Lanthanum-138 (La-138)

Identity

Protons

57

Neutrons

81

Mass number

138

Mass

137.91 ± 0.45 u

Mass excess

-86.513 MeV

Spin

5+*

Stability

Half-life: 1.03 × 10¹¹ years

Natural occurrence

0.0888 % of lanthanum

Decays to

• positron emission 65.5 % → Ba-138
• beta minus 34.5 % → Ce-138