Speaker
Dr
Daisuke Suzuki
(Riken Nishina Center)
Description
We will present the recent finding of the second $0^+$ state in $^{12}$O, the lightest oxygen nucleus ever found, in our measurement of the $^{14}$O($p$, $t$) reaction at GANIL. $^{12}$O with $Z$ = 8 is a proton-rich mirror nucleus of $^{12}$Be with $N$ = 8. The level scheme of $^{12}$Be, including its intruder $0_2^+$ state at a very low excitation energy of 2.25 MeV, has been crucial in establishing the breakdown of the shell closure at $N$ = 8. The present search for the mirror $0_2^+$ state was thus aimed at investigating if the disappearance phenomenon of the shell closure also occurs at $Z$ = 8 and if so, how the $2s_{1/2}$ orbital intruding near the Fermi surface impacts the mirror symmetry between $^{12}$O and $^{12}$Be. Despite its importance, the spectroscopy of $^{12}$O has been challenging for decades as this nucleus is unbound for two-proton emission. In the present study, we measured the two-neutron transfer ($p$, $t$) reaction using a radioactive $^{14}$O beam at 51 MeV/u produced by the LISE spectrometer via the projectile fragmentation reaction. Missing-mass spectroscopy in inverse kinematics was realized by using MUST2 telescopes, each consisting of a double-sided silicon strip detector and a CsI calorimeter, to obtain resonance energies and differential cross sections of unbound states. The shell closure at $Z$ = 8 and the mirror symmetry with respect to $^{12}$Be will be discussed from the final result of the experiment.
Primary author
Dr
Daisuke Suzuki
(Riken Nishina Center)
Co-authors
Dr
Adrien Matta
(IPN Orsay)
Dr
Alain Gillibert
(CEA-Saclay)
Dr
Alexis Ramus
(IPN Orsay)
Dr
Antoine Drouart
(CEA-Saclay)
Dr
Christelle Stodel
(GANIL)
Dr
Costel M. Petrache
(CSNSM)
Dr
Dan-Yang Pang
(GANIL)
Dr
Didier Beaumel
(IPN Orsay)
Dr
Emmanuel Pollacco
(CEA-Saclay)
Dr
Fairouz Hammache
(IPN Orsay)
Dr
Farheen Naqvi
(Institut für Kernphysik, Univesität zu Köln,)
Dr
François De Oliveira Santos
(GANIL)
Dr
François Maréchal
(IPN Orsay)
Dr
Hideaki Otsu
(RIKEN Nishina Center)
Dr
Hidetada Baba
(Riken Nishina Center)
Dr
Hironori Iwasaki
(National Superconducting Cyclotron Laboratory, Michigan State University)
Dr
Hiroyoshi Sakurai
(RIKEN Nishina Center)
Dr
Iulian Stefan
(IPN Orsay)
Dr
Jacques Guillot
(IPN Orsay)
Dr
Jean-Antoine Scarpaci
(CSNSM)
Dr
Julien Gibelin
(LPC Caen)
Dr
Julien Pancin
(GANIL)
Dr
Laurent Nalpas
(CEA-Saclay)
Dr
Luc Perrot
(IPN Orsay)
Ms
Marlène Assié
(IPN)
Dr
Matthias Hackstein
(Institut für Kernphysik, Univesität zu Köln,)
Dr
Nicholas Keeley
(National Centre for Nulcear Research, Poland)
Dr
Nicolas De Séréville
(IPN Orsay)
Dr
Olivier Sorlin
(GANIL)
Dr
P.C. Srivastava
(GANIL)
Dr
Patricia Roussel-Chomaz
(CEA-Saclay)
Dr
Sandra Giron
(IPN Orsay)
Dr
Satoru Terashima
(Beihang University)
Dr
Serge Franchoo
(IPN Orsay)
Dr
Shin'ichiro Michimasa
(Center for Nuclear Study, University of Tokyo)
Dr
Stéphane Grévy
(CENBG)
Dr
Valérie Lapoux
(CEA-Saclay)
Dr
W. Rother
(Institut für Kernphysik, Univesität zu Köln)
Dr
Yorick Blumenfeld
(IPN Orsay)
Dr
Yusuke Tanimura
(IPN Orsay)
