Experimental study of density dependent symmetry energy at RIBF-SPiRIT experiment*

The nuclear Equation of State (EoS) is a fundamental property of nuclear matter that describes the relationships between the parameters of the system, such as energy, density and temperature. The equation consists of the term describes the symmetric matter (N=Z) and the term describes the asymmetric matter (N≠Z), which has large uncertainty though it affects many aspects of nuclear physics and astrophysics.
An international collaboration, named SPiRIT, to study the density dependence of asymmetry term in nuclear EoS has been formed since 2009. The main aim of this collaboration is to make the constraint on the asymmetry term of nuclear EoS for higher dense region (ρ>ρ₀). By using the energetic neutron rich heavy RI beam at RIKEN-RIBF, a novel nuclear heavy collision experiment was carried out at 2016 May.
One of the main devices of experimental setup is Time Projection Chamber (TPC) which is installed in the RIBF-SAMURAI dipole magnet. The TPC measures charged pions, which is expected to be sensitive to EoS, protons and light ions simultaneously in ¹³²Sn+¹²⁴Sn, ¹²⁴Sn+¹¹²Sn, ¹¹²Sn+¹²⁴Sn, and ¹⁰⁸Sn+¹¹²Sn reactions with the beam energy of Elab ~ 270 MeV/u, where the dense matter of ρ~2ρ₀ is expected to be formed in the central collisions.
In this talk, the conceptual design of the project will be given in addition to some result of data analysis for the physics run performed at 2016 spring.