Naomi Y. Feiman, Yale UniversityTitle: K0 Short Reconstruction in STAR with Low Magnetic Field and First Year Detector SetupAuthors: N.Y. Feiman, G.J. Kunde (WNSL, Yale University)Abstract: In heavy ion collisions, the K0 short meson is of special interest because it carries much of the strangeness created in the collision, and could help indicate whether a Quark-Gluon Plasma formed as a result of the collision. The neutral K0 short meson decays into a pair of charged pions about 70% of the time. The lifetime of the K0 short is such that in RHIC collisions at STAR, K0 short decay should take place well within STAR, but several centimeters from the primary vertex. This means that it is possible to reconstruct this secondary vertex in STAR. The study was carried out for STAR's first year detector configuration, when the tracking device in place will be a Time Projection Chamber (TPC), which is only capable of tracking charged particles. Thus, the neutral Kaon will be invisible, but its charged decay products will not be. However, the TPC's tracking ability declines as the radius of curvature of the track decreases. At 350 MeV, the mean transverse momentum (pt) of the daughter pions, with a 0.5 T magnetic field in the detector, the TPC tracking efficiency is about 65%. Since the radius of curvature of the track is proportional to (pt/B), if B, the magnetic field strength, is lowered, it should be possible to track low momentum particles, such as the pions from K0 short decay, more efficiently. I used a GEANT-based simulation and the current version of the STAR tracking and neutral vertex reconstruction software to test how lowering the magnetic field in the TPC would affect the yield of reconstructed K0 short mesons. I also wrote code which allowed me to study the efficiencies of these modules and the effects of certain cuts on the yields. The first results of this study indicate that lowering the magnetic field in STAR from 0.5 Tesla to 0.25 Tesla will increase the yield of reconstructed K0 short mesons by 10%. |