inversion ratio

inversion ratio

[in′vər·zhən ‚rā·shō]
(physics)
The negative of the ratio in a maser medium of the difference in populations between two nondegenerate energy states under a condition of population inversion, to the population difference at equilibrium.
McGraw-Hill Dictionary of Scientific & Technical Terms, 6E, Copyright © 2003 by The McGraw-Hill Companies, Inc.