There exist numerous types of proton-proton collision events, and their occurrence is probabilistic. To investigate the origin of mass of elementary particles, and to search for new physics such as supersymmetry, a trigger system that efficiently selects extremely rare events plays an essential role.
At N Lab, we have been working on the construction and operation of the muon trigger, a system which selects events with high-momentum muons in the final state. By developing electronics for the TGC (Fig. 1), a multi-wire gas detector that can identify incoming muons every 25 nanoseconds, and by performing careful tuning and stable operation of the system, we led to the discovery of the Higgs boson, the origin of mass of elementary particles. In addition, we have taken initiative in the creation of a list of events to be selected by the triggers, and this has led to the realization of a variety of searches for new physics.
In the years 2025-2027, the LHC accelerator and the ATLAS detector will be significantly upgraded, to start the next-generation experiment that will generate proton-proton collisions at a rate 7.5 times higher than the current experiment. At the N Lab, we are developing an improved muon trigger system which will perform event selections more efficiently. To build a system with a high radiation resistance and a capability to transmit data at 3 terabytes per second, we are developing prototypes and verifying their performance (Fig. 2). We are also developing a front-end logic that can measure muon momenta with higher precision, and a back-end decision-making tool that incorporates multi-threading.
N-Lab is advancing the development, operation, and improvement of the trigger system that utilizes state-of-the-art technologies, by making use of our solid development skills. By realizing these activities, we will strongly support the development of elementary particle physics by proton-proton collision experiments at the world's highest energy.
Figure 1: TGC detector of the LHC-ATLAS experiment. This detector is a gigantic device with a height of 22 meters.
Figure 2: IGLOO2 integrated circuit test board with high radiation resistance (upper figure), and a prototype for the TGC front-end electronics with high-speed data transmission capability (lower figure).