Elementary particle reactions

4 — Conclusion

On the assumption that the quantum numbersA andB are conserved, a procedure has been devised for writing down all the reaction products composed of particles in Table I. Table III lists these reaction products up to four particles together with the production threshold when the projectile is a photon, electron, pion, kaon, anti-kaon, nucleon or anti-nucleon and the target is a stationary nucleon or a 25 MeV nucleon with momentum toward the projectile. Threshold energies have also been calculated for the Feldman two stage process.

As expected, lowest thresholds for the production of any given elementary particles are associated with the e + N or γ + N process, although the difference of thresholds of that process and the two stage process becomes less marked at high energies. The two stage process lowers the threshold over the analogous one-stage by roughly 20% to 25%. Furthermore, in the single stage process, the threshold for a 25 MeV target nucleon is some 25% lower than that for a target nucleon at rest.

It seems worthwhile to point out that the most massive anti-hyperon, the ^-_Ξ , with can be made by the process, energy + N → 2Λ⁰ + Ξ, has a threshold by two the stage process of about 5.3 GeV, and therefore presumably can be made at Berkeley.