arXiv subjects

Siew Yan Hoh

Publications and source records attributed to Siew Yan Hoh.

6 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 $π$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↗

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↗

arXiv2015

Dark Matter Searches at the Large Hadron Collider

Dark Matter is a hypothetical particle proposed to explain the missing matter expected from the cosmological observation. The motivation of Dark Matter is overwhelming however as it is mainly deduced from its gravitational interaction, for it does little to pinpoint what Dark Matter really is. In WIMPs Miracle, weakly interactive massive particle being the Dark Matter candidate is correctly producing the current thermal relic density at weak scale, implying the possibility of producing and detecting it in Large Hadron Collider. Assuming WIMPs being the maverick particle within collider, it is expected to be pair produced in association with a Standard Model particle. The presence of the WIMPs pair is inferred from the Missing Transverse Energy (MET) which is the vector sum of the imbalance in the transverse momentum plane recoils a Standard Model Particle. The collider is able to produce light mass Dark Matter which the traditional detection fail to detect due to the small momentum transfer involved in the interaction; on the other hand, the traditional detection is robust in detecting a higher Dark matter masses but the collider is su ered from the parton distribution function suppression. Topologically the processes are similar to the scattering processes in the direct detection thus complementary to the traditional Dark Matter detection. The collider searches are strongly motivated as the results are usually translated to the annihilation and scattering rates at more traditional Dark Matter-oriented experiments, thus a concordance approach is adapted. An overview of Dark Matter searches at the Large Hadron Collider will be covered in this paper.

hep-ex↗

arXiv2015

Dark Matter Benchmark Models for Early LHC Run-2 Searches: Report of the ATLAS/CMS Dark Matter Forum

This document is the final report of the ATLAS-CMS Dark Matter Forum, a forum organized by the ATLAS and CMS collaborations with the participation of experts on theories of Dark Matter, to select a minimal basis set of dark matter simplified models that should support the design of the early LHC Run-2 searches. A prioritized, compact set of benchmark models is proposed, accompanied by studies of the parameter space of these models and a repository of generator implementations. This report also addresses how to apply the Effective Field Theory formalism for collider searches and present the results of such interpretations.

hep-ex↗