Speaker
Description
The COMET experiment searches for the coherent neutrinoless conversion of a muon to an electron in an aluminum atomic nucleus, a charged Lepton Flavor Violation process forbidden in the Standard Model. The experiment proceeds in two phases, with Phase-I aiming for a single event sensitivity of $3×10^{-15}$—improving the current limit by a factor of 100—using a high-intensity proton beam to produce stopped muons.
The Cylindrical Detector System (CyDet), which is the main detector system in COMET Phase-I,consists of the Cylindrical Drift Chamber (CDC) for momentum measurement and the Cylindrical Trigger Hodoscope (CTH) for primary trigger generation and timing measurement. The trigger system is required to operate with a latency below 7 μs due to hardware constraints, and the maximum trigger rate is limited by the data acquisition (DAQ) system. Under high-intensity beam conditions, many background hits are
expected to occur, with an accidental trigger of about 200 kHz at CTH.
To address this, a new multi-stage trigger system has been developed using 86 CDC readout boards,10 trigger front-end boards, and one merger board. The production of all boards has been completed, and the assembly and performance assessments are ongoing. The system has achieved 3.2 μs trigger latency and a communication error rate between electronics below $4.6 × 10^{-5}$ /s, satisfying the requirement for a DAQ livetime above 99% at a 95% confidence level.
On the software side, an online software framework that consists of DAQ and slow control (SC) systems is also being developed. To handle the expected high trigger rates and ensure scalable, reliable data processing, the DAQ system is being upgraded using the NestDAQ, which provides a distributed and asynchronous DAQ architecture that eliminates central bottlenecks. A real-time Data Quality Monitoring system has been developed and successfully tested with CDC using cosmic-ray events, confirming the
feasibility of a fully distributed DAQ environment. For SC, the SlowDash platform offers a web-based SC interface for device control and status monitoring, supporting modern communication protocols and databases. The COMET SC platform is now being developed to integrate seamlessly with the CDC system.
In this presentation, we report the current status and performance of the CDC trigger system and the progress in developing the online framework for COMET Phase-I.
