Exploring Non-Exponential Decay in Isomeric Transitions

Wade Scates

Idaho State University

Department of Physics

In quantum mechanics the survival probability of unstable systems are predicted
to deviate from the classical exponential law when the time after production
of the system – the "age" of the system" -- is very small (*t* <<
*t*_{½}) or very large (*t* >> *t*_{½}).
This effect is commonly referred to as non-exponential decay, or NED.
Though this effect is predicted to occur in all unstable systems, the nuclear
system in which it is expected to be easiest to observe is long-lived isomeric
transitions. Through the experiments reported herein, bounds are placed
on the time after production that non-exponential decay effects influence
the survival probability of the isomeric state. An upper bound
between the early NED effects and exponential decay, or *t*_{s},
was found to be *t*_{s} <1.2x10^{-4} *t*_{½}.
Furthermore, a lower bound between exponential decay and the late NED effects, *t*_{l},
was measured to be *t*_{l} >19.5 *t*_{½}.