Role Of The Delta Resonance In The Population Of Excited States In High-Energy Reactions

The 54Fe nucleus was populated from a 56Fe beam with an energy of E=A=500 MeV. The internal decay of the 10+ metastable state via g-ray emission was observed. The structure of this isomeric state has to involve at least four unpaired nucleons, therefore it cannot be populated in a simple two-neutron removal reaction from the ground state of 56Fe, and we suggest that it was populated via the decay of the D0 resonance into a proton. This process allows the population of four-nucleon states, such as the observed isomer. Therefore, the population of the four-particle 10+ isomer in 54Fe is a consequence of the quark structure of the nucleons. The possible use of this reaction mechanism for producing exotic nuclei is discussed.