Open charm measurement with HFT at STAR
Anisotropic flow measurements have demonstrated development of partonic collectivity in 200 GeV Au+Au collisions at RHIC.
To understand the partonic EOS, one must address thermalization in these collisions. Given their large masses,
collective motion of heavy-flavor (c,b) quarks could 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
low region (0.5-2 GeV/c).
The Heavy Flavor Tracker (HFT), a proposed upgrade to the STAR experiment at midrapidity, will measure
of open-charm hadrons to very low by reconstructing their displaced decay vertices. The HFT
consists of a fast strip detector layer - the Intermediate Silicon Tracker (IST) and the PIXEL
detector, which is made of two low mass monolithic active pixel sensor (MAPS) layers. The IST
is essential to improve hit identification at the PIXEL detector when running at full RHIC-II luminosity,
while the PIXEL detector enables a high precision position measurement close to the collision vertex. Given
its large acceptance and high efficiency, HFT can also measure open charm spectra to high
which can be used to investigate heavy-quark energy loss and medium properties.
Using the full Geant simulation of the STAR tracking system with the HFT, we will show
that the HFT can directly reconstruct open-charm hadrons on event-by-event basis with high signal to background
ratio, for central Au+Au collisions at full RHIC-II luminosity. Its performance in a broad range
will be demonstrated on GeV/c) and GeV/c) measurements of meson. Results
of reconstruction of baryon in heavy-ion collisions will also be shown.