Haruka Asada

The International Linear Collider (ILC) is on the table now as a new global energy-frontier accelerator laboratory taking data in the 2030s. The ILC addresses key questions for our current understanding of particle physics. It is based on a proven accelerator technology. Its experiments will challenge the Standard Model of particle physics and will provide a new window to look beyond it. This document brings the story of the ILC up to date, emphasizing its strong physics motivation, its readiness for construction, and the opportunity it presents to the US and the global particle physics community.

The High-Luminosity LHC (HL-LHC) is planned to start the operation in 2026 with an instantaneous luminosity of 7.5×10 34 cm -2 s -1 .In order to cope with higher proton-proton collision rate, the trigger and readout electronics of ATLAS Thin Gap Chamber (TGC) needs to be replaced.All hit data will be transferred from the frontend to the backend boards, and a fast-tracking algorithm will be applied on these hits for the first-level muon triggering.The first prototype of the frontend board has been developed with full functions required for HL-LHC runs including the data transfer of 256 channels with a 16 Gbps bandwidth and the control of the discriminator threshold.They were demonstrated at the CERN SPS beam facility.The rate of single event upsets in Kintex-7 FPGA integrated on the prototype board was measured in the ATLAS detector area, and automatic error correction was demonstrated.The fast-tracking algorithm was performed using a Monte-Carlo sample and data taken by ATLAS.The result indicates that the advanced trigger based on fast-tracking reduces the trigger rate by 30% while increasing the efficiency by a few percent.These studies provide essential ingredients in the development of ATLAS TGC electronics for HL-LHC.

The ATLAS trigger system is essential to efficiently select the events of high interest for physics analyses.Development of a new muon trigger is ongoing for High-Luminosity LHC, which is scheduled to start in 2026.The first stage of the new trigger system assumes muon track reconstruction from Thin Gap Chamber (TGC) hits with an angular resolution of 4 mrad.An algorithm with pattern matching for a pseudorapidity range of 2.13-2.16was implemented in an XCVU9P FPGA and demonstrated with test samples including seven hits on seven TGC layers.The implemented algorithm reconstructed tracks successfully with an angular resolution of less than 4 mrad.In addition, GTY transceiver on XCVU9P FPGA was tested.Measured bit error ratio was less than 2.5 × 10 -16 , and the power consumption for 100 pairs of transmitters and receivers was estimated to be about 30 W.

The design of the Level-0 endcap muon trigger for the ATLAS experiment at the High-Luminosity LHC (HL-LHC) and the status of the system development are presented. The HL-LHC is planned to start the operation in 2026. The peak luminosity will ultimately reach $\mathcal{L} = 7.5 \times 10^{34}~\rm{cm^{-2}s^{-1}}$. The new Level-0 endcap muon trigger system reconstructs primitive muon candidates using Thin Gap Chamber~(TGC) hits with an improved momentum resolution to suppress the trigger rate, while achieving an efficiency better than the current system. A high-speed serial link between TGC on-detector and off-detector boards with the recovery clock was demonstrated, and the bit error ratio was found to be lower than $4.8 \times 10^{-16}$. The track reconstruction of primitive muon candidates is based on a pattern-matching algorithm using predefined sets of hits corresponding to tracks. An initial test of the algorithm with the Xilinx evaluation kit VCU118 showed a high efficiency with reasonable memory resources. The muon candidate selection with several subdetectors in the inner layers was demonstrated, using Monte Carlo simulation samples produced with HL-LHC conditions. The selection efficiency for a single muon was estimated to be greater than 90\%, a few percent higher than the current system. The rate was evaluated with proton-proton collision data taken with the random trigger overlaid to account for a number of pileup events of 200, which is expected at the HL-LHC. The obtained value for the momentum threshold of $20~\rm{GeV}$, the primary threshold assumed for a single muon trigger, is about $30~\rm{kHz}$. Precise momentum determination by Monitored Drift Tube is expected to further reduce the rate.

The design of the Level-0 endcap muon trigger for the ATLAS experiment at the High-Luminosity LHC (HL-LHC) and the status of the system development are presented.The HL-LHC is planned to start the operation in 2026.The peak luminosity will ultimately reach L = 7.5×10 34 cm -2 s -1 .The new Level-0 endcap muon trigger system reconstructs primitive muon candidates using Thin Gap Chamber (TGC) hits with an improved momentum resolution to suppress the trigger rate, while achieving an efficiency better than the current system.A high-speed serial link between TGC on-detector and off-detector boards with the recovery clock was demonstrated, and the bit error ratio was found to be lower than 4.8 × 10 -16 .The track reconstruction of primitive muon candidates is based on a pattern-matching algorithm using predefined sets of hits corresponding to tracks.An initial test of the algorithm with the Xilinx evaluation kit VCU118 showed a high efficiency with reasonable memory resources.The muon candidate selection with several subdetectors in the inner layers was demonstrated, using Monte Carlo simulation samples produced with HL-LHC conditions.The selection efficiency for a single muon was estimated to be greater than 90%, a few percent higher than the current system.The rate was evaluated with protonproton collision data taken with the random trigger overlaid to account for a number of pileup events of 200, which is expected at the HL-LHC.The obtained value for the momentum threshold of 20 GeV, the primary threshold assumed for a single muon trigger, is about 30 kHz.Precise momentum determination by Monitored Drift Tube is expected to further reduce the rate.

The International Linear Collider (ILC) is on the table now as a new global energy-frontier accelerator laboratory taking data in the 2030s. The ILC addresses key questions for our current understanding of particle physics. It is based on a proven accelerator technology. Its experiments will challenge the Standard Model of particle physics and will provide a new window to look beyond it. This document brings the story of the ILC up to date, emphasizing its strong physics motivation, its readiness for construction, and the opportunity it presents to the US and the global particle physics community.