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Nuclide reference

Np-240m — Neptunium-240m

Np-240m की half-life 7.22 min है। मुख्य decay mode: β⁻ decay → Pu-240 (99.88%)।

Identification

तत्व
Neptunium (Np)
Atomic number Z
93
Mass number A
240
State
Radioactive

Key quantities

Half-life
7.22 min
विशिष्ट गतिविधि
4.015e+18 Bq/g
Gamma constant Γ
—
D-value (НП-067-24)
—

Decay modes

  • β⁻ decay → Pu-240 — 99.88 %
  • isomeric transition → Np-240 — 0.12 %

Main gamma lines

Energy, keVYield, %
554.620.87
18.1431 · X-ray line13.3
14.2742 · X-ray line11.94
597.411.69
1,496.91.328
817.891.278
938.021.209
758.611.179
263.371.139
915.981.019

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

Alpha and beta particles

RadiationEnergy, keVYield, %
β⁻, E max2,165.241.95
1,610.630.96
2,2089.988
1,307.73.795

For β⁻ the endpoint (maximum) energy of the spectrum is given. ENDF/B-VIII.0.

Related calculators

Decayगतिविधि ↔ द्रव्यमानDose 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 1 m पर H*(10) है, ICRP-107 spectra (NIST µ_en/ρ, ICRP-74 Table A.21) से गणना की गई, equilibrium में short-lived progeny सहित (जैसे Cs-137/Ba-137m, Ra-226 series); specific activity molar mass M ≈ mass number A का उपयोग करती है।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.

Neptunium-240m (Np-240m) — reference data

What is in the card

This card gathers the key data of radionuclide Np-240m 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 Np-240m 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.