arXiv subjects

Jun Kai Ng

Publications and source records attributed to Jun Kai Ng.

6 recordsLinked to original sources

arXiv2026

Simulation study of accelerator-based muography using the GeV-scale forward muon component at SHINE

Muography exploits the penetrating power of muons to image the interior of large dense objects, but cosmic-ray sources provide only ~1 {cm}^{-2} {min}^{-1} predominantly from above, limiting imaging speed and accessible geometries. Electron-driven muon production has recently been demonstrated with laser-wakefield accelerators, but shot-to-shot fluctuations hinder systematic studies required for quantitative accelerator muography. Using Geant4 Monte Carlo simulations, we model the full experimental setup at Shaft 2 of the Shanghai High repetition rate XFEL and Extreme light facility (SHINE), from a 3 GeV, 50 pC, 50 Hz commissioning electron beam interacting with a muon target through 25 m of beamline structures and a 3 m-thick concrete isolation wall. Approximately 0.28 effective reconstructed single-muon events per bunch, with residual kinetic energies below 1.2 GeV after traversing the wall, reach the downstream muography test area (~14 s^{-1}). The wall absorbs most charged background particles below ~1 GeV, while residual neutrons can be discriminated by their characteristic detector energy deposition. Scattering-tomography simulations show that $3\times 10^{5}$ effective muon events, accumulated in approximately 6 h at the commissioning rate, yield a Structural Similarity Index above 0.9, demonstrating the feasibility of quantitative accelerator-based muography using SHINE's electron-driven GeV-scale forward muon source. At the 8 GeV/50 kHz benchmark, the projected muon intensity exceeds $5 \times 10^{4}$ μ/s, corresponding conservatively to approximately one muon per bunch at the detector. This exceeds the cosmic-ray flux by orders of magnitude, while SHINE's superconducting linac provides a stable, controlled platform for developing electron-on-target muography.

physics.acc-ph↗

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

Architecture of Tianyu Software: Relative Photometry as a Case Study

Tianyu telescope, an one-meter robotic optical survey instrument to be constructed in Lenghu, Qinghai, China, is designed for detecting transiting exoplanets, variable stars and transients. It requires a highly automated, optimally distributed, easily extendable, and highly flexible software to enable the data processing for the raw data at rates exceeding 500MB/s. In this work, we introduce the architecture of the Tianyu pipeline and use relative photometry as a case to demonstrate its high scalability and efficiency. This pipeline is tested on the data collected from Muguang observatory and Xinglong observatory. The pipeline demonstrates high scalability, with most processing stages increasing in throughput as the number of consumers grows. Compared to a single consumer, the median throughput of image calibration, alignment, and flux extraction increases by 41%, 257%, and 107% respectively when using 5 consumers, while image stacking exhibits limited scalability due to I/O constraints. In our tests, the pipeline was able to detect two transiting sources. Besides, the pipeline captures variability in the light curves of nine known and two previously unknown variable sources in the testing data. Meanwhile, the differential photometric precision of the light curves is near the theoretical limitation. These results indicate that this pipeline is suitable for detecting transiting exoplanets and variable stars. This work builds the fundation for further development of Tianyu software. Code of this work is available at https://github.com/ruiyicheng/Tianyu_pipeline.

astro-ph.IM↗

arXiv2025

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 $π$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↗