arXiv subjects

Henry Tsz-King Wong

Publications and source records attributed to Henry Tsz-King Wong.

14 recordsLinked to original sources

arXiv2026

Estimation of systematic error from bulk deformation of end test mass induced by photon calibrator for LIGO post-O5 gravitational wave projects

We studied the bulk deformation of the end test masses (ETMs) of gravitational wave (GW) detectors caused by calibration devices named Photon Calibrator (Pcal). This bulk deformation is one of the source of calibration error since it induces non-linear displacement from the ideal pendulum motion of the ETM. Particularly, it is the dominant error source above 1500 Hz which is crucial to the studies of neutron star mergers. The displacement also depends on beam offsets of the main interferometer (IFO) beam and Pcal beams. We conceptually described frequency dependent effect of bulk deformation and evaluated it in several cases of the beam offset with finite-element analysis (FEA) software, for ETM models of Advanced LIGO (aLIGO), KAGRA, Advanced Virgo (AdVirgo), and LIGO A#.

astro-ph.IM↗

arXiv2026

Unified framework for precise background modeling to enhance rare event detection at the Kuo-Sheng nuclear reactor laboratory

A comprehensive GEANT4 simulation framework was developed to model the background of the TEXONO experiment, including contributions from radioactive isotopes in detector components and the surrounding environment. The HPGe detector front-end electronics (pre-amplifier) were modeled with trace amounts of naturally occurring radionuclides 238U, 232Th, and 235U from manufacturing materials. Results show that the 238U and 232Th decay chains dominate the background below 400 keV, each contributing O(1) counts kg^-1 keV^-1 day^-1. Trace impurities were also introduced into the anti-Compton veto (ACV) detectors to represent realistic materials: 40K in the NaI(Tl) crystal and 137Cs in the CsI(Tl) detector. Simulations identified measurable background contributions from both isotopes, with the residual spectrum dominated by 40K gamma-rays and smaller contributions from 137Cs. The 40K background rate is about 0.1 counts kg^-1 keV^-1 day^-1, nearly 10 times larger than that from 137Cs below 400 keV. Environmental radioactivity was modeled using 60Co, 54Mn, and 135Xe distributed in the air gap between the copper end-cap and the NaI(Tl) ACV detector, representing airborne and surface contamination. These sources contribute minor background components below 100 keV, at levels of about 10^-2, 10^-2, and 0.1 counts kg^-1 keV^-1 day^-1 for 135Xe, 54Mn, and 60Co, respectively. Comparison of simulated and measured spectra shows good overall agreement, with only minor deviations at specific gamma-lines, validating the background model and demonstrating the robustness of the simulation framework for detector and shielding design.

hep-ex↗

arXiv2026

CHRONOS: Cryogenic sub-Hz cROss torsion bar detector with quantum NOn-demolition Speed meter

We propose a next-generation ground-based gravitational-wave detector, Cryogenic sub-Hz cROss torsion-bar detector with quantum NOn-demolition Speed meter (CHRONOS), optimized for the unexplored $0.1$-$10\,\mathrm{Hz}$ band between the space-based LISA and future ground-based detectors such as Cosmic Explorer and the Einstein Telescope. CHRONOS combines a ring-cavity Sagnac interferometer with torsion-bar test masses to realize the first quantum nondemolition (QND) measurement of angular momentum in a macroscopic system. By implementing a speed-meter readout in the rotational degree of freedom, CHRONOS coherently cancels quantum radiation-pressure noise and enables sub-Hz observations. We calculate, for the first time, that detuned power-recycling and cavity-length optimization can simultaneously relax technical requirements on both torsion bars and speed meters. Assuming a realistic optical design with 1m torsion bar, we estimate strain sensitivities of $h \simeq 5\times10^{-19}\,\mathrm{Hz^{-1/2}}$ at $2\,\mathrm{Hz}$ for detectors with arm lengths of $2.5$ m, $40$ m, and $300$ m. These sensitivities enable (i) direct detection of intermediate-mass black hole binaries up to 340\,Mpc with SNR=3, (ii) probing SGWB down to $Ω_{\mathrm{GW}}\sim\ 3\times10^{-4}$ at 0.2 Hz with 5 year accumulation. Furthermore, CHRONOS enable to prompt detection of gravity-gradient signals from M 5.5 earthquakes even with a $2.5$ m prototype. CHRONOS thus opens new opportunities for quantum-limited geophysical observation and multi-band, multi-messenger gravitational-wave astronomy.

astro-ph.IM↗

arXiv2025

Molecular Dynamics Simulations on Nuclear Recoils in Silicon Crystals towards Single Electron-Hole Pair Ionization Yields

We have developed a novel methodology utilizing molecular dynamics simulations to evaluate the ionization yields of nuclear recoils in crystalline silicon. This approach enables analytical exploration of atomic-scale transport within the lattice without necessitating parameterization. The quenching factors across the nuclear recoil energy range from 20 eV to 10 keV have been thoroughly investigated. A remarkable agreement with experimental data is achieved, particularly for the minimal energy regime conducted to date, reaching the level of a single electron-hole pair. This work presents evidence of a crucial and fundamental distribution of the quenching factor, which can be associated to the collisional interactions underlying the transport phenomena. The region below 4 keV of the quenching factor, where discrepancies have been observed with the Lindhard's model, is found to be significantly attributed to the lattice binding effect and the specific crystal structure. In contrast, a gradual functional relationship is identified below approximately 100 eV, indicating that the quenching factor is influenced by the crystallographic orientation of the target material. From a distributional perspective, our analysis allows for the determination of the minimum exclusion mass for the dark matter nucleon elastic scattering channel at 0.29 $\mathrm{GeV}/c^2$, thereby significantly enhancing sensitivity for the sub-$\mathrm{GeV}/c^2$ mass region.

astro-ph.IM↗

arXiv2025

Germanium Atomic Compton Scattering Measurements and ${ab}$ ${initio}$ Many-Body Calculations: Implications for Electronic recoil Dark Matter Detection

Diverse searches for direct dark matter (DM) in effective electromagnetic and leptophilic interactions resulting from new physics, as well as Weakly Interacting Massive Particles (WIMPs) with unconventional electronic recoils, are intensively pursued. Low-energy backgrounds from radioactive $γ$ rays via Compton scattering and photon coherent scattering are unavoidable in terrestrial detectors. The interpretation of dark matter experimental data is dependent on a better knowledge of the background in the low-energy region. We provide a 2.3% measurement of atomic Compton scattering in the low momentum transfer range of 180 eV/c to 25 keV/c, using a 10-g germanium detector bombarded by a $^{137}\mathrm{Cs}$ source with a 7.2 m-Curie radioactivity and the scatter photon collected by a cylindrical NaI[Tl] detector. The ability to detect Compton scattering's doubly differential cross section (DDCS) gives a special test for clearly identifying the kinematic restraints in atomic many-body systems, notably the Livermore model. Additionally, a low-energy-background comparison is made between coherent photon scattering and Compton scattering replacing the scattering function of ${GEANT4}$@software, which uses a completely relativistic impulse approximation (RIA) together with Multi-Configuration Dirac-Fock (MCDF) wavefunctions. For the purpose of investigating sub-GeV mass and electronic-recoil dark matter theories, signatures including low energy backgrounds via high energy $γ$ rays in germanium targets are discussed.

astro-ph.IM↗

arXiv2025

Bulk-Surface Event Discrimination in Point Contact Germanium Detectors at Near-Threshold Energies with Shape-Matching Pulse-Shape Methods

The p-type point-contact germanium (pPCGe) detectors have been widely adopted in searches for low energy physics events such as neutrinos and dark matter. This is due to their enhanced capabilities of background rejection, sensitivity at energies as low as the sub-keV range and particularly fine energy resolution. Nonetheless, the pPCGe is subject to irregular behaviour caused by surface effects for events near the passivated surface. These surface events can, in general, be distinguished from events that occur in the germanium crystal bulk by its slower pulse rise time. Unfortunately, the rise-time spectra of bulk and surface events starts to convolve with each other at sub-keV energies. In this work, we propose a novel method based on cross-correlation shape-matching combined with a low-pass filter to constrain the initial parameter estimates of the signal pulse. This improvement at the lowest level leads to a 50% reduction in computation time and refinements in the rise-time resolution, which will, in the end, enhance the overall analysis. To evaluate the performance of the method, we simulate artificial pulses that resembles bulk and surface pulses by using a programmable pulse generator module (pulser). The pulser-generated pulses are then used to examine the pulse behaviours at near-threshold energies, suggesting a roughly 70% background-leakage reduction in the bulk spectrum. Finally, the method is tested on data collected from the TEXONO experiment, where the results are consistent with our observations in pulser and demonstrated the possibility of lowering the analysis threshold by at least 10eV.

physics.ins-det↗

arXiv2024

Signatures of afterglows from light dark matter boosted by supernova neutrinos in current and future large underground detectors

Supernova neutrino boosted dark matter (SN$ν$ BDM) and its afterglow effect have been shown to be a promising signature for beyond Standard Model (bSM) physics. The time-evolution feature of SN$ν$ BDM allows for %the possibly direct inference of DM mass $m_χ$, and results in significant background suppression with improving sensitivity. This paper extends the earlier study and provides a general framework for computing the SN$ν$ BDM fluxes for a supernova that occurs at any location in our galaxy. A bSM $U(1)_{L_μ-L_τ}$ model with its gauge boson coupling to both DM and the second and third generation of leptons is considered, which allows for both DM-$ν$ and DM-$e$ interactions. Detailed analysis of the temporal profile, angular distribution, and energy spectrum of the SN$ν$ BDM are performed. Unique signatures in SN$ν$ BDM allowing extraction of $m_χ$ and detail features that contain information of the underlying interaction type are discussed. Expected sensitivities on the above new physics model from Super-Kamiokande, Hyper-Kamiokande, and DUNE detections of BDM events induced by the next galactic SN are derived and compared with the existing bounds.

hep-ph↗

arXiv2024

Searching for Afterglow: Light Dark Matter Boosted by Supernova Neutrinos

A novel analysis is performed, incorporating time-of-flight (TOF) information to study the interactions of dark matter (DM) with standard model particles. After supernova (SN) explosions, DM with mass $m_χ\lesssim\mathcal{O}({\rm MeV})$ in the halo can be boosted by SN neutrinos (SN$ν$) to relativistic speed. The SN$ν$ boosted DM (BDM) arrives on Earth with TOF which depends only on $m_χ$ and is independent of the cross section. These BDMs can interact with detector targets in low-background experiments and manifest as afterglow events after the arrival of SN$ν$. The characteristic TOF spectra of the BDM events can lead to large background suppression and unique determination of $m_χ$. New cross section constraints on $\sqrt{σ_{χe} σ_{χν}}$ are derived from SN1987a in the Large Magellanic Cloud with data from the Kamiokande and Super-Kamiokande experiments. Potential sensitivities for the next galactic SN with Hyper-Kamiokande are projected. This analysis extends the existing bounds on $\sqrt{σ_{χe}σ_{χν}}$ over a broad range of $r_χ=σ_{χν}/σ_{χe}$. In particular, the improvement is by 1-3 orders of magnitude for $m_χ<\mathcal{O}(100\,{\rm keV})$ for $σ_{χe}\simσ_{χν}$. Prospects of exploiting TOF information in other astrophysical systems to probe exotic physics with other DM candidates are discussed.

hep-ph↗

arXiv2023

Exploring dark photons via a subfrequency laser searchin gravitational wave detectors

We propose a novel idea to detect a dark photon in gravitational wave experiments. Our setups are capable of performing the whole process of dark photon production, its decay products, and new physics signal discovery. This mini-LHC is inspired by the recent idea of dark photon detection using laser light in light shining through the wall (LSW) experiments such as ALPS II. Taking the subfrequency light emitted from the laser source as the new physics signal, we show that the sensitivity of our proposal is 2orders of magnitude better than the original idea in the LSW studies.

hep-ph↗

arXiv2018

Required sensitivity to search the neutrinoless double beta decay in $^{124}Sn$

\textbf{T}he \textbf{IN}dia's \textbf{TIN} (TIN.TIN) detector is under development in the search for neutrinoless double-$β$ decay (0$νββ$) using 90\% enriched $^{124}$Sn isotope as the target mass. This detector will be housed in the upcoming underground facility of the \textbf{I}ndia based \textbf{N}eutrino \textbf{O}bservatory. We present the most important experimental parameters that would be used in the study of required sensitivity for the TIN.TIN experiment to probe the neutrino mass hierarchy. The sensitivity of the TIN.TIN detector in the presence of sole two neutrino double-$β$ decay (2$νββ$) decay background is studied at various energy resolutions. The most optimistic and pessimistic scenario to probe the neutrino mass hierarchy at 3$σ$ sensitivity level and 90\% C.L. is also discussed.

hep-ph↗

arXiv2016

Taiwan EXperiment On NeutrinO -- History, Status and Prospects

We present an overview of the foundation, evolution, contributions and future prospects of the TEXONO Collaboration and its research programs on neutrino physics and dark matter searches at the Kuo-Sheng Reactor Neutrino Laboratory in Taiwan and, as a founding partner of the CDEX program, at the China Jinping Underground Laboratory in China.

hep-ex↗

arXiv2014

Study of the material photon and electron background and the liquid argon detector veto efficiency of the CDEX-10 experiment

The China Dark Matter Experiment (CDEX) is located at the China Jinping underground laboratory (CJPL) and aims to directly detect the WIMP flux with high sensitivity in the low mass region. Here we present a study of the predicted photon and electron backgrounds including the background contribution of the structure materials of the germanium detector, the passive shielding materials, and the intrinsic radioactivity of the liquid argon that serves as an anti-Compton active shielding detector. A detailed geometry is modeled and the background contribution has been simulated based on the measured radioactivities of all possible components within the GEANT4 program. Then the photon and electron background level in the energy region of interest (<10^-2 events kg-1 day-1 keV-1 (cpkkd)) is predicted based on Monte Carlo simulations. The simulated result is consistent with the design goal of CDEX-10 experiment, 0.1 cpkkd, which shows that the active and passive shield design of CDEX-10 is effective and feasible.

physics.ins-det↗

arXiv2007

Neutrino Physics and Astrophysics : Highlights

This article presents an overview of neutrino physics research, with highlights on the physics goals, results and interpretations of the current neutrino experiments and future directions and program. It is not meant to be a comprehensive account or detailed review article. Interested readers can pursue the details via the listed references.

hep-ex↗

arXiv2002

Research Program of the TEXONO Collaboration: Status and Highlights

This article reviews the research program and efforts for the TEXONO Collaboration among scientists from Taiwan and China. These include reactor-based neutrino physics at the Kuo-Sheng Power Plant in Taiwan as well as various R&D efforts related to the various experimental techniques in neutrino and astro-particle physics.

hep-ex↗