Role of the Δ Resonance in the Population of a Four-Nucleon State in the 56Fe → 54Fe Reaction at Relativistic Energies

Zs Podolyák, C. M. Shand, Natasa Lalovic, J. Gerl, D. Rudolph, T. Alexander, P. Boutachkov, M. L. Cortés, M. Górska, I. Kojouharov, N. Kurz, C. Louchart, E. Merchán, C. Michelagnoli, R. M. Pérez-Vidal, S. Pietri, D. Ralet, M. Reese, H. Schaffner, Ch StahlH. Weick, F. Ameil, G. De Angelis, T. Arici, R. Carroll, Zs Dombrádi, A. Gadea, P. Golubev, M. Lettmann, C. Lizarazo, D. Mahboub, H. Pai, Z. Patel, N. Pietralla, P. H. Regan, L. G. Sarmiento, O. Wieland, E. Wilson, B. Birkenbach, B. Bruyneel, I. Burrows, L. Charles, E. Clément, F. C L Crespi, D. M. Cullen, P. Désesquelles, J. Eberth, V. González, T. Habermann, L. Harkness-Brennan, H. Hess, D. S. Judson, A. Jungclaus, W. Korten, M. Labiche, A. Maj, D. Mengoni, D. R. Napoli, A. Pullia, B. Quintana, G. Rainovski, P. Reiter, M. D. Salsac, E. Sanchis, J. J. Valiente Dóbon

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The Fe54 nucleus was populated from a 56Fe beam impinging on a Be target with an energy of E/A=500 MeV. The internal decay via γ-ray emission of the 10+ metastable state was observed. As the structure of this isomeric state has to involve at least four unpaired nucleons, it cannot be populated in a simple two-neutron removal reaction from the 56Fe ground state. The isomeric state was produced in the low-momentum (-energy) tail of the parallel momentum (energy) distribution of 54Fe, suggesting that it was populated via the decay of the Δ0 resonance into a proton. This process allows the population of four-nucleon states, such as the observed isomer. Therefore, it is concluded that the observation of this 10+ metastable state in 54Fe is a consequence of the quark structure of the nucleons.

Original languageEnglish
Article number222302
Number of pages5
JournalPhysical Review Letters
Issue number22
Publication statusPublished - 2016 Nov 23

Subject classification (UKÄ)

  • Subatomic Physics

Free keywords

  • isomer decay
  • gamma-ray spectroscopy
  • relativistic projectile fragmentation


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