“…( M it was considered, that presence of a neutron and an antineutron among secondary particles should sharply increase the value of missing mass. For each multiplicity selection of antiproton-proton interactions, classified as annihilation events, began with events having smaller missing masses and stopped, when the total number of selected events corresponded to evaluate antiproton-proton "annihilation" cross-section [11,13]. Chosen boundary values of .…”