Observation of 10He

Abstract The reactions 11 Li + CD 2 → 10 He + X and 11 Li + C → 10 He + X at a beam energy of 61 A MeV have been studied by measuring the triple coincidence of 8 He and two neutrons. Experimental data show a peak that can be explained as a resonance 10 He, which is unbound by 1.2±0.3 MeV and its width is less than 1.2 MeV. Theinvariant mass spectra of 8 He+n show a peak that is consistent with the decay 10 He → 8 He + n + n .