Hypernuclear spectroscopy of products from Li-6 projectiles on a carbon target at 2 A GeV

Abstract A novel experiment, aiming at demonstrating the feasibility of hypernuclear spectroscopy with heavy ion beams, was conducted. Using the invariant mass method, the spectroscopy of hypernuclear products of 6 Li projectiles on a carbon target at 2 A GeV was performed. Signals of the Λ -hyperon and H Λ 3 and H Λ 4 hypernuclei were observed for final states of p + π − , He 3 + π − and He 4 + π − , respectively, with significance values of 6.7, 4.7 and 4.9 σ . By analyzing the proper decay time from secondary vertex distribution with the unbinned maximum likelihood fitting method, their lifetime values were deduced to be 262 − 43 + 56 ± 45 ps for Λ , 183 − 32 + 42 ± 37 ps for H Λ 3 , and 140 − 33 + 48 ± 35 ps for H Λ 4 .