The $e^+ e^-$ and $π^+ π^-$ pair peak positions in the relative momentum components spectra

One of the main problem in the metastable π+ π- bound states observation in the DIRAC Experiment is the separation of π+ and π- pairs produced in Be target and pairs, produced by breakdown metastable atoms in Pt foil . Therefore we used a horizontal magnetic field to separate these π+ π- pairs . In this field the Qy component of the relative momentum is significant larger for π+ π- pairs produced in Be target, as long as π+ π- pairs produced in the Pt foil have smaller Qy . The present paper evaluate the se Qy values based on e+ and e- pairs produced in the Be target and e+ and e- pairs produced in the Pt foil. The particle pairs produced in the Be target have a mean value Qy ≈ 12.7 MeV/c and the pairs produced in the Pt foil have a mean value Qy ≈ 2.3MeV/c.