Improving the dE/dx calibration of the STAR TPC for the high-pT hadron identification
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- 作者：Yichun Xu ; Olga Barannikova ; Hans Bichsel ; Xin Dong ; Patricia Fachini ; Yuri Fisyak ; Adam Kocoloski ; Bedanga Mohanty ; Pawan Netrakanti ; Lijuan Ruan ; Maria Cristina Suarez ; Zebo Tang ; Gene van Buren ; Zh
- 关键词：TPC ; Ionization energy loss ; Relativistic rise
- 刊名：Nuclear Instruments and Methods in Physics Research Section A: Accelerators, Spectrometers, Detectors and Associated Equipment
- 出版年：2010
- 出版时间：21 February 2010
- 年：2010
- 卷：614
- 期：1
- 页码：28-33
- 全文大小：445 K
文摘
We derive a method to improve particle identification (PID) at high transverse momentum (pT) using the relativistic rise of the ionization energy loss (dE/dx) when charged particles traverse the Time Projection Chamber (TPC) at STAR. Electrons triggered and identified by the Barrel Electro-Magnetic Calorimeter (BEMC), pure protons (anti-protons) and pions from Λ (), and decays are used to obtain the dE/dx value and its width at given βγ=p/m. We found that the deviation of the dE/dx from the Bichsel function can be up to 0.4σ (3 % ) in p+p collisions at taken and subsequently calibrated in year 2005. The deviation is approximately a function of βγ independent of particle species and can be described with the function f(x)=A+B/(C+x2). The deviations obtained with this method are used in the data sample from p+p collision for physics analysis of identified hadron spectra and their correlations up to transverse momentum of 15 GeV/c. The ratio of e−/e+ (dominantly from γ-conversion) is also used to correct for the residual momentum distortion in the STAR TPC.