  Quantum mechanics predicts that the decay rate of unstable systems could be
effectively modified by the process of the measurement of the survival
probability. Depending on the intrinsic properties of the unstable system and
the experimental setup for the observation, one could obtain the so called
(direct) quantum Zeno and inverse quantum Zeno effects corresponding to a
slowing down or a speeding up of the decay, respectively. We argue that the
inverse quantum Zeno effect is in principle detectable at a percent level for
the neutron decay in experiments with trapped ultracold neutrons. Conversely,
this effect is basically undetectable in experiments in which the neutron
lifetime is measured by measuring the decays of beams of neutrons. As a test of
our claim, we propose a simple qualitative correlation between the number of
neutrons in the trap and the neutron lifetime: the larger the number, the
faster the decay. Finally we discuss also the presently available measurements
of the neutron lifetime and address the issue of the possible discrepancy that
has been reported among the results obtained by the different experimental
techniques.
