This table presents an evaluated set of values for the experimental quantities that characterize the decay of radioactive nuclides. A list of the major references used in this evaluation is given below. When uncertainties are not listed, they are assumed to be five or less in the last digit quoted. If the uncertainty in the value exceeds five in the last digit, the value is preceded by an approximate sign.
For quasi-stable nuclides, the measured width, Γ, of the resonance is given. To estimate the approximate half-life, the Heisenberg relationship may be used: the half-life = 4.56 × 10-22 seconds / Γ (MeV). The effective literature cutoff date for data in this edition of the table is October 2016.
Column heading | Definition |
Elem. or Isot. | For elements, the atomic number and chemical symbol are listed. For nuclides, the mass number and chemical symbol are listed. Isomers are indicated by the addition of m, m1, or m2. |
Natural abundance | The abundance of an isotope in normal terrestrial samples of an element, listed in atom percent. |
Atomic mass or weight | Atomic mass relative to 12C = 12. Atomic weight of elements is given on the same scale. |
Half-life/Resonance width | Half-life in decimal notation. µs = microseconds; ms = milliseconds; s = seconds; m = minutes; h = hours; d = days; and a = years. For quasi-stable nuclides, the measured width at half-maximum of the energy resonance is given. |
Decay mode/Energy | Decay modes are α = alpha particle emission; β = negative beta emission; β+ = positron emission; ec = orbital electron capture; IT = isomeric transition from upper to lower isomeric state; n = neutron emission; p = proton emission; sf = spontaneous fission; ββ, ECEC, 2p, 2n, 3n = double beta, double EC, two proton and multiple neutron decay. Total disintegration energy in MeV units. |
Particle energy/Intensity | End point energies of beta transitions and discrete energies of alpha particles, neutrons, and protons are given in MeV units and their intensities in percent. |
Spin | Nuclear spin or angular momentum of the nuclides in units of h/2π; parity is positive or negative. |
Nuclear magnetic mom. | Magnetic dipole moments in nuclear magneton units. An absolute value is indicated in the absence of a positive or a negative sign. |
Elect. quadr. mom. | Electric quadrupole moments in barn units (10-24 cm2). An absolute value is indicated in the absence of a positive or a negative sign. |
γ-Energy/Intensity | Gamma ray energies are given in MeV units and intensities in percent. Annihilation radiation (ann.rad.) refers to the 511.006 keV photons emitted in the annihilation of positrons in matter. |
The following references represent the major sources of the nuclear data presented, along with subsequent published journal articles and reports:
This research was carried out under the auspices of the U.S. Department of Energy Contract No. DE-AC02-98CH10886. The author is at Brookhaven National Laboratory, Upton, NY, and can be contacted at [email protected].
Element | Elem. or Isot. | Natural abundance (Atom %) | Atomic mass or weight | Half-life/Resonance width (MeV) | Decay mode/Energy (MeV) | Particle energy/Intensity (MeV/%) | Spin (h/2π) | Nuclear magnetic mom. (nm) | Elect. quadr. mom. (b) | γ-Energy/Intensity (MeV/%) |
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Neutron | on | 1.008664916 | 610.5 s | β- /0.78235 | 0.782/100. | 1/2+ | -1.913043 | |||
Neutron | on | β-, γ | / 0.0031 | |||||||
Hydrogen | 1H | 1.00784-1.00811 | ||||||||
Hydrogen | 1H | 99.972 - 99.999 | 1.007825032 | >2.8 ×1023 a | 1/2+ | +2.7928473 | ||||
Hydrogen | 2H | 0.001-0.028 | 2.014101778 | 1+ | +0.8574382 | +2.86 mb | ||||
Hydrogen | 3H | 3.016049282 | 12.31 a | β-/0.01859 | 0.01860/100. | 1/2+ | +2.9789624 | |||
Hydrogen | 4H | 4.026 | Γ = 1.2 | n/ | /100 | 2- | ||||
Hydrogen | 5H | 5.035 | Γ < 0.5 | n/ | /100 | (1/2+) | ||||
Hydrogen | 6H | 6.045 | Γ ~ 6. | n/ | (2-) | |||||
Hydrogen | 7H | 7.05 | Γ ~ 0.1 | |||||||
Helium | 2He | 4.002602(2) | ||||||||
Helium | 3He | 0.0002(2) | 3.016029323 | 1/2+ | -2.127750 | |||||
Helium | 4He | 99.9998(2) | 4.0026032541 | 0+ | ||||||
Helium | 5He | 5.0121 | Γ = 0.60(2) | n, α | 3/2- | |||||
Helium | 6He | 6.0188859 | 0.8069 s | β-/3.508 | 3.510/100. | 0+ | ||||
Helium | 6He | β, d | 0.35/0.00017 | |||||||
Helium | 7He | 7.02799 | Γ ~ 0.19 | n | (3/2)- | |||||
Helium | 8He | 8.033934 | 0.119 s | β-/10.65 | /84. | 0+ | 0.9807/84. | |||
Helium | 8He | β- n/ | /16. | 0.4776/5. |