Identification

Element: Bismuth (Bi)
Atomic number Z: 83
Mass number A: 209
State: Radioactive

Key quantities

Half-life: 1.9e+10 billion years
Specific activity: 0.000003331 Bq/g
Gamma constant Γ: —
D-value (НП-067-24): —

Decay modes

α decay → Tl-205 — 100 %

Alpha and beta particles

Radiation	Energy, keV	Yield, %
α	3,077	99.92
	2,876	0.04

Related calculators

Decay Activity ↔ mass Dose rate

Other isotopes of this element

Bi-213

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.

Bismuth-209 (Bi-209) — reference data

What is in the card

This card gathers the key data of radionuclide Bi-209 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 Bi-209 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.