1947NO01: ³H; measured T_1/2.

1950JE60: ³H; measured T_1/2.

1951JO15: ³H; measured T_1/2.

1952LA19: ³H.

1955JO20: ³H; measured T_1/2.

1958FR50: ³H.

1958GR93: ³H.

1958PO64: ³H.

1959PO78: ³H.

1961JOZZ: ³H.

1961PI01: ³H; measured not abstracted; deduced nuclear properties.

1963EIZZ: ³H; measured T_1/2.

1964MO29: ³H; measured not abstracted; deduced nuclear properties.

1967JO09: ³H; measured not abstracted; deduced nuclear properties.

1967JO10: ³H; measured not abstracted; deduced nuclear properties.

1969DA18: ³H; measured E_β; deduced Q_β, ν rest mass, ft.

1969SA21: ³H; measured E_β; deduced ν rest mass, Gamow-Teller matrix element.

1970LE15: ³H; measured E_β; deduced ft.

1972BE11: ³H; analyzed E_β; deduced Q, ft-value, axial-vector matrix element.

1973PI01: ³H; measured E_β; deduced end-point energy, log ft, Q.

1974RO08: ³H; measured E_β.

1975SM02: ³H; measured atomic mass.

1976TR07: ³H; measured E_β.

1977RUZZ: ³H(β^-); analyzed data; deduced T_1/2.

1980UN01: ³H.

1981LU07: ³H; measured E_β, I_β; deduced neutrino rest mass limit, β-decay energy.

1983DE47: ³H(β^-); measured β-spectra; deduced β-endpoint energy, antineutrino mass upper limit.

1985BO34: ³H(β^-); measured β-spectrum in Valine molecule, end-point energy; deduced neutrino mass upper limit. ³H, ³He deduced atomic mass difference.

1985BO53: ³H(β^-); measured E_β, I_β; deduced β-endpoint energy, neutrino mass lower limit. ³He, ³H deduced mass difference.

1985RU09: ³H(β^-); measured I(β), I(ce).

1985SI07: ³H(β^-); measured E_β, endpoint energy; deduced Q.

1986FR09: ³H(β^-); measured β-spectrum endpoint; deduced neutrino mass upper limit.

1986FR13: ³H(β^-); measured endpoint region of β-spectrum; deduced an upper limit for mass of ν(bar)(e).

1986GE03: ³H(β^-); measured β-spectra; deduced energy loss uncertainty exclusion.

1986KAZL: ³H(β^-); measured E_β; deduced ν mass limit.

1986SIZU: ³H(β^-); measured E_β, I_β; deduced T_1/2. High precision.

1987BO07: ³H(β^-); measured beta spectrum; deduced neutrino mass.

1987BO35: ³H(β^-); analyzed data; deduced β-endpoint energy, neutrino mass.

1987BU28: ³H.

1987GE04: ³H(β^-); measured maximum, average β- energies; deduced heating powers.

1987KAZD, 1987KAZG: ³H(β^-); measured E_β; deduced ν mass upper limit.

1987OL04: ³H(β^-); measured T_1/2.

1987SI01: ³H(β^-); measured T_1/2, β-endpoint energy; deduced (G(a)/G(V))x<σ(τ)>.

1987WI07: ³H(β^-); measured molecular beta spectrum; deduced electron-antineutrino mass limit.

1988BRZN: ³H(β^-); measured E_β. ³H, ³He deduced mass difference.

1988CH45: ³H(β^-); measured β-detector efficiency.

1988KA12, 1988KA32: ³H(β^-); measured E(β); deduced β-endpoint energy, electron antineutrino mass upper limit.

1988KU03: ³H(β^-); measured β-endpoint energy; deduced neutrino mass upper limit.

1988WI07: ³H(β^-); measured β-spectra; deduced neutrino mass upper limit.

1989BO06, 1989BOZS: ³H(β^-); measured external bremsstrahlung spectrum; deduced electron antineutrino mass upper limit.

1989KAYX: ³H(β^-); measured E_β. Neutrino mass.

1989ST05: ³H(β^-); measured E(γ), I(γ). ³H, ³He deduced atomic mass difference.

1989TA08: ³H(β^-); measured β-activity; deduced quenching correction role in nuclide identification.

1991BU12: ³; measured bremsstrahlung spectra; deduced β-decay end point. ³H, ³He deduced mass difference.

1991BU13: ³H; measured T_1/2.

1991KA40: ³H(β^-); measured β-spectrum Kurie plot; deduced electron anti-neutrino mass upper limit, 95% confidence limit.

1991KA41: ³H(β^-); measured β-spectra.

1991RO07: ³H(β^-); measured β-decay spectrum shape; deduced electron antineutrino mass upper limit.

1992BAZT: ³H(β^-); measured β-spectra; deduced improved limit for m(ν).

1992BU13: ³H(β^-); measured internal, external bremsstrahlung X-ray spectra following β-decay; deduced maximum electron kinetic energy.

1992HO09: ³H(β^-); measured β-spectra; deduced ν-mass upper limit.

1992TA23: ³H(β^-); measured γ-ray energy distribution; deduced upper limit for E_γ.

1993BA08, 1993BAZF: ³H(β^-); measured E_β near endpoint; deduced (ν-bar)(e) rest mass. ³H, ³He deduced mass difference.

1993SU32: ³H(β^-); measured β-endpoint energy; deduced ((ν-bar)(e)), mass upper limit.

1993WE03: ³H(β^-); measured β-spectrum endpoint energy; deduced electron-antineutrino mass upper limit. ³H, ³He deduced atomic mass difference.

1994GR04: ³H(β^-); measured β-counting rates, spectra

1994GR22: ³H(β^-); measured activity vs quench values.

1994HO11: ³H(β^-); measured integral β-counting rates, high accuracy modifield integral counting method.

1994WA35: ³H(β^-); measured β-spectra, E_β distributions.

1995BA82: ³H(β^-); measured direct limit on heavy neutrino.

1995BE35: ³H(β^-); measured β-spectrum in end-point region; deduced ν rest mass, 95% confidence limit.

1995GR04: ³H(β^-); measured spectra, β-distributions maximum points.

1995ST26: ³H; measured β end point energy spectra; deduced anomalous structure, ν-mass implications.

1996SZ04: ³H(β^-); measured βγ-, (e)γ-, (X-ray)γ-coin.

1997KA29: ³H(β^-); analyzed, reviewed neutrino mass estimates from β-decay data analyses.

1997ZI03: ³H(β^-); compiled, reviewed data; deduced consistency of national ³H standard disseminated by several laboratories.

1998AK06: ³H(β^-); measured T_1/2 difference for atomic, molecular tritium.

1998LO14: ³H(β^-); measured β-spectrum in end-point region; deduced origin of spectrum anomaly, neutrino mass upper limit.

1998LO21: ³H(β^-); measured β spectra; deduced neutrino rest mass upper limit.

1998VA22: ³H(β^-); measured E_β, I_β(H, θ); deduced asymmetry coefficient.

1999BB29: ³H(β^-); analyzed β spectrum; deduced neutrino mass limit.

1999HA46: ³H(β^-); measured β spectra; deduced electron screening potential.

1999LO09, 1999LO10, 1999LO23: ³H(β^-); measured β spectra; deduced endpoint energy, neutrino mass limit.

1999WE13: ³H(β^-); measured β spectra; deduced endpoint energy, neutrino mass limit.

2000AK09: ³H(β^-); analyzed T_1/2 for atomic, molecular tritium, related data.

2000BO26, 2000BO32: ³H(β^-); measured E_β, I_β; deduced ν mass upper limit.

2000DE16, 2000ER02: ³H(β^-); measured E_β, I_β.

2000DE20: ³H(β^-); measured E_β; deduced neutrino mass limit.

2000LO08: ³H(β^-); analyzed β-spectra anomalies; neutrino mass upper limit.

2000LO09: ³H(β^-); measured E_β, I_β; deduced ν mass upper limit.

2000LU17: ³H(β^-); compiled, evaluated T_1/2.

2001BO06: ³H(β^-); measured E_β, I_β; deduced neutrino mass limits.

2001LO02: ³H(β^-); measured E_β, I_β; deduced neutrino mass limits.

2002BO27, 2002BO31: ³H(β^-); analyzed E_β; deduced neutrino mass.

2003KR17: ³H(β^-); measured E_β; deduced neutrino mass limits.

2004AK16: ³H(β^-); measured chemical shift in decay constant between atomic and molecular tritium; deduced atomic tritium T_1/2.

2005AK04: ³H(β^-); analyzed data; deduced bare triton decay T_1/2, coupling constants ratio.

2005DO15: ³H(β^-); calculated E_β, effect of external electromagnetic wave field. Implications for neutrino mass determination discussed.

2005KR03: ³H(β^-); measured E_β; deduced neutrino mass limit.

2006BI13: ³H(β^-); analysed data; deduced neutrino mass limit and spectrum shapes.

2006WE03: ³H(β^-); compiled, analyzed decay data, neutrino mass limits.

2010OT02: ³H(β^-); measured I_e, E_e; deduced β-spectrum, neutrino mass.

2011AS10: measured ³H decay; deduced anti-neutrino mass.

2013BI07: ³H(β^-); measured decay products, E_β, I_β.

2016PO08: ³H(β^-); measured decay products; deduced exponential nature of nuclear decay.

2017AB05: ³H(β^-); measured decay products, E_β, I_β; deduced β-spectrum.

2019KL03: ³H(β^-); analyzed available data.

2019FR06: ³H(β^-); measured decay products, E_β, I_β; deduced neutrino mass.

2020AK02: ³H(β^-); measured decay products, E_β, I_β; deduced Q-value, β spectra.

2020HI10: ³H; ompiled experimental results for half-life of hypertriton from 1964 to 2019, and the evaluated data from Particle Data Group (PDG).

2020LI16: ³H(β^-); measured decay products, E_β, I_β; deduced branching ratios and uncertainties to specific ionization states.

Measured half-life for ³H(β^-)³He

Recommended value (September, 2015):	12.323 ± 0.020 years	(Weighted Average Method: uncertainties of (1955JO20) and (1977RUZZ) adjusted to
		12.262 ± 0.030 and 12.3232 ± 0.0246 as suggested in (2000LU17).)
Summary Table of Uncertainty Analysis:	(PDF)
Measured values:	12.33 ± 0.02 years	(2000UN02: see also 12.43 ± 0.05 years in (1980UN01).)
	12.31 ± 0.03 years	(1991BU13: see also 12.29 ± 0.15 years in (1987BU28).)
	12.279 ± 0.033 years	(Akulov et al, Zh. Tekh. Fiz. 14 (1988) 940; Sov. Tech. Phys. Lett. 14 (1988) 416.
		See discussion on a comparison of the molecular lifetime vs. the atomic lifetime in (2004AK16),
		where T1/2(atomic) ≈ 12.264 ± 0.018 years is obtained.)
	12.38 ± 0.03 / 0.04 years	(1987OL04 / 1989OL03)
	12.32 ± 0.03 years	(1987SI01)
	12.3232 ± 0.0043 years	(1977RUZZ: see also 12.346 ± 0.002 years in (1967JO09) and 12.355 ± 0.010 years in (1963EIZZ).)
	12.25 ± 0.08 years	(1967JO10)
	12.31 ± 0.13 years	(Merritt and Taylor, Chalk River Rept. AECL-2510 (1966))
	12.58 ± 0.18 years	(1958PO64)
	12.262 ± 0.004 years	(1955JO20)
	12.41+0.15-0.25 years	(1951JO15)
	12.46 ± 0.1 years	(1950JE60)
	12.1 ± 0.5 years	(1947NO01)
	10.7 ± 2.0 years	(1947GO08)
Other Reviews:	12.312 ± 0.025 years	(DDEP)
	12.312 ± 0.011 years	(2006MA57)
	12.320 ± 0.022 years	(2000LU17)

Previous Measurements

 

Reference	Method or forms of 3H sources	End Point Energy (keV)	Heat Output (W/γ)
(1952LA19)	magnetic	17.95 ± 0.1	(1950JE60)	0.321 ± 0.003
(1958FR50)	mass	18.65 ± 0.2 a	(1958GR93)	0.319 ± 0.001
(1959PO78)	magnetic	18.61 ± 0.1	(1958PO64)	0.312 ± 0.001
(1964MO29)	mass	18.47 ± 0.17 a	(1961JOZZ)	0.3244 ± 0.0013
(1969SA21)	electrostatic	18.70 ± 0.06 b	(1961PI01)	0.3240 ± 0.0009
(1969DA18)	magnetic	18.570 ± 0.075	Average Eβ (keV)
(1970LE15)	3H implanation	18.540 ± 0.095	(1950JE60)	5.69 ± 0.04; calorimetry
(1972BE11)	magnetic-electrostatic	18.610 ± 0.016	(1958GR93)	5.57 ± 0.01; calorimetry
(1973PI01)	magnetic	18.578 ± 0.040	(1961PI01)	5.73 ± 0.03; calorimetry
(1974RO08)	magnetic	18.648 ± 0.026
(1975SM02)	mass difference	18.559 ± 0.007
(1976TR07)	magnetic	18.575 ± 0.013
(1981LU07)	magnetic	18.577 ± 0.013
(1983DE47)	thermal diffuse	18.562 ± 0.006
(1985SI07)	3H implanation	18.577 ± 0.007
(1985BO34)	magnetic	18.5842 ± 0.0016
(1987BO07)	valine	18.5794 ± 0.004
(1993BA08)	moleculare tritium	18.5748 ± 0.0006
(1993SU32)	C14H15T6O2N3	18.5783 ± 0.0051
(1995ST26)	gaseous tritium	18.5685 ± 0.002
(2003KR17)	gaseous tritium	18.5705

a) Assumes anti-neutrino mass to be zero.

b) Not correct for resolution effects.

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Last modified: 17 August 2021