Breakdown of the Z=8 shell closure in unbound 12O and its mirror symmetry.

Authors :: Suzuki D
Iwasaki H
Beaumel D
Nalpas L
Pollacco E
Assié M
Baba H
Blumenfeld Y
De Séréville N
Drouart A
Franchoo S
Gillibert A
Guillot J
Hammache F
Keeley N
Lapoux V
Maréchal F
Michimasa S
Mougeot X
Mukha I
Okamura H
Otsu H
Ramus A
Roussel-Chomaz P
Sakurai H
Scarpaci JA
Sorlin O
Stefan I
Takechi M
Source :: Physical review letters [Phys Rev Lett] 2009 Oct 09; Vol. 103 (15), pp. 152503. Date of Electronic Publication: 2009 Oct 09.
Publication Year :: 2009
Abstract: An excited state in the proton-rich unbound nucleus 12O was identified at 1.8(4) MeV via missing-mass spectroscopy with the 14O(p,t) reaction at 51 AMeV. The spin-parity of the state was determined to be 0+ or 2+ by comparing the measured differential cross sections with distorted-wave calculations. The lowered location of the excited state in 12O indicates the breakdown of the major shell closure at Z=8 near the proton drip line. This demonstrates the persistence of mirror symmetry in the disappearance of the magic number 8 between 12O and its mirror partner 12Be.