Spin in Isospin Physics

by Dr Tomohiro Uesaka (RIKEN Nishina Center, Japan)

Thursday May 12, 2011, 5:00 PM → 6:00 PM Asia/Seoul

206호 (제1과학관)

Recent experimental and theoretical studies have revealed that spin degrees of freedom play a more vital role in exotic nuclei than in stable nuclei. Tensor force effects on the evolution of shell and possible occurrence of p-n pairing in the proton-rich region are good examples of manifestations of spin degrees of freedom. 
In exploring the spin effects in exotic nuclei, scattering with polarized protons should be a powerful tool. We have constructed a novel polarized proton solid target aiming to shed a light of polarization to the physics of exotic nuclei. A distinguished feature of the target system is that it works under a low magnetic field of 0.1 T and a high temperature of 100 K, which exhibits a striking contrast to standard DNP targets working in extreme conditions of several Tesla and sub-Kelvin. 
The polarized proton target was applied, for the first time, to measurement of vector analyzing power in the proton elastic scattering of neutron-rich 6,8He nuclei at 71MeV/nucleon[1,2]. 
The data of vector analyzing power indicate that 
1)spin-orbit potentials in neutron-rich 6,8He nuclei are considerably shallower that those of stable nuclei and 2)the α clusters in 6,8He are major origins of the spin-orbit potentials. In particular, it is indicated that the α-cluster distribution is a possible key for understanding spin-orbit coupling in those nuclei. 
In the colloquium, I will begin with a general overview of spin physic of exotic nuclei and present results from the proton elastic scattering experiments. I will also touch on future experiments planned at RI Beam Factory.