Photoneutron cross sections for unstable neutron-rich oxygen isotopes.
The dipole response of stable and unstable neutron-rich oxygen nuclei of masses A = 17 to A = 22 has been investigated experimentally utilizing electromagnetic excitation in heavy-ion collisions at beam energies about 600 MeV/nucleon. A kinematically complete measurement of the neutron decay channel in inelastic scattering of the secondary beam projectiles from a Pb target was performed. Differential electromagnetic excitation cross sections d sigma/dE were derived up to 30 MeV excitation energy. In contrast to stable nuclei, the deduced dipole strength distribution appears to be strongly fragmented and systematically exhibits a considerable fraction of low-lying strength.
Leistenschneider
A
A
Institut für Kernphysik, Johann Wolfgang Goethe-Universität, D-60486 Frankfurt, Germany.
Aumann
T
T
Boretzky
K
K
Cortina
D
D
Cub
J
J
Datta Pramanik
U
U
Dostal
W
W
Elze
T W
TW
Emling
H
H
Geissel
H
H
Grünschloss
A
A
Hellstr
M
M
Holzmann
R
R
Ilievski
S
S
Iwasa
N
N
Kaspar
M
M
Kleinböhl
A
A
Kratz
J V
JV
Kulessa
R
R
Leifels
Y
Y
Lubkiewicz
E
E
Münzenberg
G
G
Reiter
P
P
Rejmund
M
M
Scheidenberger
C
C
Schlegel
C
C
Simon
H
H
Stroth
J
J
Sümmerer
K
K
Wajda
E
E
Walús
W
W
Wan
S
S