Observation of strong low-lying E1 strength in the two-neutron halo nucleus 11Li.
An exclusive measurement has been made of the Coulomb dissociation of the two-neutron halo nucleus 11Li at 70 MeV/nucleon at RIKEN. Strong low-energy (soft) E1 excitation is observed, peaked at about Ex = 0.6 MeV with B(E1) = 1.42(18) e2fm2 for Erel < or = 3 MeV, which was largely missed in previous measurements. This excitation represents the strongest E1 transition ever observed at such low excitation energies. The spectrum is reproduced well by a three-body model with a strong two-neutron correlation, which is further supported by the E1 non-energy-weighted cluster sum rule.
Nakamura
T
T
Department of Physics, Tokyo Institute of Technology, Meguro, Tokyo 152-8551, Japan.
Vinodkumar
A M
AM
Sugimoto
T
T
Aoi
N
N
Baba
H
H
Bazin
D
D
Fukuda
N
N
Gomi
T
T
Hasegawa
H
H
Imai
N
N
Ishihara
M
M
Kobayashi
T
T
Kondo
Y
Y
Kubo
T
T
Miura
M
M
Motobayashi
T
T
Otsu
H
H
Saito
A
A
Sakurai
H
H
Shimoura
S
S
Watanabe
K
K
Watanabe
Y X
YX
Yakushiji
T
T
Yanagisawa
Y
Y
Yoneda
K
K