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Nuclide reference

I-126 — Iodine-126

The half-life of I-126 is 12.93 d. Main decay mode: β⁺ decay / electron capture to Te-126 (52.7%).

Identification

Element
Iodine (I)
Atomic number Z
53
Mass number A
126
State
Radioactive

Key quantities

Half-life
12.93 d
Specific activity
2.965e+15 Bq/g
Gamma constant Γ
—
A1 / A2 for transport (SSR-6, НП-053-16)
2 TBq / 1 TBq
D-value (НП-067-24)
0.1 TBq

Decay modes

  • β⁺ decay / electron capture → Te-126 — 52.7 %
  • β⁻ decay → Xe-126 — 47.3 %

Main gamma lines

Energy, keVYield, %
388.63335.57
666.33132.88
27.472 · X-ray line20.83
27.202 · X-ray line11.18
753.8194.147
491.2432.881
510.999 · annihilation 511 keV2.016
879.8760.7434
1,420.190.3039
2,045.090.004604

Lines of the bare nuclide (ENDF/B-VIII.0), without daughter ingrowth.

Alpha and beta particles

RadiationEnergy, keVYield, %
β⁻, E max869.3733.43
1,25810.31
378.123.623
β⁺, E max1,1330.8102
466.660.198

For β⁻ and 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

I-123I-124I-125I-129I-131
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.

Iodine-126 (I-126) — reference data

What is in the card

This card gathers the key data of radionuclide I-126 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 I-126 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.