Neptunium: Properties


Isotopes
  Natural
Abun. (%)
Atomic
Mass
Half-
life
Decay Mode
/Energy (/MeV)
Part. En.
/Intensity
(MeV/%)
Cross-sect.
Ther. Neut.
(b)
Spin
(h/2 pi)
Magnetic
Dipl.Mom.
(nm)
Electric
Quad. Mom.
(b)
Gamma En.
/Intensity
(MeV/%)
 226Np     0.03s alpha 8.04         
 227Np     0.51s alpha 7.65         
 228Np     1m S.E.           
 229Np   229.03623 4m alpha/ 7.01 6.89         
 230Np   230.93781 4.6m E.C./ 3.62
alpha
 
6.66
        
 231Np   231.03824 48.8m E.C./ 1.84
alpha/ 6.368
 
6.28
 5/2+     0.2629
0.3475
0.3703
 232Np   232.04002 14.7m E.C./ 2.7    4-     U L x rays
U k x rays
0.3268
0.81925
0.86683
 233Np   233.0408 36.2m E.C./ 1.1    5/2+     U L x rays
U k x rays
0.29887
0.31201
 234Np   234.042888 4.4d +,E.C./ 1.81 0.79  0+     U L x rays
U k x rays
1.5272
1.5587
1.6022
 235Np   235.044056 1.085y E.C./ 0.124
alpha/ 5.191
  160 b5/2+     U k x rays
 236mNp     22.5h E.C.,-          U L x rays
Pu L x rays
U k x rays
0.64235
0.68759
 236Np   236.04655 1.55x105y E.C./ 0.99
-/ 0.54
         U L x rays
U k x rays
0.10423
0.16031
 237Np   237.048167 2.16x106y alpha/ 4.957 4.6395/ 6.2
4.766/ 8
4.7715/ 25
4.7884/ 47
4.558 - 4.873
180 b5/2+ 3.14 nm 3.89 b Pa L x rays
Pa k x rays
0.02938
0.08653
0.03 - 0.28
 238Np   238.050941 2.117d -/ 1.292 1.2  2+     Pu L x rays
Pu k x rays
0.98447
1.02855
 239Np   239.052933 2.355d -/ 0.722 0.341/ 30
0.438/ 48
51 b5/2+     Pu L x rays
Pu k x rays
0.10613
0.22819
0.2776
0.04 - 0.5
 240mNp     7.22m -,I.T. 2.18  1+     0.25143
0.26333
0.55454
0.59735
 240Np   240.05605 1.032h -/ 2.2 0.89  5+     0.1471
0.5664
0.6008
 241Np   241.05825 13.9m -/ 1.3 1.3  5/2+     0.133
0.174
0.28
 242mNp     2.2m -    1+     0.1591
0.2651
0.7857
0.9448
 242Np   242.06164 5.5m -/ 2.7 2.7  6+     0.6209
0.7362
0.78074
1.4734
0.04 - 2.37