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Nuclide reference

Co-57 — Cobalt-57

The half-life of Co-57 is 271.74 d. Main decay mode: electron capture to Fe-57 (100%).

Identification

Element
Cobalt (Co)
Atomic number Z
27
Mass number A
57
State
Radioactive

Key quantities

Half-life
271.74 d
Specific activity
3.119e+14 Bq/g
Gamma constant Γ (H*(10))
0.02091 µSv·m²/(MBq·h)
Dose rate, 1 GBq at 1 m
≈ 20.9 µSv/h
A1 / A2 for transport (SSR-6, НП-053-16)
10 TBq / 10 TBq
D-value (НП-067-24)
0.7 TBq

Decay modes

  • electron capture → Fe-57 — 100 %

Main gamma lines

Energy, keVYield, %
122.06185.6
6.403 · X-ray line32.78
6.39 · X-ray line16.72
136.47410.68
14.41299.16
692.410.149
570.090.0158
706.540.005
339.690.0037
352.330.003

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

Related calculators

DecayActivity ↔ massSource categoryDose rateA1/A2 and package type

Other isotopes of this element

Co-60
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.Dose rate example: point source, no shielding or scatter, Ḣ = Γ·A/r².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.

Cobalt-57 (Co-57) — reference data

What is in the card

This card gathers the key data of radionuclide Co-57 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 Co-57 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.