Study of the gluon polarization in the proton with a silicon vertex   upgrade at RHIC/PHENIX
  PHENIX has a well defined program for measuring the polarized gluon distribution in the nucleon. We measure the gluon polarization in the proton with polarized $p$-$p$ collisions at PHENIX. The measurements of gluon polarization $via$ the direct-photon production and the heavy-flavor production can be significantly improved by the silicon vertex tracker upgrade. We have studied the possible improvements of the gluon polarization measurements using Monte Carlo simulation and they are shown and discussed in this paper. 
Manabu Togawa (for the PHENIX collaboration)