Commissioning of the ALICE-PHOS trigger
Commissioning of the ALICE-PHOS trigger
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DOI：
10.1088/1742-6596/293/1/012062
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发表时间：
2011-04
期刊：
影响因子：
--
通讯作者：
Lijiao Liu
中科院分区：
文献类型：
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作者：
Lijiao Liu
LHC ALICE 实验的光子能谱仪 (PHOS) 是一款高分辨率电磁量热仪，专用于精确测量 p+p 和 Pb+Pb 碰撞中的直接光子和中性介子产率，pT 范围高达 100 GeV/c。多级触发系统选择感兴趣的事件并减少总体数据流。 PHOS 生成两个触发器： i) 用于高光度 p+p 运行的 0 级 (L0) 触发器，主要充当光谱仪触发器，并用于选择 Pb+Pb 和 p+p 碰撞中的高 pT 光子； ii) Level1 (L1) 触发器对应于更复杂的簇射分析，可细化 pT 选择。该算法对过采样雪崩光电二极管 (APD) 信号执行脉冲形状分析，然后使用滑动窗口簇查找器。两种触发器均在固件中实现，由于使用了基于 SRAM 的 FPGA，因此可以在运行之间在线更改。触发系统是由宇宙射线和粒子相互作用产生的。将呈现触发系统的状态和第一个结果。
The Photon Spectrometer (PHOS) of the ALICE experiment at LHC is a high-resolution electromagnetic calorimeter dedicated to the precise measurement of direct photon and neutral meson yields in p+p and Pb+Pb collisions at mid-rapidity in a pT range up to 100 GeV/c. A multi-level trigger system selects events of interest and reduces the overall data flow. PHOS generates two triggers: i) the Level 0 (L0) trigger for high luminosity p+p runs acting mainly as a spectrometer trigger and for selecting high pT photons in Pb+Pb and in p+p collisions; ii) the Level1 (L1) trigger corresponds to a more sophisticated shower analysis which refines the pT selection. The algorithms perform a pulse-shape analysis of the oversampled Avalanche Photo Diode (APD) signal followed by a sliding-window cluster finder. Both triggers are implemented in the firmware which, since SRAM-based FPGAs are used, can be changed on-line between runs. The trigger system was commissioned by cosmic rays and particles from interactions. The status of the trigger system and first results will be presented.