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.7
Abstract: 2WB.00007 : Isomer spectroscopy using RI beam
5:00 PM–5:30 PM
Preview Abstract
Abstract
Author:
Atsuko Odahara
(Dep. of Phys., Osaka Univ. )
We have studied systematically high-spin oblate shape isomers
in the $N$=83 isotones,
which have revealed the characteristics of nuclear structure,
such as the preserving pairing interactions
at high-spin states, decrease of $Z$=64 proton shell gap energy
as the decrease of proton number from 64 to 60
and so on.
Recently, it became possible to search for isomers
by the secondary fusion reaction at high-spin states in nuclei,
which could not be populated by the stable beam and stable
target,
using RCNP RI beam line at Osaka University.
RI beams enable us to study high-spin states in nuclei in wide
mass region.
By using the RI beams delivered by RIBF
and the high-efficiency $\gamma$-ray detection system GRETINA,
it will be possible to investigate nuclei far from the
stability line.
Single-particle energies and nucleon-nucleon interactions
of these nuclei close to drip line
are expected to be the test ground of nuclear models,
such as shell structures.
We have a plan to search for isomers
with half lives of $\sim$$\mu$sec to $\sim$msec
and to explore the decay mechanism of isomers
in the proton-rich nuclei along $N$=$Z$ line with 80$<
$$A$$<$100.
Moreover we try to search for nuclei beyond the proton drip
line,
which could be defined that isomeric states
would be bound by the centrifugal potential
although the ground states would be unbound against the proton
emission.
Isomers are expected to reveal the following characteristics of
these nuclei.
(1) Existence of isomers could prove the magicity of $N$=$Z$=50
and the large neutron-proton interaction,
as one of the candidates of isomers is spin-gap isomer
which is caused by the lowering of excitation energies
resulting from the stretch coupling of spins of high-$j$ (g$_
{9/2}$) holes
of the $^{100}$Sn core.
(2) Isomers could prove the nuclear deformation
which is caused by the evolution of shell structure.
One of spin-gap isomers in $^{94}$Ag
was reported to have large prolate deformation.
(3) This mass region is on the way of the rapid proton (rp)
synthesis pass.
Recently, neutrino reactions in the super novae
were reported to play a role of the synthesis of the rp-process
nuclei.
In the case of no path or slow down of rp process,
isomers could contribute to synthesis of rp-nuclei
with larger $Z$,
although the production rates of isomers are small.
To cite this abstract, use the following reference: http://meetings.aps.org/link/BAPS.2009.HAW.2WB.7