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radioactive decay

Definition/Summary
Radioactive decay is the process in which an unstable atomic nucleus loses energy by emitting radiation in the form of particles or electromagnetic waves. 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.

Equations
The activity (A) of a radioactive sample (the number of decays per unit time) is found to be proportional to the number of radioactive nuclei (N) in a given sample. That is,

[tex]A = - \frac{dN}{dt} = \lambda N[/tex]

Where [itex]\lambda[/itex] is the constant of proportionality and is called the decay constant. The above expression is a separable ODE and has a solution,

[tex]A = A_0e^{-\lambda t}[/tex]

Where [itex]A_0[/itex] represents the initial activity of the sample at t=0. Equivalently, one can form an expression for the number of remaining radioactive nuclei,

[tex]N = N_0e^{-\lambda t}[/tex]

Where [itex]N_0[/itex] represents the initial number of radioactive nuclei at t=0.

Scientists
Henri Becquerel (1852-1908)
Pierre Curie (1859-1906)
Marie Curie (1867-1934)
Ernest Rutherford (1871-1937)

Recent forum threads on radioactive decay
 
Breakdown
Physics
> Nuclear & Particle
>> Nuclear

See Also
beta particle
half-life

Images

Extended explanation
[Moved to Equations]

Commentary

prachanda @ 03:54 AM Jul7-11
Could anybody please make me clear about bound state ß(minus) decay??

Fightfish @ 10:47 AM Dec10-09
Perhaps there should be some mention of the nature of radioactive decay ie it being spontaneous and random? Also, might want to explain decay constant (its significance) a bit.

jacksonpeeble @ 11:48 AM Jan11-09
I wrote a separate tutorial in the forums that I think is more beneficial and practical, but overall I think that this library post is relatively accurate although very general and only geared at radioactive decay.

http://www.physicsforums.com/showthread.php?p=2030419

umasangeetha @ 03:52 AM Aug16-08
YOU HAV GIVEN THE GENERAL DEFINITION FOR RADIO ACTIVE DECAY BUT CAN U SAY HOW MANY DIFFERENT TYPES OF DECAY AND DOES THE FORMULA IS SAME FOR ALL THE DECAY

Phy6explorer @ 03:58 AM May21-08
Yes I accept with Mayday.It would be better to have a separate page on half-life.

Astronuc @ 07:35 PM May20-08
In addition to emission, there may be 'electron capture', in which an electron from the K-shell, or even L-shell is captured by the nucleus, in which a proton is transformed into a neutron and a neutrino

sirissa @ 10:01 AM May19-08
I don't know but i think that there should be more explanation.

_Mayday_ @ 04:13 AM May19-08
Would it not be a good idea to have a separate half life page.

Hootenanny @ 05:59 PM May18-08
As an after-thought it may be useful to briefly mention the different modes of decay, but discuss them in depth in their own individual entries.

Hootenanny @ 05:57 PM May18-08
Added extended explanation. Perhaps a discussion of the half-life would also be appropriate.