lifetime

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lifetime

1. 
a. the length of time a person or animal is alive
b. (as modifier): a lifetime supply
2. Physics the average time of existence of an unstable or reactive entity, such as a nucleus, excited state, elementary particle, etc.; mean life

Lifetime

 

in physics, the average duration τ of existence of (1) excited states of atoms and molecules, which end with the spontaneous transition of particles to a less excited or basic (unexcited) state; the lifetime is an important characteristic of the energy levels of particles (the lifetime on a level); (2) unstable (radioactive) atomic nuclei as well as elementary particles; their lifetime is linked with their half-life period T by the formula τ = T/In 2; and (3) quasiparticles (elementary excitations) in solids and in liquid helium, particularly electrons and holes in semiconductors.

lifetime

[′līf‚tīm]
(physics)
References in periodicals archive ?
The broad range of stochastic prices is the consequence of the broad range of likely lifetimes and the fact that the present value of cash flows decreases rapidly as lifetime until death increases.
Even with a relatively high usage rate, media lifetime ranges are projected in decades, which is significantly longer than what has been seen historically in the hardware and software technologies used to run them.
H's estate benefits from his lifetime exemption and eliminates any estate tax liability from W's estate.
After a typical lifetime of 80,000-120,000 castings, molds may wear to the point that the casting produced exceeds original tolerances and will no longer set up properly in fixtures for subsequent machining operations.
9], storage lifetimes were measured together with the flux of UCN thermally up-scattered at the trap walls.
We present a progress report on an experimental program to improve the measurement of the neutron lifetime, [[tau].