Halo structure of the island of inversion nucleus 31Ne.
The cross sections for single-neutron removal from the very neutron-rich nucleus 31Ne on Pb and C targets have been measured at 230 MeV/nucleon using the RIBF facility at RIKEN. The deduced large Coulomb breakup cross section of 540(70) mb is indicative of a soft E1 excitation. Comparison with direct-breakup model calculations suggests that the valence neutron of 31Ne occupies a low-l orbital (most probably 2p(3/2)) with a small separation energy (S(n) approximately < 0.8 MeV), instead of being predominantly in the 1f(7/2) orbital as expected from the conventional shell ordering. These findings suggest that 31Ne is the heaviest halo system known.
Nakamura
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T
Department of Physics, Tokyo Institute of Technology, 2-12-1 O-Okayama, Meguro, Tokyo 152-8551, Japan.
Kobayashi
N
N
Kondo
Y
Y
Satou
Y
Y
Aoi
N
N
Baba
H
H
Deguchi
S
S
Fukuda
N
N
Gibelin
J
J
Inabe
N
N
Ishihara
M
M
Kameda
D
D
Kawada
Y
Y
Kubo
T
T
Kusaka
K
K
Mengoni
A
A
Motobayashi
T
T
Ohnishi
T
T
Ohtake
M
M
Orr
N A
NA
Otsu
H
H
Otsuka
T
T
Saito
A
A
Sakurai
H
H
Shimoura
S
S
Sumikama
T
T
Takeda
H
H
Takeshita
E
E
Takechi
M
M
Takeuchi
S
S
Tanaka
K
K
Tanaka
K N
KN
Tanaka
N
N
Togano
Y
Y
Utsuno
Y
Y
Yoneda
K
K
Yoshida
A
A
Yoshida
K
K