Based on collisions between the 100 PW laser and 8 GeV superconducting linear accelerator under construction in the Shanghai High Repetition Rate X-ray Free Electron Laser and Extreme Light Facility, the construction of GeV-level γ -ray as well as positron beams was proposed according to particle-in-cell simulations. Key processes were considered, involving the nonlinear inverse Compton scattering for γ -ray generation and the multiphoton Breit–Wheeler process for electron–positron pair production. Regardless of laser polarization, the simulations indicated that γ -ray beams achieved energies up to 8 GeV, brilliance of approximately 1027 photons/( s·mm^2·mrad^2 ), and emittance as low as 0.1 mm·mrad , whereas positron beams attained energies up to 7 GeV, brilliance of approximately 4 × 1024 positrons/( s·mm^2·mrad^2 ), and emittance as low as 0.1 mm·mrad . Various applications could benefit from the possible high-energy γ -ray and positron beams, which may potentially be built in SHINE, including validation of the fundamental physics of strong-field quantum electrodynamics theory, nuclear physics, nuclear astrophysics, and imaging.

The nuclear phase diagram remains a fundamental challenge, where uncovering how the cluster degree of freedom evolves with temperature and energy is essential to understand the intriguing crossover between cluster, nucleon, and nuclear astrophysics. A new first-order phase transition, the nuclear solid-liquid phase transition (SLPT), emerges spontaneously from nucleonic degrees of freedom in low-energy heavy-ion collisions. Clear signals of the SLPT are identified as a region of negative heat capacity in smaller systems (e.g., ^12C + ^12C and ^16O + ^12C) and a caloric plateau in larger systems (e.g., ^28Si + ^12C and ^40Ca + ^12C), along with prominent behaviors in the number of fragment species and information entropy. Moreover, the pairwise distance probability density function provides a direct spatial fingerprint of the melting, where long-range crystalline α-cluster peaks vanish above the transition temperature, giving way to a liquid-like distribution. This new phase transition unifies the many-body dynamics of finite constituents, extending from nanoscale clusters to nuclear systems. Beyond advancing nuclear structure and phase diagrams, these insights offer profound implications for astrophysics, notably linking structural evolution to astrophysical phase transitions via nuclear cluster dissolution in supernovae.

A systematic study of relaxed low-energy cluster configurations for all nuclides listed in the AME2020 database is performed within the extended quantum molecular dynamics (EQMD) framework, with frictional cooling enabling stable relaxation. A unified classification-quantification framework based on the dimensionless parameters BHTU is established to characterize bubble-like nuclear morphologies. The factor B, determined from the number of inflection points in the radial density profile, categorizes nuclei into droplet (B=0), bubble (B=1), and toroidal bubble (B=2). The parameter H defines the degree of central density depletion, while T and U characterize the relative surface thickness and the relative size of the internal low-density region, respectively. Light nuclei are predominantly droplet-like with B=0, H=0, T=1, U=0. Most medium-mass nuclei have B=1, consistent with previous studies, especially in the vicinity of ^40Ca and the neutron-rich region, where nuclei show a pronounced central hollowing with large H and U values, identifying them as prime candidates for experimental searches for bubble structures. Toroidal bubble nuclei (B=2), emerging for Z≈25 and prevalent in heavy systems, display a local density minimum at intermediate radius together with a shell-like low-density region. Furthermore, bubble structures are found to be widespread in the superheavy region, in agreement with earlier studies. This parameter scheme not only reveals the morphological richness of nuclei but also establishes a predictive framework for exploring exotic nuclear shapes, thereby opening new avenues for future theoretical and experimental investigations.

In this study, a compact 16-channel integrated charge- and current-sensitive preamplifier, called CCPA, was developed for a large-scale detector array used in nuclear physics experiments. The CCPA was designed to achieve pulse-shape discrimination for silicon detectors. CCPA has a fast response of typically less than 6 ns for the pulse rise time and a low equivalent noise of 1.5 keV at zero input capacitance. The energy dynamic range and pulse decay time can be easily adjusted for different applications by changing feedback capacitance C_f and resistance R_f . A good energy resolution of 26.87 keV was achieved for 5.486 MeV α particles from ^241Am . The pulse-shape discrimination method was applied for the first time in an experiment carried out on the Radioactive Ion Beam Line in Lanzhou (RIBLL1), and CCPA demonstrated high resolution and stability in beam experiments. The experiment identified low-energy α particles as low as 5 MeV by the pulse-shape discrimination method, as well as hundreds of MeV charged particles. This provides a new routine for the high-precision measurement of low-energy charged particles emitted by light nuclear reactions.

This study introduces a quantum information perspective to analyze the internal structure of atomic nuclei, focusing on the quantum entanglement between alpha clusters in the 0+ state of 8Be. A wave function based on angular momentum coupling is developed to transform the two-cluster wave function from the conventional center of mass and relative coordinate basis (1-lRc.m. (R) 1-lr) into the individual particle basis (1-l1 (R) 1-l2), which is essential for a precise quantification of entanglement. Within this method, the von Neumann entropy is employed to quantify the entanglement arising from the mixing of angular momentum channels. Additionally, we introduce the concept of spatially resolved entropy, which measures entanglement as a function of the radial separation between clusters. Our analysis reveals that the entanglement is strongly correlated with the spatial configuration at the femtometer scale. As the intercluster separation vanishes, the system approaches a separable S-wave state, indicating that entanglement is dynamically generated during the spatial separation of the clusters. This research provides a new tool for investigating nonlocal quantum correlations in nuclear structure, complementing existing descriptions.

Gas-gain calibration is essential for achieving good energy resolution in large-area, pixelated detectors used in active-target time projection chambers. In this work, a fast gain calibration method based on least-squares minimization is applied to TPC calibration. The method simultaneously extracts all pixel gains by solving a global least-squares problem that models the shared charge response from each 55Fe X-ray event. Compared with conventional pixel-by-pixel X-ray spectrum fitting, the proposed method requires significantly fewer calibration data while providing stable and accurate gain determination. The method is validated using a multi-component alpha source, and an energy resolution of 2.1% at 6.35 MeV is achieved after calibration. This approach offers an efficient solution for gain calibration in large-area, pixel-readout TPC systems.

This study introduces a quantum information perspective to analyze the internal structure of atomic nuclei, focusing on the quantum entanglement between α clusters in the 0^+ state of ^8Be. A wave function based on angular momentum coupling is developed to transform the two-cluster wave function from the conventional center of mass and relative coordinate basis (ℋ_R_c.m.⊗ℋ_r) into the individual particle basis (ℋ_1 ⊗ℋ_2), which is essential for a precise quantification of entanglement. Within this method, the von Neumann entropy is employed to quantify the entanglement arising from the mixing of angular momentum channels. Additionally, we introduce the concept of spatially resolved entropy, which measures entanglement as a function of the radial separation between clusters. Our analysis reveals that the entanglement is strongly correlated with the spatial configuration at the femtometer scale. As the inter cluster separation vanishes, the system approaches a separable S-wave state, indicating that entanglement is dynamically generated during the spatial separation of the clusters. This research provides a new tool for investigating nonlocal quantum correlations in nuclear structure, complementing existing descriptions.

We conduct particle-in-cell simulations to estimate the effects of circularly and linearly polarized SEL 100 PW lasers on flat Th targets with thicknesses of 50 nm, 100 nm and 250 nm, as well as easy to manufacture conical Th targets with angularity either on the left or right. As the thickness of the three types of targets increases and under the same polarized laser, the average energy, maximum energy and energy conversion efficiency of Th ions decrease as it is well-known, and except for the circularly polarized laser hit on the conical target with angularity on the left, the Th ion beam emittance also decreases, while its beam intensity increases conversely. The linearly polarized laser, compared to the circularly polarized laser with the same laser intensity, exhibits higher beam intensity, beam emittance and energy conversion efficiency for the same type and thickness of Th target. The conical Th target with angularity on the left and intermediate thickness, compared to the flat target and conical target with angularity on the right of the same thickness, possesses both higher ion average energy up to 7 GeV and virtually the same beam intensity up to 0.8 MA under the linearly polarized laser. The results lead us to an easier way of controlling laser-accelerated high-quality heavy ion beam by switching to an optimal laser-target configuration scheme, which may enable the synthesis of superheavy nuclei in a high-temperature and high-density extreme plasma environment in astronuclear physics.

Possible Majorana nature of neutrinos is new physics far beyond the Standard Model and is a key scientific question at the modern frontiers of nuclear and particle physics. Neutrinoless double beta decay (0v beta beta) experiment is the only viable approach to determine the Majorana property. The discovery of 0v beta beta will has a great impact on outstanding puzzles of neutrino absolute mass scale, violation of lepton quantum number and matter anti-matter asymmetry of the universe. Among possible technological approaches to 0v beta beta study, cryogenic crystal bolometer with the advantages of superior energy resolution, operational stability and background discrimination, is one of the leading detector choices for next generation of 0v beta beta experiments. We will briefly review the current international efforts on bolometric experiment technology development for 0v beta beta search, and introduce China Jinping cryogenic bolometer experiment and recent R&D progress. Perspectives on neutrinoless double beta decay search based on scintillating crystal bolometer technology at China Jinping Underground Laboratory are also discussed.

Quasi-monochromatic gamma-ray beams are produced in the laser Compton slant-scattering at the Shanghai Laser Electron Gamma Source (SLEGS) of the Shanghai Synchrotron Radiation Facility. A high-power CO(2 )laser is operated in Gated CW mode in a wide range of pulse repetition frequencies of 1-100 kHz and pulse width > 1 mu s. The Gated CW operation of the CO(2 )laser generates pulse gamma-ray beams with a variety of time structure and gamma flux. We report fundamental laser properties in the Gated CW operation and the gamma flux in two cases of gamma-ray beams suited to nuclear physics experiments and industrial applications.

Based on collisions between the 100 PW laser and 8 GeV superconducting linear accelerator constructing at the Shanghai hard X-ray free electron laser system (SHINE), the building of GeV-level γ-ray as well as positron beams are proposed according to particle-in-cell simulations. Key processes are considered involving the nonlinear inverse Compton scattering for γ-ray generation and the multiphoton Breit-Wheeler process for electron-positron pair production. Regardless of laser polarization, the simulations indicate that γ-ray beams achieve energy up to 8 GeV, brilliance around 10^27 photons/(s mm^2 mrad^2), and emittance as low as 0.1 mm mrad, while positron beams reach energy up to 7 GeV, brilliance around 4 × 10^24 positrons/(s mm^2 mrad^2), and emittance as low as 0.1 mm mrad. Various applications could benefit from the possible high-energy γ-ray and positron beams built at the SHINE facility, including fundamental physics of strong-field quantum electrodynamics theory validation, nuclear physics, radiopharmaceutical preparation, and imaging, etc.

A new method for rapidly extracting structural information about two-body clusters from resonance scattering cross sections has been constructed. It assumes that the nonlocal interaction potential between clusters is treated as a small perturbation for the nonantisymmetrized trial wave function, and the wave function derived from the corresponding local potential is employed as the approximate trial wave function within the resonating group method (RGM). The antisymmetrization method of RGM is then applied to compensate for the Pauli blocking absent in the phase function method (PFM). The approach of treating dynamical behavior and antisymmetrization effects separately dates back to 1976. This method significantly reduces the computational effort required to obtain structural information about two-body clusters. In cross-model comparative analyses, this method was used for calculations on 8Be, 20Ne, and 7Li. The resulting phase shifts, cross sections, energy levels, and wave function overlaps demonstrated the effectiveness of the method for two SU(3) scalar clusters.

Active target time projection chambers are state-of-the-art tools in the field of low-energy nuclear physics and are particularly suitable for experiments using low-intensity radioactive ion beams or gamma rays. The Fudan multi-purpose active target time projection chamber (fMeta-TPC) with 2048 channels was developed to study α-clustering nuclei. This study focused on the photonuclear reaction with a laser Compton scattering gamma source, particularly for the decay of the highly excited α cluster state. The design of fMeta-TPC is described in this paper. A comprehensive evaluation of its offline performance was conducted using an ultraviolet laser and 241Am α source. The results showed that the intrinsic angular resolution of the detector was within 0.30°, and the detector had an energy resolution of 6.85

Laser-accelerated high-flux-intensity heavy-ion beams are important for new types of accelerators. A particle-in-cell program (Smilei) is employed to simulate the entire process of Station of Extreme Light (SEL) 100 PW laser-accelerated heavy particles using different nanoscale short targets with a thickness of 100 nm Cr, Fe, Ag, Ta, Au, Pb, Th and U, as well as 200 nm thick Al and Ca. An obvious stratification is observed in the simulation. The layering phenomenon is a hybrid acceleration mechanism reflecting target normal sheath acceleration and radiation pressure acceleration, and this phenomenon is understood from the simulated energy spectrum, ionization and spatial electric field distribution. According to the stratification, it is suggested that high-quality heavy-ion beams could be expected for fusion reactions to synthesize superheavy nuclei. Two plasma clusters in the stratification are observed simultaneously, which suggest new techniques for plasma experiments as well as thinner metal targets in the precision machining process.

The exploration of exotic shapes and properties of atomic nuclei, e.g., α cluster and toroidal shape, is a fascinating field in nuclear physics. To study the decay of these nuclei, a novel detector aimed at detecting multiple α -particle events was designed and constructed. The detector comprises two layers of double-sided silicon strip detectors (DSSD) and a cesium iodide scintillator array coupled with silicon photomultipliers array as light sensors, which has the advantages of their small size, fast response, and large dynamic range. DSSDs coupled with cesium iodide crystal arrays are used to distinguish multiple α hits. The detector array has a compact and integrated design that can be adapted to different experimental conditions. The detector array was simulated using Geant4, and the excitation energy spectra of some α -clustering nuclei were reconstructed to demonstrate the performance. The simulation results show that the detector array has excellent angular and energy resolutions, enabling effective reconstruction of the nuclear excited state by multiple α particle events. This detector offers a new and powerful tool for nuclear physics experiments and has the potential to discover interesting physical phenomena related to exotic nuclear structures and their decay mechanisms.

Particle identification plays an important role in heavy-ion collisions at low and intermediate energies. The task of particle identification is to identify the particles’ atomic number (Z) and mass number (A) in heavy-ion collisions. However, traditional particle identification methods have several problems, including experience-dependency, poor repeatability, and time-consuming challenges. This paper proposes a particle identification method based on particle swarm optimization (PSO) to overcome these challenges. The verification by Geant4 simulation data show that it can effectively identify particle data of heavy-ion collisions at low and intermediate energies. Compared with traditional supervised and unsupervised learning algorithms, this method can reduce data requirements and effectively address complex data distribution. It is expected to become the technical basis for developing professional particle identification software.

The angle-differential cross sections of neutron-induced d production from carbon were measured at 12 neutron en-ergies at Back-n white neutron source of China Spallation Neutron Source(CSNS).By employing the ⊿E-E telescopes of the Light-charged Particle Detector Array(LPDA)system from 24.5° to 155.5° in the laboratory system,the angle-differen-tial cross sections of the 12C(n,d)x reactions were measured.The experimental results are in good agreement with the previ-ous ones.The present work can provide a reference to the data library considering the lack of experimental data.

The bubble nuclei are important components of exotic nuclear structures characterized by special depletions of central densities. Focusing on bubble structures of ^36Ar, the characterizations of bubble nuclei were explored with the framework of the extended quantum molecular dynamics model. Three density distribution modes were uncovered for the first time, i.e. micro-bubble, bubble, and cluster resonances, which show unique spectral signature compared to the monopole resonance spectrum as the excitation intensity was increased in bubbles. Of pivotal importance is the revelation that the bubble mode's oscillation frequency closely resembles macroscopic bubble dynamics, building a connection between classical macroscopic phenomena and the quantum complexity of the nuclear structure. The discovery marks a crucial step forward in deciphering the relationship between classical and quantum domains within the enigmatic world of atomic nuclei.

Total-energy responses of a 76 mm × 200 mm BGO detector were used to deduce energy distributions of quasi-monoenergetic gamma-rays generated at the Shanghai Laser Electron Gamma Source (SLEGS) of the Shanghai Synchrotron Radiation Facility. Responses of the BGO detector to monoenergetic gamma-rays produced in (p,γ) reactions on LiF, 27Al, and 13C targets were measured at the China Institute of Atomic Energy. A direct unfolding of BGO total-energy responses into gamma-ray energy distributions was iteratively performed by solving a set of linear equations with the monoenergetic response of the BGO detector being the matrix element. We present resultant energy distributions of gamma-ray beams produced in the slant-scattering at SLEGS.