Hypernuclear fine structure in (9)(lambda)Be.
With a germanium detector array (Hyperball), we observed two gamma-ray peaks corresponding to the two transitions (5/2(+)-->1/2(+) and 3/2(+)-->1/2(+)) in the (9)(Lambda)Be hypernucleus which was produced by the 9Be(K-,pi(-)) reaction. The energies of the gamma rays are 3029 +/- 2 +/- 1 keV and 3060 +/- 2 +/- 1 keV. The energy difference was measured to be 31.4(+2.5)(-3.6) keV, which indicates a very small Lambda-spin-dependent spin-orbit force between a Lambda and a nucleon. This is the smallest level splitting by far ever measured in a hypernucleus.
Akikawa
H
H
Department of Physics, Kyoto University, Kyoto 606-8502, Japan.
Ajimura
S
S
Chrien
R E
RE
Eugenio
P M
PM
Franklin
G B
GB
Franz
J
J
Gang
L
L
Imai
K
K
Khaustov
P
P
May
M
M
Pile
P H
PH
Quinn
B
B
Rusek
A
A
Sasao
J
J
Sawafta
R I
RI
Schmitt
H
H
Tamura
H
H
Tang
L
L
Tanida
K
K
Yuan
L
L
Zhou
S H
SH
Zhu
L H
LH
Zhu
X F
XF