Direct production of pionic atoms from radiative trapping of pions in flight

Abstract

The reaction π −A→( π b −A) γ with T π =10−30 MeV producing a π − bound in the nucleus is studied to see its viability as an instrument to produce deeply bound pionic atoms in nuclei. We obtain cross sections of the order of tens of μb/ (sr MeV) for the production of the 1s and 2p states of 208Pb and negligible background from radiative pion capture and the other sources. The negligible background expected in the present reaction is unique among all other reactions so far proposed. The cross sections obtained are three orders of magnitude bigger than those in the best electromagnetic reactions previously proposed. The small background, the large cross sections and the present available fluxes and resolution of low energy pion beams make this reaction ideal for producing deeply bound pionic states.