Speaker
Ms
Yoshiko Sasamto
(Center for Nuclear Study, University of Tokyo)
Description
RI-beam induced charge exchange reactions have unique properties which are missing in stable-beam induced reactions and can be used to reveal new aspect of spin-isospin responses in nuclei.
We are performing a series of experiments taking advantages of RI-beam induced reactions, by using the SHARAQ spectrometer\cite{Uesaka08} at RI Beam Factory (RIBF).
There are some cases where the spectroscopic capability is strengthened by introducing $\gamma$-ray tagging to the reaction studies.
In the symposium, result from an experiment as an example of Heavy-ion charge exchange reaction combined with $\gamma$-ray tagging will be reported.
Incompressibility of nuclear matter attracts a focus of experimental and theoretical studies because of its fundamental importance to define the equation of state of nuclear matter.
Isovector monopole resonances which are oscillation modes of the isovector density $\rho_{IV} = \rho_{n} - \rho_{p}$ are expected to be a key to approach us to asymmetric nuclear matter\cite{colo2003}.
A natural way to study isovector excitations is by charge-exchange reactions such as (p,n) and ($^{3}$He,t) reactions.
However, not only the $\Delta T = 1, \Delta S = 0$ excitations but also, and even stronger, the $\Delta T = 1, \Delta S = 1$ transitions are excited in such reactions.
Thus, the signature of $\Delta T = 1, \Delta S = 0$ excitation is almost invisible.
We propose a new probe ($^{10}$C,$^{10}$B$\gamma$) to excite $\Delta S=0$ mode selectively in combination with $\gamma$-ray tagging.
Our idea to establish a probe to isovector non-spin-flip states is based on use of a super-allowed Fermi transition between isobaric analog states for the projectile.
The analog state of the $^{10}$C ground state is found at $E_{x}$~=~1.740 MeV with 0$^{+}$ spin-parity in $^{10}$B.
To identify the 0$^{+}$ $\rightarrow$ 0$^{+}$ transition in the projectile, which is a pure $\Delta S=0$ transition, assures the non-spin-flip excitation in the target.
The transition to the 1.740MeV-state in $^{10}$B
can be experimentally discriminated by tagging the emitted $\gamma$-ray of 1.022~MeV.
The experiment was performed last October using the SHARAQ spectrometer at RIBF.
The experimental results and future perspective will be presented.
\bibitem{Uesaka08} T. Uesaka et. al., Nucl. Instrum. Meth. in Phys. Res. {\bf B266}, (2008) 4218.
\bibitem{colo2003} G. Colo et. al., Phys. Rev. C {\bf 67}, (2003) 044306.
Primary author
Ms
Yoshiko Sasamto
(Center for Nuclear Study, University of Tokyo)
Co-author
Dr
Tomohiro Uesaka
(RIKEN)
