  We study the kinetics of the quasiparticle capture and emission process in a
small superconducting island (Cooper-pair box) connected by a tunnel junction
to a massive superconducting lead. At low temperatures, the charge on the box
fluctuates between two states, even and odd in the number of electrons.
Assuming that the odd-electron state has the lowest energy, we evaluate the
distribution of lifetimes of the even- and odd-electron states of the
Cooper-pair box. The lifetime in the even-electron state is an exponentially
distributed random variable corresponding to a homogenous Poisson process of
``poisoning'' the island with a quasiparticle. The distribution of lifetimes of
the odd-electron state may deviate from the exponential one. The deviations
come from two sources - the peculiarity of the quasiparticle density of states
in a superconductor and the possibility of quasiparticle energy relaxation via
phonon emission. In addition to the lifetime distribution, we also find
spectral density of charge fluctuations generated by capture and emission
processes. The complex statistics of the quasiparticle dwell times in the
Cooper-pair box may result in strong deviations of the noise spectrum from the
Lorentzian form.
