Antiproton production at rest in the center of mass

Most antiproton production schemes make use of the fact that the yield of antiprotons into an element of invariant phase space is a maximum when the production occurs at rest in the center of mass system. The purpose of this note is to extract these invariant cross sections for pp collisions at zero transverse momentum and X* = 0. (X* = P/sub cm//P/sub cm//sup max/). There are no direct measurements of the desired cross sections