Vol.36,

Doping with Ga effectively enhances the crystal quality and optical detection efficiency of zinc oxide (ZnO) single crystals, which has attracted considerable research interest in radiation detection. The application of ZnO:Ga (GZO in nuclear energy is particularly significant and fascinating at the fundamental level, enabling neutron/gamma discrimination while preserving the response time properties of the single crystal in sub-nanoseconds, maximizing the effective counting rate of the pulsed radiation field. In this study, the single-particle waveform discrimination characteristics of GZO were evaluated for five charged particles (α, β, H⁺,Li⁺, and O⁸⁺ and two prevalent uncharged particles (neutrons and gamma rays). Based on the time correlation single-photon counting (TCSPC) method, the luminescence decay time constants of the charged particles in the GZO crystal were determined as follows: 1.21 ns for H⁺, 1.50 ns for Li⁺, 1.70 ns for O⁸⁺, 1.56 ns for α particles, and 1.09 ns for β particles. Visible differences in the excitation time spectra curves were observed. Using the conventional time-domain or frequency-domain waveform discrimination techniques, waveform discrimination of 14.9 MeV neutrons and secondary gamma rays generated by the CPNG-6 device based on GZO scintillation was successfully implemented. The neutron signal constituted 77.93% of the total, indicating that GZO exhibited superior neutron/gamma discrimination sensitivity compared with that of a commercial stilbene crystal. Using the neutron/gamma screening outcomes, we reconstructed the voltage pulse height, charge height, and neutron multiplication time spectra of the pulsed neutron radiation field. The reconstructed neutron multiplication time spectrum exhibited a deviation of less than 3% relative to the result obtained using a commercial stilbene scintillator. This is the first report in the open literature on the neutron/gamma discrimination and reconstruction of ZnO pulsed radiation-field information.

The Taishan Antineutrino Observatory(TAO or JUNO-TAO) is a satellite experiment of the Jiangmen Underground Neutrino Observatory(JUNO), located near the Taishan nuclear power plant(NPP). The TAO aims to measure the energy spectrum of reactor antineutrinos with unprecedented precision, which would benefit both reactor neutrino physics and the nuclear database. A detector geometry and event visualization system was developed for the TAO. The software was based on ROOT packages and embedded in the TAO offline software framework. This provided an intuitive tool for visualizing the detector geometry, tuning the reconstruction algorithm, understanding neutrino physics, and monitoring the operation of reactors at NPP. Further applications of the visualization system in the experimental operation of TAO and its future development are discussed.

Waveform generation and digitization play essential roles in numerous physics experiments. In traditional distributed systems for large-scale experiments, each frontend node contains an FPGA for data preprocessing, which interfaces with various data converters and exchanges data with a backend central processor. However, the streaming readout architecture has become a new paradigm for several experiments benefiting from advancements in data transmission and computing technologies. This paper proposes a scalable distributed waveform generation and digitization system that utilizes fiber optical connections for data transmission between frontend nodes and a central processor. By utilizing transparent transmission on top of the data link layer, the clock and data ports of the converters in the frontend nodes are directly mapped to the FPGA firmware at the backend. This streaming readout architecture reduces the complexity of frontend development and maintains the data conversion in proximity to the detector. Each frontend node uses a local clock for waveform digitization. To translate the timing information of events in each channel into the system clock domain within the backend central processing FPGA, a novel method is proposed and evaluated using a demonstrator system.

Precise transverse emittance assessment in electron beams is crucial for advancing high-brightness beam injectors. As opposed to intricate methodologies that use specialized devices, quadrupole focusing strength scanning (Q-scanning) techniques offer notable advantages for various injectors owing to their inherent convenience and cost-effectiveness. However, their stringent approximation conditions lead to inevitable errors in practical operation, thereby limiting their widespread application. This study addressed these challenges by revisiting the analytical derivation procedure and investigating the effects of the underlying approximation conditions. Preliminary corrections were explored through a combination of data processing analysis and numerical simulations. Furthermore, based on theoretical derivations, virtual measurements using beam dynamics calculations were employed to evaluate the correction reliability. Subsequent experimental validations were performed at the Huazhong University of Science and Technology injector to verify the effectiveness of the proposed compensation method. Both the virtual and experimental results confirm the feasibility and reliability of the enhanced Q-scanning-based diagnosis for transverse emittance in typical beam injectors operating under common conditions. Through the integration of these corrections and compensations, enhanced Q-scanning-based techniques emerge as promising alternatives to traditional emittance diagnosis methods.

In scenarios such as vehicle radiation monitoring and unmanned aerial vehicle radiation detection, rapid measurements using a NaI(Tl) detector often result in low photon counts, weak characteristic peaks, and significant statistical fluctuations. These issues can lead to potential failures in peak-searching-based identification methods. To address the low precision associated with short-duration measurements of radionuclides, this paper proposes an identification algorithm that leverages heterogeneous spectral transfer to develop a low-count energy spectral identification model. Comparative experiments demonstrated that transferring samples from 26 classes of simulated heterogeneous gamma spectra aids in creating a reliable model for measured gamma spectra. With only 10% of target domain samples used for training, the accuracy on real low-count spectral samples was 95.56%. This performance shows a significant improvement over widely employed full-spectrum analysis methods trained on target domain samples. The proposed method also exhibits strong generalization capabilities, effectively mitigating overfitting issues in low-count energy spectral classification under short-duration measurements.

Stripping injection overcomes the limitations of Liouville’s theorem and is widely used for beam injection and accumulation in high-intensity synchrotrons. The interaction between the stripping foil and beam is crucial in the study of stripping injection, particularly in low-energy stripping injection synchrotrons such as the XiPAF synchrotron. The foil thickness is the main parameter that affects the properties of the beam after injection. The thin stripping foil is reinforced with collodion during its installation. However, the collodion on the foil surface makes it difficult to determine its equivalent thickness, because the mechanical measurements are not sufficiently reliable or convenient for continuously determining foil thickness. We propose an online stripping foil thickness measurement method based on the ionization energy loss effect, which is suitable for any foil thickness and does not require additional equipment. Experimental studies were conducted using the XiPAF synchrotron. The limitation of this method was examined, and the results were verified by comparing the experimentally obtained beam current accumulation curves with the simulation results. This confirms the accuracy and reliability of the proposed method for measuring the stripping foil thickness.

To accurately reconstruct the tomographic gamma scanning (TGS) transmission measurement image, this study optimized the transmission reconstruction equation based on the actual situation of TGS transmission measurement. Using the transmission reconstruction equation and the Monte Carlo program Geant4, an innovative virtual trajectory length model was constructed. This model integrated the solving process for the trajectory length and detection efficiency within the same model. To mitigate the influence of the angular distribution of γ-rays emitted by the transmitted source at the detector, the transport processes of numerous particles traversing a virtual nuclear waste barrel with a density of zero were simulated. Consequently, certain amount of information was captured at each step of particle transport. Simultaneously, the model addressed the nonuniform detection efficiency of the detector end face by considering whether the energy deposition of particles in the detector equaled their initial energy. Two models were established to validate the accuracy and reliability of the virtual trajectory length model. Model 1 was a simplified nuclear waste barrel. Whereas, Model 2 closely resembled the actual structure of a nuclear waste barrel. The results indicated that the proposed virtual trajectory length model significantly enhanced the precision of the trajectory length determination, substantially increasing the quality of the reconstructed images. For example, the reconstructed images of Model 2 using the “point-to-point” and average trajectory models revealed a signal-to-noise ratio increase of 375.0% and 112.7%, respectively. Thus, the virtual trajectory length model proposed in this study holds paramount significance for the precise reconstruction of transmission images. Moreover, it can provide support for the accurate detection of radioactive activity in nuclear waste barrels.

Burnup measurement is crucial for the management and disposal of spent fuel. The conventional approach indirectly estimates burnup by examining the fission product or actinide content. Compared to the first two methods, the active neutron method exhibit a lower dependence on the irradiation history and initial enrichment degree of the spent fuel. In addition, it can be used to directly determine the content of fissile nuclides in spent fuel. This study proposed the design of a burnup measurement equipment specifically crafted for plate segments by utilizing a compact D-D neutron generator. The equipment initiates the fission of fissile nuclides within the spent fuel plate segment through thermal neutrons provided by the moderators. Subsequently, the burnup is determined by analyzing the transmitted thermal neutrons and counting the fission fast neutrons. The Monte Carlo program Geant4 was used to simulate the relationship between spent fuel plate segment assembly burnup and the detector count of 10MW material test reactor designed by the International Atomic Energy Agency. Consequently, the feasibility of the method and rationality of the detector design were verified.

Tungsten (W) is the leading plasma-facing candidate material for the International Thermonuclear Experimental Reactor (ITER) and next-generation fusion reactors. The impact of synergistic helium (He), irradiation-induced microstructural changes, and the corresponding thermal-mechanical property degradation of W are critically important but are not well understood yet. Predicting the performance of W in fusion environments requires understanding the fundamentals of He–defect interactions and the resultant He bubble nucleation and growth in W. In this study, He retention in helium-ion-implanted W was assessed using neutron depth profiling (NDP), laser ablation mass spectrometry (LAMS), and thermal desorption spectroscopy (TDS) following 10 keV room-temperature He implantation at various fluences. These three experimental techniques enabled the determination of the He depth profile and retention in He-implanted W. A cluster dynamics model based on the diffusion-reaction rate theory was applied to interpret the experimental data. The model successfully predicted the He spatial depth-dependent profile in He-implanted W, which was in good agreement with the LAMS measurements. The model also successfully captured the major features of the He desorption spectra observed in the THDS measurements. The NDP quantified total He concentration values for the samples; they were similar to those estimated by LAMS. However, the depth profiles from NDP and LAMS were not comparable due to several factors. The combination of modeling and experimentation enabled the identification of possible trapping sites for He in W and the evolution of He-defect clusters during the TDS thermal annealing process.

This paper presents the design and optimization of a lutetium yttrium oxyorthosilicate (LYSO) crystal electromagnetic calorimeter (ECAL) for the DarkSHINE experiment, which aims to identify dark photons as potential mediators of dark forces. The ECAL design was evaluated through comprehensive simulations, focusing on optimizing dimensions, material selection, energy distribution, and energy resolution. The configuration consisted of 21×21×11 LYSO crystals, each measuring 2.5 cm×2.5 cm×4 cm, arranged in a staggered layout to enhance signal detection efficiency. A 4 GeV energy dynamic range was established to ensure accurate energy measurements without saturation, which is essential for background rejection and signal identification. A detailed digitization model was developed to simulate scintillation, silicon photomultiplier, and analog-to-digital converter behaviors, providing a realistic representation of the detector’s performance. Additionally, the study assessed radiation damage in the ECAL region, emphasizing the importance of using radiation-resistant scintillators and silicon sensors.

The neutron capture resonance parameters for ¹⁵⁹Tb are crucial for validating nuclear models, nucleosynthesis during the neutron capture process, and nuclear technology applications. In this study, resonance analyses were performed for the neutron capture cross-sections of ¹⁵⁹Tb measured at the China Spallation Neutron Source (CSNS) backscattering white neutron beamline (Back-n) facility. The resonance parameters were extracted from the R-Matrix code SAMMY and fitted to the experimental capture yield up to the 1.2 keV resolved resonance region (RRR). The average resonance parameters were determined by performing statistical analysis on the set of the resonance parameters in the RRR. These results were used to fit the measured average capture cross sections using the FITACS code in the unresolved resonance region from 2 keV to 1 MeV. The contributions of partial waves l=0, 1, 2 to the average capture cross-sections are reported.

The dinuclear system approach, coupled with the statistical decay model GEMINI++, was used to investigate multinucleon transfer reactions. Experimental production cross-sections in the reaction ¹²⁹Xe+²⁴⁸Cm were reproduced to assess the reliability of these theoretical models. The production of neutron-deficient transcalifornium nuclei with Z = 99-06 was examined in multinucleon transfer reactions, including ¹²⁴Xe + ²⁴⁸Cm, ¹²⁴Xe +²⁴⁹Cf, and ¹²⁹Xe+ ²⁴⁹Cf. Both the driving potential and the neutron-to-proton equilibration ratio were found to dominate the nucleon transfer process. The reaction ¹²⁴Xe + ²⁴⁹Cf is proposed as a promising projectile-target combination for producing neutron-deficient isotopes with Z = 99-106, with the optimal incident energy identified as E_{c. m.} = 533.64 MeV. Production cross-sections of 25 unknown neutron-deficient trancalifornium isotopes with cross-sections greater than 1 pb were predicted.

In this work, we study the impacts of the isospin-independent momentum-dependent interaction (MDI) and near-threshold NN→NΔ cross sections (σNN→NΔ) on the nucleonic flow and pion production observables in the ultra-relativistic molecular dynamics (UrQMD) model. With the updated isospin-independent MDI and the near-threshold NN→NΔ cross-sections in the UrQMD model, 17 observables, which are the directed flow (v₁) and elliptic flow (v₂) of neutrons, protons, Hydrogen (H), and charged particles as a function of transverse momentum (p_T/A) or normalized rapidity (y0lab), and the observables constructed from them, the charged pion multiplicity (M(π)) and its ratio (M(π^-)/M(π⁺)), can be simultaneously described at certain forms of symmetry energy. The refinement of the UrQMD model provides a solid foundation for further understanding the effects of the missed physics, such as the threshold effect, the pion potential, and the momentum-dependent symmetry potential. Circumstantial constraints on the symmetry energy at the flow characteristic density 1.2± 0.6 ρ₀ and the pion characteristic density 1.5± 0.5ρ₀ were obtained with the current version of UrQMD, and the corresponding symmetry energies were S(1.2ρ₀)=34± 4 MeV and S(1.5ρ₀)=36± 8 MeV, respectively. Furthermore, the discrepancies between the data and the calculated results of v2n and v2p at high p_t (rapidity) imply that the roles of the missing ingredients, such as the threshold effect, the pion potential, and the momentum-dependent symmetry potential, should be investigated by differential observables, such as the momentum and rapidity distributions of the nucleonic and pionic probes over a wide beam energy range.

Lead (Pb) plays a significant role in the nuclear industry and is extensively used in radiation shielding, radiation protection, neutron moderation, radiation measurements, and various other critical functions. Consequently, the measurement and evaluation of Pb nuclear data are highly regarded in nuclear scientific research, emphasizing its crucial role in the field. Using the time-of-flight (ToF) method, the neutron leakage spectra from three ^natPb samples were measured at 60 and 120 based on the neutronics integral experimental facility at the China Institute of Atomic Energy (CIAE). The ^natPb sample sizes were 30 cm × 30 cm × 5 cm, 30 cm × 30 cm × 10 cm, and 30 cm × 30 cm × 15 cm. Neutron sources were generated by the Cockcroft–Walton accelerator, producing approximately 14.5 MeV and 3.5 MeV neutrons through the T(d,n)⁴He and D(d,n)³He reactions, respectively. Leakage neutron spectra were also calculated by employing the Monte Carlo code of MCNP-4C, and the nuclear data of Pb isotopes from four libraries: CENDL-3.2, JEFF-3.3, JENDL-5, and ENDF/B-VIII.0 were used individually. By comparing the simulation and experimental results, improvements and deficiencies in the evaluated nuclear data of the Pb isotopes were analyzed. Most of the calculated results were consistent with the experimental results; however, a few areas did not fit well. In the (n,el) energy range, the simulated results from CENDL-3.2 were significantly overestimated; in the (n,inl)D and the (n,inl)C energy regions, the results from CENDL-3.2 and ENDF/B-VIII.0 were significantly overestimated at 120, and the results from JENDL-5.0 and JEFF-3.3 are underestimated at 60 in the (n,inl)D energy region. The calculated spectra were analyzed by comparing them with the experimental spectra in terms of the neutron spectrum shape and C/E values. The results indicate that the theoretical simulations, using different data libraries, overestimated or underestimated the measured values in certain energy ranges. Secondary neutron energies and angular distributions in the data files have been presented to explain these discrepancies.

Nuclear β-decay, a typical decay process for unstable nuclei, is a key mechanism for producing heavy elements in the Universe. In this study, neural networks were employed to predict β-decay half-lives and, for the first time, to identify abnormal trends in nuclear β-decay half-lives based on deviations between experimental values and the predictions of neural networks. Nuclei exhibiting anomalous increases, abrupt peaks, sharp decreases, abnormal odd-even oscillations, and excessively large experimental errors in their β-decay half-lives, which deviate from systematic patterns, were identified through deviations. These anomalous phenomena may be associated with shell effects, shape coexistence, or discrepancies in the experimental data. The discovery and analysis of these abnormal nuclei provide a valuable reference for further investigations using sophisticated microscopic theories, potentially offering insights into new physics through studies of nuclear β-decay half-lives.

This study investigates photonuclear reaction (γ,n) cross-sections using Bayesian neural network (BNN) analysis. After determining the optimal network architecture, which features two hidden layers, each with 50 hidden nodes, training was conducted for 30,000 iterations to ensure comprehensive data capture. By analyzing the distribution of absolute errors positively correlated with the cross-section for the isotope ¹⁵⁹Tb, as well as the relative errors unrelated to the cross-section, we confirmed that the network effectively captured the data features without overfitting. Comparison with the TENDL-2021 Database demonstrated the BNN’s reliability in fitting photonuclear cross-sections with lower average errors. The predictions for nuclei with single and double giant dipole resonance peak cross-sections, the accurate determination of the photoneutron reaction threshold in the low-energy region, and the precise description of trends in the high-energy cross-sections further demonstrate the network’s generalization ability on the validation set. This can be attributed to the consistency of the training data. By using consistent training sets from different laboratories, Bayesian neural networks can predict nearby unknown cross-sections based on existing laboratory data, thereby estimating the potential differences between other laboratories’ existing data and their own measurement results. Experimental measurements of photonuclear reactions on the newly constructed SLEGS beamline will contribute to clarifying the differences in cross-sections within the existing data.

A coalescence model was employed to form deuterons (d), tritons (t), and helium-3 (³He) nuclei from a uniformly-distributed volume of protons (p) and neutrons (n). We studied the ratio NtNp/Nd2 of light nuclei yields as a function of the neutron density fluctuations. We investigated the effect of finite transverse momentum (p_T) acceptance on the ratio, in particular, the “extrapolation factor” (f) for the ratio as a function of the p_T spectral shape and the magnitude of neutron density fluctuations. The nature of f was found to be monotonic in p_T spectra “temperature” parameter and neutron density fluctuation magnitude; variations in the latter are relatively small. We also examined f in realistic simulations using the kinematic distributions of protons measured from the heavy-ion collision data. The nature of f was found to be smooth and monotonic as a function of the beam energy. Therefore, we conclude that extrapolation from limited p_T ranges does not create, enhance, or reduce the local peak of the NtNp/Nd2 ratio in the beam energy. Our study provides a necessary benchmark for light nuclei ratios as a probe for nucleon density fluctuations, an important observation in the search for the critical point of nuclear matter.

The radioisotope actinium-225 (²²⁵Ac) has been successfully used for targeted alpha therapy in preclinical and clinical applications because of its excellent nuclear characteristics. Medium- and high-energy proton-spallation reactions on thorium are the most important methods for producing ²²⁵Ac. This study examines the possibility of producing ²²⁵Ac by irradiating thorium oxide with medium-energy protons. Thorium-oxide sheets were irradiated with 40-, 50-, 60-, 70-, and 80-MeV protons on the Associated Proton-beam Experiment Platform (APEP) of the China Spallation Neutron Source (CSNS). The cross sections for the formation of ²²⁵Ac were measured using the activation method and offline gamma-ray spectrometric technique. The experimental results were compared with the existing data from EXFOR as well as the theoretical data from the TALYS-based evaluated nuclear-data library. Based on the experimental cross section and theoretical calculations, the production yield of ²²⁵Ac in the irradiated thorium targets was examined. The results showed that APEP can produce sufficient quantities of ²²⁵Ac for purification and clinical therapy. This work is the first measurement of proton-induced nuclear-reaction cross sections at the CSNS APEP.