The high-intensity heavy-ion accelerator facility (HIAF), currently under construction in Huizhou, Guangdong Province, China, is expected to be completed by 2025. This facility will be capable of delivering proton and heavy-ion beams with energies of up to several GeV, thereby providing a versatile platform for advanced fundamental physics research. Key scientific objectives include exploring physics beyond the standard model through the search for new particles and interactions, testing fundamental symmetries, investigating exotic hadronic states such as dibaryons, pentaquark states, and multi-strange hypernuclei, conducting precise measurements of hadron and hypernucleus properties, and probing the phase boundary and the critical point of nuclear matter. To facilitate these investigations, we propose the construction of a dedicated experimental apparatus at HIAF—the Huizhou Hadron Spectrometer (HHaS). This paper presents the conceptual design of HHaS, which comprises a solenoid magnet, a five-dimensional silicon pixel tracker, a Low-Gain Avalanche Detector (LGAD) for time-of-flight measurements, and a Cherenkov–scintillation dual-readout electromagnetic calorimeter. The design targets an unprecedented event rate of 1–100 MHz, extensive particle acceptance, a track momentum resolution at the 1 ∼ 3 % at 1 GeV, and broad particle-identification capability. Such capabilities position HHaS as a powerful instrument for high-precision experimental studies in particle and nuclear physics. The successful realization of HHaS is expected to strongly promote the development of medium- and high-energy physics research within China.

The identification of low-energy charged particles is essential for measuring key nuclear astrophysics reaction cross sections within the stellar Gamow window, where the emitted particles typically carry energies of only a few MeV. This work proposes a low-cost particle identification scheme for low-energy particle detection in nuclear astrophysics, based on pulse-shape discrimination using double-sided silicon strip detectors. The system employs a single-stage charge-sensitive preamplifier and an 80MHz analog-to-digital converter. By applying an interpolation-differentiation procedure to the digitized signals, effective discrimination between 1.7MeV protons and alpha particles is achieved. The results demonstrate that reliable pulse-shape discrimination performance can be maintained while significantly reducing the complexity and cost of the electronics, providing a practical solution for low-energy particle spectroscopy experiments.

We investigate the clustering structure of 10C using a microscopic four-body alpha + alpha + p + p cluster model. The calculated low-lying energy spectrum agrees well with the experimental data. Based on the analysis of reduced width amplitudes and spectroscopic factors for the two-body configurations (9B + p, 6Be + alpha, and 8Be + 2p), as well as the three-body configuration (8Be + p + p), several cluster structures are suggested. The analysis reveals that the 0+1 state corresponds to a compact structure, while the 0+ 2 and 2+3 states show nonnegligible diproton clustering components. In particular, the 0+ 2 state is found to exhibit a mixed structure, involving both the 6Be + alpha and 8Be + p + p configurations, consistent with previous theoretical predictions and experimental observations. It is also indicated that the 2+1 and 2+2 states are dominated by the 9B +p configuration, while the 0+3 state features a more spatially extended configuration.

To meet the precision requirements of future high-energy physics experiments, improving the energy resolution of hadronic calorimeters remains a critical challenge. This work presents a systematic investigation of hadronic energy reconstruction using machine learning, highlighting the roles of various signal channels, including scintillation light, Cherenkov light, charged particles, and the full three-dimensional topology of hadronic showers in the energy range up to 10 GeV. Throughout this study, detector effects are not taken into account. Under these conditions, the intrinsic resolution of hadronic showers reaches approximately (10.8±0.3)% / √(E/GeV) when all signal channels and the full 3D shower information are fully utilized. Compared with the traditional signal-summing approach, machine-learning-based reconstruction can significantly improve energy resolution, even under a limited sampling fraction of 10%, enhancing it from (57.6±3.7)%/√(E/GeV) to (34.1±2.8)%/√(E/GeV). These results highlight the critical importance of both multi-channel information and detailed spatial shower features in hadronic energy reconstruction, and demonstrate the substantial potential of combining high-granularity and dual-readout calorimeter designs with machine-learning-based reconstruction techniques for future experiments.

Chirality lies at the heart of low-energy QCD, governing the symmetry structure that shapes hadron masses and strong interaction dynamics. Among the most compelling open questions tied to chiral dynamics and spontaneous chiral symmetry breaking is the longstanding Λ polarization puzzle, in which Λ hyperons produced in unpolarized hadronic collisions exhibit a surprisingly large transverse polarization that remains theoretically unexplained. This whitepaper presents the proposal for the Hyperon-Nucleon Spectrometer (H-NS) at the High-Intensity heavy-ion Accelerator Facility (HIAF). Leveraging the high energy and high intensity of HIAF's proton and heavy-ion beams, the H-NS experiment will perform systematic studies of hyperon polarization phenomena and their underlying mechanisms in proton-proton (pp), proton-nucleus (pA), and nucleus-nucleus (AA) collisions in the fixed target mode. A wide-range beam energy scan, including proton beams from 3 GeV up to 9.3 GeV (HIAF) and up to 32 GeV (upgraded HIAF), will be conducted to examine the dependence of polarization on collision energy. The spectrometer is designed with specialized detectors capable of high-precision reconstruction of final-state baryon polarizations. Among its many interesting and important measurements, H-NS will simultaneously measure hyperon and proton spin observables to explore the polarization mechanism in hadronic interactions and the spin structure of baryons. Furthermore, the use of pA and AA collisions will enable detailed investigations of cold and hot nuclear matter effects on spin polarization. Its physics program and detector development will significantly benefit the future Electron-ion Collider in China.

sPHENIX is a state-of-the-art experiment at the Relativistic Heavy Ion Collider at Brookhaven National Lab. The primary scientific objective of the sPHENIX collaboration is to study the properties of the Quark-Gluon Plasma through precise measurements of hard probes within p+p, p+Au and Au+Au collisions. Notably, sPHENIX can provide measurements in the low transverse momentum region and offer kinematic overlap with the experiments at the Large Hadron Collider at CERN. The scientific pursuits of sPHENIX encompass a quartet of central themes: jet and photon physics, upsilon spectroscopy, open heavy flavor and the realm of cold quantum chromodynamics. This proceeding elucidates the experiment's overarching scientific mission, expounds upon its ingeniously crafted detector design, and delineates the paramount performance criteria that underpin its operation. Conclusively, a glimpse into the anticipated outcomes of select measurements is also proffered for consideration.

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.

The physical origin of spacetime discreteness remains a central open problem in quantum gravity, with most existing approaches relying on specific microscopic structures or model-dependent assumptions. In this letter, spacetime discreteness can arise instead as a consequence of consistent microscopic measurement. By treating infinitesimal spacetime intervals as scale-dependent measurement outcomes rather than predefined geometric entities, we formulate a Micro-Measurement Principle in which spacetime quantum fluctuations are encoded directly in the scaling structure. An equivalent dual representation of microscopic lengths leads to discrete, equidistant measurement outcomes, with the corresponding scaling-deformed uncertainty relation thereby reducing to the standard Heisenberg form. The microscopic lengths are further governed by a geometric renormalization-group flow admitting finite-length fixed points. This construction preserves Lorentz invariance and general covariance without ad hoc cutoffs or symmetry breaking. Our results show that the classical continuous-spacetime description corresponds to an unstable limiting regime, whereas a finite microscopic length and a discrete spacetime structure arise naturally from the fundamental requirements of micro-measurement consistency.

Planck-scale physics challenges the classical smooth-spacetime picture by introducing quantum fluctuations that imply a nontrivial spacetime microstructure. We present a framework that encodes these fluctuations by promoting local scale factors, rather than the metric tensor, to fundamental dynamical variables while preserving general covariance. The construction employs a two-tiered hierarchy of scale manifolds, comprising a first-order manifold of scale coordinates and a second-order manifold of fluctuation amplitude coordinates. On the first-order manifold, we formulate differential geometry, field equations, and a canonical quantization procedure. The theory yields a geometric renormalization-group flow for scale variables and implies spacetime discreteness at the microscopic level. By constructing a quadratic action and performing spectral decomposition with a stabilizing potential, we obtain discrete modal degrees of freedom quantized as harmonic oscillators. The framework proposes a microscopic description for zero-point energy of spacetime and explores implications for vacuum energy and ultraviolet regularization, suggesting a potential dynamical mechanism that could ameliorate the cosmological constant problem. Main results include a generalized uncertainty relation with scale-dependent coefficients, locally scaled Klein-Gordon and Dirac equations, geodesic equations for scale spacetime, and a microscopic area operator whose state counting is consistent with the Bekenstein-Hawking entropy. This work develops a scale-based quantization procedure, providing a foundation for further mathematical analysis and phenomenological tests of spacetime quantization.

The study of physics at the Planck scale has garnered significant attention due to its implications for understanding the fundamental nature of the universe. At the Planck scale, quantum fluctuations challenge the classical notion of spacetime as a smooth continuum, revealing a complex microstructure that defies traditional models. This study introduces a novel scaling-based framework to investigate the properties of spacetime microstructures. By deriving a scaling-characterized metric tensor and reformulating fundamental equations—including the geodesic, Einstein field, Klein-Gordon, and Dirac equations—into scaling forms, the research reveals new properties of local spacetime dynamics. Remarkably, the golden ratio emerges naturally in linear scale measurements, offering a potential explanation for the role of the Planck length in resolving ultraviolet (UV) divergence. Furthermore, the study demonstrates how scale invariance in spacetime can restore classical geometric stability through the renormalization group equations. These findings significantly revise classical geometric intuitions, providing a fresh lens for understanding quantum fluctuations and offering promising insights for advancing quantum gravity theories.

We present an integral density method for calculating the multifractal dimension spectrum for nucleon distribution in atomic nuclei. This method is then applied to analyze the non-uniformity of density distribution in several typical types of nuclear matter distributions, including the Woods-Saxon distribution, halo structure, and tetrahedral α clustering. The subsequent discussion provides a comprehensive and detailed exploration of the results obtained. The multifractal dimension spectrum shows a remarkable sensitivity to the density distribution, establishing it as a simple and novel tool for studying the distribution of nucleons in nuclear multibody systems.

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.

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

This study explores the role of information entropy in understanding nuclear density distributions, including both stable configurations and non-traditional structures such as neutron halos and α-clustering. By quantifying the uncertainty and disorder inherent in nucleon distributions in nuclear many-body systems, information entropy provides a macroscopic measure of the physical properties of the system. A more dispersed and disordered density distribution results in a higher value of information entropy. This intrinsic relationship between information entropy and system complexity allows us to quantify uncertainty and disorder in nuclear structures by analyzing various geometric parameters such as nuclear radius, diffuseness, neutron skin, and cluster structural features.

The integration of a scintillator, wavelength -shifting fiber, and silicon photomultiplier (SiPM) has demonstrated superior performance in the K -long and Muon detector (KLM) of the Belle II experiment. This study outlines our research and development (R&D) initiatives aimed at harnessing similar detection technologies, incorporating a novel scintillator and SiPM, for potential use in a muon detector for the proposed Circular Electron Positron Collider (CEPC) experiment. Our R&D activities have been focused on evaluating the efficacy of a newly developed 150 cm -long scintillator, alongside the NDL SiPM featuring a sensitive area of 3 mm x 3 mm, or the Hamamatsu MPPC with a 1 . 3 mm x 1 . 3 mm sensitive surface. The project also includes the fabrication of a detector strip and the implementation of techniques designed to optimize light collection efficiency. Cosmic ray testing has shown that both NDL SiPMs and MPPCs are capable of highly efficient photon collection, achieving efficiencies significantly exceeding 90% when employing a threshold of 8 photoelectrons. Additionally, the time resolution for detecting events at the distant end of a scintillator strip has been measured to be better than 1.7 ns. The remarkable performance observed lays the foundation for advancing R&D including prototype modules aiming for reference Technical Design Report of CEPC detector recently.

The sPHENIX experiment is a new generation of large acceptance detectors at the relativistic heavy ion collider at Brookhaven National Laboratory, with scientific goals focusing on probing the strongly interacting Quark–Gluon plasma with hard probes of jets, open heavy flavor particles, and Υ production. The EMCal detector, which covers the pseudo-rapidity region of |η | ≤ 1.1 , is an essential subsystem of sPHENIX. In this study, we focused on producing and testing EMCal blocks covering a pseudo-rapidity of |η | ∈ [0.8, 1.1] . These, in conjunction with the central pseudo-rapidity EMCal blocks, significantly enhance the sPHENIX physics capability of the jet and Υ particle measurements. In this paper, the detector module production and testing of sPHENIX W-powder/scintillating fiber (W/ScFi) electromagnetic calorimeter blocks are presented. The selection of the tungsten powder, mold fabrication, QA procedures, and cosmic ray test results are discussed.

Active target time projection chambers are important tools in low energy radioactive ion beams or gamma rays related researches. In this work, we present the application of machine learning methods to the analysis of data obtained from an active target time projection chamber. Specifically, we investigate the effectiveness of Visual Geometry Group (VGG) and the Residual neural Network (ResNet) models for event classification and reconstruction in decays from the excited 2^+_2 state in ^12C Hoyle rotation band. The results show that machine learning methods are effective in identifying ^12C events from the background noise, with ResNet-34 achieving an impressive precision of 0.99 on simulation data, and the best performing event reconstruction model ResNet-18 providing an energy resolution of σ_E<77 keV and an angular reconstruction deviation of σ_θ<0.1 rad. The promising results suggest that the ResNet model trained on Monte Carlo samples could be used for future classifying and predicting experimental data in active target time projection chambers related experiments.

A combination of scintillator, wavelength shifting (WLS) fiber, and silicon photomultiplier (SiPM) shows excellent performance in the `$K_{L}$ and $\mu$ detector (KLM)' of the Belle II experiment. We describe the R&D for a similar detection technology with a new scintillator and SiPM, which can be implemented for a muon detector for the proposed CEPC experiment and the upgrade of KLM in Belle II. The R&D contains the study of the performance of a new scintillator with a length of 150 cm, the NDL SiPM with a sensitive surface of 3 mm $\times$ 3 mm or the Hamamatsu MPPC with a sensitive surface of 1.3 mm $\times$ 1.3 mm, the construction of a detector strip, and the methods to achieve excellent light collection. The cosmic ray tests show good photon collections by NDL SiPM or MPPC, efficiencies well above 90% with a threshold of 8 p.e., and time resolutions of better than 1.7 ns for the hits at the far end of a scintillator strip. The performance shows a good option for an excellent muon detector for CEPC and the possible upgrade of Belle II KLM.

The β-delayed γ decay properties of proton-rich nucleus 29S were studied with three double-sided silicon strip de-tectors surrounded by five high-purity germanium detectors on the HIRFL-RIBLL1 facility.The most precise half-life of 29S was obtained to be 183(4)ms in this experiment.The measurements of β-delayed y rays of 29S were achieved for the first time and four β-γ rays were observed accurately.The β-decay branching ratio for the low-lying excited states of 29P was de-termined and a partial decay scheme of 29S was established.Based on experimental data,the isospin symmetry breaking in the mirror decay process of the 29S→29P/29Al→29Si was studied.