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  2. Exponential decay - Wikipedia

    en.wikipedia.org/wiki/Exponential_decay

    Symbolically, this process can be expressed by the following differential equation, where N is the quantity and λ is a positive rate called the exponential decay constant, disintegration constant, [1] rate constant, [2] or transformation constant: [3]

  3. Geiger–Nuttall law - Wikipedia

    en.wikipedia.org/wiki/Geiger–Nuttall_law

    Geiger–Nuttall law. In nuclear physics, the Geiger–Nuttall law or Geiger–Nuttall rule relates the decay constant of a radioactive isotope with the energy of the alpha particles emitted. Roughly speaking, it states that short-lived isotopes emit more energetic alpha particles than long-lived ones. The relationship also shows that half ...

  4. Alpha decay - Wikipedia

    en.wikipedia.org/wiki/Alpha_decay

    v. t. e. Alpha decay or α-decay is a type of radioactive decay in which an atomic nucleus emits an alpha particle (helium nucleus) and thereby transforms or "decays" into a different atomic nucleus, with a mass number that is reduced by four and an atomic number that is reduced by two. An alpha particle is identical to the nucleus of a helium ...

  5. Radioactive decay - Wikipedia

    en.wikipedia.org/wiki/Radioactive_decay

    the equation indicates that the decay constant λ has units of t −1, and can thus also be represented as 1/ τ, where τ is a characteristic time of the process called the time constant. In a radioactive decay process, this time constant is also the mean lifetime for decaying atoms.

  6. Bateman equation - Wikipedia

    en.wikipedia.org/wiki/Bateman_equation

    The Bateman equation is a classical master equation where the transition rates are only allowed from one species (i) to the next (i+1) but never in the reverse sense (i+1 to i is forbidden). Bateman found a general explicit formula for the amounts by taking the Laplace transform of the variables. (it can also be expanded with source terms, if ...

  7. Half-life - Wikipedia

    en.wikipedia.org/wiki/Half-life

    Rutherford applied the principle of a radioactive element's half-life in studies of age determination of rocks by measuring the decay period of radium to lead-206. Half-life is constant over the lifetime of an exponentially decaying quantity, and it is a characteristic unit for the exponential decay equation. The accompanying table shows the ...

  8. Fermi's interaction - Wikipedia

    en.wikipedia.org/wiki/Fermi's_interaction

    W−. boson (which then decays to electron and antineutrino) is not shown. In particle physics, Fermi's interaction (also the Fermi theory of beta decay or the Fermi four-fermion interaction) is an explanation of the beta decay, proposed by Enrico Fermi in 1933. [1] The theory posits four fermions directly interacting with one another (at one ...

  9. Time constant - Wikipedia

    en.wikipedia.org/wiki/Time_constant

    First order LTI systems are characterized by the differential equation + = where τ represents the exponential decay constant and V is a function of time t = (). The right-hand side is the forcing function f(t) describing an external driving function of time, which can be regarded as the system input, to which V(t) is the response, or system output.