Improving the dE/dx calibration of the STAR TPC for the high-pT hadron identification
Improving the dE/dx calibration of the STAR TPC for the high-pT hadron identification
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DOI：
10.1016/j.nima.2009.12.011
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发表时间：
2008-07
影响因子：
1.4
通讯作者：
Yichun Xu;O. Barannikova;H. Bichsel;Xin Dong;P. Fachini;Y. Fisyak;Adam Kocolosky;B. Mohanty;P. Netrakanti;L. Ruan;M. Suárez;Zebo Tang;G. Buren;Zhangbu Xu
中科院分区：
文献类型：
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作者：
Yichun Xu;O. Barannikova;H. Bichsel;Xin Dong;P. Fachini;Y. Fisyak;Adam Kocolosky;B. Mohanty;P. Netrakanti;L. Ruan;M. Suárez;Zebo Tang;G. Buren;Zhangbu Xu
利用星星上带电粒子穿过时间投影室（TPC）时电离能损失（dE/dx）的相对论性上升，推导出一种在高横动量（pT）下提高粒子识别（PID）的方法。由桶式电磁量热计（BEMC）触发和识别的电子、来自Λ（Λ-bar）的纯质子（反质子）和π介子以及KS 0衰变被用于获得给定βγ= p/m时的dE/dx值及其宽度。我们发现在2005年进行的200 GeV的p+ p碰撞实验中，dE/dx与Bichsel函数的偏差可达0.4 σ（± 3%）.该偏差近似为βγ的函数，与粒子种类无关，可用函数f（x）= A+ B/（C+ x2）来描述。用这种方法得到的偏差用于p+ p碰撞的数据样本中，对所识别的强子谱及其关联进行了物理分析，直到横动量为15 GeV/c。e-/e+的比值（主要来自γ-转换）也用于校正星星TPC中的剩余动量畸变。
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 (Λ-bar), and KS0 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 0.4 σ (∼ 3%) in p+ p collisions at√(sNN)= 200GeV 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.