Performance and geant4 simulation of the proton polarimeter 2nd-FPP for (p,2p) measurements

The 2nd-FPP is a focal plane proton polarimeter to measure the recoil proton polarization in the (p,2p) reaction. Recently, we newly introduced four MWDCs to improve the position and angle resolution. The performance was investigated by using protons of polarization $P$=0.99 by p-C elastic scattering at 65 MeV. The position resolution of about 0.34 mm has been achieved, which is significantly better than that obtained from plastic scintillator information. The resulting effective analyzing powers at angles larger than 60 degrees are consistent with the design values based on p-C analyzing powers. However, those at small angles are significantly small. Thus, we have been developing a geant4 simulation to evaluate the effect of p-p scattering contribution in the plastic scintillator material. In this contribution, we will give the experimental results and the progress of the geant4 simulation with the polarization effects to access the p-C and p-p contributions on the effective analyzing powers.