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Radionuclide Dosimetric Data Sheets
Neptunium-240
Summary data
General
Classification
Isotope: Np-240
Atomic number (Z): 93
Mass number (A): 240
Neutron number (N): 147
Radioactive decay
Decay modes: β-
Half-life: 61.9 [m]
Decay constant: 1.8663e-04 [1/s]
Daughters: Pu-240 (100.0%)
Radioactive daughters: Pu-240
Dosimetric constants
Mean alpha energy: 0.0 [MeV]
Mean electron energy: 0.50945 [MeV]
Mean photon energy: 1.05379 [MeV]
Air kerma rate constant, Γ10: 5.747e-17 [Gy·m2/Bq·s]
Air kerma coefficient, Kair: 5.747e-17 [Gy·m2/Bq·s]
Equilibrium dose constant for weakly-penetrating radiations (α and/or
electrons), Δwp: 8.162e-14 [Gy·kg/Bq·s]
Equilibrium dose constant for alphas, Δα: 0.000e+00
[Gy·kg/Bq·s]
Equilibrium dose constant for betas/electrons, Δβ-,β+,e-:
8.162e-14 [Gy·kg/Bq·s]
Equilibrium dose constant for photons, Δp: 1.688e-13
[Gy·kg/Bq·s]
Summary spectra (plot)
Spectra source: ICRP Publication 107: Nuclear Decay Data for Dosimetric Calculations. Ann. ICRP 2008, 38 (3).
Download tabulated summary spectra file here: www.mirdsoft.org/products/MIRDspecs/Np-240 Summary Spectrum.csv
Beta spectra (plot)
Spectra source: ICRP Publication 107: Nuclear Decay Data for Dosimetric Calculations. Ann. ICRP 2008, 38 (3).
Download tabulated beta spectra file here: www.mirdsoft.org/products/MIRDspecs/Np-240 Beta Spectrum.csv
Tabulated data
Summary spectra (table)
Spectra source: ICRP Publication 107: Nuclear Decay Data for Dosimetric Calculations. Ann. ICRP 2008, 38 (3).
Note: Radiations with yield < 0.01 are excluded from the table, but are available in the linked *.csv data.
Download tabulated summary spectra file here: www.mirdsoft.org/products/MIRDspecs/Np-240 Summary Spectrum.csv
|
Energy [MeV] |
Yield [#/nt] if > 0.01 |
Radiation type |
|
7.20413e-05 |
2.386e+01 |
X-ray |
|
3.45636e-03 |
1.571e-01 |
X-ray |
|
1.21689e-02 |
2.277e-02 |
X-ray |
|
1.40932e-02 |
3.619e-02 |
X-ray |
|
1.42941e-02 |
3.178e-01 |
X-ray |
|
1.72768e-02 |
6.761e-02 |
X-ray |
|
1.79612e-02 |
1.316e-02 |
X-ray |
|
1.83932e-02 |
3.382e-01 |
X-ray |
|
2.15284e-02 |
7.806e-02 |
X-ray |
|
2.22515e-02 |
1.560e-02 |
X-ray |
|
9.89000e-02 |
4.810e-02 |
Gamma |
|
9.99790e-02 |
8.457e-02 |
X-ray |
|
1.04279e-01 |
1.339e-01 |
X-ray |
|
1.16802e-01 |
1.552e-02 |
X-ray |
|
1.17801e-01 |
3.045e-02 |
X-ray |
|
1.47200e-01 |
1.175e-02 |
Gamma |
|
1.52700e-01 |
6.701e-02 |
Gamma |
|
1.75400e-01 |
4.682e-02 |
Gamma |
|
1.93300e-01 |
5.600e-02 |
Gamma |
|
2.71300e-01 |
5.692e-02 |
Gamma |
|
4.48010e-01 |
1.230e-01 |
Gamma |
|
4.66700e-01 |
1.074e-02 |
Gamma |
|
5.07300e-01 |
1.671e-02 |
Gamma |
|
5.66340e-01 |
2.534e-01 |
Gamma |
|
6.00570e-01 |
1.836e-01 |
Gamma |
|
6.06100e-01 |
1.625e-02 |
Gamma |
|
8.21200e-01 |
1.065e-02 |
Gamma |
|
8.67200e-01 |
8.078e-02 |
Gamma |
|
8.88800e-01 |
2.295e-02 |
Gamma |
|
8.95800e-01 |
1.359e-01 |
Gamma |
|
9.16000e-01 |
1.221e-02 |
Gamma |
|
9.59100e-01 |
1.689e-02 |
Gamma |
|
9.73900e-01 |
2.378e-01 |
Gamma |
|
9.87700e-01 |
6.701e-02 |
Gamma |
|
1.16710e+00 |
4.498e-02 |
Gamma |
|
2.76221e-01 |
6.775e-01 |
Beta |
|
3.29613e-01 |
4.517e-02 |
Beta |
|
3.46583e-01 |
1.355e-01 |
Beta |
|
3.75614e-01 |
7.227e-02 |
Beta |
|
4.88001e-01 |
3.613e-02 |
Beta |
|
6.63949e-01 |
2.891e-02 |
Beta |
|
8.91110e-05 |
6.532e+00 |
Auger electron |
|
1.76454e-04 |
4.113e-02 |
Auger electron |
|
1.91741e-04 |
3.720e+00 |
Auger electron |
|
2.37110e-04 |
6.260e+00 |
Auger electron |
|
5.77322e-04 |
9.689e-01 |
Auger electron |
|
1.53519e-03 |
2.586e-01 |
Auger electron |
|
2.56474e-03 |
2.047e+00 |
Auger electron |
|
3.09803e-03 |
4.201e-01 |
Auger electron |
|
3.75847e-03 |
2.526e-02 |
Auger electron |
|
1.07985e-02 |
5.049e-01 |
Auger electron |
|
1.43479e-02 |
2.621e-01 |
Auger electron |
|
1.79383e-02 |
3.200e-02 |
Auger electron |
|
1.96780e-02 |
1.402e-02 |
Conversion electron |
|
2.04290e-02 |
3.910e-01 |
Conversion electron |
|
2.47290e-02 |
3.381e-01 |
Conversion electron |
|
2.48500e-02 |
5.762e-02 |
Conversion electron |
|
3.03500e-02 |
1.314e-02 |
Conversion electron |
|
3.82501e-02 |
2.076e-01 |
Conversion electron |
|
4.28000e-02 |
7.407e-02 |
Conversion electron |
|
7.09500e-02 |
1.197e-01 |
Conversion electron |
|
7.57780e-02 |
1.791e-02 |
Conversion electron |
|
7.65290e-02 |
3.449e-01 |
Conversion electron |
|
8.08290e-02 |
2.286e-01 |
Conversion electron |
|
9.43501e-02 |
1.664e-01 |
Conversion electron |
|
9.89000e-02 |
5.953e-02 |
Conversion electron |
|
1.24078e-01 |
1.024e-02 |
Conversion electron |
|
1.30329e-01 |
6.942e-02 |
Conversion electron |
|
1.34629e-01 |
3.778e-02 |
Conversion electron |
|
1.48150e-01 |
3.176e-02 |
Conversion electron |
|
1.48950e-01 |
4.516e-02 |
Conversion electron |
|
1.52700e-01 |
1.141e-02 |
Conversion electron |
|
1.70178e-01 |
2.118e-02 |
Conversion electron |
|
4.43990e-01 |
2.823e-02 |
Conversion electron |
Useful Links
Isotope decay characteristics are periodically updated as better measurements can be made - changes that may not be reflected on this page. Please see useful links:
National Nuclear Data Center (NNDC): https://www.nndc.bnl.gov/nudat3/mird/
International Atomic Energy Agency (IAEA) Livechart: https://www-nds.iaea.org/relnsd/vcharthtml/VChartHTML.html
Reference Links
ICRP Report 107: https://www.icrp.org/publication.asp?id=ICRP%20Publication%20107
Graves et al. Dose Point Kernels: https://doi.org/10.1002/mp.13789
MIRD Decay Schemes 2nd Edition: https://sites.snmmi.org/SNMMI-MAIN/iCore/Store/StoreLayouts/Item_Detail.aspx?iProductCode=0-932004-80-6
MIRDsoft MIRDspecs version 20250101 (www.mirdsoft.org)
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