=Date and Place=
September 28th (Tue) 2021, 13:30~ via ZOOM meeting system
Dr. TadaAki Isobe
(Senior Researcher, Radioactive Isotope Physics Lab. RNC)
Measurement of spectral pion ratio in Sn+Sn collisions for the constraint of density dependent nuclear symmetry energy
Neutron star is believed to be created as a remnant of super nova explosion. In order to determine a thermodynamical character of outer core of neutron star through terrestrial experiments, we have performed a series of measurements using RIKEN Radio Isotope Beam Factory (RIBF). Various central collisions between neutron-rich tin nucleus and normal tin nucleus were measured. The density achieved by the collisions nearly corresponds to the one for the outer core of neutron star: \rho~2 \times \rho_0. Both positive and negative pions emitted from the high density nuclear matter were detected by a newly developed large time projection chamber which can provide 3-dimensional image of their tracks. Based on the comparison of spectral charged pion ratio with one of the transport models, we deduce the slope of the symmetry energy to be 42 < L < 117 MeV, which is consistent with the result given by the recent measurement of the neutron skin thickness of Pb-208.