Re-analysis of Some Bubble Chamber Data on Nn Annihilation

A re-analysis of some pp and pn data, at rest and in flight, obtained in bubble chamber experiments, is presented. The (ππ) and (KSKS) final states for the channels (2ππ) and (KSKSπ) are investigated. Evidence for a narrow meson resonance structure, cautiously suggested as f0(1500), is given. In the (π π) invariant mass distribution from pn annihilations in flight, using the method of difference spectra, a very clear evidence for ρ, f2(1270) and f0(1500) is first time obtained from these data. This re-analysis suggests that the old bubble chamber data can still provide relevant information on the annihilation process in liquid hydrogen and deuterium, and can elucidate controversial aspects of the annihilation mechanism. keywords: nucleon-antinucleon annihilations, meson resonance