3rd Joint Meeting of the APS Division of Nuclear Physics and the Physical Society of Japan
Volume 54, Number 10
Tuesday–Saturday, October 13–17, 2009;
Waikoloa, Hawaii
Session 2WB: Workshop on Physics Opportunities with GRETINA II
2:00 PM–5:30 PM,
Tuesday, October 13, 2009
Room: Kona 4
Chair: Cornelius Beausang, University of Richmond
Abstract ID: BAPS.2009.HAW.2WB.1
Abstract: 2WB.00001 : Lifetime measurements of RI beam and high-spin studies with degraded beams
2:00 PM–2:30 PM
Preview Abstract
Abstract
Author:
Eiji Ideguchi
(Center for Nuclear Study, University of Tokyo)
The development of RI beams has opened a wide region to study the
nuclear
structure far from the stability line. During the extensive
studies of
neutron-rich nuclei in the light mass region, new phenomena such
as the
disappearance of N=8, 20 magic numbers associated with the
deformed ground
states were revealed. Gamma-ray spectroscopy was employed for the
study of
the deformed structure. Based on the relatively low excitation
energy of
2$^{+}$ state and the large B(E2) value, large deformation of the
ground
state was identified. Observation of the excited levels was thus
far limited
to the low-lying states, but the study of higher-spin states will
be useful
to understand the collectivity since a presence of a rotational
band is one
of the clear evidences of the deformed structure.
In order to realize a high-resolution gamma-ray spectroscopy of
exotic
nuclei, we have developed a segmented Ge detector array, CNS
GRAPE, and plan
to investigate unstable nuclei in the heavier mass region. To study
collective structures of unstable nuclei, we plan to perform
life-time
measurements of 2$^{+}$ and higher excited sates utilizing direct
reactions
with high-intensity fast RI beams. At present, RI beam factory
(RIBF) at
RIKEN has a potential to provide world's highest intensity.
In addition, experiments using low-energy reactions are planned
to study
high-spin states. Previously, we have successfully developed an
energy-degraded $^{46}$Ar beam produced by the fragmentation of
64AMeV
$^{48}$Ca primary beam. It was used for a fusion-evaporation
reaction with a
$^{9}$Be target. Gamma rays emitted from high-spin states were
clearly
observed. Same technique to make low-energy RI beam could be
applied to
heavier RI beams at RIBF and the study of high-spin states will
be widely
expanded.
In the talk, lifetime measurements and studies of high-spin
states of
unstable nuclei far from the stability using high-efficiency
position-sensitive Ge detector array at RIBF will be discussed.
To cite this abstract, use the following reference: http://meetings.aps.org/link/BAPS.2009.HAW.2WB.1