STAR inner tracking upgrade-a performance study

Anisotropic flow measurements have demonstrated development of partonic collectivity in 200 GeV Au + Au collisions at RHIC. To understand the partonic EOS, thermalization must be addressed. Collective motion of heavy-flavor (c, b) quarks can be used to indicate the degree of thermalization of the light-flavor quarks (u, d, s). Measurement of heavy-flavor quark collectivity requires direct reconstruction of heavy-flavor hadrons in the low p(T) region. Measurement of open charm spectra to high p(T) can be used to investigate heavy-quark energy loss and medium properties. The Heavy Flavor Tracker (HFT), a proposed upgrade to the STAR experiment at midrapidity, will measure nu(2) of open-charm hadrons to very low p(T) by reconstructing their displaced decay vertices. The innermost part of the HFT is the PIXEL detector (made of two low mass monolithic active pixel sensor layers), which delivers a high precision position measurement close to the collision vertex. The Intermediate Silicon Tracker (IST), a 1-layer strip detector, is essential to improve hit identification in the PIXEL detector when running at full RHIC-II luminosity. Using a full GEANT simulation, open charm measurement capabilities of STAR with the HFT will be shown. Its performance in a broad pT range will be demonstrated on nu(2) (p(T) > 0.5 GeV/c) and R-CP (p(T) < 10 GeV/c) measurements of D-0 meson. Results of reconstruction of Lambda(C) baryon in heavy-ion collisions are presented.