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Nuclide reference

Es-253 — Einsteinium-253

The half-life of Es-253 is 20.47 d. Main decay mode: α decay to Bk-249 (100%).

Identification

Element
Einsteinium (Es)
Atomic number Z
99
Mass number A
253
State
Radioactive

Key quantities

Half-life
20.47 d
Specific activity
9.329e+14 Bq/g
Gamma constant Γ
—
D-value (НП-067-24)
—

Decay modes

  • α decay → Bk-249 — 100 %
  • spontaneous fission — 0.0000087 %

Main gamma lines

Energy, keVYield, %
15.304 · X-ray line1.139
19.5744 · X-ray line1.082
41.790.03083
389.180.0264
387.10.0181
51.960.006694
428.940.00604
381.10.00555
42.980.004
30.830.0032

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

Alpha and beta particles

RadiationEnergy, keVYield, %
α6,632.589.9
6,590.56.6
6,5400.85
6,6240.8

Related calculators

DecayActivity ↔ massDose rate
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.

Einsteinium-253 (Es-253) — reference data

What is in the card

This card gathers the key data of radionuclide Es-253 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 Es-253 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.