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Radionuclide Dosimetric Data Sheets
Neptunium-235
Summary data
General
Classification
Isotope: Np-235
Atomic number (Z): 93
Mass number (A): 235
Neutron number (N): 142
Radioactive decay
Decay modes: α, Electron capture
Half-life: 396.1 [d]
Decay constant: 2.0254e-08 [1/s]
Daughters: U-235 (99.6%), U-235m (0.399%), Pa-231 (0.0026%)
Radioactive daughters: U-235, U-235m, Pa-231
Dosimetric constants
Mean alpha energy: 0.0001 [MeV]
Mean electron energy: 0.01054 [MeV]
Mean photon energy: 0.0071 [MeV]
Air kerma rate constant, Γ10: 8.453e-18 [Gy·m2/Bq·s]
Air kerma coefficient, Kair: 8.453e-18 [Gy·m2/Bq·s]
Equilibrium dose constant for weakly-penetrating radiations (α and/or
electrons), Δwp: 1.705e-15 [Gy·kg/Bq·s]
Equilibrium dose constant for alphas, Δα: 1.602e-17
[Gy·kg/Bq·s]
Equilibrium dose constant for betas/electrons, Δβ-,β+,e-:
1.689e-15 [Gy·kg/Bq·s]
Equilibrium dose constant for photons, Δp: 1.138e-15
[Gy·kg/Bq·s]
Dose point kernels (plot)
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-235 DPK.csv
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-235 Summary 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-235 Summary Spectrum.csv
|
Energy [MeV] |
Yield [#/nt] if > 0.01 |
Radiation type |
|
7.54208e-05 |
1.322e+01 |
X-ray |
|
3.25575e-03 |
7.635e-02 |
X-ray |
|
1.34452e-02 |
1.549e-02 |
X-ray |
|
1.36268e-02 |
1.361e-01 |
X-ray |
|
1.64469e-02 |
2.854e-02 |
X-ray |
|
1.65865e-02 |
3.278e-02 |
X-ray |
|
1.73072e-02 |
3.613e-02 |
X-ray |
|
1.74784e-02 |
2.851e-02 |
X-ray |
|
7.20499e-05 |
3.601e+00 |
Auger electron |
|
1.63204e-04 |
2.286e-02 |
Auger electron |
|
1.89172e-04 |
3.470e+00 |
Auger electron |
|
1.94716e-04 |
1.961e+00 |
Auger electron |
|
5.93905e-04 |
6.353e-01 |
Auger electron |
|
1.55173e-03 |
4.483e-01 |
Auger electron |
|
2.43725e-03 |
1.092e+00 |
Auger electron |
|
2.91476e-03 |
2.055e-01 |
Auger electron |
|
3.53903e-03 |
1.212e-02 |
Auger electron |
|
1.03308e-02 |
2.274e-01 |
Auger electron |
|
1.36854e-02 |
1.157e-01 |
Auger electron |
|
1.70946e-02 |
1.388e-02 |
Auger electron |
|
2.44360e-02 |
1.088e-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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