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Nuclide reference

U-235m — Uranium-235m

The half-life of U-235m is 26 min. Main decay mode: isomeric transition to U-235 (100%).

Identification

Element
Uranium (U)
Atomic number Z
92
Mass number A
235
State
Radioactive

Key quantities

Half-life
26 min
Specific activity
1.139e+18 Bq/g
Gamma constant Γ
—
D-value (НП-067-24)
—

Decay modes

  • isomeric transition → U-235 — 100 %

Related calculators

DecayActivity ↔ massDose rate

Other isotopes of this element

U-235U-238
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.

Uranium-235m (U-235m) — reference data

What is in the card

This card gathers the key data of radionuclide U-235m 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 U-235m 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.