arXiv subjects

H. T. Wong

Publications and source records attributed to H. T. Wong.

65 records · Page 4Linked to original sources

arXiv2012

Constraints on Non-Commutative Physics Scale with Neutrino-Electron Scattering

Neutrino-electron scatterings ($ν- e$) are purely leptonic processes with robust Standard Model (SM) predictions. Their measurements can therefore provide constraints to physics beyond SM. Non-commutative (NC) field theories modify space-time commutation relations, and allow neutrino electromagnetic couplings at the tree level. Their contribution to neutrino-electron scattering cross-section was derived. Constraints were placed on the NC scale parameter $Λ_{NC}$ from $ν- e$ experiments with reactor and accelerator neutrinos. The most stringent limit of $Λ_{NC} > 3.3 TeV$ at 95% confidence level improves over the direct bounds from collider experiments.

hep-ph↗

arXiv2008

Limits on Low-Mass WIMP Dark Matter with an Ultra-Low-Energy Germanium Detector at 220 eV Threshold

An energy threshold of (220$\pm$10) eV was achieved at an efficiency of 50% with a four-channel ultra-low-energy germanium detector each with an active mass of 5 g\cite{wimppaper}. This provides a unique probe to WIMP dark matter with mass below 10 GeV. With low background data taken at the Kuo-Sheng Laboratory, constraints on WIMPs in the galactic halo were derived. Both spin-independent WIMP-nucleon and spin-dependent WIMP-neutron bounds improve over previous results for WIMP mass between 3$-$6 GeV. These results, together with those on spin-dependent couplings, will be presented. Sensitivities for full-scale experiments were projected. This detector technique makes the unexplored sub-keV energy window accessible for new neutrino and dark matter experiments.

astro-ph↗

arXiv2008

Studies of Neutrino-Electron Scattering at the Kuo-Sheng Reactor Neutrino Laboratory

Studies on electron antineutrino-electron elastic scattering were performed using a 200-kg CsI(Tl) scintillating crystal detector array at the Kuo-Sheng Nuclear Power Plant in Taiwan. The measured cross section of R(exp) = [1.00 +- 0.32(stat)]xR(SM) is consistent with the Standard Model expectation and the corresponding weak mixing angle derived is sin2T = 0.24 +- 0.05 (stat). The results are consistent with a destructive interference effect between neutral and charged-currents in this process. Limits on neutrino magnetic moment of mu(nu_(e)) < 2.0 x 10^(-10) mu_(B) at 90% confidence level and on electron antineutrino charge radius of r^(2) < (0.12 +- 2.07)x10^(-32) cm^2 were also derived.

hep-ex↗

arXiv2007

Prospects of cold dark matter searches with an ultra-low-energy germanium detector

The report describes the research program on the development of ultra-low-energy germanium detectors, with emphasis on WIMP dark matter searches. A threshold of 100 eV is achieved with a 20 g detector array, providing a unique probe to the low-mas WIMP. Present data at a surface laboratory is expected to give rise to comparable sensitivities with the existing limits at the $\rm{5 - 10 GeV}$ WIMP-mass range. The projected parameter space to be probed with a full-scale, kilogram mass-range experiment is presented. Such a detector would also allow the studies of neutrino-nucleus coherent scattering and neutrino magnetic moments.

hep-ex↗

arXiv2006

Search of Neutrino Magnetic Moments with a High-Purity Germanium Detector at the Kuo-Sheng Nuclear Power Station

A search of neutrino magnetic moments was carried out at the Kuo-Sheng Nuclear Power Station at a distance of 28 m from the 2.9 GW reactor core. With a high purity germanium detector of mass 1.06 kg surrounded by scintillating NaI(Tl) and CsI(Tl) crystals as anti-Compton detectors, a detection threshold of 5 keV and a background level of 1 $\cpd$ near threshold were achieved. Details of the reactor neutrino source, experimental hardware, background understanding and analysis methods are presented. Based on 570.7 and 127.8 days of Reactor ON and OFF data, respectively, at an average Reactor ON electron anti-neutrino flux of $\rm{6.4 \times 10^{12} cm^{-2} s^{-1}}$, the limit on the neutrino magnetic moments of $\rm{\munuebar < 7.4 \times 10^{-11} \mub}$ at 90% confidence level was derived. Indirect bounds on the $\nuebar$ radiative decay lifetimes were inferred.

hep-ex↗

arXiv2005

Observation of Fluorescence Emissions from Single-Bubble Sonoluminescence in Water doped with Quinine

Sonoluminescence is a phenomenon involving the transduction of sound into light. The detailed mechanism as well as the energy-focusing potentials are not yet fully explored and understood. So far only optical photons are observed, while emissions in the ultra-violet range are only inferred. By doping the fluorescent dye quinine into water with dilute sulphuric acid, the high energy photons can be converted into the optical photons with slower decay constants. These sonoluminescence and fluorescent emissions were observed in coincidence, and the emitted signals of the two modes can be differentiated by their respective timing profiles. Plans for using this technique as a diagnostic tool to quantitatively study ultra-violet and other high energy emissions in sonoluminescence are discussed.

physics.flu-dyn↗

arXiv2003

Highlights of the TEXONO Research Program on Neutrino and Astroparticle Physics

This article reviews the research program and efforts for the TEXONO Collaboration on neutrino and astro-particle physics. The ``flagship'' program is on reactor-based neutrino physics at the Kuo-Sheng (KS) Power Plant in Taiwan. A limit on the neutrino magnetic moment of $\munuebar < 1.3 X 10^{-10} \mub}$ at 90% confidence level was derived from measurements with a high purity germanium detector. Other physics topics at KS, as well as the various R&D program, are discussed

hep-ex↗

arXiv2002

Status on the Searches of Neutrino Magnetic Moment at the Kuo-Sheng Power Reactor

The TEXONO collaboration has been built up among scientists from Taiwan and China to pursue an experimental program in neutrino and astro-particle physics. The flagship efforts have been the study of low energy neutrino physics at the Kuo-Sheng Power Reactor Plant in Taiwan. The Reactor Laboratory is equipped with flexibly-designed shieldings, cosmic veto systems, electronics and data acquisition systems which can function with different detector schemes. Data are taken during the Reactor Period June-01 till April-02 with a high purity germanium detector and 46 kg of CsI(Tl) crystal scintillator array operating in parallel. A threshold of 5 keV has been achieved for the germanium detector, and the background level comparable to those of Dark Matter experiments underground is achieved. Based on 62/46 days of analyzed Reactor ON/OFF data, a preliminary result of $\rm{(\munue / 10^{-10} \mub)^2 = - 1.1 \pm 2.5}$ can be derived for neutrino magnetic moment $\munue$. Sensitivity region on neutrino radiative decay lifetime is inferred. The complete data set would include 180/60 days of ON/OFF data.

hep-ex↗

arXiv2002

Intrinsic Radioactivity in a GSO Crystal and Limits on Double Beta Decay of Gd-160

Scintillating crystal detector offers potential advantages in low-energy low-background experiments for particle physics and astrophysics. The GSO crystal is an interesting detector to explore for future neutrino physics experiments. The contributions to background due to the various channels of intrinsic radio-isotopes from the Th-232 and U-238 series are identified and studied with time-correlation analysis and detailed fits to the spectral shape. Good agreement is achieved between measured and simulated spectra, indicating background suppression factors to the 10^{-2} - 10^{-3} level are possible. The procedures can be adopted for background understanding and suppression in other low-count-rate experiments where the dominant source of background is from internal radioactivity. Based on 1656 hours of data taking, limits on the double beta decay half-life for the various channels in Gd-160 are presented. The limit for the neutrinoless mode is T^{0 νββ}_{1/2} > 2.0(0.8) X 10^{20} y at 68(90)% confidence level.

hep-ex↗

arXiv2001

Prospect of a very long baseline neutrino oscillation experiment: HIPA to Beijing

We discuss the prospects of a very long baseline neutrino oscillation experiment from HIPA to Beijing. The current understanding of neutrino oscillations, both theoretically and experimentally, are summarized. The figure of merits for interested physics measurements are defined and compared at different distances: 300 km, 700 km, 2100 km and 3000 km. We conclude that a baseline more than 2100 km is optimal. A large water cerenkov calorimeter was proposed and its performance is satisfactory from a Monte Carlo simulation study. Such a large detector can do many other measurements on cosmic-rays physics and astrophysics.

hep-ph↗

arXiv2000

Prospects of Scintillating Crystal Detector in Low-Energy Low-Background Experiments

Scintillating crystal detector offers potential advantages in low-energy (keV-MeV range) low-background experiments for particle physics and astrophysics. The merits are discussed using CsI(Tl) crystal as illustrations. The various physics topics which can be pursued with this detector technology are summarized. A conceptual design for a generic detector is presented.

hep-ex↗