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Radionuclide Dosimetric Data Sheets

Neptunium-240m

Isotope:  Np-240m
Atomic number (Z):  93
Mass number (A):  240
Neutron number (N):  147

Decay modes:  β-, Internal transition
Half-life:  7.22 [m]
Decay constant:  1.6001e-03 [1/s]
Daughters:  Pu-240 (99.9%), Np-240 (0.11%)
Radioactive daughters:  Pu-240, Np-240

Mean alpha energy:  0.0 [MeV]
Mean electron energy:  0.67793 [MeV]
Mean photon energy:  0.32249 [MeV]
Air kerma rate constant, Γ₁₀:  1.801e-17 [Gy·m²/Bq·s]
Air kerma coefficient, K_air:  1.801e-17 [Gy·m²/Bq·s]
Equilibrium dose constant for weakly-penetrating radiations (α and/or electrons), Δ_wp:  1.086e-13 [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-:  1.086e-13 [Gy·kg/Bq·s]
Equilibrium dose constant for photons, Δ_p:  5.167e-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-240m 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-240m 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-240m 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-240m Summary Spectrum.csv

 

Energy [MeV]	Yield [#/nt] if > 0.01	Radiation type
7.20450e-05	7.627e+00	X-ray
3.45637e-03	5.024e-02	X-ray
1.40932e-02	1.173e-02	X-ray
1.42941e-02	1.030e-01	X-ray
1.72768e-02	2.192e-02	X-ray
1.83932e-02	1.098e-01	X-ray
2.15284e-02	2.534e-02	X-ray
2.63370e-01	1.139e-02	Gamma
5.54600e-01	2.088e-01	Gamma
5.97400e-01	1.169e-01	Gamma
7.58610e-01	1.179e-02	Gamma
8.17890e-01	1.279e-02	Gamma
9.15980e-01	1.019e-02	Gamma
9.38020e-01	1.209e-02	Gamma
1.49690e+00	1.329e-02	Gamma
2.02151e-01	2.335e-02	Beta
4.12734e-01	1.279e-02	Beta
4.20658e-01	1.421e-02	Beta
4.34998e-01	3.857e-02	Beta
4.50123e-01	2.538e-02	Beta
5.52104e-01	3.147e-01	Beta
6.90242e-01	1.523e-02	Beta
7.72776e-01	4.263e-01	Beta
7.90053e-01	1.015e-01	Beta
8.91205e-05	2.088e+00	Auger electron
1.76436e-04	1.315e-02	Auger electron
1.91646e-04	1.191e+00	Auger electron
2.36949e-04	2.001e+00	Auger electron
5.73395e-04	3.088e-01	Auger electron
1.48181e-03	7.156e-02	Auger electron
2.56497e-03	6.549e-01	Auger electron
3.09833e-03	1.344e-01	Auger electron
1.07728e-02	1.622e-01	Auger electron
1.43195e-02	8.416e-02	Auger electron
1.79054e-02	1.027e-02	Auger electron
2.04530e-02	2.779e-01	Conversion electron
2.47530e-02	2.403e-01	Conversion electron
3.82741e-02	1.476e-01	Conversion electron
4.28240e-02	5.265e-02	Conversion electron
7.64890e-02	1.220e-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

 

 

 

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