Low-energy pion production with 800 MeV/ N Ne 20

Doubly differential cross sections for production of positive pions ($20 \mathrm{MeV}\ensuremath{\le}{T}_{\ensuremath{\pi}}^{\mathrm{Lab}}\ensuremath{\le}100 \mathrm{MeV}$) in bombardment of $^{20}\mathrm{Ne}$ on NaF, Cu and Pb targets at 800 MeV/N have been measured with a range telescope. The results showed that the angular distribution of low-energy pions in the nucleon-nucleon center of mass (${T}_{\ensuremath{\pi}}^{\mathrm{c}.\mathrm{m}.}\ensuremath{\le}50$ MeV) was isotropic, even 90\ifmmode^\circ\else\textdegree\fi{} peaking at \ensuremath{\sim} 15 MeV c.m. The intermediate-energy pions ($50\ensuremath{\le}{T}_{\ensuremath{\pi}}^{\mathrm{c}.\mathrm{m}.}\ensuremath{\le}300$ MeV) were forward and backward peaked, reflecting the individual nucleon-nucleon process in the isobar model of production. The observed cross sections were shown to be generally reproduced by an incoherent superposition of the experimental ($p$ + nucleus) cross sections.