Abstrak

Kembali

We have observed a deeply bound state of the  −–14N system that decayed into twin singlehypernuclei in nuclear emulsion exposed in the E373 experiment at KEK-PS. The process is uniquely identified as  − + 14N → 10  Be + 5 He. We have measured the binding energy of the  −–14N system, B−, to be 4.38 ± 0.25MeV, which is significantly larger than that of the  −– 14N 3D atomic state (0.17 MeV), if both single-hypernuclei are emitted in the ground state from at-rest capture of a  − hyperon. If the 10  Be nucleus is produced in an excited state, the B− value mentioned above decreases by the excitation energy. Model calculations based on known values for 9Be excited states have predicted two excited states in the bound region. Even in the case of 10  Be production in the highest excited state, the B− value is far from the 3D atomic level of the  −–14N system by more than 3.7 standard deviations. The event provides the first clear evidence of a deeply bound state of the  −–14N system by an attractive N interaction.