<= Return to MIRDspec isotope database

Radionuclide Dosimetric Data Sheets

Neptunium-238

Isotope:  Np-238
Atomic number (Z):  93
Mass number (A):  238
Neutron number (N):  145

Decay modes:  β-
Half-life:  2.117 [d]
Decay constant:  3.7896e-06 [1/s]
Daughters:  Pu-238 (100.0%)
Radioactive daughters:  Pu-238

Mean alpha energy:  0.0 [MeV]
Mean electron energy:  0.25191 [MeV]
Mean photon energy:  0.58789 [MeV]
Air kerma rate constant, Γ₁₀:  2.790e-17 [Gy·m²/Bq·s]
Air kerma coefficient, K_air:  2.790e-17 [Gy·m²/Bq·s]
Equilibrium dose constant for weakly-penetrating radiations (α and/or electrons), Δ_wp:  4.036e-14 [Gy·kg/Bq·s]
Equilibrium dose constant for alphas, Δ_α:  0.000e+00 [Gy·kg/Bq·s]
Equilibrium dose constant for betas/electrons, Δ_β-,β+,e-:  4.036e-14 [Gy·kg/Bq·s]
Equilibrium dose constant for photons, Δ_p:  9.419e-14 [Gy·kg/Bq·s]

Dose point kernel source:  Graves, et al. Medical Physics. 2019 Nov.; 46(11):5284-5293.

Note: Bins are spaced every 0.1 mm until a radius of 10 cm, and every 1 mm until a radius of 2 m.

Download tabulated dose point kernel file here:  www.mirdsoft.org/products/MIRDspecs/Np-238 DPK.csv

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-238 Summary Spectrum.csv

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-238 Beta Spectrum.csv

 

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-238 Summary Spectrum.csv

 

Energy [MeV]	Yield [#/nt] if > 0.01	Radiation type
7.20452e-05	8.520e+00	X-ray
3.45656e-03	5.611e-02	X-ray
1.40932e-02	1.304e-02	X-ray
1.42941e-02	1.145e-01	X-ray
1.72768e-02	2.437e-02	X-ray
1.83932e-02	1.228e-01	X-ray
2.15284e-02	2.835e-02	X-ray
9.23980e-01	2.620e-02	Gamma
9.84450e-01	2.519e-01	Gamma
1.02587e+00	8.716e-02	Gamma
1.02854e+00	1.829e-01	Gamma
6.00768e-02	1.148e-01	Beta
7.22093e-02	4.482e-01	Beta
9.19825e-02	1.256e-02	Beta
4.12298e-01	4.102e-01	Beta
8.91193e-05	2.332e+00	Auger electron
1.76443e-04	1.469e-02	Auger electron
1.91667e-04	1.330e+00	Auger electron
2.37001e-04	2.236e+00	Auger electron
5.74239e-04	3.454e-01	Auger electron
1.48754e-03	8.133e-02	Auger electron
2.56517e-03	7.313e-01	Auger electron
3.09860e-03	1.501e-01	Auger electron
1.07803e-02	1.808e-01	Auger electron
1.43276e-02	9.384e-02	Auger electron
1.79146e-02	1.146e-02	Auger electron
2.09580e-02	1.115e-02	Conversion electron
2.17090e-02	3.087e-01	Conversion electron
2.60090e-02	2.650e-01	Conversion electron
3.95301e-02	1.634e-01	Conversion electron
4.40800e-02	5.831e-02	Conversion electron
7.95290e-02	1.571e-02	Conversion electron
8.38290e-02	1.029e-02	Conversion electron

 

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

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)

<= Return to MIRDspec isotope database