Deeply bound pionic atoms from the $(\gamma,p)$ reaction in nuclei

Abstract

We study the $(\gamma,p)$ reaction on $^{208}Pb$ leading to $^{207}Pb$ with a bound pion attached to it in the lowest 1s or 2p pionic levels. The reaction can be made recoilless to optimize the production cross section but we must choose a bit higher photon energy to overcome the Coulomb barrier in the proton emission. The cross sections obtained are easily measurable and can be larger than 50 per cent of the background from inclusive ($\gamma$,p). This makes it a clear case for the detection of the pionic atom signals, converting this reaction into a practical tool to produce deeply bound pionic atoms.