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  2. Radioactive decay - Wikipedia

    en.wikipedia.org/wiki/Radioactive_decay

    t. e. Radioactive decay (also known as nuclear decay, radioactivity, radioactive disintegration, or nuclear disintegration) is the process by which an unstable atomic nucleus loses energy by radiation. A material containing unstable nuclei is considered radioactive. Three of the most common types of decay are alpha, beta, and gamma decay.

  3. Exponential decay - Wikipedia

    en.wikipedia.org/wiki/Exponential_decay

    A quantity is subject to exponential decay if it decreases at a rate proportional to its current value. Symbolically, this process can be expressed by the following differential equation , where N is the quantity and λ ( lambda ) is a positive rate called the exponential decay constant , disintegration constant , [1] rate constant , [2] or ...

  4. Particle decay - Wikipedia

    en.wikipedia.org/wiki/Particle_decay

    Particle decay. In particle physics, particle decay is the spontaneous process of one unstable subatomic particle transforming into multiple other particles. The particles created in this process (the final state) must each be less massive than the original, although the total mass of the system must be conserved.

  5. Orbital decay - Wikipedia

    en.wikipedia.org/wiki/Orbital_decay

    t. e. Orbital decay is a gradual decrease of the distance between two orbiting bodies at their closest approach (the periapsis) over many orbital periods. These orbiting bodies can be a planet and its satellite, a star and any object orbiting it, or components of any binary system. If left unchecked, the decay eventually results in termination ...

  6. Time constant - Wikipedia

    en.wikipedia.org/wiki/Time_constant

    In physics and engineering, the time constant, usually denoted by the Greek letter τ (tau), is the parameter characterizing the response to a step input of a first-order, linear time-invariant (LTI) system. [1] [note 1] The time constant is the main characteristic unit of a first-order LTI system. In the time domain, the usual choice to ...

  7. Specific activity - Wikipedia

    en.wikipedia.org/wiki/Specific_activity

    One gram of rubidium-87 and a radioactivity count rate that, after taking solid angle effects into account, is consistent with a decay rate of 3200 decays per second corresponds to a specific activity of 3.2 × 10 6 Bq/kg. Rubidium atomic mass is 87 g/mol, so one gram is 1/87 of a mole. Plugging in the numbers:

  8. Bateman equation - Wikipedia

    en.wikipedia.org/wiki/Bateman_equation

    In nuclear physics, the Bateman equation is a mathematical model describing abundances and activities in a decay chain as a function of time, based on the decay rates and initial abundances. The model was formulated by Ernest Rutherford in 1905 [1] and the analytical solution was provided by Harry Bateman in 1910. [2]

  9. Alpha decay - Wikipedia

    en.wikipedia.org/wiki/Alpha_decay

    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-4 ...