arXiv subjects

Tianqi Hu

Publications and source records attributed to Tianqi Hu.

9 recordsLinked to original sources

arXiv2026

Construction and characterization of a muon trigger detector for the PSI muEDM experiment

We present the upgraded design, construction, and beam test results for the Muon Trigger Detector (MTD) developed for the muon Electric Dipole Moment (muEDM) experiment at the Paul Scherrer Institute (PSI) in Switzerland. This experiment aims to improve the sensitivity of the muon EDM measurement by more than three orders of magnitude beyond the current limit established by the BNL Muon $g-2$ experiment. Precise identification of storable incoming muons at the entrance of the storage solenoid is essential, as the MTD must rapidly trigger a pulsed magnetic kicker to confine muons in the central region of the solenoid, where a weakly focusing magnetic field is maintained. The MTD comprises two subsystems: a \SI{0.1}{mm}-thick plastic scintillator ``gate detector'' read out by four silicon photomultipliers (SiPMs), and a \SI{5}{mm}-thick CNC-machined plastic scintillator ``active aperture detector'' read out by six SiPMs. The geometry of the active aperture detector was optimized through acceptance studies to maximize both storage efficiency and background veto efficiency. Integrated fast electronics generate an LVTTL trigger signal under an anti-coincidence condition -- a muon detected in the gate but not in the aperture -- ensuring selective triggering of storable muon events for the EDM measurement. The system was tested at the PSI $\pi$E1 beamline using \SI{22.5}{MeV/\textit{c}} muons under scaled-down conditions to characterize detector response and trigger performance. A Geant4 simulation incorporating detailed optical photon transport and SiPM response modeling was developed and reproduces the measured event topologies with ${\sim}97\%$ agreement. These results validate the detector design and demonstrate the MTD's readiness for deployment in the full muEDM Phase-1 setup.

physics.ins-det↗

arXiv2026

Plant Taxonomy Meets Plant Counting: A Fine-Grained, Taxonomic Dataset for Counting Hundreds of Plant Species

Visually cataloging and quantifying the natural world requires pushing the boundaries of both detailed visual classification and counting at scale. Despite significant progress, particularly in crowd and traffic analysis, the fine-grained, taxonomy-aware plant counting remains underexplored in vision. In contrast to crowds, plants exhibit nonrigid morphologies and physical appearance variations across growth stages and environments. To fill this gap, we present TPC-268, the first plant counting benchmark incorporating plant taxonomy. Our dataset couples instance-level point annotations with Linnaean labels (kingdom -> species) and organ categories, enabling hierarchical reasoning and species-aware evaluation. The dataset features 10,000 images with 678,050 point annotations, includes 268 countable plant categories over 242 plant species in Plantae and Fungi, and spans observation scales from canopy-level remote sensing imagery to tissue-level microscopy. We follow the problem setting of class-agnostic counting (CAC), provide taxonomy-consistent, scale-aware data splits, and benchmark state-of-the-art regression- and detection-based CAC approaches. By capturing the biodiversity, hierarchical structure, and multi-scale nature of botanical and mycological taxa, TPC-268 provides a biologically grounded testbed to advance fine-grained class-agnostic counting. Dataset and code are available at https://github.com/tiny-smart/TPC-268.

cs.CV↗

arXiv2025

Nanomechanics of Shear Rate-Dependent Stiffening in Micellar Electrically Conductive Polymers

Electrically conducting polymers with mechanical adaptability are essential for flexible electronics, yet most suffer structural degradation under rapid deformation. In this study, multiscale coarse-grained (MSCG) simulations are used to uncover the nanoscale origins of an unusual strain-rate-dependent stiffening in a poly(2-acrylamido-2-methyl-1-propanesulfonic acid) (PAMPSA)-polyaniline (PANI) blend. The self-assembled morphology consists of semi-crystalline PANI-rich micellar cores dispersed in a soft, viscoelastic PAMPSA matrix. At low shear rates, micelles migrate and coalesce into larger aggregates, enhancing local crystallinity and transient entanglement density while dissipating stress through matrix deformation. At high shear rates, micelles cannot reorganize quickly enough, leading to core dissociation and the emergence of highly aligned PANI filaments that directly bear the load, with PAMPSA serving as a weak but extended support phase. These contrasting regimes (densification-driven local alignment versus dissociation-driven global alignment) enable reversible mechanical stiffening across three orders of magnitude in shear rate. The results provide a molecular-level framework for designing solid-state polymers with tunable, rate-adaptive mechanical properties.

cond-mat.soft↗

arXiv2025

First Place Solution to the MLCAS 2025 GWFSS Challenge: The Devil is in the Detail and Minority

In this report, we present our solution during the participation of the MLCAS 2025 GWFSS Challenge. This challenge hosts a semantic segmentation competition specific to wheat plants, which requires to segment three wheat organs including the head, leaf, and stem, and another background class. In 2025, participating a segmentation competition is significantly different from that in previous years where many tricks can play important roles. Nowadays most segmentation tricks have been well integrated into existing codebases such that our naive ViT-Adapter baseline has already achieved sufficiently good performance. Hence, we believe the key to stand out among other competitors is to focus on the problem nature of wheat per se. By probing visualizations, we identify the key -- the stem matters. In contrast to heads and leaves, stems exhibit fine structure and occupy only few pixels, which suffers from fragile predictions and class imbalance. Building on our baseline, we present three technical improvements tailored to stems: i) incorporating a dynamic upsampler SAPA used to enhance detail delineation; ii) leveraging semi-supervised guided distillation with stem-aware sample selection to mine the treasure beneath unlabeled data; and iii) applying a test-time scaling strategy to zoom in and segment twice the image. Despite being simple, the three improvements bring us to the first place of the competition, outperforming the second place by clear margins. Code and models will be released at https://github.com/tiny-smart/gwfss25.

cs.CV↗

arXiv2025

Towards Non-Invasive Sediment Monitoring Using Muography: A Pilot Run at the Shanghai Outer Ring Tunnel

This study demonstrates the application of cosmic-ray muography as a non-invasive method for monitoring sediment accumulation and tidal influences in the Shanghai Outer Ring Tunnel, an immersed tube tunnel located beneath the Huangpu River in Shanghai, China. A portable, dual-layer plastic scintillator detector was deployed to conduct muon flux scans along the tunnel's length and to continuously monitor muon flux, allowing for the study of tidal effects. Geant4 simulations validated the correlation between muon attenuation and overburden thickness, incorporating sediment, water, and concrete layers. Key findings include a strong anti-correlation between the measured muon flux and the water levels observed at a nearby tide gauge. The results align with geotechnical data and simulations, especially in the region of interest, confirming muography's sensitivity to sediment dynamics. This work establishes muography as a robust tool for long-term, real-time monitoring of submerged infrastructure, offering significant advantages over conventional invasive techniques. The study underscores the potential for integrating muography into civil engineering practices to enhance safety and operational resilience in tidal environments.

physics.app-ph↗

arXiv2025

Bayesian optimization of beam injection and storage in the PSI muEDM Experiment

The muEDM experiment at the Paul Scherrer Institute aims to measure the electric dipole moment with an unprecedented sensitivity of $6 \times 10^{-23}\,\mathrm{e}\cdot\mathrm{cm}$. A key aspect of this experiment is the injection and storage of the muon beam, which traverses a long, narrow superconducting channel before entering a solenoid magnet. The muon is then kicked by a pulsed magnetic field into a stable orbit within the solenoid's central region, where the electric dipole moment is measured. To study the beam injection and storage process, we developed a G4beamline simulation to model the dynamics of beam injection and storage, incorporating all relevant electric and magnetic fields. We subsequently employed a Bayesian optimization technique to improve the muon storage efficiency for Phase I of the muEDM experiment. The optimization is demonstrated using data simulated by G4beamline. We have observed an enhancement in the beam injection and storage efficiency, which increased to 0.556\% through the utilization of Bayesian optimization with Gaussian processes, compared to 0.324\% when employing the polynomial chaos expansion. This approach can be applied to adjust actual experimental parameters, aiding in achieving the desired performance for beam injection and storage in the muEDM experiment.

physics.acc-ph↗

arXiv2025

Development of Fast Front-End Electronics for the Muon Trigger Detector in the PSI muEDM Experiment

This paper outlines the design and development of a fast front-end electronic readout board for the muon trigger detector in the muEDM experiment at the Paul Scherrer Institute. The trigger detector, which consists of a gate and aperture detector, is strategically located at the end of the superconducting injection channel to generate trigger signals for a magnetic kicker, which activates upon the injection of muons into the central region of the storage solenoid. Within the magnetic field of the solenoid, the system configuration is optimized to meet stringent performance specifications, including minimal signal propagation delays, high detection efficiency, non-magnetic properties, and consistent operational stability under varying experimental conditions. Additionally, the design incorporates robust methods for rejecting positron contamination in the muon beamline. The results presented include performance evaluations from both bench testing and actual beam tests, highlighting the effectiveness and reliability of the electronic design.

physics.ins-det↗

arXiv2024

Beam test performance of a prototype muon trigger detector for the PSI muEDM experiment

We report on the performance evaluation of a prototype muon trigger detector for the PSI muEDM experiment, conducted as a proof-of-principle test at the $\pi$E1 beamline of the Paul Scherrer Institute (PSI) using \SI{27.5}{MeV/c} muons. The detector is designed to identify muons within the acceptance phase space of a compact storage solenoid and activate a pulsed magnetic kicker for muon storage; it was tested without the application of a magnetic field. It comprises a telescope made up of four scintillators in anticoincidence with a gate scintillator, all read out by silicon photomultipliers. The study focused on characterizing the detector's response to various muon trajectories and the light yield of its plastic scintillators. Experimental results demonstrated strong agreement with Geant4 Monte Carlo simulations that incorporate optical photon modeling, confirming the detector's concept and its potential for meeting the stringent requirements of the muEDM experiment.

physics.ins-det↗

arXiv2023

Status of the muEDM experiment at PSI

Permanent electric dipole moments (EDMs) are excellent probes of physics beyond the Standard Model, especially on new sources of CP violation. The muon EDM has recently attracted significant attention due to discrepancies in the magnetic anomaly of the muon, as well as potential violations of lepton-flavor universality in B-meson decays. At the Paul Scherrer Institute in Switzerland, we have proposed a muon EDM search experiment employing the frozen-spin technique, where a radial electric field is exerted within a storage solenoid to cancel the muon's anomalous spin precession. Consequently, the EDM signal can be inferred from the upstream-downstream asymmetry of the decay positron count versus time. The experiment is planned to take place in two phases, anticipating an annual statistical sensitivity of $3\times10^{-21}$ $e\cdot$cm for Phase~I, and $6\times10^{-23}$ $e\cdot$cm for Phase~II. Going beyond $10^{-21}$ $e\cdot$cm will enable us to probe various Standard Model extensions.

hep-ex↗