TIME-DEPENDENCE IN STIMULATED GAMMA-RAY EMISSION - IMPLICATIONS FOR GRASERS

We discuss the limitations of the cross-section concept in estimating the performance of a GRASER and the implications of this for evaluatin g conceptual systems and for experimental detection of stimulated gamm a-radiation. We derive the time-dependent cross-section for stimulatin g emission of gamma-radiation from a nucleus and show, not only that t he asymptotic cross-section is extremely small for transitions from a long-lived isomeric state to a shorter-lived excited lower state, but also that, for any transition from a long-lived state, the cross-secti on remains small compared with its asymptotic value for a time of the order of the reciprocal linewidth.