Production of nuclei and hypernuclei in pion-induced reactions near threshold energies

The ultrarelativistic quantum molecular dynamics model is employed to simulate π-+C and π-+W collisions at plab=1.7 GeV motivated by the recent HADES results. By comparing the proton and Λ transverse momentum spectra, it was observed that the data and transport model calculation show a good agreement, if cluster formation is included to obtain the free proton spectra. Predictions of light cluster (d, t, He3, He4, as well as HΛ3 and ΞN) multiplicities and spectra are made using a coalescence mechanism. The resulting multiplicities suggest that the pion beam experiment can produce a substantial amount of HΛ3, especially in π-+W collisions due to the stopping of the Λ inside the large tungsten nucleus. The findings are supplemented by a statistical multifragmentation analysis suggesting that even larger hyperfragments are produced copiously. It is suggested that even double strange hypernuclei are in reach and might be studied in more detail using a slightly higher pion beam momentum.