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

The ultrarelativistic quantum molecular dynamics model is employed to simulate pi- +C and pi- +W collisions at plab = 1.7 GeV motivated by the recent HADES results. By comparing the proton and Lambda 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, 3He, 4He, as well as H-3(Lambda) and Xi N) multiplicities and spectra are made using a coalescence mechanism. The resulting multiplicities suggest that the pion beam experiment can produce a substantial amount of H-3(Lambda), especially in pi- + W collisions due to the stopping of the Lambda 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.