Measurements of Identified Particle Spectra in Diffractive pp Collisions with the STAR Detector at RHIC

摘要

We present the diffractive program with the STAR Roman Pot detectors at RHIC, focusing on the spectra of identified charged particles as pions, kaons and protons and their anti-particle counterparts in Single Diffraction (p + p → p + X) and Central Diffraction (p + p → p + X + p) processes. Moreover, the p/p ratio as a function of rapidity is presented to study the baryon number transfer from forward to midrapidity in Single Diffraction. Similar effect has been studied in proton-proton and proton-photon interactions but it is the first measurement in proton-Pomeron interaction. The forward proton(s) were tagged in the STAR Roman Pot system while the identified charged particle tracks were reconstructed in the STAR Time Projection Chamber (TPC). Ionization energy loss and time-of-flight of charged particles were used for particle identification. In addition, the status and future prospects of the diffractive meaurements at RHIC is described.