Cerium-139 (Ce-139)

Identity

Protons

58

Neutrons

81

Mass number

139

Mass

138.9 ± 2.2 u

Mass excess

-86.958 MeV

Spin

3/2+*

Stability

Half-life: 138 days

Natural occurrence

Not found in nature

Decays to

• electron capture → La-139