  We propose a new method for the Coulomb wave function correction including
the momentum resolution for charged hadron pairs and apply it to the precise
data on $\pi^+\pi^-$ correlations obtained in $p + \mbox{Ta}$ reaction at 70
GeV/c. It is found that interaction regions of this reaction (assuming Gaussian
source function) are $5.6 \pm 3.0$ and $4.4 \pm 2.6$ fm for the thicknesses of
the target $8$ and $1.4$ microns, respectively. The physical picture of the
source size obtained in this way is discussed.
