Hierarchical trigger of the ALICE calorimeters
Hierarchical trigger of the ALICE calorimeters
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DOI：
10.1016/j.nima.2009.06.097
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发表时间：
2010-05
影响因子：
1.4
通讯作者：
H. Muller;T. Awes;N. Novitzky;J. Kral;J. Rak;J. Schambach;Yaping Wang;Dong Wang;D. Zhou
中科院分区：
文献类型：
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作者：
H. Muller;T. Awes;N. Novitzky;J. Kral;J. Rak;J. Schambach;Yaping Wang;Dong Wang;D. Zhou
ALICE电磁量热计的触发器在两个分层连接的电子层中实现。在低层，0级算法在局部限定的触发区域单元（TRU）中搜索阈值以上的簇射能量。顶层被实现为单个全局触发单元，其从所有TRU接收触发数据作为1级算法的输入。该架构最初是为PHOS高pTphoton触发器开发的，后来被EMCal采用，也用于喷射触发器。TRU单元从前端电子设备（FEE）接收多达112个模拟输入信号，并将其数字流集中在单个FPGA中。电荷和时间求和算法与峰值探测器相结合，抑制杂散噪声，并精确到单个LHC束。在150 MeV的峰-峰噪声水平下，阈值以上的线性动态范围从215 GeV的MIP能量跨越到50 GeV。LHC碰撞后，本地0级决策需要不到600 ns的时间，在此之后，所有TRU将其0级触发数据传输到上游全局触发模块，该模块在剩余的1级延迟内搜索高pTgamma簇射（PHOS）和/或射流锥区（EMCaL）。
The trigger of the ALICE electromagnetic calorimeters is implemented in 2 hierarchically connected layers of electronics. In the lower layer, level-0 algorithms search shower energy above threshold in locally confined Trigger Region Units (TRU). The top layer is implemented as a single, global trigger unit that receives the trigger data from all TRUs as input to the level-1 algorithm. This architecture was first developed for the PHOS high pTphoton trigger before it was adopted by EMCal also for the jet trigger. TRU units digitize up to 112 analogue input signals from the Front End Electronics (FEE) and concentrate their digital stream in a single FPGA. A charge and time summing algorithm is combined with a peakfinder that suppresses spurious noise and is precise to single LHC bunches. With a peak-to-peak noise level of 150MeV the linear dynamic range above threshold spans from MIP energies at 215 up to 50GeV. Local level-0 decisions take less than 600ns after LHC collisions, upon which all TRUs transfer their level-0 trigger data to the upstream global trigger module which searches within the remaining level-1 latency for high pTgamma showers (PHOS) and/or for Jet cone areas (EMCaL).