Unexpected high-energy γ emission from decaying exotic nuclei
A. Gottardo
(1)
,
D. Verney
(1)
,
I. Deloncle
(2)
,
S. Péru
(3)
,
C. Delafosse
(1)
,
S. Roccia
(2)
,
I. Matea
(1)
,
C. Sotty
,
C. Andreoiu
,
C. Costache
,
M.-C. Delattre
(1)
,
A. Etilé
(3)
,
S. Franchoo
(1)
,
C. Gaulard
(2)
,
J. Guillot
(1)
,
F. Ibrahim
(1)
,
M. Lebois
(1)
,
M. Maccormick
(1)
,
N. Marginean
,
R. Marginean
,
M. Martini
(4)
,
C. Mihai
,
I. Mitu
,
L. Olivier
(1)
,
C. Portail
(1)
,
L. Qi
(1)
,
B. Roussière
(1)
,
L. Stan
,
D. Testov
,
J. Wilson
(1)
,
D.T. Yordanov
(1)
C. Delafosse
- Fonction : Auteur
- PersonId : 1264426
- IdHAL : c-delafosse
C. Sotty
- Fonction : Auteur
C. Andreoiu
- Fonction : Auteur
C. Costache
- Fonction : Auteur
N. Marginean
- Fonction : Auteur
R. Marginean
- Fonction : Auteur
M. Martini
- Fonction : Auteur
- PersonId : 1344676
- IdHAL : mmartini75
- ORCID : 0000-0003-4823-639X
C. Mihai
- Fonction : Auteur
I. Mitu
- Fonction : Auteur
L. Stan
- Fonction : Auteur
D. Testov
- Fonction : Auteur
- PersonId : 762754
- ORCID : 0000-0003-3193-5311
Résumé
The N=52 Ga83 β decay was studied at ALTO. The radioactive 83 Ga 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.