  After observing and investigating the double-exotic $\pi^+\pi^-$ atom with
the ground state lifetime $\tau$ of about $3 \times 10^{-15}$~s, the upgraded
DIRAC experiment at the CERN PS accelerator observes for the first time
long-lived states of the same atom with lifetimes of about $10^{-11}$~s and
more. The number of characteristic pion pairs resulting from the breakup
(ionisation) of long-lived $\pi^+\pi^-$ atoms amounts to $436\pm61$,
corresponding to a signal-to-error ratio of better than 7 standard deviations.
This observation opens a new possibility to measure energy differences between
$p$ and $s$ atomic states and so to determine $\pi \pi$ scattering lengths.
