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Nuclide reference

Cf-251 — Californium-251

The half-life of Cf-251 is 898 years. Main decay mode: α decay to Cm-247 (100%).

Identification

Element
Californium (Cf)
Atomic number Z
98
Mass number A
251
State
Radioactive

Key quantities

Half-life
898 years
Specific activity
5.868e+10 Bq/g
Gamma constant Γ
—
A1 / A2 for transport (SSR-6, НП-053-16)
7 TBq / 0.0007 TBq
D-value (НП-067-24)
0.1 TBq

Decay modes

Main gamma lines

Energy, keVYield, %
14.9569 · X-ray line25.81
19.1329 · X-ray line25.81
177.5217.3
227.386.8
285.411.13
265.860.43
61.670.4
291.20.3
256.650.13
165.70.12

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

Alpha and beta particles

RadiationEnergy, keVYield, %
α5,679.335.4
5,85427.6
6,01712.5
5,6354.9

Related calculators

DecayActivity ↔ massSource categoryDose rateA1/A2 and package type

Other isotopes of this element

Cf-252
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.

Californium-251 (Cf-251) — reference data

What is in the card

This card gathers the key data of radionuclide Cf-251 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 Cf-251 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.