Mega-electron volt-scale attosecond gamma-ray pulses open unprecedented avenues for interrogating ultrafast electron and nuclear dynamics. However, their generation remains hampered by complex experimental configurations and limited tunability. Here, we propose and numerically validate a compact scheme where a relativistic right-handed circularly polarized Laguerre-Gaussian laser irradiates a thin plasma foil in the presence of a co-propagating aligned magnetic field. The magnetic field significantly reduces the synchrotron radiation lifetime, enabling an efficient temporal compression of gamma-ray pulses to approximately 57% of their original duration, while simultaneously enhancing the stability of the photon number, radiation energy, and control over the orbital angular momentum (OAM) of the emitted gamma-rays. Under strong magnetic fields, a reversal of the gamma-ray OAM is observed. The compression exhibits a nonmonotonic dependence on field strength. This mechanism offers a robust pathway toward compact, structure-tunable attosecond gamma-ray sources with controllable OAM, suitable for high-field quantum electrodynamics studies and next-generation light sources.

In this study, we extend our previous high-speed photographic studies (Xie et al. 2022 and Han et al. 2025) to direct characterization of the central channel and its flow velocity distribution in an analytical inductively coupled plasma source. The strong plasma emission was successfully suppressed by optimising the high-speed camera's aperture size and shutter duration, allowing us to directly observe the central channel and the discrete ion cloud. The width of the central channel was determined from the luminance distribution rather than the analyte ion distribution, unlike the commonly used method. The effect of the addition percentage of oxygen and nitrogen to the sample flow on the channel width was investigated. By injecting and tracking five types of suspension particles with various inertial properties, the axial flow velocity in the central channel was determined using the time-of-flight method. The axial flow velocity distributions at varying r.f. power, sample flow rate, and addition fraction of oxygen and nitrogen in the sample flow were finally experimentally determined. Results show that the width of the central channel in pure Ar-ICP is 7.2 mm under the investigated operating conditions. The presented width value is comparable with the peak-to-peak distance of the plasma parameter distributions but about three times that determined from the analyte ion distribution. In the mixed-gas ICP, the width increases with increasing nitrogen addition percentage in the sample flow but is insensitive to the oxygen addition fraction. Compared with the flow velocity, no particle slipping or dragging was observed, indicating that the flow velocity was well represented by that of the suspension particles used. In pure Ar-ICP, Ar-O2 ICP and Ar-N2 ICP, the axial flow velocity tends to increase and then decrease with the axial position with respect to the torch outlet. In pure Ar-ICP, a cubic polynomial fitting of the axial flow velocity with the quadratic root of the axial position is proposed for velocity estimation. A velocity plateau is clearly observed in the normal analytical zone (NAZ). The present work provides detailed information on the central channel for pure argon, Ar-O2 ICP, and Ar-N2 ICP. Experimental data on the axial flow velocity distribution across a wide range in the ICP source are also presented.

The identification and classification of Fermi blazars are core topics in high-energy astrophysics. To enable precise spatial cross-identification, we constructed two high-precision catalogues: the updated 4FGL-Xiang-DR2 (DR2) and a supplementary version of the fifth edition of Roma-BZCAT (5BZCAT_err). We then developed and applied a novel four-step analytical pipeline combining cross-matching with the statistical analysis of multiband flux distributions to identify new Fermi blazars. The analytical pipeline has yielded several key results in the systematic comparison of BZBs and BZQs. We found that among single statistical metrics, kurtosis is the most powerful discriminator (MAD > 1.64). At the overall distribution level, the 1.4 GHz, 843 MHz, 5 GHz, 0.1-2.4 keV, and 0.3-10 keV bands show significant divergence (JSD > 0.3). Building on these findings, our proposed 'Box-Cox+TND' model successfully fits the observed flux distributions between BZBs and BZQs. Applying this entire pipeline, we successfully identified 17 new blazars. The validity of these associations is strongly supported by our multiwavelength flux model, which confirms that 15 of the 17 candidates are statistically consistent with the known blazar population, falling within the 2 sigma confidence interval. Although the two remaining sources exhibit some statistical deviation in the gamma-ray band, their strong consistency in other wavebands, coupled with high spatial association probabilities, leads us to conclude that their associations are also reliable and should not be readily excluded.

Intense laser-plasma interactions generate high-order harmonics, providing a route to coherent extreme ultraviolet and x-ray sources, but their complex spatial properties limit practical applications. Two-dimensional particle-in-cell simulations show that tailoring the laser transverse profile controls the spatial characteristics of high-order harmonics through modification of the plasma surface curvature. At fixed peak intensity, increasing the beam waist radius from 2 lambda L to 4 lambda L reduces the full width at half maximum (FWHM) of the harmonic emission by approximately 26%. Under fixed laser energy, a larger beam waist radius improves harmonic collimation at the expense of intensity, revealing a trade-off between brightness and beam confinement. Compared with a Gaussian laser, a super-Gaussian laser reduces the harmonic FWHM by approximately 65% while increasing the peak intensity by more than 150%. These results identify the beam waist radius and transverse laser profile as key parameters for optimizing harmonic collimation and brightness.

Many numerical simulation models for analytical and industrial ICP sources have been developed; hence, experimental verification is essential. Compared with plasma temperature, the flow velocity profile is a direct and reliable criterion for model verification. In this paper, an experimental study on the dynamic properties of a home-made analytical ICP source and its tail flame is conducted using a high-speed colour camera and a high-speed fibre-optic spectrometer, and the spatially resolved pulsation frequency and flow velocity are presented. The pulsation frequencies of the plasma area and emission intensity were experimentally determined, respectively. The spatially resolved pulsation frequency indicates that pulsation of the normal analytical zone (NAZ) is very stable and synchronous, and the tail flame fluctuates due to ambient air entrainment. The flow velocity in the coolant gas was characterised by tracking the trajectories of injected alumina powder particles. After correcting for the velocity difference between the powder particle with high inertia and the surrounding flow, a plausible range of axial (Vz) and radial (Vr) velocity at the outer edge of the coolant gas is proposed. The flow velocity on the axis downstream of the NAZ was experimentally determined by tracking and interpolating the velocity of discrete erbium ion clouds originating from individual erbia suspension particles. By comparing the simulated profile of axial velocity with the experimental profile, the power coupling efficiency of the present ICP facility is estimated to be around 80%. A linear expression is presented to describe the variation of Vz with the axial position (z) in the range of 0 <= z <= 50 mm. Because erbium ion clouds were not distinguishable from the very bright emission background within the NAZ, a novel method is proposed to determine the flow velocity in the NAZ by combining the dependence of the audio frequency of plasma pulsation on the flow velocity profile, the simulated profile of axial velocity, and the experimental value of pulsation frequency. The determined value of axial velocity at the torch outlet axis operating at an r.f. power of 1200 W is in good agreement with the fitted value. This work presents complete experimental data on flow velocity in a single ICP facility and experimentally verifies the previously developed 2D numerical model.

High-order harmonic generation (HHG) plays a key role in producing coherent extreme ultraviolet (EUV) and x-ray radiation, which is crucial for applications in attosecond science and high-energy density physics. The intensity and order of high-order harmonics are crucial for advancing their applications. In this paper, a scheme is proposed to generate harmonics by the relativistic oscillating mirror (ROM) based on the energy exchange between electron and excited plasma wave by Landau damping, which employs dual laser pulses to sequentially excite the plasma surface electron oscillation to enhance the intensity and order of harmonics. Through theory and numerical analysis, we discover that our scheme significantly enhances the intensity of higher-order harmonics by an order of magnitude compared to typical harmonic generation methods of the same energy, and observe the higher-order harmonics. Furthermore, we investigate the essential factors affecting energy exchange in Landau damping and find that there exists an optimal pulse interval and energy ratio to maximize the energy exchange. The scheme based on Landau damping for generating high-order harmonics offers an alternative perspective for advancing HHG research and applications.

High-energy proton beams are essential for fundamental research and applied physics. The combined acceleration mechanism based on radiation pressure acceleration has made great progress in obtaining high-energy protons. However, Rayleigh–Taylor instability (RTI) is still a potential influencing factor that will limit the quality of high-energy proton beams. Different from the previous suppression and neglect of RTI, this paper introduces a parabolic density plasma channel to accelerate protons by virtue of the characteristics of RTI. Three-dimensional Particle-in-cell simulations reveal that this scheme achieves high-energy protons with cut-off energy of 39 GeV , total charge of 0.97 nC , and the emittance of 1.12 mm mrad in both the y and z directions. There are locally distributed electrons in the parabolic density plasma channel, and the focusing field around them can effectively focus protons. Compared with the uniform density plasma channel, the parabolic density plasma channel can significantly improve the quality of the proton beam, which could offer significant guidance for the generation and application of high-energy proton beams.

A plasma mirror is an optical device for high-power, ultrashort-wavelength electromagnetic fields, utilizing a sheet of relativistic oscillating electrons to generate and manipulate light. This work proposes that the spatiotemporally varying plasma oscillation, induced by an ultra-high-intensity laser beam, functions as a "spacetime mirror" with significant potential for exploring quantum light. This study finds that the spacetime mirror exhibits several exotic features: i) a superluminal spacetime boundary, ii) time reflection and refraction, and iii) quantum light sources with pair generation via vacuum squeezing. These theoretical and simulation results are in excellent agreement, and experimental verification is underway. This work demonstrates the interplay with emerging fields such as time-varying media, suggesting the plasma mirror as an ideal platform to study strong-field quantum optics at extremes.

The Circular Electron-Positron Collider (CEPC) performs precision measurements of Higgs boson properties, which require MeV-level precision in beam energy calibration. In the W/Z factory mode, the requirements for beam energy calibration are an order of magnitude higher than those in the Higgs operation. To address this need, we utilize a beam energy calibration scenario based on inverse Compton scattering, using a laser beam heading on the electron bunch and a bending dipole. Our Monte-Carlo simulations demonstrate that the beam energy can be calibrated to a precision of about 1 MeV, using the position distribution of scattered photons and scattered electrons. Additionally, the systematic deviations caused by the magnetic field and the synchrotron radiation are analyzed. The error of the method of measuring the scattering position by measuring the scattering angle is divided into two parts, which are 9.75 and 5.76 MeV, respectively. The estimated systematic deviation of the calibration energy caused by the electron beam emittance angle is approximately 3.4 keV.

The identification and classification of Fermi blazars are core topics in high-energy astrophysics. To enable precise spatial cross-identification, we constructed two high-precision catalogs: the updated 4FGL-Xiang-DR2 (DR2) and a supplementary version of the fifth edition of Roma-BZCAT (). We then developed and applied a novel four-step analytical pipeline combining cross-matching with the statistical analysis of multi-band flux distributions to identify new Fermi blazars. The analytical pipeline has yielded several key results in the systematic comparison of BZBs and BZQs. We found that among single statistical metrics, kurtosis is the most powerful discriminator (MAD > 1.64). At the overall distribution level, the 1.4 GHz, 843 MHz, 5 GHz, 0.1–2.4 keV, and 0.3–10 keV bands show significant divergence (JSD > 0.3). Building on these findings, our proposed “Box-Cox+TND” model successfully fits the observed flux distributions between BZBs and BZQs. Applying this entire pipeline, we successfully identified 17 new blazars. The validity of these associations is strongly supported by our multi-wavelength flux model, which confirms that 15 of the 17 candidates are statistically consistent with the known blazar population, falling within the 2σ confidence interval. Although the two remaining sources exhibit some statistical deviation in the gamma-ray band, their strong consistency in other wavebands, coupled with high spatial association probabilities, leads us to conclude that their associations are also reliable and should not be readily excluded.

The impressive progress in high-powered lasers has resulted in all-optical nonlinear inverse Compton scattering emerging as a potential method for generating ultra-short, brilliant γ ray in a remarkably compact setup. Nonetheless, the conversion efficiency and energy of currently implemented Compton γ -ray sources are still low. We present three-dimensional particle-in-cell simulations investigating the γ -ray emission resulting from the interaction of a femtosecond laser pulse ( I = 5 × 10^21 W/cm^2 ) with a down-ramp density plasma. Our study reveals that a down-ramp density plasma affects the self-injection of electrons, resulting in a lower self-injection threshold. Consequently, more electrons can be trapped in the wakefield for acceleration. The simulation results demonstrate the production of high-energy γ ray with a maximum energy of E_γ , max = 148.18 MeV and a low emittance of θ _γ = 4.2 mm·mrad . Compared to the scheme without down-ramp density plasma, the conversion efficiency of laser energy to photons is improved from approximately 0.13 to 0.29 γ ray by using shaped-intensity laser pulses. This broadens the application range of all-optical Compton scattering.

The Circular Electron Positron Collider (CEPC) is a large scientific project initiated and hosted by China, fostered through extensive collaboration with international partners. The complex comprises four accelerators: a 30 GeV Linac, a 1.1 GeV Damping Ring, a Booster capable of achieving energies up to 180 GeV, and a Collider operating at varying energy modes (Z, W, H, and ttbar). The Linac and Damping Ring are situated on the surface, while the Booster and Collider are housed in a 100 km circumference underground tunnel, strategically accommodating future expansion with provisions for a Super Proton Proton Collider (SPPC). The CEPC primarily serves as a Higgs factory. In its baseline design with synchrotron radiation (SR) power of 30 MW per beam, it can achieve a luminosity of 5e34 /cm^2/s^1, resulting in an integrated luminosity of 13 /ab for two interaction points over a decade, producing 2.6 million Higgs bosons. Increasing the SR power to 50 MW per beam expands the CEPC's capability to generate 4.3 million Higgs bosons, facilitating precise measurements of Higgs coupling at sub-percent levels, exceeding the precision expected from the HL-LHC by an order of magnitude. This Technical Design Report (TDR) follows the Preliminary Conceptual Design Report (Pre-CDR, 2015) and the Conceptual Design Report (CDR, 2018), comprehensively detailing the machine's layout and performance, physical design and analysis, technical systems design, R&D and prototyping efforts, and associated civil engineering aspects. Additionally, it includes a cost estimate and a preliminary construction timeline, establishing a framework for forthcoming engineering design phase and site selection procedures. Construction is anticipated to begin around 2027-2028, pending government approval, with an estimated duration of 8 years. The commencement of experiments could potentially initiate in the mid-2030s.

We employ an efficient method for identifying γ-ray sources across the entire sky, leveraging advanced algorithms from Fermipy, and cleverly utilizing the Galactic diffuse background emission model to partition the entire sky into72 regions, thereby greatly enhancing the efficiency of discovering new sources throughout the sky through multithreaded parallel computing. After confirming the reliability of the new method, we applied it for the first time to analyze data from the Fermi Large Area Telescope(Fermi-LAT) encompassing approximately 15.41 yr of all-sky surveys. Through this analysis, we successfully identified 1379 new sources with significance levels exceeding 4σ,of which 497 sources exhibited higher significance levels exceeding 5σ. Subsequently, we performed a systematic analysis of the spatial extension, spectra, and light variation characteristics of these newly identified sources. We identified 21 extended sources and 23 sources exhibiting spectral curvature above 10 GeV. Additionally, we identified 44 variable sources above 1 GeV.

High-energy proton beams have broad application prospects in medical imaging, tumor therapy and nuclear fusion physics. Laser plasma acceleration is a new particle acceleration method with great potential because its acceleration gradient can reach 103-106 times that of traditional acceleration method, so it can theoretically accelerate electrons and ions to high energies in the scale of a few centimeters to a few meters. Radiation pressure acceleration (RPA) is considered to be the most promising mechanism of high energy proton acceleration in laser plasma acceleration, but the Rayleigh-Taylor instability (RTI) inherent in the process of radiation pressure acceleration will cause transverse density modulation on the target surface, resulting in the premature termination of the proton acceleration process and the failure to obtain high energy proton beams. In order to obtain high-energy proton beams, an acceleration scheme combining radiation pressure acceleration with laser wakefield is proposed. In this scheme, a high-energy proton beam with peak energy of 22.2 GeV, cutoff energy of 36.4 GeV and charge of 0.67 nC is obtained by adding a uniform density plasma channel at the back end of the thin target with critical density, the cut-off energy of the high energy proton can be increased by two orders of magnitude compared with the proton only in the radiation pressure acceleration process. The results confirm that in a uniform-density plasma channel connected behind a thin target, the laser wakefield can capture protons pre-accelerated by the radiation pressure process and maintain the acceleration for a long period of time, finally obtain high-energy protons. The acceleration of protons in plasma channels with different uniform densities is also investigated in this work, and it is found that the higher the density, the higher the peak energy, cut-off energy and charge of the accelerated protons are. The combined acceleration scheme is instructive for the generation and application of high-energy proton beams.

Realtime trigger and localization of bursts are the key functions of GECAM, an all-sky gamma-ray monitor launched on 2020 December 10. We developed a multifunctional trigger and localization software operating in the CPU of the GECAM Electronic Box. This onboard software has the following features: high trigger efficiency for real celestial bursts with a suppression of false triggers caused by charged particle bursts and background fluctuation, dedicated localization algorithm optimized for both short and long bursts, and low time latency of the trigger information which is downlinked through the Global Short Message Communication service of the global BeiDou navigation system. This paper provides a detailed description of the design and development of the trigger and localization software system for GECAM. It covers the general design, workflow, the main functions, and the algorithms used in the system. The paper also includes on-ground trigger tests using simulated gamma-ray bursts generated by a dedicated X-ray tube, as well as an overview of the performance for real celestial bursts during its in-orbit operation.

The High Energy Cosmic-Radiation Detection (HERD) facility is a space astronomy and particle astrophysics experiment planned to be installed on the China Space Station. HERD can detect high-energy cosmic rays ranging from GeV to PeV and high-energy gamma rays. The silicon charge detector (SCD) is one of the subdetectors of HERD, measuring the charge and trajectory of incident ions. An ion beam test of the SCD prototype was conducted at CERN in 2022. A novel charge reconstruction algorithm based on the capacitive coupling was developed to study the charge resolution of the SCD prototype, and compared with the classical reconstruction algorithm.

A likely starburst galaxy (SBG), IRAS 13052–5711, which is the most distant SBG candidates discovered to date, was found by analyzing 14.4 yr of data from the Fermi large-area telescope. This SBG’s significance level is approximately 6.55 σ in the 0.1–500 GeV band. Its spatial position is close to that of 4FGL J1308.9–5730, determined from the Fermi large telescope fourth-source Catalog (4FGL). Its power-law spectral index is approximately 2.1, and its light curve for 14.4 yr has no significant variability. These characteristics are highly similar to those of SBGs found in the past. We calculate the SBG’s star formation rate (SFR) to be 29.38 M ⊙ yr −1 , which is within the SFR range of SBGs found to date. Therefore, IRAS 13052-5711 is considered to be a likely SBG. In addition, its 0.1–500 GeV luminosity is (3.28 ± 0.67) × 10 42 erg s −1 , which deviates from the empirical relationship of the γ -ray luminosity and the total infrared luminosity. We considered a hadronic model to explain the GeV spectrum of IRAS 13052-5711.

The Gravitational wave high-energy Electromagnetic Counterpart All-sky Monitor (GECAM) consists of two small satellites operating in the same Earth orbit with opposite phases. Its scientific goal is to monitor the electromagnetic counterparts associated with Gravitational Wave events (GWE) and other cosmic high energy transient sources. As the main detector, the Gamma-Ray Detector (GRD) adopts LaBr $$_{3}$$ :Ce scintillator coupled with SiPM array. Each GRD has two output channels, i.e. high gain channel (8 $$\sim $$ 250 keV) and low gain channel (50 $$\sim $$ 6000 keV). In this paper, we present the low gain calibration results of GRDs with radioactive sources on ground, including the E-C relation, energy resolution, absolute detection efficiency and spatial response. Meanwhile, the consistency between the measurements and Geant4 simulation demonstrates the accuracy of the simulation code.

The Circular Electron-Positron Collider (CEPC) requires a 3% precision in the measurement of dE/dx to identify long-lived charged particles. However, the measurement of dE/dx has a blind area that includes charged particles of π/K, π/P, and K/P, having transverse momenta of 1 GeV/c, 1.6 GeV/c, and 2 GeV/c respectively. One potential solution is to use a high-precision Time of Flight (TOF) detector with a time resolution of less than 50 ps to fill the blind area. To address this, we propose a small particle Time of Flight detector that uses small plastic scintillators (1 cm × 1 cm × 0.3 cm) for readout with silicon photomultipliers. In this article, we introduce the construction of the detector and calibrate its performance using 90Sr electron collimators and high-speed waveform acquisition electronics. Using a constant fraction timing method, the results indicate that the time resolution of the detector is about 48 ps, satisfying the CEPC's requirements for Time of Flight detection.