The results of a search for hydrogen-like atoms consisting of $pi^{mp}K^{pm}$ mesons are presented. Evidence for $pi K$ atom production by 24 GeV/c protons from CERN PS interacting with a nickel target has been seen in terms of characteristic $pi K$
pairs from their breakup in the same target ($178 pm 49$) and from Coulomb final state interaction ($653 pm 42$). Using these results the analysis yields a first value for the $pi K$ atom lifetime of $tau=(2.5_{-1.8}^{+3.0})$ fs and a first model-independent measurement of the S-wave isospin-odd $pi K$ scattering length $left|a_0^-right|=frac{1}{3}left|a_{1/2}-a_{3/2}right|= left(0.11_{-0.04}^{+0.09} right)M_{pi}^{-1}$ ($a_I$ for isospin $I$).
We present evidence for the first observation of electromagnetically bound $pi^pm K^mp$-pairs ($pi K$-atoms) with the DIRAC experiment at the CERN-PS. The $pi K$-atoms are produced by the 24 GeV/c proton beam in a thin Pt-target and the $pi^pm$ and $
K^mp$-mesons from the atom dissociation are analyzed in a two-arm magnetic spectrometer. The observed enhancement at low relative momentum corresponds to the production of 173 $pm$ 54 $pi K$-atoms. The mean life of $pi K$-atoms is related to the s-wave $pi K$-scattering lengths, the measurement of which is the goal of the experiment. From these first data we derive a lower limit for the mean life of 0.8 fs at 90% confidence level.
