arXiv subjects

P. Wang

Publications and source records attributed to P. Wang.

At least 19 recordsLinked to original sources

arXiv2026

EBS and in-beam $\gamma$-ray investigation of FCVA-prepared Cr$_2$O$_3$ targets for low-energy $^{16}$O+$^{16}$O fusion experiments

The Cr$_2$O$_3$ solid target for low-energy $^{16}$O+$^{16}$O fusion experiments was fabricated using filtered cathodic vacuum arc (FCVA) deposition. Its composition, oxygen areal density and impurity content were characterized by elastic backscattering spectrometry (EBS), and the impurity-induced background contributions were investigated by in-beam $\gamma$-ray spectroscopy. EBS results indicate that the Cr$_2$O$_3$ film exhibits good stoichiometry and uniformity, with $^{16}$O areal densities ranging from $(3.24-3.25)\times10^{17}$ atoms/cm$^2$. The EBS analysis reveals a carbon atomic fraction of approximately 1.25-1.29\% in the Cr$_2$O$_3$ layer, while a large amount of carbon impurities are also identified on the surface of Cr substrate. In-beam $\gamma$-ray spectra reveal prominent transitions associated with $^{27}$Al and $^{24}$Mg at 844, 1015, and 1369 keV, mainly originating from $^{12}$C+$^{16}$O fusion reactions induced by carbon impurities under $^{16}$O irradiation. Meanwhile, characteristic $\gamma$-rays emissions from evaporation channels of the $^{16}$O+$^{16}$O reaction, including $^{31}$S, $^{31}$P, and $^{28}$Si, were also observed and can be used to extract the $^{16}$O+$^{16}$O fusion cross sections. This work provides an experimental basis for the development of high-purity oxide targets and the optimization of target configurations for future low-background $^{16}$O+$^{16}$O fusion cross section measurements.

physics.ins-det↗

arXiv2026

Scintillation of the first-known pulsar planetary system

We present a scintillation study of the first-known pulsar planetary system, PSR~B1257+12, using the Five-hundred-meter Aperture Spherical radio Telescope (FAST). A total of 31 observations with durations greater than or equal to 30 minutes were analyzed. For 14 longer observations (greater than or equal to 120 minutes), one-dimensional autocorrelation function analyses yielded the scintillation timescale, scintillation bandwidth, and frequency-drift rate for 12 epochs. Two observations show strong periodic modulation in the frequency-domain auto-correlation function, likely caused by astronomical-unit-scale structures along the propagation path, preventing reliable measurements of the scintillation timescale and bandwidth. In three observations, secondary spectra reveal simultaneous detections of inner, middle, and outer arcs. Analysis of the annual modulation of the inner-arc curvature indicates isotropic scattering, with a screen distance of $233\pm28$~pc and transverse velocity $V_{\rm scr,\alpha}=-7.16\pm2.16$ km~s$^{-1}$, $V_{\rm scr,\delta}=-41.07\pm5.69$ km~s$^{-1}$. Delay-profile analysis for both the inner and outer arcs suggest spectral exponents consistent with, or smaller than, the Kolmogorov value. Under isotropic scattering, the screen--pulsar distances are $354\pm22$~pc and $166\pm12$~pc for the middle and outer arcs. Combining the results from long-term timing analyses with our scintillation measurements, we find that the dispersion measure (DM) variations are primarily dominated by plasma located further away from the pulsar. The low DM-change rate of the outer arc and the absence of nearby scattering screens suggest that the immediate environment of the pulsar may be relatively clean. Alternatively, scattering screens closer to the pulsar may exist but remain undetected, requiring higher-sensitivity or longer-duration observations.

astro-ph.HE↗

arXiv2026

The GRB joint scientific analysis pipeline of the ECLAIRs and GRM instruments on board SVOM

The study of the prompt high-energy emission of Gamma-Ray Bursts (GRBs) with SVOM relies on the observations performed by ECLAIRs (4-150 keV) and the Gamma-Ray Monitor (GRM, 0.015-5 MeV), the two wide field-of-view instruments on board the satellite. In this article, we introduce the eclgrm pipelines running at the French Science Center of SVOM, which combine the ECLAIRs and GRM data to generate scientific data products describing the GRB broad-band temporal and spectral properties. The architecture of the pipelines is presented, as well as their activation following each onboard trigger, and their workflow. The statistical data analysis methods employed by the pipelines are described, along with the scientific data products that are created in real time or from the full event data. We also present the eclgrm-ui user interface which allows the scientists on shift to monitor the automated data processings in the pipelines, and to optimize the analysis results interactively.

astro-ph.HE↗

arXiv2026

XRF 241001A/SN 2024aiiq: A faint soft X-ray transient detected by SVOM with a broad-line type Ic supernova revealed by JWST

X-ray flashes (XRFs) are a type of gamma-ray burst (GRB) with prompt emission predominantly below 30 keV and have been poorly detected by previous missions. The advent of the SVOM mission, with its wide-field instrument ECLAIRs, provides a new way to detect soft X-ray transients. We present photometric and spectroscopic observations of XRF 241001A detected by SVOM, a soft, subluminous, and low-energetic burst located in a poorly populated region of the Amati relation. We investigated the origin of its faint, soft high-energy emission to assess its connection to the long GRB population. We analyzed the SVOM/ECLAIRs prompt emission and modeled its afterglow emission from X-ray to-radio. We present JWST/NIRSpec and SVOM/VT observations of the associated supernova (SN 2024aiiq), and we compared its properties with previously detected GRB/SNe. The event XRF 241001A is located at z = 0.573 and has a prompt emission dominated by photons below 20 keV with a duration of T90 = 3.14 seconds. Its spectrum is consistent with both thermal and nonthermal models, each implying a low Epeak < 10 keV and Eiso ~ 8x10^49 erg. The X-ray-to-radio afterglow modeling favors an origin from a relativistic jet viewed on-axis. In the optical, XRF 241001A exhibits an early blue emission, similar to that detected in some eFXTs and inconsistent with synchrotron emission. The JWST/NIRSpec observations firmly established its collapsar origin by revealing a SN Type Ic with broad lines, comparable to SN 1998bw and SN 2025kg-like events. The event XRF 241001A is a soft low-luminosity collapsar event produced by a weak relativistic jet observed on-axis, supporting the view that part of the XRF population forms the low-energy soft tail of the long GRB population. Its observation demonstrates the potential of SVOM/ECLAIRs to probe the soft regime of the high-energy transient population that remains largely unexplored.

astro-ph.HE↗

arXiv2026

Single-Pulse Study of the Pseudo-nulling Pulsar PSR J1820-0509 Based on FAST Observations

Using two observations obtained with the Five-hundred-meter Aperture Spherical radio Telescope (FAST), we present a detailed single-pulse analysis of the high-nulling pulsar PSR J1820-0509. We measure an exceptionally high nulling fraction of approximately 81.78%, significantly exceeding previous estimates from Parkes observations. The single-pulse energy distribution exhibits a clear bimodal structure, consistent with classical nulling behavior. However, stacking the identified null pulses reveals a statistically significant residual profile above the noise level, indicating that the nulls correspond to a very weak emission state rather than a complete cessation of radio emission. The pulsar shows clustered burst activities spanning several hundred rotation periods, with prominent quasi-periodicities at 1191 +/- 81 and 590 +/- 15 pulse periods in the two observations. Based on temporal clustering and integrated profile morphology, we identify three distinct emission modes (A, B, and C) and a pseudo-null state (D). These modes exhibit systematic differences in pulse morphology, polarization, and energy statistics. The pulse width-energy relations reveal clear transitions between low- and high-energy regimes. The energy distributions of Modes A and C are well described by lognormal functions, while Mode B follows a composite Gaussian-lognormal distribution. These results suggest that the radio emission of PSR J1820-0509 is governed by multiple quasi-stable magnetospheric states. The presence of weak emission during pseudo-nulls, together with systematic mode-dependent variations, supports the interpretation that pulsar nulling reflects transitions between different magnetospheric activity levels rather than a complete shutdown of emission.

astro-ph.HE↗

arXiv2025

Electron spectral shape of the third-forbidden $\beta$-decay of $^{87}$Rb measured using a Rb$_2$ZrCl$_6$ crystal scintillator

In recent years, interest in experimental studies of $\beta$-decay electron spectra -- often referred to as $\beta$ spectra -- has been growing. This is particularly true for $\beta$ transitions where the electron spectra are sensitive to the effective value of the weak axial coupling, $g_{\rm A}$. Such measurements serve as important benchmarks for nuclear physics calculations and can also be used to characterize background in astroparticle physics experiments. In this work, a dedicated experiment has been carried out to investigate the spectral shape of the third-forbidden $^{87}$Rb $\beta$-decays, with the goal of estimating the effective $g_{\rm A}$ value for this transition and of deriving the T$_{1/2}$ value. This was done by comparing the experimental spectral shape with the estimates from various phenomenological models. The $^{87}$Rb source was embedded directly within the detector material of a new Rb$_2$ZrCl$_6$ crystal scintillator; the data taking was performed deep underground at Gran Sasso National Laboratory. The obtained experimental half-life value for the studied process is T$_{1/2} = 5.08(13) \times$ 10$^{10}$ yr; while a $g_{\rm A}$ value in the range 0.4 to 0.6 is obtained when accounting for uncertainties and depending on the model adopted as discussed in detail in the text.

nucl-ex↗

arXiv2025

$C_{3}$-Symmetry-induced Antisymmetric Planar Hall effect and Magnetoresistance in Single-Crystalline Ferromagnets

The planar Hall effect (PHE) is typically symmetric under magnetic field reversal, as required by the Onsager reciprocity relations. Recent advances have identified the antisymmetric PHE (under magnetic field reversal) as an intriguing extension in magnetic systems. While new mechanisms have been proposed, the role of conventional anisotropic magnetoresistance (AMR) in this phenomenon remains unclear. Here, we report the experimental discovery of an antisymmetric (with respect to both magnetic field and magnetization) PHE and magnetoresistance in single-crystal $Co_{30}Pt_{70}$ (111) thin films with $C_{3}$ rotational symmetry and perpendicular magnetic anisotropy (PMA). We demonstrate that both antisymmetric effects arise naturally from the intrinsic fourth-rank AMR tensor inherent to C3-symmetric planes, assisted by PMA. Our findings link conventional AMR to antisymmetric galvanomagnetic responses, offering new insights into symmetry-governed transport in crystalline ferromagnets.

cond-mat.mtrl-sci↗

arXiv2025

Nonlocal effective field theory and its applications

We review recent applications of nonlocal effective field theory, focusing in particular on nonlocal chiral effective theory and nonlocal quantum electrodynamics (QED), as well as an extension of nonlocal effective theory to curved spacetime. For the chiral effective theory, we discuss the calculation of generalized parton distributions (GPDs) of the nucleon at nonzero skewness, along with the corresponding gravitational (or mechanical) form factors, within the convolution framework. In the QED application, we extend the nonlocal formulation to construct the most general nonlocal QED interaction, in which both the propagator and fundamental QED vertex are modified due to the nonlocal Lagrangian, while preserving the Ward-Green-Takahashi identities. For consistency with the modified propagator, a solid quantization is proposed, and the nonlocal QED is applied to explain the lepton $g-2$ anomalies without the introduction of new particles or interactions. Finally, with an extension of the chiral effective action to curved spacetime, we investigate the nonlocal energy-momentum tensor and gravitational form factors of the nucleon with a nonlocal pion-nucleon interaction.

hep-ph↗

arXiv2025

Scintillating properties of Cs${_2}$ZrCl${_6}$ crystals in the temperature range of 5-300 K

A new comprehensive study on the Cs${_2}$ZrCl${_6}$ (CZC) crystal scintillating properties under different types of irradiation was performed over a wide temperature range from 5 to 300 K. The light yield (LY) at room temperature (RT), measured under irradiation by 662 keV $\gamma$ quanta of $^{137}$Cs, was evaluated to be 53,300 $\pm$ 4,700 photons/MeV corresponding to approximately 71% of its estimated absolute value. The maximum light emission was observed in the temperature interval 135-165 K, where the LY reached 56,900 photons/MeV and 19,700 photons/MeV for $\gamma$ quanta and $\alpha$ particles, respectively. The quenching factor (QF) for $\alpha$ particles increases smoothly from QF = 0.30 at RT to QF = 0.36 at 135 K. The shape of scintillation pulses induced by $\alpha$ particles is characterized by three time-constants (0.3, 2.5 and 11.8 $\mu$s at RT), whereas the average pulse of $\gamma$ induced events is characterized by two time-constants (1.3 and 11.5 $\mu$s at RT). At the same time, scintillating properties and pulse-shape discrimination capability of the CZC exhibit an acute deterioration at temperatures below 135 K. The optimal operating conditions to maximize the scintillating performance of undoped CZC crystals are discussed.

physics.ins-det↗

arXiv2025

FPGA-Based RoCEv2-RDMA Readout Electronics for the CTAO-LST Advanced Camera

CTAO's (Cherenkov Telescope Array Observatory) largest telescopes type, the LST (Large-Sized Telescope), are being installed at the northern site of the Cherenkov Telescope Array (CTA) at the Observatorio del Roque de los Muchachos on the Canary island of La Palma. Their aim is to capture the lowest-energy gamma rays of the observatory. The hereby proposed readout electronics architecture, serving as a proof-of-concept for its advanced camera upgrade, relies on a custom high-channel count fast sampling hardware digitizer board acting as a Front-End. The design includes a versatile pre-amplification stage and high-speed serial links for streaming JESD204C-compliant data at rates approaching 12 Gb/s per lane. The data get transferred to Back-End electronics for a first data-processing and trigger before being transmitted to event-building servers through 10 Gb/s Ethernet links. The performance of the link is exploited by implementing RDMA communication in hardware, thanks to a RoCEv2 core written in Bluespec SystemVerilog, enabling the possibility of transfer data directly to processing units without CPU intervention. Hardware design and characterization of the Front End board are reported, as well as a detailed description and tests of the Back End RDMA firmware.

astro-ph.IM↗

arXiv2025

Decadal evolution of a repeating fast radio burst source

The origin of fast radio bursts (FRBs), the brightest cosmic radio explosions, is still unknown. Bearing critical clues to FRBs' origin, the long-term evolution of FRBs has yet to be confirmed, since the field is still young and most FRBs were seen only once. Here we report clear evidence of decadal evolution of FRB~20121102A, the first precisely localized repeater. In conjunction with archival data, our FAST and GBT monitoring campaign since 2020 reveals a significant 7% decline of local dispersion measure (DM). The rotation measure (RM) of 30,755$\pm$16 $\mathrm{rad\,m^{-2}}$ detected in the last epoch represents a 70% decrease compared to that from December 2016. The $\sigma_{RM}$ parameter, which describes the complexity of the magneto-ionic environment surrounding the source, was shown to have decreased by 13%. These general trends reveal an evolving FRB environment, which could originate from an early-phase supernova associated with an enhanced pair wind from the FRB central engine.

astro-ph.HE↗

arXiv2025

Measurement of the Parity-Violating Asymmetry in the N to $\Delta$ Transition at Low $Q^2$

We report the measurement of the parity-violating asymmetry in the N to $\Delta$ transition via the $e^- + p \rightarrow e^- + \Delta ^+$ reaction at two different kinematic points with low four-momentum transfer Q$^2$. Measurements were made with incident electron beam energies of 0.877 and 1.16 GeV, corresponding to $Q^2$ values of 0.0111 and 0.0208 (GeV/c)$^2$, respectively. These measurements put constraints on a low-energy constant in the weak Lagrangian, $d_\Delta$, corresponding to a parity-violating electric-dipole transition matrix element. This matrix element has been shown to be large in the strangeness-changing channel, via weak hyperon decays such as $\Sigma ^+ \rightarrow p\gamma$. The measurements reported here constrain $d_\Delta$ in the strangeness-conserving channel. The final asymmetries were -0.65 +- 1.00 (stat.) +- 1.02 (syst) ppm (parts per million) for 0.877 GeV and -3.59 +- 0.82 (stat.) +- 1.33 (syst.} ppm for 1.16 GeV. With these results we deduce a small value for $d_\Delta$, consistent with zero, in the strangeness-conserving channel, in contrast to the large value for $d_\Delta$ previously reported in the strangeness-changing channel.

nucl-ex↗

arXiv2025

Single-Pulse Morphology of PSR J1935+1616 (B1933+16) Based on archival data from FAST

We utilized archived data from the Five-hundred-meter Aperture Spherical Radio Telescope (FAST) to analyze the single-pulse profile morphology of PSR J1935$+$1616 (B1933$+$16). The results show that PSR J1935$+$1616 exhibits significant micropulses as well as various changes in single-pulse profile morphology. In the FAST archived data, a total of 969 single pulses with microstructure were identified, accounting for 9.69$\%$ of the total pulse sample, with characteristic widths of $127.63^{+70.74}_{-46.25}$ $\mu$s. About half of these pulses display quasiperiodic micropulses, with a periodicity of 231.77 $\pm$ 9.90 $\mu$s. Among the 520 single pulses with quasiperiodic microstructure, 208 also exhibit quasiperiodicity in circular polarization, with a characteristic period of $244.70^{+45.66}_{-21.05}$ $\mu$s. The micropulse characteristic width in circular polarization is 106.52 $\pm$ 46.14 $\mu$s. Compared to normal pulses, the relative energy (E/ ) of single pulse with microstructure follows a double Gaussian distribution, while that of normal pulses follows a single Gaussian distribution. Based on the intensity of the leading and trailing components in the single-pulse profile morphology of PSR J1935+1616, we classified the pulses into four morphological modes (A, B, C, and D). The relative energy distribution of pulses in mode A is significantly different from the others, following a double Gaussian distribution, while the relative energy distributions in modes B, C, and D follow a single Gaussian distribution. Our study also suggests a possible correlation between micropulses and single-pulse profile morphology. Single pulse with micropulses are most likely to occur in mode A, while their occurrence is least likely in mode D.

astro-ph.HE↗

arXiv2025

Unveiling the emission properties of three long-period pulsars using FAST

We detail the emission behaviors of three long-period pulsars detected using the Five-hundred-meter Aperture Spherical radio Telescope (FAST) during the CRAFTS survey. Their rotational periods range from 1.83 s to 4.75 s, and the null fractions measure between 28% and 53%. PSR J1945+1211 and PSR J2323+1214 exhibited quasi-periodic nulls, with duration of around 57 seconds. The longest null was observed in PSR J1945+1211, lasting 76 seconds. PSR J2323+1214 displayed varying null fractions between its leading and trailing components. For the first time in PSR J2323+1214, we detected five dwarf pulses, which are much weaker and narrower pulses than typical burst pulses. In addition, we investigate the microstructure of PSR J1900-0134 for the first time, revealing intricate pulses of up to 2.05 milliseconds and noting its complex emission characteristics. Bright pulses occur in all of these sources at different rates. These observations suggest complex magnetospheric processes, potentially related to magnetic reconnections, and provide insights into the origins of bright and microstructure pulses, as well as their distinctions from ordinary pulses.

astro-ph.HE↗

arXiv2025

A universal break in energy functions of three hyperactive repeating fast radio bursts

Fast radio bursts (FRBs) are millisecond-duration pulses occurring at cosmological distances with a mysterious origin. Observations show that at least some FRBs are produced by magnetars. All magnetar-powered FRB models require some triggering mechanisms, among which the most popular is the crust cracking of a neutron star, which is called starquake. However, so far there has been no decisive evidence for this speculation. Here we report the energy functions of the three most active repeating FRBs, which show a universal break around $10^{38}$ erg. Such a break is similar to that of the frequency-magnitude relationship of earthquakes. The break and change of the power-law indices below and above it can be well understood within the framework of FRBs triggered by starquakes in the magnetar models. The seed of weak FRBs can grow both on the magnetar surface and in the deeper crust. In contrast, the triggering of strong FRBs is confined by the crustal thickness and the seed of strong FRBs can only grow on the surface. This difference in dimensionality causes a break in the scaling properties from weak to strong FRBs, occurring at a point where the penetration depth of starquakes equals the crustal thickness. Our result, together with the earthquake-like temporal properties of these FRBs, strongly supports that FRBs are triggered by starquakes, providing a new opportunity to study the physical properties of the neutron star crust.

astro-ph.HE↗

arXiv2025

BASSET: Bandpass-Adaptive Single-pulse SEarch Toolkit -- Optimized Sub-Band Pulse Search Strategies for Faint Narrow-Band FRBs

The existing single-pulse search algorithms for fast radio bursts (FRBs) do not adequately consider the frequency bandpass pattern of the pulse, rendering them incomplete for the relatively narrow-spectrum detection of pulses. We present a new search algorithm for narrow-band pulses to update the existing standard pipeline, Bandpass-Adaptive Single-pulse SEarch Toolkit (BASSET). The BASSET employs a time-frequency correlation analysis to identify and remove the noise involved by the zero-detection frequency band, thereby enhancing the signal-to-noise ratio (SNR) of the pulses. The BASSET algorithm was implemented on the FAST real dataset of FRB 20190520B, resulting in the discovery of additional 79 pulses through reprocessing. The new detection doubles the number of pulses compared to the previously known 75 pulses, bringing the total number of pulses to 154. In conjunction with the pulse calibration and the Markov Chain Monte Carlo (MCMC) simulated injection experiments, this work updates the quantified parameter space of the detection rate. Moreover, a parallel-accelerated version of the BASSET code was provided and evaluated through simulation. BASSET has the capacity of enhancing the detection sensitivity and the SNR of the narrow-band pulses from the existing pipeline, offering high performance and flexible applicability. BASSET not only enhances the completeness of the low-energy narrow-band pulse detection in a more robust mode, but also has the potential to further elucidate the FRB luminosity function at a wider energy scale.

astro-ph.IM↗

arXiv2024

Luminescence of the Cs2ZrCl6 under high pressure

The luminescence and Raman spectra of the Cs2ZrCl6 crystal in a wide range of pressures were studied in this work for the first time. Luminescence measurements were performed up to 10 GPa, while the Raman spectra were measured up to 20 GPa. The luminescence data revealed a linear blue shift of the emission maximum from about 2.5 eV at ambient pressure to 3.1 eV at 5 GPa and a strong intensity quenching. The indirect-to-direct bandgap transition at about 5 GPa, a phenomenon previously predicted only theoretically, was used to explain the strong quenching of the luminescence. This model was confirmed by fitting luminescence intensity data and analysis of the luminescence decay kinetics, which exhibited a shortening of the pulse decay time with the pressure increase. Raman spectra confirmed the stability of Cs2ZrCl6 up to 20 GPa and showed no evidence of the pressure-induced structural phase transitions. An energetic scheme of excitonic levels, which takes into account the indirect-to-direct band gasp transition, was proposed to explain the rapid luminescence quenching with increasing pressure.

cond-mat.mtrl-sci↗

arXiv2024

MIMIC-IV-Ext-PE: Using a large language model to predict pulmonary embolism phenotype in the MIMIC-IV dataset

Pulmonary embolism (PE) is a leading cause of preventable in-hospital mortality. Advances in diagnosis, risk stratification, and prevention can improve outcomes. There are few large publicly available datasets that contain PE labels for research. Using the MIMIC-IV database, we extracted all available radiology reports of computed tomography pulmonary angiography (CTPA) scans and two physicians manually labeled the results as PE positive (acute PE) or PE negative. We then applied a previously finetuned Bio_ClinicalBERT transformer language model, VTE-BERT, to extract labels automatically. We verified VTE-BERT's reliability by measuring its performance against manual adjudication. We also compared the performance of VTE-BERT to diagnosis codes. We found that VTE-BERT has a sensitivity of 92.4% and positive predictive value (PPV) of 87.8% on all 19,942 patients with CTPA radiology reports from the emergency room and/or hospital admission. In contrast, diagnosis codes have a sensitivity of 95.4% and PPV of 83.8% on the subset of 11,990 hospitalized patients with discharge diagnosis codes. We successfully add nearly 20,000 labels to CTPAs in a publicly available dataset and demonstrate the external validity of a semi-supervised language model in accelerating hematologic research.

cs.CL↗