Studies of Unstable Nuclei with Spin-Polarized Proton Target

Roles of spin-dependent interactions in unstable nuclei have been investigated via the direct reaction of radioactive ions with a solid spin-polarized proton target. The target has a unique advantage of a high polarization of 20–30% under low magnetic field of 0.1 T and at a high temperature of 100 K, which allow us to detect recoil protons with good angular resolution. Present status of on-going experimental studies at intermediate energies, such as proton elastic scattering and (p, 2p) knockout reaction, and new physics opportunities expected with low-energy RI beams are overviewed.