The Fe54 nucleus was populated from a Fe56 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 Fe56 ground state. The isomeric state was produced in the low-momentum (-energy) tail of the parallel momentum (energy) distribution of Fe54, 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 Fe54 is a consequence of the quark structure of the nucleons.
Role of the Δ Resonance in the Population of a Four-Nucleon State in the Fe 56 → Fe 54 Reaction at Relativistic Energies / Z. Podolyák, C.M. Shand, N. Lalović, 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, C. Stahl, H. Weick, F. Ameil, G. De Angelis, T. Arici, R. Carroll, Z. 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. - In: PHYSICAL REVIEW LETTERS. - ISSN 0031-9007. - 117:22(2016 Nov), pp. 222302.1-222302.6. [10.1103/PhysRevLett.117.222302]
Role of the Δ Resonance in the Population of a Four-Nucleon State in the Fe 56 → Fe 54 Reaction at Relativistic Energies
F.C.L. Crespi;A. Pullia;
2016
Abstract
The Fe54 nucleus was populated from a Fe56 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 Fe56 ground state. The isomeric state was produced in the low-momentum (-energy) tail of the parallel momentum (energy) distribution of Fe54, 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 Fe54 is a consequence of the quark structure of the nucleons.File | Dimensione | Formato | |
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