SPONTANEOUS EMISSION AND NONLOCALITY IN QUANTUM-MECHANICS

We describe a thought experiment in which the decay rate of an ensembl e of excited atoms turns out to depend on both the efficiency and geom etry of the counters used to detect the emitted photons. This quantum mechanical effect, of intrinsically non-local nature, implies an enhan cing of the atomic decay rate and is present under experimental condit ions completely different from those giving rise to the freezing of at omic decay corresponding to quantum Zeno effect.