The radioactive-decay rate of impurity Te-123m atoms in MgO was observ
ed to decrease with the temperature lowered from 295 to 80 K. It is as
sumed that this phenomenon is connected with stimulated gamma emission
of the long-lived isomer Te-123m, whose probability should increase w
ith decreasing temperature due to the increase of the Mossbauer factor
for 88-keV gamma photons. A phenomenological description of the effec
t of stimulated gamma radiation (SGR) on the radioactive-decay rate is
proposed, and a parameter is introduced which characterizes the SGR i
ntensity such that, as this parameter approaches one, a single-pass la
ser-shot mode should set in. It is shown that in the geometry used thi
s critical mode for MgO:Te-123m can be initiated by increasing the spe
cific activity by two orders of magnitude. (C) 1998 American Institute
of Physics. [S1063-7834(98)01310-0].