The DIRAC experiment at CERN

The DIRAC experiment at CERN aims to measure the lifetime of the pionium atom ($A_{2\pi }$), a ${\pi }^{+}{\pi }^{-}$ bound state with an accuracy of 10%. The experimental setup consists of a high precision magnetic double arm spectrometer, located at the high intensity proton beam of the CERN Proton Synchrotron. This measurement will provide - in a model independent way - the S-wave pion scattering length difference $\mathrm{\mid }{a}_0-a_2\mathrm{\mid }$ with 5% precision.