Half Lives of Some Selected Isotopes
Isotope
Half-Life (t½)
Decay mode

Isotope
Half life (t½)
Decay Mode
H-3
12.3 y
β

Pb-212
10.6 h
β
C-14
5770 y
β

Bi-212
60.6 min
α , β
O-15
1.97 m
β+

Po-212
3.0 X 10-7 s
α
Na-22
15.0 h
β, γ

Po-216
0.160 s
α




Po-218
3.05 min
α , β
S-30
1.40 s
β+

Rn-220
51.5 s
α
P-32
14.3 d
β

Rn-222
3.82 d
α
Cl-36
3.00 X 105 y
β

Ra-224
3.64 d
α
K-40
1.3 X 109 y
β, γ

Ra-226
1.62 X 103 y
α , γ
Ca-45
1.65 X 102 d
β

Ra-228
6.70 y
β
Fe-59
44.3 d
β

Ac-228
6.13 h
β
Co-60
5.26 y
β, γ

Th-228
1.91 y
α
Ga-67
75 h
β

Th-232
1.4 X 1010 y

Sr-90
28.8 y
β

Pu-239
24,360 y
 
Tc-99m
2 X 105 y
γ

Ra-226
1620 y

Te-123
1.2 X 1013 y
e- capture

U-235
7.1 X 108 y
α , γ
I-131
8.07 d
β, γ

U-238
4.5 X 109 y
α
Nd-144
5 X 1015 y
α

Pu-239
2.44 X 104 y
α , γ
Sm-149
4 X 1014 y
α

Am-242
16.0 h
αβ
Re-187
7 X 1010 y
β

Am-243
7.37 X 103 y
α
W-187
24 h





Pt-197
18 h





Au-198
2.69 d