Cs
Alkali metal
Cesium
Z 55A 133mass 132.91
Slow-motion stage
Cesium-137
proton
neutron
electron (β⁻)
Parent nucleus · 137 nucleons
55 protons (coral) and 82 neutrons (blue) are packed together and held by the strong force.
A real decay takes about 10⁻²¹ s. At ⅓× this stage stretches it across eleven seconds.
Choose a reaction
Reaction
13755Cs13756Ba+β⁻+ ν̄
A neutron turns into a proton. An electron and an antineutrino fly out.
Z
5556
+1
A
137137
no change
n⁰
8281
-1
Energy released
0.514MeV
Electron (max)0.514 MeV
Mass convertedE = Δm c²0.00055 u
In joules8.24 × 10-14 J
Compared with a bonda C–C bond is 3.6 eV≈ 142,778 ×
Half-life of Cesium-137
30.17 years
Leaves barium-137, usually in an excited state.
The particle
- Charge
- −1
- Mass
- 1/1836 u
- Speed
- Up to 99.9% of the speed of light
- Ionising power
- Moderate
- Stopped by
- A few millimetres of aluminium