12B

¹²B

β^--Decay Evaluated Data

Measurements

1972AL31: ¹²B(β^-); measured βγ-coin; deduced log ft, β-branching.
1974MC11: ¹²B; measured E_β, I_β, βγ-coin; deduced log ft.
1978AL01: ¹²B(β^-); measured E_β, I_β, βγ-coin, T_1/2; deduced β-branching, mirror asymmetries, ft.
1981KA31: ¹²B(β^-); measured βγ-coin, βγ(t); deduced I_β, log ft.
1983HAZE: ¹²B(β^-); measured β asymmetry.
1985MAZL: ¹²B(β^-); measured I_β(θ); deduced alignment correlation coefficients.
1986CU01: ¹²B(β^-); measured β-decay T_1/2.
1986RO27: ¹²B(β^-); measured T_1/2.
1987MI20: ¹²B(β^-); measured I_β(θ), aligned nuclei; deduced weak nucleon current parity conservation in isospin space.
1988NA09: ¹²B; measured I(β), I(γ), βγ-coin; deduced mirror asymmetry. Deduced Gamow-Teller ?-decay branching ratio.
1988SA04: ¹²B(β^-); measured β-decay T_1/2.
1988SHZO: ¹²B(β^-); measured E_β; deduced shape factor.
1990CA10: ¹²B(β^-); measured spectral shape factors.
1991SOZW: ¹²B(β^-); measured NMR, β asymmetry. ¹²B deduced quadrupole moment.
1992BA11: ¹²B; calculated Gamow-Teller β-decay ft-value asymmetry. R-matrix approach.
1992OHZW: ¹²B(β^-); measured NMR. ¹²B deduced Q.
1992SHZI: ¹²B(β^-); measured E_β.
1992SOZS: ¹²B(β^-); measured β(E, θ); deduced polarization correlation coeffecient.
1992TAZP: ¹²B(β^-); measured T_1/2. ¹²C deduced levels, ft-value asymmetries.
1993MI32: ¹²B(β^-); measured I_β(θ); deduced alignment coefficients, Gamow-Teller matrix elements axial vector time component ratio.
1993MI36: ¹²B(β^-); measured modified β-NMR spectra in Mg; deduced quadrupole moment.
1993OH05: ¹²B(β^-); measured modified β-NMR spectra; deduced hyperfine interactions, quadrupole moment.
1994MO23: ¹²B(β^-); analyzed I_β(θ) data, aligned nuclei; deduced induced tensor current limit, axial charge.
1994OH03: ¹²B(β^-); measured β-NMR. ¹²B level deduced quadrupole moment.
1995KO28: ¹²B(β^-);
1995OK04: ¹²B(β^-); measured β NMR; deduced μ.
1996IZ02: ¹²B(β^-); measured β-NMR. Deduced electric quadrupole moments.
1997CO15: ¹²B(β^-); measured β-asymmetry; deduced alignment related features.
1997MA21: ¹²B(β^-); measured E_β, β(θ). ¹²B deduced μ.
1997MIZS: ¹²B(β^-); measured alignment correlation terms in β-ray angular distribution from aligned ¹²B; deduced validity of G-parity conservation law.
1997NE01: ¹²B(β^-); measured β-asymmetry; deduced ¹²B alignment related features. Level mixing resonance method.
1997OZZY: ¹²B(β^-); measured β(t), T_1/2.
1997YAZW: ¹²B(β^-); measured alignment correlation terms in β-ray angular distribution from aligned ¹²B; deduced large enhancement in the axial charge.
1998MA27: ¹²B(β^-); measured β-NMR; deduced alignment correlation terms.
1998MI14: ¹²B(β^-); measured β-ray angular distribution from oriented nuclei; deduced nonzero G-parity violating induced tensor form factor.
1998MIZU: ¹²B(β^-); measured I_β(θ) from spin aligned nuclei; deduced alignment correlation coefficients, second class weak nucleon current.
1998OHZZ: ¹²B(β^-); measured E_β; deduced spectral shape factor.
1999CO09: ¹²B(β^-); measured β asymmetry. ¹²B deduced μ, quadrupole moment.
1999MI41: ¹²B(β^-); measured E_β, I_β(θ) from aligned nuclei; deduced G-parity violating induced tensor form factor.
2000MI11: ¹²B(β^-); measured β angular distributions from aligned nuclei; deduced axial charge.
2000MIZQ: ¹²B(β^-); measured β-NMR; deduced G-parity irregularity.
2000ST19: ¹²B(β^-); measured E_β, I_β.
2002MI01: ¹²B(β^-); measured E_β, angular distributions from spin-aligned sources; deduced axial charge.
2002MI03, 2002MI49, 2002MIZZ: ¹²B(β^-); measured E_β, angular distributions from spin-aligned sources; deduced tensor form factor, constraints on Kubodera-Delorme-Rho parameters.
2002MI36: ¹²B(β^-); measured E_β, I_β(θ, H, t) from oriented nuclei; deduced alignment correlation terms, axial charge.
2003MI24: ¹²B(β^-); measured E_β, angular distributions from spin-aligned sources; deduced G-parity irregular induced tensor coefficient.
2003ZH32: ¹²B(β^-); measured β-NMR, T_1/2; deduced μ.
2004FY02: ¹²B(β^-); analyzed β-delayed E_α, αα-coin. ¹²C deduced resonance features.
2005DI16: ¹²B(β^-); measured β-delayed E_α, αα-coin. ¹²C deduced excited states, J, π. R-matrix analysis.
2007MI49: ¹²B(β^-); measured β-assymetry for spin polarized nuclei implanted in Pt foil using the β-NMR method.
2007PEZY: ¹²B(β^-); measured branching β-decay ratios.

Measured half-life for ¹²B(β^-)¹²C

Recommended value:	20.20 ± 0.02 ms	(1978AL01)
Measured values:	20.20 ± 0.02 ms	(1978AL01)
	20.3 ± 0.1 ms	(1963FI05)
	20.2 ± 0.2 ms	(1963PE10)
	20.80 ± 0.15 ms	(1962NE14)
	20.15 ± 0.2 ms	(1962PO02)
	20.31 ± 0.20 ms	(1961SC09)
	20.4 ± 0.4 ms	(1959FA03)
	18.87 ± 0.50 ms	(KR59A)
	20.7 ± 0.3 ms	(BU58E)
	20.6 ± 0.2 ms	(1958KR65)
	18^+1.5_-1.3	(1957CO57)
	22 ± 1 ms	(BR53D)
	27 ± 2 ms	(1948JE03)
	22 ± 2 ms	(BE39)

**Previous Measurements**
Decay to ¹²C* (MeV ± keV)	J^π	Branching Ratio (%)		Log ft
0 ^b	0⁺	(1958CO66)	97	(1958CO66) ^a	4.1 ± 0.1
		(1974MC11)	97.13 ± 0.31	(1974MC11)	4.072 ± 0.002
		(1978AL01)	97.14 ± 0.30	(1978AL01) ^f	4.067 ± 0.002
				^g	4.075 ± 0.002
			97.22 ± 0.30	^k	4.066 ± 0.002
4.43891 ± 0.31 ^c	0⁺	(1956TA07)	1.7 ± 0.4	(1958CO66) ^a	5.1 ± 0.2
		(1958KA31)	1.4 ± 0.4
		(1963PE10)	1.3 ± 0.1
		mean	1.33 ± 0.09	^g	5.10 ± 0.03
		(1972AL31)	1.27 ± 0.06
		mean ^h	1.29 ± 0.05	ⁱ	5.11 ± 0.02
		(1978AL01)	1.276 ± 0.05
		^j	1.283 ± 0.04	^j	5.110 ± 0.014
			1.283 ± 0.04		5.108 ± 0.014 ^k
		(1981KA31)	1.182 ± 0.0019	(1981KA31)	5.144 ± 0.007
			1.182 ± 0.0019		5.143 ± 0.007 ^k
7.6543 ± 2.1 ^d	0⁺	(1957CO59, 1958CO66)	1.3 ± 0.4	(1958CO66) ^a	4.2 ± 0.3
		(1963AL15)	1.7 ± 0.5
		mean	1.5 ± 0.3	^g	4.14 ± 0.10
		mean	1.5 ± 0.3	^k	4.13 ± 0.09
10.3 ± 300 ^e	(0⁺) ^l	(1958CO66)	0.13 ± 0.04	(1958CO66) ^a	4.1 ± 0.4
		(1963WI05)	0.07 ± 0.02
		mean	0.08 ± 0.02	^g	4.2 ± 0.2

^a) Based on T_1/2 = 20.6 ms.

^b) E_β^- = 13.381 ± 0.041 MeV (1962MA22).

^c) See (1967CH19).

^d) Based on the atomic mass of ⁴He (A.H. Wapstra, private communication to Fay Ajzenberg-Selove (1990AJ01)) and the decay energy for the breakup of this state into 3α measured by (1973BA73) [Q = 379.6 ± 2.0 keV].

^e) Γ = 3.0 ± 0.7 MeV, θ²_α = 1.5 (1966SC23).

^f) Based on Q_m and T_1/2 = 20.20 ms.

^g) Based on Q_m and T_1/2 = 20.41 ms: see (BA66A).

^h) Mean of 1.33 ± 0.09 and 1.27 ± 0.06 (1972AL31).

ⁱ⁾ See (1974MC11).

^j) Mean calculated by (1978AL01), including (1.276 ± 0.05)% measured by these authors.

^k) Based on Q_m and T_1/2 = 20.20 ± 0.02 ms (M.J. Martin, private communication to Fay Ajzenberg-Selove (1990AJ01).

^l) (1958CO66) suggest J = 0⁺.

¹²Be(β^-)¹²B Evaluated Data

¹²N(β⁺)¹²C Evaluated Data

A = 12 Beta-Decays Diagram

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Last modified: 08 July 2009