Estimation of beam time needed for measurement of pion-kaon s-wave scattering length combination $a_{\bar{0}}$ with a statistical accuracy 5%

Measurement of s-wave pion-kaon scattering length combina tion $a_{\bar{0}} = 1/3( a^{1/2}_0 − a^{3/2}_0)$ with an accuracy 5% provides check of prediction made by Chir al Perturbation theory and Lattice QCD. Estimation of beam time for 450 GeV proton beam, needed for achievement this accuracy, has been done on a base of accuracy of |$a_{\bar{0}}$| measurement, performed in DIRAC experiment.