Searching for charged lepton flavour violation with the Mu3e experiment -- Data Acquisition

Mu 3e第一阶段实验的主要目标是寻找带电荷轻子味破坏衰变gamma -> e e e，在90%置信水平（CL）下BR（gamma -> e e e）< 5 × 10−15，与现有的界限相比，相应地提高了200倍。为了达到Mu 3e第一阶段的灵敏度目标，必须在大约一年的数据采集时间内观察到每秒10^8 μ子的衰变。由此产生的巨大数据速率必须通过数据采集（DAQ）系统从探测器中传输出来，并通过能够可靠有效地识别感兴趣的衰变的滤波器群来降低。为此，我们已经开发了一个紧凑的现场可编程门阵列（FPGA）和光链路为基础的DAQ和图形处理单元（GPU）为基础的过滤器农场和数据处理，重建和选择算法的实验。DAQ项目包括Mu 3e DAQ和过滤器场的建设、调试和校准以及维护和操作，以及过滤器场在线和离线的数据分析。

The main goal of the Mu3e Phase I experiment is the search for the charged lepton flavour violating decay gamma -> e e e with a sensitivity of BR(gamma -> e e e) < 5 × 10−15 at 90% confidence level (CL), corresponding to a factor 200 improvement compared to the existing bound. In order to reach the Mu3e Phase I sensitivity goal, of order 10^8 muon decays per second have to be observed for about a year of data taking time. The resulting enormous data rates have to be transported out of the detector by the data acquisition (DAQ) system and reduced by a filter farm capable of reliably and efficiently identifying decays of interest. To this end we have developed a compact Field Programmable Gate Array (FPGA) and optical link based DAQ and a Graphics Processing Unit (GPU) based filter farm and data processing, reconstruction and selection algorithms tailored to the experiment. The DAQ project includes the construction of the Mu3e DAQ and filter farm, their commissioning and calibration as well as maintenance and operation, and the data analysis, both on-line in the filter farm and off-line.