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Nuclide reference

Rn-218 — Radon-218

The half-life of Rn-218 is 35 ms. Main decay mode: α decay to Po-214 (100%).

Identification

Element
Radon (Rn)
Atomic number Z
86
Mass number A
218
State
Radioactive

Key quantities

Half-life
35 ms
Specific activity
5.471e+22 Bq/g
Gamma constant Γ
—
D-value (НП-067-24)
—

Decay modes

Main gamma lines

Energy, keVYield, %
609.310.124
799.7 (Po-214)0.0104

Includes daughter nuclides in equilibrium: Po-214 (yield per decay of Rn-218); the emitting nuclide is in brackets. Equilibrium is reached in about 0.0012 s.

Alpha and beta particles

RadiationEnergy, keVYield, %
α7,129.299.87
6,531.10.127
7,686.8 (Po-214)100.5
6,902.2 (Po-214)0.01045

Related calculators

DecayActivity ↔ massDose rate

Other isotopes of this element

Rn-222
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.

Radon-218 (Rn-218) — reference data

What is in the card

This card gathers the key data of radionuclide Rn-218 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 Rn-218 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.