C.
1961WA16: 14C; measured not abstracted; deduced nuclear properties.
1962OL04: 14C; measured not abstracted; deduced nuclear properties.
1964HU09: 14C; measured not abstracted; deduced nuclear properties.
1968BE47: 14C; measured not abstracted; deduced nuclear properties.
1968REZZ: 14C; measured T1/2.
1971GO40: 14C; deduced log ft.
1972EM01: 14C; measured T1/2.
1985RU09: 14C(β-); measured I(β), I(ce).
1987GE04: 14C(β-); measured maximum, average β- energies.
1987MO19: 14C(β-); measured β-spectra.
1987SM06: 14C(β-); measured βγ-coin, β-count rate.
1988RA37: 14C(β-); measured internal bremsstrahlung spectra following β-decay; deduced total internal bremsstrahlung yields.
1989BA33: 14C(β-); measured β-spectra, I(ce).
1989TA08: 14C(β-); measured β-activity.
1991NO07: 14C(β-); measured β-spectra; deduced heavy neutrino evidence, mass, emission probability.
1993GR07: 14C(β-); measured β-spectra unfolding, quench intensities.
1994GR04: 14C(β-); measured β-counting rates, spectra.
1994HO11: 14C(β-); measured integral β-counting rates.
1994SI21: 14C(β-); measured activity. Triple-to-double coincidence ratio.
1994VA14: 14C(β-); measured β-spectra.
1994YA05: 14C(β-); measured Eβ, Iβ(θ); deduced anisotropy origin.
1995WI20: 14C(β-); measured β-endpoint energy; deduced Qβ, no 17 keV neutrino evidence.
1996BE48: 14C(β-); measured 2π-β counting rates; calculated 2π-β counting rates, Eβ, Iβ(θ).
1996SZ04: 14C(β-); measured βγ-, (e)γ-, (X-ray)γ-coin.
1998AL07: 14C(β-); measured β-spectra.
2000KU25: 14C(β-); measured Eβ, Iβ.
2001CE02: 14C(β-); measured β spectra.
2004KR10: 14C(β-); measured Eβ.
2008AY04: 14C(β-); compiled T1/2 from various ISOL facilities.
2012AS03: 14C(β-); analyzed data; deduced non-exponential nature of the decay from radiocarbon dating.
2016PO08: 14C(β-); measured decay products; deduced exponential nature of nuclear decay.
Measured half-life for 14C(β-)14N

Recommended value (September, 2015):  5686 ± 40 years: Weighted average of all values below excluding (1952JE11).
Note: Weighted average of the five most recent values is 5699 ± 20 years.
Summary Table of Uncertainty Analysis:     Table 14C preview (PDF)  
Measured values: 5736 ± 56 years (1972EM01, 1968REZZ)
5660 ± 30 years (1968BE47)
5745 ± 50 years (1964HU09: Adjustment of 5760 ± 50 years from (1961MA32).
Note: an estimated adjusted value of 5740 ± 50 years was used
in determining 5730 ± 40 years in (1962GO33) below.)
5680 ± 40 years (1962OL04)
5780 ± 65 years (1961WA16)
  5900 ± 250 years (1954CA41)
5100 ± 85 years (1952JE11) (Excluded)
  5370 ± 200 years (1951MA30)
5580+90-45 years (1950EN59: 5580 ± 45 years is the published adjustment by -2.5% from 5720 ± 47 years in
Engelkemeir, et al., Phys. Rev. 75 (1949) 1825. The value is often cited as 5580 ± 90 years.
We take 5580+90-45 years.)
  6360 ± 190 years (1950MI10)
  5513 ± 165 years (1950MI10)
  6360 ± 200 years (1949HA52)
5589 ± 75 years (1949JO07)
  5100 ± 200 years (1948NO02)
  7200 ± 500 years (1948YA02)
  4700 ± 400 years (1946RE10)
Other Reviews: 5730 ± 40 years (1962GO33: Value adopted at the 5th Radiocarbon Dating Conference, Cambridge, 1962.
The value is the unweighted average of (1961WA16), (1962OL04) and 5740 ± 50 years from
discussion in (1964HU09) Table 14C preview (PDF). This value remains adopted in that community.)
5568 ± 30 years (1951AN1A: In the text the authors mention the value 5568 ± 30 years based on
(Engelkemeir, et al., Phys. Rev. 75 (1949) 1825, 1949HA52, 1949JO07, 1950MI10, 1950EN59)
Table 14C preview (PDF). This value was widely used in the radiocarbon dating community. It is difficult to
obtain this value using any combination of the pre 1951 values.)

Previous Measurements


End Point Energy (keV) log ft
(1951LI26) 155 ± 1 a (1954CA41) 9.03
d 155 ± 1.5 (1955LI1D) b 9.03
(1957LI51) 156 ± 1    (1966BA1A) c 9.03
    (1969KA1B) c 9.02
    (1971GO40) c 9.04
a) Mean value.
b) See also (1958ST50).
c) Using Qm.
d) Lane and Zaffarano, Iowa State College Report 439 (1954).

14Be(β-)14B Evaluated Data

14B(β-)14C Evaluated Data

14O(β+)14N Evaluated Data

A = 14 Beta-Decays Diagram

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Last modified: 21 May 2018