Decay energy

	Nuclear physics
Classical decays
	Alpha decay · Beta decay · Gamma radiation
Advanced decays
	Double beta decay · Double electron capture · Internal conversion · Isomeric transition · Cluster decay · Spontaneous fission
Emission processes
	Neutron emission · Positron emission · Proton emission
Capturing
	Electron capture · Neutron capture; R · S · P · Rp
High energy processes
	Spallation · Cosmic ray spallation · Photodisintegration
Nucleosynthesis
	Stellar Nucleosynthesis; Big Bang nucleosynthesis; Supernova nucleosynthesis
Scientists
	Becquerel · Bethe · Marie Curie · Pierre Curie · Fermi
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The decay energy is the energy released by a radioactive decay. Radioactive decay is the process in which an unstable atomic nucleus loses energy by emitting ionizing particles and radiation. This decay, or loss of energy, results in an atom of one type, called the parent nuclide transforming to an atom of a different type, called the daughter nuclide.

[edit] Decay calculation

The energy difference of the reactants is often written as Q:

$Q = (Kinetic\ energy)_{after} - (Kinetic\ energy)_{before}\,\!$ $Q = ((Rest\ mass)_{after} * c^2) - ((Rest\ mass)_{before} * c^2)\,\!$

Decay energy is usually quoted in terms of the energy units MeV (million electronvolts) or KeV (thousand electronvolts).

Types of radioactive decay include

gamma ray
beta decay (decay energy is divided between the emitted electron and the neutrino which is emitted at the same time)
alpha decay

The decay energy is the mass difference dm between the parent and the daughter atom and particles. It is equal to the energy of radiation E. If A is the radioactive activity, i.e. the number of transforming atoms per time, M the molar mass, then the radiation power W is: $W = dm * \left ( \frac{A}{M} \right )\,\!$ or $W = E * \left ( \frac{A}{M} \right )\,\!$

Example: Cobalt-60 decays into Ni60. The mass difference dm is 0.003u. The radiated energy is approximately 2.8 MeV. The molar weight is 59.93. The half life T of 5.7a corresponds to the activity A=N*ln(2)/T, where N is the number of atoms per mol. Taking care of the units the radiation power for Co60 is 17.9 W/g

Radiation power in W/g for several isotopes:

Co60: 17.9

Pu238: 0.57

Cs137: 0.6

Am241: 0.1

Po210: 140 (T=136 d)

Sr90: 0.9