β--Decay Evaluated Data

1965PO03: 12Be; measured not abstracted; deduced nuclear properties.
1978AL10: 12Be; measured T1/2, delayed neutrons; deduced upper limit delayed neutron branch.
1984DU15: 12Be(β-); measured T1/2.
1986CU01: 12Be(β-); measured β-decay T1/2.
1986HAYX: 12Be; measured β-decay T1/2.
1994KE06: 12Be(β-); measured βγ-coin, T1/2; deduced ft. 12B levels deduced β-branching ratio.
1994RE1R, 1991RE02: 12Be(β-n); measured T1/2, neutron emission probabilities.
1997SO34: 12Be(β-n); measured decay products, En, In; deduced neutron emission probabilities.
1998KOZP: 12Be(β-n); measured decay products, Eβ, Iβ, En, In; deduced T1/2, neutron emission probability.
1999BE53: 12Be(β-); measured β-delayed neutrons, βn and nn time correlations. 12Be deduced neutron emission probabilities, branching ratios.
2000KOZH: 12Be(β-n); measured decay products, Eγ, Iγ, En, In; deduced γ-ray energies, T1/2, nuclear magnetic moments, β-delayed neutron emission probabilities. Comparison with available data.
2001BE53: 12Be(β-); measured T1/2, βn and β2n branching ratios, neutron spectra.
2002BE53: 12Be(β-)(β-n); measured Eβ, β-delayed neutron spectra, T1/2. Deduced decay branching ratios.

Measured half-life for 12Be(β-)12B

Recommended value (September, 2015): 21.46 ± 0.05 ms (Weighted Average)
Summary Table of Uncertainty Analysis:  Table 12Be preview (PDF)  
Measured values: 21.49 ± 0.03 ms (2001BE53, 2002BE53)
21.34 ± 0.23 ms (1998KOZP)
13.1 ± 0.5 ms (1997SO34) (Excluded: insufficient experimental details)
21.32 ± 0.06 ms (1994RE1R: see also (1991RE02) and 21.3 ± 0.1 ms in the unpublished
private communications of (2008REZZ)/(1995REZZ).)
26.1 ± 2.4 ms (1994KE06)
21.3 ± 2.2 ms (1986CU01)
24.0 ± 1.0 ms (1984DU15)
24.4 ± 3.0 ms (1978AL10)
11.4 ± 0.5 ms (1965PO03) (Excluded)
Other Reviews: 21.47 ± 0.04 ms (2015BI05)

Previous Measurements

Decay to
12B (MeV)
log ft Eβ-(max) (MeV)
(1965PO03) a b c (1965PO03)
0 3.5 3.84 ± 0.06 3.834 ± 0.017 3.7952 ± 0.0017 ≈ 11.7
a) M.J. Martin, private communication to Fay Ajzenberg-Selove (1980AJ01).
b) M.J. Martin, private communication to Fay Ajzenberg-Selove (1990AJ01).
c) Assuming a (99.50 ± 0.03)% branching ratio to the ground state (1999BE53).

12B(β-)12C Evaluated Data

12N(β+)12C Evaluated Data

A = 12 Beta-Decays Diagram

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Last modified: 28 June 2021