Accueil du site > Publications récentes > Unexpected high-energy γ emission from decaying exotic nuclei
A. Gottardo, D. Verney, I. Deloncle, S. Péru, C. Delafosse, S. Roccia, I. Matea, C. Sotty, C. Andreoiu, C. Costache, M.-C. Delattre, A. Etilé, S. Franchoo, C. Gaulard, J. Guillot, F. Ibrahim, M. Lebois, M. MacCormick, N. Marginean, R. Marginean, M. Martini, C. Mihai, I. Mitu, L. Olivier, C. Portail, L. Qi, B. Roussière, L. Stan, D. Testov, J. Wilson, D.T. Yordanov
The
N = 52 83Ga β decay was studied at ALTO. The radioactive 83Ga
beam was produced through the ISOL photofission technique and
collected on a movable tape for the measurement of γ -ray
emission following β decay. While β-delayed neutron emission
has been measured to be 56–85% of the decay path, in this
experiment an unexpected high-energy 5–9 MeV γ -ray yield of
16(4)% was observed, coming from states several MeVs above the
neutron separation threshold. This result is compared with
cutting-edge QRPA calculations, which show that when neutrons
deeply bound in the core of the nucleus decay into protons via
a Gamow–Teller transition, they give rise to a dipolar
oscillation of nuclear matter in the nucleus. This leads to
large electromagnetic transition probabilities which can
compete with neutron emission, thus affecting the β-decay
path. This process is enhanced by an excess of neutrons on the
nuclear surface and may thus be a common feature for very
neutron-rich isotopes, challenging the present understanding
of decay properties of exotic nuclei.
Voir en ligne : Physics Letters B 772 (2017) 359–362
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