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Nuclide reference

Ra-224 — Radium-224

The half-life of Ra-224 is 3.66 d. Main decay mode: α decay to Rn-220 (100%).

Identification

Element
Radium (Ra)
Atomic number Z
88
Mass number A
224
State
Radioactive

Key quantities

Half-life
3.66 d
Specific activity
5.893e+15 Bq/g
Gamma constant Γ
—
A1 / A2 for transport (SSR-6, НП-053-16)
0.4 TBq / 0.02 TBq
D-value (НП-067-24)
0.05 TBq

Decay modes

Main gamma lines

Energy, keVYield, %
238.632 (Pb-212)49.62
2,614.51 (Tl-208)41.3
583.187 (Tl-208)35.19
77.109 (Pb-212) · X-ray line19.17
74.817 (Pb-212) · X-ray line11.45
510.77 (Tl-208)9.356
727.33 (Bi-212)7.677
860.557 (Tl-208)5.175
240.9864.1
300.087 (Pb-212)3.756

Includes daughter nuclides in equilibrium: Rn-220, Po-216, Pb-212, Bi-212, Po-212, Tl-208 (yield per decay of Ra-224); the emitting nuclide is in brackets. Equilibrium is reached in about 3.5 d. In transient equilibrium a daughter's activity exceeds the parent's, so a yield can be above 100%. Equilibrium with radon requires a sealed source.

Alpha and beta particles

RadiationEnergy, keVYield, %
α5,685.494.92
6,288.1 (Rn-220)99.9
6,778.3 (Po-216)100
8,784.9 (Po-212)73.75
β⁻, E max331.27 (Pb-212)94.57
569.9 (Pb-212)13.54
2,252.1 (Bi-212)63.74
1,801.3 (Tl-208)20.33

For β⁻ the endpoint (maximum) energy of the spectrum is given. ENDF/B-VIII.0.

Related calculators

DecayActivity ↔ massSource categoryDose rateA1/A2 and package type

Other isotopes of this element

Ra-223Ra-226
Reference data vs computed valuesHalf-life, gamma lines and D-value are reference data (ENDF/B-VIII.0, НП-067-24).Gamma constant Γ is H*(10) at 1 m computed from ICRP-107 spectra (NIST µ_en/ρ, ICRP-74 Table A.21) including short-lived progeny in equilibrium (e.g. Cs-137/Ba-137m, Ra-226 series); specific activity uses molar mass M ≈ mass number A.K-series X-ray energies are from NIST SRD 128 (Deslattes et al., 2003): in ENDF/B-VIII.0 they are given to 1 % and shifted by up to 0.7 keV for heavy elements. L-series lines and all yields are ENDF/B-VIII.0.

Radium-224 (Ra-224) — reference data

What is in the card

This card gathers the key data of radionuclide Ra-224 in one place: half-life, decay modes, main gamma lines, alpha and beta particle energies, gamma constant, specific activity and the D-value for source categorization. Decay and emission data are from ENDF/B-VIII.0; the D-value follows NP-067-24; the gamma constant is the ambient dose equivalent H*(10) at 1 m, computed from ICRP-107 spectra.

How to use the data

Half-life and specific activity let you recalculate the activity of a Ra-224 source to the delivery or disposal date — use the decay calculator. Gamma lines with yields identify the nuclide from a spectrum and pick the line for gamma spectrometry; the gamma constant Γ gives the dose rate at a distance, while the D-value and A1/A2 set the source category and the package type for transport.