12-23 October 2020
GMT timezone

An FPGA-based Trigger System with Online Track Recognition in COMET Phase-I

14 Oct 2020, 16:11
Mini Oral and Poster Trigger Systems Poster session C-01


Mr NAKAZAWA, Yu (Osaka University)


The COMET Phase-I experiment plans to search for the muon-to-electron conversion with a single event sensitivity of $3\times10^{-15}$, which has never been observed. The event signature is a mono-energetic electron of $105\,\mathrm{MeV/c}$ for muonic atoms formed in aluminum. This electron is detected by a cylindrical drift chamber (CDC) and a trigger hodoscope in a 1-T solenoidal magnetic field.
A highly intense muon beam is used to reach our sensitivity goal. It gives an unacceptably high trigger rate for data acquisition. To solve this problem, we are developing an FPGA-based online trigger system where the CDC-hit information is utilized with machine learning (ML) technique. A classifier optimized by the ML is implemented on FPGAs in the form of small look-up tables (LUTs). Using them, this system finds out the conversion-electron events and significantly suppresses the background trigger rate. Adopting a distributed trigger architecture makes it possible to handle data for ~5000 CDC channels. All the processes need to be finished within the required latency which is limited by a buffer size of the CDC readout electronics. The LUTs carry out the ML-based classification in parallel within a clock cycle, and it keeps the latency short enough.
The trigger algorithm was implemented on the trigger-related electronics. In an operation test, the total latency was measured and met the requirement. The performance of the COTTRI system was estimated in a simulation study. In this presentation, we report details about the trigger algorithm, the operation-test result, and the expected performance.

Are you a student? Yes
Minioral Yes
IEEE Member No

Primary authors

Mr NAKAZAWA, Yu (Osaka University) Dr FUJII, Yuki (Monash University) Mr IKENO, Masahiro (High Energy Accelerator Research Organization (KEK)) Prof. KUNO, Yoshitaka (Osaka University) Dr LEE, MyeongJae (Institute for Basic Science (Korea)) Prof. MIHARA, Satoshi (KEK) Mr SHOJI, Masayoshi (High Energy Accelerator Research Organization (KEK)) Dr UCHIDA, Tomohisa (KEK) Dr UENO, Kazuki (KEK) Dr YOSHIDA, Hisataka (Osaka University)

Presentation materials