Decay energy

Nuclear physics

Nucleus · Nucleons (p, n) · Nuclear force · Nuclear structure · Nuclear reaction
Nuclear models and stability Liquid drop · Nuclear shell model · Nuclear structure · Binding energy · p–n ratio · Drip line · Island of stability · Valley of stability
Nuclides' classification Isotopes – equal Z Isobars – equal A Isotones – equal N Isodiaphers – equal N − Z Isomers – equal all the above Mirror nuclei – Z ↔ N Stable · Magic · Even/odd · Halo
Radioactive decay Alpha α · Beta β (2β, β⁺) · K/L capture · Isomeric (Gamma γ · Internal conversion) · Spontaneous fission · Cluster decay · Neutron emission · Proton emission Decay energy · Decay chain · Decay product · Radiogenic nuclide
Nuclear fission Spontaneous · Products (pair breaking) · Photofission
Capturing processes electron · neutron (s · r) · proton (p · rp)
High energy processes Spallation (by cosmic ray) · Photodisintegration
Nucleosynthesis topics Nuclear fusion Processes: Stellar · Big Bang · Supernova Nuclides: Primordial · Cosmogenic · Artificial
Scientists Alvarez · Becquerel · Bethe · A.Bohr · N.Bohr · Chadwick · Cockcroft · Ir.Curie · Fr.Curie · Pi.Curie · Skłodowska-Curie · Davisson · Fermi · Hahn · Jensen · Lawrence · Mayer · Meitner · Oliphant · Oppenheimer · Proca · Purcell · Rabi · Rutherford · Soddy · Strassmann · Szilárd · Teller · Thomson · Walton · Wigner

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).

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\times \left({\frac {A}{M}}\right).

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

References

Radioactivity Radionuclides Radiation by Joseph Magill and Jean Galy, Springer Verlag, 2005

External links

University of Waterloo science

This article is issued from Wikipedia - version of the 11/15/2016. The text is available under the Creative Commons Attribution/Share Alike but additional terms may apply for the media files.