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Nuclide reference

Cr-51 — Chromium-51

The half-life of Cr-51 is 27.701 d. Main decay mode: electron capture to V-51 (100%).

Identification

Element
Chromium (Cr)
Atomic number Z
24
Mass number A
51
State
Radioactive

Key quantities

Half-life
27.701 d
Specific activity
3.42e+15 Bq/g
Gamma constant Γ (H*(10))
0.00547 µSv·m²/(MBq·h)
Dose rate, 1 GBq at 1 m
≈ 5.47 µSv/h
A1 / A2 for transport (SSR-6, НП-053-16)
30 TBq / 30 TBq
D-value (НП-067-24)
2 TBq

Decay modes

  • electron capture → V-51 — 100 %

Main gamma lines

Energy, keVYield, %
4.952 · X-ray line13.21
320.0829.91
4.944 · X-ray line6.72

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

Related calculators

DecayActivity ↔ massSource categoryDose rateA1/A2 and package type
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.

Chromium-51 (Cr-51) — reference data

What is in the card

This card gathers the key data of radionuclide Cr-51 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 Cr-51 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.