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Radionuclide Dosimetric Data Sheets

Neptunium-237

Summary data

General

Classification

Isotope:  Np-237
Atomic number (Z):  93
Mass number (A):  237
Neutron number (N):  144

Radioactive decay

Decay modes:  α
Half-life:  2144000.0 [y]
Decay constant:  1.0245e-14 [1/s]
Daughters:  Pa-233 (100.0%)
Radioactive daughters:  Pa-233

Dosimetric constants

Mean alpha energy:  4.8493 [MeV]
Mean electron energy:  0.0681 [MeV]
Mean photon energy:  0.03495 [MeV]
Air kerma rate constant, Γ10:  1.553e-17 [Gy·m2/Bq·s]
Air kerma coefficient, Kair:  1.553e-17 [Gy·m2/Bq·s]
Equilibrium dose constant for weakly-penetrating radiations (α and/or electrons), Δwp:  7.879e-13 [Gy·kg/Bq·s]
Equilibrium dose constant for alphas, Δα:  7.769e-13 [Gy·kg/Bq·s]
Equilibrium dose constant for betas/electrons, Δβ-,β+,e-:  1.091e-14 [Gy·kg/Bq·s]
Equilibrium dose constant for photons, Δp:  5.600e-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-237 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-237 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-237 Summary Spectrum.csv

 

Energy [MeV]

Yield [#/nt] if > 0.01

Radiation type

7.65371e-05

1.653e+01

X-ray

3.16304e-03

9.550e-02

X-ray

1.14081e-02

1.402e-02

X-ray

1.31269e-02

2.312e-02

X-ray

1.32994e-02

2.032e-01

X-ray

1.60398e-02

4.230e-02

X-ray

1.67859e-02

1.650e-01

X-ray

1.96582e-02

3.704e-02

X-ray

2.93740e-02

1.500e-01

Gamma

8.64770e-02

1.240e-01

Gamma

9.26782e-02

1.729e-02

X-ray

9.63371e-02

2.781e-02

X-ray

6.46349e-05

4.028e+00

Auger electron

1.56249e-04

2.708e-02

Auger electron

1.65453e-04

4.372e+00

Auger electron

1.93701e-04

2.475e+00

Auger electron

5.20349e-04

7.183e-01

Auger electron

1.24611e-03

2.264e-01

Auger electron

2.38397e-03

1.426e+00

Auger electron

2.82970e-03

2.572e-01

Auger electron

3.42911e-03

1.495e-02

Auger electron

4.06060e-03

6.622e-02

Conversion electron

4.62200e-03

1.616e-02

Conversion electron

8.22000e-03

2.373e-02

Conversion electron

8.26100e-03

7.461e-02

Conversion electron

8.97200e-03

1.210e-01

Conversion electron

9.97533e-03

3.446e-01

Auger electron

1.26310e-02

1.527e-01

Conversion electron

1.31998e-02

1.733e-01

Auger electron

1.64587e-02

2.055e-02

Auger electron

2.52146e-02

8.982e-02

Conversion electron

2.93740e-02

3.001e-02

Conversion electron

3.01690e-02

2.504e-02

Conversion electron

3.67020e-02

2.728e-01

Conversion electron

4.03610e-02

2.290e-01

Conversion electron

5.29446e-02

1.412e-01

Conversion electron

5.71040e-02

4.921e-02

Conversion electron

6.53640e-02

5.996e-02

Conversion electron

6.60750e-02

3.808e-02

Conversion electron

6.97340e-02

3.526e-02

Conversion electron

8.23176e-02

3.276e-02

Conversion electron

8.64770e-02

1.126e-02

Conversion electron

4.63990e+00

6.355e-02

Alpha

4.66502e+00

3.414e-02

Alpha

4.76652e+00

8.227e-02

Alpha

4.77191e+00

2.571e-01

Alpha

4.78876e+00

4.833e-01

Alpha

4.80447e+00

1.604e-02

Alpha

4.81764e+00

2.571e-02

Alpha

7.97068e-02

6.355e-02

Alpha recoil

8.01383e-02

3.414e-02

Alpha recoil

8.18818e-02

8.227e-02

Alpha recoil

8.19744e-02

2.571e-01

Alpha recoil

8.22639e-02

4.833e-01

Alpha recoil

8.25337e-02

1.604e-02

Alpha recoil

8.27600e-02

2.571e-02

Alpha recoil

 

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

 

 

 

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