Decay Calculation
The energy difference of the reactants is often written as Q:
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: or
Example: 60Co decays into 60Ni. 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 60Co is 17.9 W/g
Radiation power in W/g for several isotopes:
- 60Co: 17.9
- 238Pu: 0.57
- 137Cs: 0.6
- 241Am: 0.1
- 210Po: 140 (T=136 d)
- 90Sr: 0.9
Read more about this topic: Decay Energy
Famous quotes containing the words decay and/or calculation:
“It had been a moving, tranquil apotheosis, immersed in the transfiguring sunset glow of decline and decay and extinction. An old family, already grown too weary and too noble for life and action, had reached the end of its history, and its last utterances were sounds of music: a few violin notes, full of the sad insight which is ripeness for death.”
—Thomas Mann (1875–1955)
““To my thinking” boomed the Professor, begging the question as usual, “the greatest triumph of the human mind was the calculation of Neptune from the observed vagaries of the orbit of Uranus.”
“And yours,” said the P.B.”
—Samuel Beckett (1906–1989)