# انرژی واپاشی

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واپاشی‌های کلاسیک

واپاشی آلفا · واپاشی بتا · پرتوزایی گاما · واپاشی کروی
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هانری بکرل · ماری کوری · پی‌یر کوری · هانس بتدیگران

انرژی واپاشی(به انگلیسی: Decay energy) عبارت است از انرژی که در حین واپاشی یک ایزوتوپ پرتوزا تولید می‌شود و با واحدهای MeV (مگا الکترون‌ولت) یا KeV (کیلو الکترونولت) گزارش می‌شود.

$Q=({\text{Kinetic energy}})_{\text{after}}-({\text{Kinetic energy}})_{\text{before}}\,\!$ $Q=(({\text{Rest mass}})_{\text{before}}\times c^{2})-(({\text{Rest mass}})_{\text{after}}\times c^{2})\,\!$ ## پیوند به بیرون

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.

## Decay calculation

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

$Q=\left({\text{Kinetic energy}}\right)_{\text{after}}-\left({\text{Kinetic energy}}\right)_{\text{before}},$ $Q=\left(\left({\text{Rest mass}}\right)_{\text{before}}\times c^{2}\right)-\left(\left({\text{Rest mass}}\right)_{\text{after}}\times c^{2}\right).$ Decay energy is usually quoted in terms of the energy units MeV (million electronvolts) or keV (thousand electronvolts).

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:

$W=dm\times \left({\frac {A}{M}}\right).$ or

$W=E\times \left({\frac {A}{M}}\right).$ 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 5.27 year 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
226Ra: 0.02