Breakdown of the Z=8 shell closure in unbound 12O and its mirror symmetry.
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.
Suzuki
D
D
Department of Physics, University of Tokyo, 7-3-1 Hongo, Bunkyo, Tokyo 113-0033, Japan.
Iwasaki
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H
Beaumel
D
D
Nalpas
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L
Pollacco
E
E
Assié
M
M
Baba
H
H
Blumenfeld
Y
Y
De Séréville
N
N
Drouart
A
A
Franchoo
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S
Gillibert
A
A
Guillot
J
J
Hammache
F
F
Keeley
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N
Lapoux
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V
Maréchal
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F
Michimasa
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S
Mougeot
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X
Mukha
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I
Okamura
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H
Otsu
H
H
Ramus
A
A
Roussel-Chomaz
P
P
Sakurai
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H
Scarpaci
J-A
JA
Sorlin
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O
Stefan
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I
Takechi
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M