Is it possible to determine the S-factor of the hep process from a laboratory experiment?

We discuss the problem of solar hep neutrinos originating from the reaction p+ 3He -> 4He + e+ + nu and obtain a relation between the astrophysical S-factorof the hep process and the cross section of the process e- + 4He -> 3H + n + nunear threshold. The relation is based on the isotopic invariance of stronginteractions. The measurement of the latter cross section would allow to obtain experimentalinformation on S(hep), the value of which, at the moment, is known only fromtheoretical calculations