arXiv subjects

Xinqiao Li

Publications and source records attributed to Xinqiao Li.

16 recordsLinked to original sources

arXiv2026

Lightweight Soft X-ray Imager (LSXI) with glass-based coded mask

The coded mask technique has been widely used in X-ray and Gamma-ray imagers, especially in space astronomy. However, the traditional design of coded mask imagers usually has problems with large size and heavy weight. Here, we propose a novel design for a coded mask imager made of glass based on microchannel plate (MCP) technology, making it lightweight (within 1 kg), compact, and self-supporting, which is very suitable for space exploration satellites. The design is initially demonstrated by reconstructing encoded patterns from measurements at the X-ray beamline. Monte Carlo simulations of the module integrated into a 6U CubeSat are conducted to assess its in-orbit detector performance, including sensitivity and source localization.

astro-ph.IM↗

arXiv2026

Study of the intrinsic resolution of LaBr3(Ce,Sr) and NaI(Tl) crystals

The Gravitational wave burst high-energy Elec?tromagnetic Counterpart All-sky Monitor (GECAM) utilizes a large number of LaBr3 and NaI(Tl) crystals as sensitive materials for its gamma-ray detectors. To address the fitting issues of the energy resolution curves in the ground calibration of the GECAM detectors, this work conducts a comprehensive testing and comparative study of the energy resolution of 1-inch LaBr3(Ce,Sr) and NaI(Tl) crystals produced from the same batch. We employed a Hard X-ray Calibration Facility (HXCF), a PMT single-photoelectron calibration system, and Geant4 Monte Carlo simulation tools to quantify seven factors influencing energy resolution. The results indicate that the contributions of various components to energy resolution differ, with pho?toelectron statistical fluctuations and intrinsic resolution being predominant. For 100 keV X-rays, the total energy resolution of the LaBr3(Ce,Sr) crystal is 3.71% \pm 0.03% (expressed as 1-σ), with a contribution from photoelectron statistical fluctuations of 2.69% \pm 0.00% and an intrinsic resolution of 2.45% \pm 0.05%. For 100 keV X-rays, the total energy resolution of the NaI(Tl) crystal is 4.41% \pm 0.14% (expressed as 1-σ), with a contribution from photoelectron statistical fluctuations of 3.20% \pm 0.00% and an intrinsic resolution of 2.90% \pm 0.21%. We discussed the sources of intrinsic resolution, and the results indicate that the intrinsic resolution of the LaBr3(Ce,Sr) crystal primarily arises from luminescence non-proportionality, while that of the NaI(Tl) crystal mainly stems from fluctuations during energy transfer. This study emphasizes precise and specific experimental measurements and comparative research, demonstrating that both factors are important contributors to intrinsic resolution.

physics.ins-det↗

arXiv2026

Spatial Guidance Field Theory: From Gradient Postulates and Charge Conservation to Gauge Group Structure

We construct a unified framework for interactions from three postulates: (1) all elementary forces arise as gradients of guidance potentials, (2) the charges that generate these potentials are conserved, and (3) the internal symmetry group must accommodate chiral fermions. The chirality postulate forces the internal symmetry group to be non-Abelian. In the non-relativistic limit, a scalar guidance field reproduces Newtonian gravity and Coulomb's law, and relativistic consistency upgrades the potentials to a spacetime metric and gauge vector fields. The central result is a rigorous derivation that the internal symmetry group must be a compact Lie group; combined with anomaly cancellation and minimal rank and representation content, this uniquely selects the Standard Model's $SU(3)_c \times SU(2)_L \times U(1)_Y$. We present a guidance-field description of strong and weak interactions, and derive coupling-modified Tolman--Oppenheimer--Volkoff equations for neutron stars, obtaining a theoretical maximum mass of $M_{\rm max}^{\rm th} \approx 2.8 \pm 0.4\,M_\odot$, naturally accommodating the $2.6\,M_\odot$ companion of GW190814. We further derive quantitative predictions for equivalence principle violation from nonlinear superposition of guidance potentials, with a QCD-scale benchmark within reach of next-generation experiments. Finally, we discuss implications for black hole interiors within a geometric framework in which charges are topological invariants of a generalized space, and provide the mathematical formulation of the total connection, its action functional, and field equations.

hep-ph↗

arXiv2025

Pitch Angle Measurement Method based on Detector Counts Distribution. -I. Basic conception

As an X-ray and gamma-ray all-sky monitor aiming for high energy astrophysical transients, Gravitational-wave high-energy Electromagnetic Counterpart All-sky Monitor (GECAM) has also made a series of observational discoveries on burst events of gamma-rays and particles in the low Earth orbit. Pitch angle is one of the key parameters of charged particles traveling around geomagnetic field. However, the usage of the GECAM-style instruments to measure the pitch angle of charged particles is still lacking. Here we propose a novel method for GECAM and similar instruments to measure the pitch angle of charged particles based on detector counts distribution. The basic conception of this method and simulation studies are described. With this method, the pitch angle of a peculiar electron precipitation event detected by GECAM-C is derived to be about 90$^\circ$, demonstrating the feasibility of our method. We note that the application of this method on GECAM-style instruments may open a new window for studying space particle events, such as Terrestrial Electron Beams (TEBs) and Lightning-induced Electron Precipitations (LEPs).

astro-ph.IM↗

arXiv2025

GECAM Discovery of Peculiar Oscillating Particle Precipitation Events

Charged particle precipitation typically manifests as a gradual increase and decrease of flux observed by space detectors. Cases with rapidly flux variation are very rare. Periodic events are even more extraordinary. These oscillating particle precipitation (OPP) events are usually attributed to the bounce motion of electrons, which are induced by lightning. Owing to the observation limitations, there has been debate regarding whether these oscillations originate from temporal flux evolution or spatial structure evolution. Here we report three peculiar charged particle precipitation events detected by GECAM during a geomagnetic storm on March 21, 2024, with two exhibiting significant periodicity. These events were observed around the same region during three consecutive orbits. Through comprehensive temporal and spectral analyses, we revealed that one of the OPP events exhibited a transition in spectral lag of mini-pulses, shifting from "softer-earlier" to "softer-later" while showing no significant time evolution in overall frequency characteristics. And there is no association found between these two OPP events and lightning activity. Several possible scenarios are discussed to explain these charged particles with a life time of more than 3.5 hours, but the nature of these three events remains an enigma. We suggest that these GECAM-detected OPP events may represent a new type of particle precipitation event or a peculiar Lightning-induced Electron Precipitations (LEPs).

astro-ph.HE↗

arXiv2023

The performance of SiPM-based gamma-ray detector (GRD) of GECAM-C

As a new member of GECAM mission, the GECAM-C (also called High Energy Burst Searcher, HEBS) is a gamma-ray all-sky monitor onboard SATech-01 satellite, which was launched on July 27th, 2022 to detect gamma-ray transients from 6 keV to 6 MeV, such as Gamma-Ray Bursts (GRBs), high energy counterpart of Gravitational Waves (GWs) and Fast Radio Bursts (FRBs), and Soft Gamma-ray Repeaters (SGRs). Together with GECAM-A and GECAM-B launched in December 2020, GECAM-C will greatly improve the monitoring coverage, localization, as well as temporal and spectral measurements of gamma-ray transients. GECAM-C employs 12 SiPM-based Gamma-Ray Detectors (GRDs) to detect gamma-ray transients . In this paper, we firstly give a brief description of the design of GECAM-C GRDs, and then focus on the on-ground tests and in-flight performance of GRDs. We also did the comparison study of the SiPM in-flight performance between GECAM-C and GECAM-B. The results show GECAM-C GRD works as expected and is ready to make scientific observations.

astro-ph.IM↗

arXiv2023

A Localization Method of High Energy Transients for All-Sky Gamma-Ray Monitor

Fast and reliable localization of high-energy transients is crucial for characterizing the burst properties and guiding the follow-up observations. Localization based on the relative counts of different detectors has been widely used for all-sky gamma-ray monitors. There are two major methods for this counts distribution localization: $χ^{2}$ minimization method and the Bayesian method. Here we propose a modified Bayesian method that could take advantage of both the accuracy of the Bayesian method and the simplicity of the $χ^{2}$ method. With comprehensive simulations, we find that our Bayesian method with Poisson likelihood is generally more applicable for various bursts than $χ^{2}$ method, especially for weak bursts. We further proposed a location-spectrum iteration approach based on the Bayesian inference, which could alleviate the problems caused by the spectral difference between the burst and location templates. Our method is very suitable for scenarios with limited computation resources or time-sensitive applications, such as in-flight localization software, and low-latency localization for rapid follow-up observations.

astro-ph.HE↗

arXiv2022

The 100-m X-ray Test Facility at IHEP

The 100-m X-ray Test Facility of the Institute of High Energy Physics (IHEP) was initially proposed in 2012 for the test and calibration of the X-ray detectors of the Hard X-ray Modulation Telescope (HXMT) with the capability to support future X-ray missions. The large instrument chamber connected with a long vacuum tube can accommodate the X-ray mirror, focal plane detector and other instruments. The X-ray sources are installed at the other end of the vacuum tube with a distance of 105 m, which can provide an almost parallel X-ray beam covering 0.2$\sim$60 keV energy band. The X-ray mirror modules of the Einstein Probe (EP) and the enhanced X-ray Timing and Polarimetry mission (eXTP) and payload of the Gravitational wave high-energy Electromagnetic Counterpart All-sky Monitor (GECAM) have been tested and calibrated with this facility. It has been also used to characterize the focal plane camera and aluminum filter used on the Einstein Probe. In this paper, we will introduce the overall configuration and capability of the facility, and give a brief introduction of some calibration results performed with this facility.

astro-ph.IM↗

arXiv2022

Flare Quasi-Periodic Pulsation Associated with Recurrent Jets

Quasi-periodic pulsations (QPPs), which carry time features and plasma characteristics of flare emissions, are frequently observed in light curves of solar/stellar flares. In this paper, we investigated non-stationary QPPs associated with recurrent jets during an M1.2 flare on 2022 July 14. A quasi-period of about 45$\pm$10 s, determined by the wavelet transform technique, is simultaneously identified at wavelengths of soft/hard X-ray and microwave emissions, which are recorded by the Gravitational wave high-energy Electromagnetic Counterpart All-sky Monitor, Fermi, and the Nobeyama Radio Polarimeters, respectively. A group of recurrent jets with an intermittent cadence of about 45$\pm$10 s are found in Atmospheric Imaging Assembly (AIA) image series at 304 Å, but they are 180-s earlier than the flare QPP. All observational facts suggest that the flare QPP could be excited by recurrent jets, and they should be associated with nonthermal electrons that are periodically accelerated by a repeated energy release process, like repetitive magnetic reconnection. Moreover, the same quasi-period is discovered at double footpoints connected by a hot flare loop in AIA 94 Å, and the phase speed is measured to 1420 km/s. Based on the differential emission measure, the average temperatures, number densities, and magnetic field strengths at the loop top and footpoint are estimated to 7.7/6.7 MK, 7.5/3.6*10^{10} cm ^{-3}, and 143/99 G, respectively. Our measurements indicate that the 45-s QPP is probably modulated by the kink-mode wave of the flare loop.

astro-ph.SR↗

arXiv2021

Gain stabilization and consistency correction approach for multiple SiPM-based gamma-ray detectors on GECAM

Each satellite of the Gravitational wave high-energy Electromagnetic Counterpart All-sky Monitor (GECAM, mission) consists of 25 SiPM based gamma-ray detectors (GRDs). Although SiPM based GRD has merits of compact size and low bias-voltage, the drift of the SiPM gain with temperature is a severe problem for GRD performance. An adaptive voltage supply source was designed to automatically adjust the SiPM bias voltage to compensate the temperature effects and keep the gain stable. This approach has been proved to be effective during both the on-ground and in-flight tests. The in-flight measured variation of the SiPM gain is within 2%. To reduce the gain non-uniformity of GRDs, an iterative bias voltage adjustment approach is proposed and implemented. The gain non-uniformity is reduced from 17% to 0.6%. In this paper, the gain stabilization and consistency correction approach are presented and discussed in detail.

physics.ins-det↗

arXiv2021

Design and test of a portable Gamma-Ray Burst simulator for GECAM

The main scientific goal of the Gravitational wave high-energy Electromagnetic Counterpart All-sky Monitor (GECAM) is to monitor various types of Gamma-Ray Bursts (GRB) originated from merger of binary compact stars, which could also produce gravitational wave, and collapse of massive stars. In order to study the response of GECAM Gamma-Ray Detectors (GRDs) to high-energy bursts and test the in-flight trigger and localization software of GECAM before the launch, a portable GRB simulator device is designed and implemented based on grid controlled X-ray tube (GCXT) and direct digital synthesis (DDS) technologies. The design of this GRB simulator which modulates X-ray flux powered by high voltage up to 20 kV is demonstrated, and the time jitter (FWHM) of the device is about 0.9 $μ$s. Before the launch in December, 2020, both two GECAM satellites were irradiated by different types of GRBs (including short and long bursts in duration) generated by this GRB simulator. The light curves detected with GECAM/GRDs are consistent with the programmed input functions within statistical uncertainties, indicating the good performance of both the GRDs and the GRB simulator.

physics.ins-det↗

arXiv2016

Investigation of NWC-induced electron precipitation and theoretical simulation

Enhancement of the electron fluxes in the inner radiation belt, which is induced by the powerful North West Cape (NWC) very-low-frequency (VLF) transmitter, have been observed and analyzed by several research groups. However, all of the previous publications have focused on NWC-induced >100-keV electrons only, based on observations from the Detection of Electro-Magnetic Emissions Transmitted from Earthquake Regions (DEMETER) and the Geostationary Operational Environmental Satellite (GOES) satellites. Here, we present flux enhancements with 30--100-keV electrons related to NWC transmitter for the first time, which were observed by the GOES satellite at night. Similar to the 100--300-keV precipitated-electron havior, the low energy 30--100-keV electron precipitation is primarily located east of the transmitter. However, the latter does not drift eastward to the same extent as the former, possibly because of the lower electron velocity. The 30--100-keV electrons are distributed in the L=1.8--2.1 shell range, in contrast to the 100--300-keV electrons which are at L=1.67--1.9. This is consistent with the perspective that the energy of the VLF-wave-induced electron flux enhancement decreases with higher L-shell values. We expand upon the rationality of the simultaneous enhancement of the 30--100- and 100--300-keV electron fluxes through comparison with the cyclotron resonance theory for the quasi-linear wave-particle interaction. In addition, we interpret the asymmetry characteristics of NWC electric power distribution in north and south hemisphere by ray tracing model. Finally, we present considerable discussion and show that good agreement exists between the observation of satellites and theory.

physics.space-ph↗

arXiv2014

Study of typical space wave-particle coupling events possibly related with seismic activity

Based on the DEMETER satellite, we found two space wave-particle coupling events during February 2010 taking place in the range of McIlwain parameter $L$($1.27\sim1.37$). There are strong spatial and temporal correlation between the particle bursts(PBs) and the electromagnetic disturbances of the coupling events. The two PBs show different energy spectrum characteristics, while the corresponding electromagnetic disturbances concentrated on different frequencies range. In agreement with the prediction of the theory of wave-particle interaction, we conclude that the two wave-particle interactions can be probably explained as following: one is electron dominant precipitation with energy of $0.09\sim0.2$ MeV induced by VLF electromagnetic wave with the frequency of $14\sim20$ kHz, and another is proton dominant precipitation with energy of $0.65\sim2.85$ MeV induced by VLF electromagnetic wave with the frequency of $\le 100$ Hz. For the first time, those particle bursts origin, from electron or proton detected by the Instrument for the Detection of Particles(IDP) on board, is inferred by theory calculation, although the Instrument has no ability to identify the particle species.

physics.geo-ph↗

arXiv2012

Common dependence on earthquake magnitudes for the trapped particles bursts approaching the earthquake

Trapped particles bursts have long been observed to be frequently occurred several hours before earthquakes, especially for strong earthquakes, from several space experiments during past decades. However, the validity of earthquake origin of particles bursts events is still unsolved. In this paper, we firstly reported the frequency distribution and time evolution of particles bursts within different time windows centered around earthquakes for various magnitudes. The results showed nearly the same systematic dependence of particle bursts frequency on earthquake magnitude and characteristic time decay behavior of average number of particles bursts for various magnitudes. These findings should strengthen the validity of earthquake origin of particles bursts and further understanding of particles bursts as possible precursor of earthquake.

physics.space-ph↗

arXiv2011

Study of the NWC electrons belt observed on DEMETER Satellite

We analyzed observation data collected by the Instrument for the Detection of Particles (IDP) on board of DEMETER satellite during the period of total seventeen months in 2007 and 2008. In the meantime, the VLF transmitter located at NWC ground station was shutdown for seven months and working for total ten months. Our analysis, for the first time, revealed in details the transient properties of the space electrons induced by the man-made VLF wave emitted by the transmitter at NWC. First, we mapped the electron flux distribution and figured out the special range what the NWC belt covered. Then we investigated the NWC electron spectrograms in a wide range of McIlwain parameter (up to L=3.0). Finally, we obtained the averaged energy spectrum of the NWC electrons within the drift loss-cone, and compared the difference during the observations between daytime and nighttime. Our results proved the fact that the VLF emissions from NWC transmitter created momentary electron enhancement with fluxes up to 3 orders of magnitude. These electrons are distributed in the region of 180 degree in longitude and 1.6 ~ 1.9 of L shell. In addition, the VLF emission induced either enhancement or loss of electrons in higher magnetic shells up to L=3, and the maximum loss was up to 60% of the original value. The energy spectra of these electrons revealed that the enhancement during the NWC daytime are more attenuated than those in the NWC nighttime, and that the shape and the cutoff energy of the spectra are also quite different. We will present the results of our analysis, compare it with previous studies, and discuss the agreement of our results with the theory of wave-particle interaction.

physics.geo-ph↗

arXiv2010

DEMETER Satellite Observations of Particle Burst Prior to Chile Earthquake

The lithosphere activity during seismogenic or occurrence of one earthquake may emit electromagnetic wave which propagate to ionosphere and radiation belt, then induce disturbance of electric and magnetic field and the precipitation of high energy charged particles. This paper, based on the data detected by DEMETER satellite, present the high energy charged particle burst(PB) with 4 to 6 times enhancement over the average value observed about ten days days before Chile earthquake. The obvious particle burst was also observed in the northern hemisphere mirror points conjugate of epicenter and no PB events in different years over the same epicenter region was found. The energy spectra of the PBs are different from the one averaged within the first three months in 2010. At the same time, the disturbance of the VLF electric spectrum in ionosphere over the epicenter detected by the DEMETER satellite are also observed in the same two orbits. Those observations from energetic PB and VLF electric spectrum disturbance demonstrates the coupling relation among the electromagnetic wave emitted by seismic activity, energetic particle and electric field in ionosphere. We eliminate the possible origination of PB including magnetic burst and Solar activities. Finally we think the PB is likely to be related to Chile earthquake and can be taken as the precursor of this earthquake.

physics.geo-ph↗