ATLAS Level-0 Endcap Muon Trigger for HL-LHC

The design for the Level-0 endcap muon trigger of the ATLAS experiment at High-Luminosity LHC (HL-LHC) and the status of the development are presented. HL-LHC is planned to start the operation in 2026 with an instantaneous luminosity of $7.5 \times 10^{34}~\rm{cm^{-2}s^{-1}}$. In order to cope with the proton-proton collision rate higher than that of LHC, the trigger and readout system needs to be replaced. The new Level-0 endcap muon trigger system is required to reconstruct muon candidates with an improved momentum resolution to suppress the trigger rate with keeping the efficiency. That can be achieved by combining the signals from various subdetectors, thin gap chambers, resistive plate chambers, micromesh gaseous detectors, and scintillator-steel hadronic calorimeters, to form more offline-like tracks. The combined muon track reconstruction was demonstrated with Monte-Carlo simulation samples produced with the condition at HL-LHC. The efficiency was estimated to be greater than 90%, a few percents higher than the current system. The trigger rate was evaluated with proton-proton collision data taken with random trigger overlaid to account for a pileup of 200, which is expected at HL-LHC. The obtained value for momentum threshold of 20 GeV, primary threshold assumed for single muon trigger, is about 30 kHz, which constitutes only about 3% of the assumed total Level-0 trigger rate of 1 MHz. Hardware implementation is planned with ATCA blades. Each blade is designed to have a Virtex UltraScale+ FPGA with about hundred pairs of transceivers, which can be used to receive detector signals, and with huge memory resources suited for track reconstruction. The track reconstruction is based on a pattern matching algorithm using the detector hits and the predefined lists of hits corresponding to tracks. A memory resource UltraRAM integrated into the FPGA is exploited to store the predefined lists of hits. Initial test with the evaluation kit VCU118 showed high efficiency and angular resolution better than the requirement with reasonable memory resources. The bit error ratio of the data transmission with GTY transceivers was evaluated with transfer rates up to 25 Gbps. The power consumption of a hundred pairs of transmitter and receiver of GTY running with 10 Gbps, which is an average transfer rate assumed for the system, was evaluated to be about 30 W

ATLAS Level-0 Endcap Muon Trigger for HL-LHC

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

Upgrade of the ATLAS Thin Gap Chamber Electronics for HL-LHC runs

The High-Luminosity LHC (HL-LHC) is planned to start the operation in 2026 with an instantaneous luminosity of $7.5 \times 10^{34}~\rm{cm^{-2}s^{-1}}$. 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 $16~\rm{Gbps}$ 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

Development of the muon tracking trigger based on Thin Gap Chamber for the ATLAS experiment at High-Luminosity 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 $2.13 - 2.16$ was 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 $2.5 \times 10^{-16}$, and the power consumption for 100 pairs of transmitters and receivers was estimated to be about 30 W

Spatial patterns of oak (Quercus crispula) regeneration on scarification site around a conspecific overstory tree

Spatial patterns have been a major topic regarding natural regeneration of oak species, but the effects may differ considerably in sites subjected to intense forestry practices, which greatly alter many aspects of site conditions. We examined the hypothesis that the regeneration of oak (Quercus crispula Blume) following scarification (displacement of inhibiting vegetation and surface soil using machinery) is enhanced at a certain distance from a conspecific overstory tree, depending on the stage of development. We conducted both field surveys in scarification sites with different stand ages (1-16 year-old) and a laboratory seeding experiment to clarify factors contributing to its early establishment. The results demonstrate that the spatial relationship between the regeneration of oak and the conspecific overstory tree at scarification sites changes considerably among stages of the establishment. In the initial stage (0-1 years after the scarification), a location beneath the crown provided favorable conditions, whereas at subsequent stages (2-4 years), the distance-dependent effects were unclear, until eventually (8-16 years) a location outside the crown became more favorable. The condition produced by the scarification was basically competition-free and resource-rich, but it can also be harsh for acorns and small seedlings, imposing a requirement for shading to moderate the environment in the initial stage. Such an effect of facilitation was found also in the later (sapling) stage via the existence of neighbors of the other regenerated fast-growing species. The current findings supported the effectivity of a shelter-wood system, in which the regeneration starts from shaded condition followed by a gap status created by a successive felling. The area away from the conspecific crown would have a potential if acorns are plentifully supplied (e.g. by direct seeding) and they withstand the initial negative factors at the initial stage of development

Impact of the SCF signaling pathway on leukemia stem cell mediated ATL initiation and progression in an HBZ transgenic mouse model

Adult T-cell leukemia (ATL) is a malignant disease caused by human T-lymphotropic virus type 1. In aggressive ATL, the response to chemotherapy is extremely poor. We hypothesized that this poor response is due to the existence of chemotherapy-resistant cells, such as leukemic stem cells. Previously, we successfully identified an ATL stem cell (ATLSC) candidate as the c-kit+/CD38−/CD71− cells in an ATL mouse model using Tax transgenic mice. Here, with a new ATL mouse model usingHBZ-transgenic mice, we further discovered that the functional ATLSC candidate,which commonly expresses c-kit, is drug-resistant and has the ability to initiate tumors and reconstitute lymphomatous cells. We characterized the ATLSCs as c-kit+/CD4−/CD8− cells and found that they have a similar gene expression profile as T cell progenitors. Additionally, we found that AP-1 gene family members, includingJunb, Jund, and Fosb, were up-regulated in the ATLSC fraction. The results of an in vitro assay showed that ATLSCs cultured with cytokines known to promote stemcell expansion, such as stem cell factor (SCF), showed highly proliferative activity and maintained their stem cell fraction. Inhibition of c-kit–SCF signaling with theneutralizing antibody ACK2 affected ATLSC self-renewal and proliferation. Experiments in Sl/Sld mice, which have a mutation in the membrane-bound c-kit ligand, found that ATL development was completely blocked in these mice. These results clearly suggest that the c-kit–SCF signal plays a key role in ATLSC self-renewal and in ATL initiation and disease progression