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Chung-Lin Shan

Publications and source records attributed to Chung-Lin Shan.

At least 19 recordsLinked to original sources
arXiv2026

Simulations of 3-Dimensional Recoil Response to Coherent Elastic Neutrino-Nucleus Scattering Events in Directional Direct Dark Matter Detectors

Following our earlier work on studying 3-dimensional nuclear recoil response to Galactic Weakly Interacting Massive Particles (WIMPs) in directional direct Dark Matter detectors, in this paper, we simulate 3-D coherent elastic neutrino-nucleus scattering (CEvNS) events induced by Solar B-8 neutrinos. Our numerical results show that, in contrast to the approximately fixed patterns of the WIMP-induced signals, the characteristic ring-like angular distributions of the nuclear recoil flux/energy of CEvNS events show clearly annual variations along the trajectories of the moving direction of incident Solar neutrinos in different celestial coordinate systems without experimentally distinguishable target dependence.

astro-ph.HE↗
arXiv2025

3-Dimensional WIMP Effective Velocity Distribution

In this talk, I discussed a 3-dimensional "effective" velocity distribution of Weakly Interacting Massive Particles (WIMPs), which, instead of the theoretically predicted velocity distribution of "entire" Galactic Dark Matter particles, describes the actual velocity distribution of WIMPs "scattering off" (specified) target nuclei in an underground detector. Based on numerical results carried out by our double Monte Carlo scattering-by-scattering simulation of 3-dimensional elastic WIMP-nucleus scattering, an (asymmetric) "forward-backward asymmetry" was also demonstrated.

astro-ph.HE↗
arXiv2022

A Possibility of Determining the WIMP Mass by Using the Angular Recoil-Energy Spectra from Directional Direct Dark Matter Detection Experiments

In this article, as an extension of our study on the angular distribution of the recoil flux of WIMP-scattered target nuclei, we demonstrate a possibility of determining the mass of incident halo WIMPs by using or combining "ridge-crater" structures of the angular recoil-energy spectra with different target nuclei observed in directional direct Dark Matter detection experiments. Our simulation results show that, for a WIMP mass of only a few tens GeV, the stereoscopic angular recoil-flux distributions of both of light and heavy target nuclei would have a (longitudinally) "ridge-like" structure. However, once the WIMP mass is as heavy as a few hundreds GeV, the angular recoil-flux distributions of heavy target nuclei would in contrast show a (latitudinally) "crater-like" structure.

hep-ph↗
arXiv2022

Normal and Reverse Annual Modulations of Elastic WIMP-Nucleus Scattering Signals

Following our earlier work on the 3-dimensional effective velocity distribution of Galactic WIMPs (not only impinging on our detectors but also) scattering off target nuclei, in this paper, we demonstrate the normal and a "reverse" annual modulations of elastic WIMP-nucleus scattering signals, which could be observed in direct Dark Matter detection experiments. Our simulations show that, once the WIMP mass is as light as only a few tens GeV, the event number and the accumulated recoil energy of WIMP-induced scattering events off both of light and heavy target nuclei would indeed be maximal (minimal) in summer (winter). However, once the WIMP mass is as heavy as a few hundreds GeV, the event number and the accumulated recoil energy of WIMP scattering events off heavy nuclei would inversely be minimal in summer. Understandably, for an intermediate WIMP mass, the event number and the accumulated recoil energy of scattering events off some middle-mass nuclei would show an approximately uniform time dependence.

hep-ph↗
arXiv2022

Incident Velocity-Recoil Angle Distribution and Angular Recoil-Energy Spectrum of 3-Dimensional WIMP-Nucleus Scattering Events

In this paper, as a supplementary of our study on the angular distribution of the recoil flux of WIMP-scattered target nuclei and on that of the WIMP effective scattering velocity distribution, we investigate the scattering probability distribution of the WIMP incident velocity versus the nuclear recoil angle in narrow recoil energy windows for different WIMP masses and target nuclei. Our simulation results show that, not only the velocity distribution of incident halo WIMPs, but also a factor of the recoil angle could affect the scattering probability distribution of the available incident velocity-recoil angle combination in a given recoil energy window. Consequently, the 1-D WIMP "effective" velocity distribution corresponding to the considered narrow energy window would not be consistent with that cut simply from the (generating) velocity distribution of incident halo WIMPs. And its contribution to the differential WIMP-nucleus scattering event rate in the considered energy window could thus not be simply estimated by integrating over the 1-D theoretical velocity distribution (of entire halo WIMPs).

hep-ph↗
arXiv2021

Some Thoughts on (the Incompleteness of) the (Double) Differential Event Rates for Elastic WIMP-Nucleus Scattering in (Directional) Direct Dark Matter Detection Physics

In this paper, we revisit the expressions for the (double) differential event rates for elastic WIMP-nucleus scattering and discuss some unusual thoughts on (the incompleteness of) the uses of these expressions in (directional) direct Dark Matter detection physics. Several not-frequently mentioned (but important) issues will be argued and demonstrated in detail.

hep-ph↗
arXiv2021

Annual modulations of the angular recoil-flux/energy distributions of WIMP-scattered target nuclei observed at an underground laboratory

In this article, we compare the target and WIMP-mass dependent "annual modulations" of the angular distributions of the recoil flux and energy of WIMP-scattered target nuclei observed at different underground laboratories. For readers' reference, simulation plots with different WIMP masses and frequently used target nuclei for all functionable underground laboratories can be found and downloaded on our online (interactive) demonstration webpage (http://www.tir.tw/phys/hep/dm/amidas-2d/).

hep-ph↗
arXiv2021

Monte Carlo Scattering-by-Scattering Simulation of 3-Dimensional Elastic WIMP-Nucleus Scattering Events

In this paper, as the first part of the third step of our study on developing data analysis procedures for using 3-dimensional information offered by directional direct Dark Matter detection experiments in the future, we present our double-Monte Carlo "scattering-by-scattering" simulation of the 3-dimensional elastic WIMP-nucleus scattering process, which can provide 3-D velocity information (the magnitude, the direction, and the incoming/scattering time) of each incident halo WIMP as well as the recoil direction and the recoil energy of the scattered target nucleus in different celestial coordinate systems. For readers' reference, (animated) simulation plots with different WIMP masses and several frequently used target nuclei for all functionable underground laboratories can be found and downloaded on our online (interactive) demonstration webpage (http://www.tir.tw/phys/hep/dm/amidas-2d/).

hep-ph↗
arXiv2021

Simulations of the Angular Recoil-Energy Distribution of WIMP-Scattered Target Nuclei for Directional Dark Matter Detection Experiments

In this paper, as the second part of the third step of our study on developing data analysis procedures for using 3-dimensional information offered by directional direct Dark Matter detection experiments in the future, we investigate the angular distributions of the recoil direction (flux) and the recoil energy of the Monte Carlo simulated WIMP-scattered target nuclei observed in different celestial coordinate systems. The "anisotropy" and the "directionality" ("annual" modulation) of the angular recoil-direction/energy distributions will be demonstrated. We will also discuss their dependences on the target nucleus and on the mass of incident halo WIMPs. For readers' reference, all simulation plots presented in this paper (and more) can be found "in animation" on our online (interactive) demonstration webpage (http://www.tir.tw/phys/hep/dm/amidas-2d/).

hep-ph↗
arXiv2021

3-Dimensional Effective Velocity Distribution of Halo Weakly Interacting Massive Particles Scattering off Nuclei in Direct Dark Matter Detectors

In this paper, as the third part of the third step of our study on developing data analysis procedures for using 3-dimensional information offered by directional direct Dark Matter detection experiments in the future, we introduce a 3-dimensional effective velocity distribution of halo Weakly Interacting Massive Particles (WIMPs), which, instead of the theoretically prediction of the entire Galactic Dark Matter particles, describes the actual velocity distribution of WIMPs scattering off (specified) target nuclei in an underground detector. Its target and WIMP-mass dependences as well as ("annual" modulations of) its "anisotropy" in the Equatorial/laboratory and even the Galactic coordinate systems will be demonstrated and discussed in detail. For readers' reference, all simulation plots presented in this paper (and more) can be found "in animation" on our online (interactive) demonstration webpage (http://www.tir.tw/phys/hep/dm/amidas-2d/).

astro-ph.HE↗
arXiv2020

Dependence of the WIMP Angular Kinetic-Energy Distribution on the Solar Galactic Orbital Velocity

In this article, we study in a little more detail the angular kinetic-energy distribution of halo Weakly Interacting Massive Particles (WIMPs) and consider two simple modifications with the Solar Galactic orbital velocity in our Monte Carlo simulations of the 3-dimensional WIMP velocity as the first trial of future investigations on distinguishing models of the Galactic structure of Dark Matter particles by using directional direct detection data.

astro-ph.HE↗
arXiv2020

Simulations of the 3-Dimensional Velocity Distribution of Halo Weakly Interacting Massive Particles for Directional Dark Matter Detection Experiments

In this paper, as a preparation of developing data analysis procedures for using 3-dimensional information offered by directional Dark Matter (DM) detection experiments, we study the patterns of the angular distribution of the Monte Carlo-generated 3-D velocity of halo Weakly Interacting Massive Particles (WIMPs) as well as apply the Bayesian fitting technique to reconstruct the radial distribution of the 3-D WIMP velocity. Besides the diurnal modulation of the angular WIMP velocity distribution, the so-called "directionality" of DM signals proposed in literature, we will also demonstrate possible "annual" modulations of both of the angular and the radial distributions of the 3-D WIMP velocity. Our Bayesian reconstruction results of (the annual modulation of) the radial WIMP velocity distribution will also be discussed in detail. For readers' reference, the angular distribution patterns of the 3-D WIMP velocity in the "laboratory (location)-dependent" reference frames of several underground laboratories are given in the Appendix.

astro-ph.HE↗
arXiv2018

Effects of Threshold Energy on Reconstructions of Properties of Low-Mass WIMPs in Direct Dark Matter Detection Experiments

In this paper, we revisit our model-independent methods developed for reconstructing properties of Weakly Interacting Massive Particles (WIMPs) by using measured recoil energies from direct Dark Matter detection experiments directly and take into account more realistically non-negligible threshold energy. All expressions for reconstructing the mass and the (ratios between the) spin-independent and the spin-dependent WIMP-nucleon couplings have been modified. We focus on low-mass (m_chi <~ 15 GeV) WIMPs and present the numerical results obtained by Monte Carlo simulations. Constraints caused by non-negligible threshold energy and technical treatments for improving reconstruction results will also be discussed.

hep-ph↗
arXiv2015

Reconstructing the WIMP Velocity Distribution from Direct Dark Matter Detection Data with a Non-Negligible Threshold Energy

In this paper, we investigate the modification of our expressions developed for the model-independent data analysis procedure of the reconstruction of the (time-averaged) one-dimensional velocity distribution of Galactic Weakly Interacting Massive Particles (WIMPs) with a non-negligible experimental threshold energy. Our numerical simulations show that, for a minimal reconstructable velocity of as high as O(200) km/s, our model-independent modification of the estimator for the normalization constant could provide precise reconstructed velocity distribution points to match the true WIMP velocity distribution with a <~ 10% bias.

astro-ph.HE↗
arXiv2014

AMIDAS-II: Upgrade of the AMIDAS Package and Website for Direct Dark Matter Detection Experiments and Phenomenology

In this paper, we give a detailed user's guide to the AMIDAS (A Model-Independent Data Analysis System) package and website, which is developed for online simulations and data analyses for direct Dark Matter detection experiments and phenomenology. Recently, the whole AMIDAS package and website system has been upgraded to the second phase: AMIDAS-II, for including the new developed Bayesian analysis technique. AMIDAS has the ability to do full Monte Carlo simulations as well as to analyze real/pseudo data sets either generated by another event generating programs or recorded in direct DM detection experiments. Moreover, the AMIDAS-II package can include several "user-defined" functions into the main code: the (fitting) one-dimensional WIMP velocity distribution function, the nuclear form factors for spin-independent and spin-dependent cross sections, artificial/experimental background spectrum for both of simulation and data analysis procedures, as well as different distribution functions needed in Bayesian analyses.

astro-ph.IM↗
arXiv2014

Bayesian Reconstruction of the Velocity Distribution of Weakly Interacting Massive Particles from Direct Dark Matter Detection Data

In this paper, we extended our earlier work on the reconstruction of the (time-averaged) one-dimensional velocity distribution of Galactic Weakly Interacting Massive Particles (WIMPs) and introduce the Bayesian fitting procedure to the theoretically predicted velocity distribution functions. In this reconstruction process, the (rough) velocity distribution reconstructed by using raw data from direct Dark Matter detection experiments directly, i.e. measured recoil energies, with one or more different target materials, has been used as "reconstructed-input" information. By assuming a fitting velocity distribution function and scanning the parameter space based on the Bayesian analysis, the astronomical characteristic parameters, e.g. the Solar and Earth's Galactic velocities, will be pinned down as the output results. Our Monte-Carlo simulations show that this Bayesian scanning procedure could reconstruct the true (input) WIMP velocity distribution function pretty precisely with negligible systematic deviations of the reconstructed characteristic Solar and Earth's velocities and 1 sigma statistical uncertainties of <~ 20 km/s. Moreover, for the use of an improper fitting velocity distribution function, our reconstruction process could still offer useful information about the shape of the velocity distribution. In addition, by comparing these estimates to theoretical predictions, one could distinguish different (basic) functional forms of the theoretically predicted one-dimensional WIMP velocity distribution function with 2 sigma to 4 sigma confidence levels.

astro-ph.HE↗
arXiv2014

Script Handbook for Interactive Scientific Website Building

In this script handbook, we collect the basic (and partially upgraded) PHP scripts used for building the AMIDAS website (http://pisrv0.pit.physik.uni-tuebingen.de/darkmatter/amidas/), an online interactive simulation/data analysis system for direct Dark Matter detection experiments and phenomenology. In this (1.73205) version, we add more materials and improve the scripts for offering a more convenient, comfortable and user-friendly environment on interactive scientific computing websites. Some basic, often used commands of (X)HTML, CSS, JavaScript, HTML DOM, and PHP are also given in Appendix. Online demonstrations and downloadable template scripts are given on http://www.tir.tw/iswb/ss2012/templates.php.

physics.ins-det↗