X-ray photon correlation spectroscopy (XPCS) has emerged as a powerful tool for probing the nanoscale dynamics of soft condensed matter and strongly correlated materials owing to its high spatial resolution and penetration capabilities. This technique requires high brilliance and beam coherence, which are not directly available at modern synchrotron beamlines in China. To facilitate future XPCS experiments, we modified the optical setup of the newly commissioned BL10U1 USAXS beamline at the Shanghai Synchrotron Radiation Facility (SSRF). Subsequently, we performed XPCS measurements on silica suspensions in glycerol, which were opaque owing to their high concentrations. Images were collected using a high frame rate area detector. A comprehensive analysis was performed, yielding correlation functions and several key dynamic parameters. All the results were consistent with the theory of Brownian motion and demonstrated the feasibility of XPCS at SSRF. Finally, by carefully optimizing the setup and analyzing the algorithms, we achieved a time resolution of 2 ms, which enabled the characterization of millisecond dynamics in opaque systems.

The infrared microspectroscopy beamline (BL06B) is a phase II beamline project at the Shanghai Synchrotron Radiation Facility (SSRF). The construction and optical alignment of BL06B were completed by the end of 2020. By 2021, it became accessible to users. The synchrotron radiation infrared (SRIR) source included edge radiation (ER) and bending-magnet radiation (BMR). The extracted angles in the horizontal and vertical directions were 40 and 20 mrad, respectively. The photon flux, spectral resolution, and focused spot size were measured at the BL06B end station, and the experimental results were consistent with theoretical calculations. SRIR light has a small divergence angle, high brightness, and a wide wavelength range. As a source of IR microscopy, it can easily focus on a diffraction-limited spatial resolution with a high signal-to-noise ratio (SNR). The BL06B end station can be applied in a wide range of research fields, including materials, chemistry, biology, geophysics, and pharmacology.

The high-energy photon source (HEPS) is the first fourth-generation synchrotron light source facility in China. The HEPS injector consists of a linear accelerator (Linac) and a full energy booster. The booster captures the electron beam from the Linac and increases its energy to the value required for the storage ring. The full-energy beam could be injected to the storage ring directly or after "high-energy accumulation." On November 17, 2023, the key booster parameters successfully reached their corresponding target values. These milestone results were achieved based on numerous contributions, including nearly a decade of physical design, years of equipment development and installation, and months of beam commissioning. As measured at the extraction energy of 6 GeV, the averaged beam current and emittance reached 8.57 mA with 5 bunches and 30.37 nm.rad with a single-bunch charge of 5.58 nC, compared with the corresponding target values of 6.6 mA and 35 nm.rad, respectively. This paper presents the physical design, equipment development, installation, and commissioning process of the HEPS booster.

Observing nuclear neutrinoless double beta (0vββ) decay would be a revolutionary result in particle physics. Observing such a decay would prove that the neutrinos are their own antiparticles, help to study the absolute mass of neutrinos, explore the origin of their mass, and may explain the matter-antimatter asymmetry in our universe by lepton number violation. We propose developing a time projection chamber (TPC) using high-pressure ⁸²SeF₆ gas and Topmetal silicon sensors for readout in the China Jinping Underground Laboratory (CJPL) to search for neutrinoless double beta decay of ⁸²Se, called the Nv DEx experiment. Besides being located at CJPL with the world’s thickest rock shielding, Nv DEx combines the advantages of the high Qββ (2.996 MeV) of ⁸² Se and the TPC’s ability to distinguish signal and background events using their different topological characteristics. This makes N DEx unique, with great potential for low-background and high-sensitivity 0vββ searches. NvDEx-100, a NvDEx experiment phase with 100 kg of SeF₆ gas, is being built, with plans to complete installation at CJPL by 2025. This report introduces 0vββ physics, the NvDEx concept and its advantages, and the schematic design of NvDEx-100, its subsystems, and background and sensitivity estimation.

The optical potential ambiguity is a long-standing problem in the analysis of elastic scattering data. For a specific colliding system, ambiguous potential families can lead to different behaviors in the nearside and farside scattering components. By contrast, the envelope method can decompose the experimental data into two components with negative and positive deflection angles, respectively. Hence, a question arises as to whether the comparison between the calculated nearside (or farside) component and the derived positive-deflection-angle (or negative-deflection-angle) component can help analyze the potential ambiguity problem. In this study, we conducted a trial application of the envelope method to the potential ambiguity problem. The envelope method was improved by including uncertainties in the experimental data. The colliding systems of ¹⁶O+²⁸Si at 215.2 MeV and ¹²C+¹²C at 1016 MeV were considered in the analyses. For each colliding system, the angular distribution experimental data were described nearly equally well by two potential sets, one of which is "surface transparent" and the other is refractive. The calculated angular distributions were decomposed into nearside and farside scattering components. Using the improved envelope method, the experimental data were decomposed into the positive-deflection-angle and negative-deflection-angle components, which were then compared with the calculated nearside and farside components. The capability of the envelope method to analyze the potential ambiguities was also discussed.

Ultrashort and powerful laser interactions with a target generate intense wideband electromagnetic pulses (EMPs). In this study, we report EMPs generated by the interactions between petawatt (30 fs, 1.4×10²⁰ W/cm²) femtosecond (fs) lasers with metal flat, plastic flat, and plastic nanowire-array (NWA) targets. Detailed analyses are conducted on the EMPs in terms of their spatial distribution, time and frequency domains, radiation energy, and protection. The results indicate that EMPs from metal targets exhibit larger amplitudes at varying angles than those generated by other types of targets and are enhanced significantly for NWA targets. Using a plastic target holder and increasing the laser focal spot can significantly decrease the radiation energy of the EMPs. Moreover, the composite shielding materials indicate an effective shielding effect against EMPs. The simulation results show that the NWA targets exert a collimating effect on thermal electrons, which directly affects the distribution of EMPs. This study provides guidance for regulating EMPs by controlling the laser focal spot, target parameters, and target rod material and is beneficial for electromagnetic-shielding design.

A digital data-acquisition system based on XIA LLC products was used in a complex nuclear reaction experiment using radioactive ion beams. A flexible trigger system based on a field-programmable gate array (FPGA parametrization was developed to adapt to different experimental sizes. A user-friendly interface was implemented, which allows converting script language expressions into FPGA internal control parameters. The proposed digital system can be combined with a conventional analog data acquisition system to provide more flexibility. The performance of the combined system was verified using experimental data.

The microscopic global nucleon–nucleus optical model potential (OMP) proposed by Whitehead, Lim, and Holt, the WLH potential [1], which was constructed in the framework of many-body perturbation theory with state-of-the-art nuclear interactions from chiral effective field theory (EFT), was tested with (p,d) transfer reactions calculated using adiabatic wave approximation. The target nuclei included both stable and unstable nuclei and the incident energies reached 200 MeV. The results were compared with experimental data and predictions using the phenomenological global optical potential of A. J. Koning and J. P. Delaroche, the KD02 potential. Overall, we found that the microscopic WLH potential described the (p,d) reaction angular distributions similarly to the phenomenological KD02 potential; however, the former was slightly better than the latter for radioactive targets. On average, the obtained spectroscopic factors (SFs) using both microscopic and phenomenological potentials were similar when the incident energies were below approximately 120 MeV. However, their difference tended to increase at higher incident energies, which was particularly apparent for the doubly magic target nucleus ⁴⁰Ca.

The relativistic mean-field approach was implemented in the Lanzhou quantum molecular dynamics transport model (LQMD.RMF). Using the LQMD.RMF, the properties of collective flow and pion production were investigated systematically for nuclear reactions with various isospin asymmetries. The directed and elliptic flows of the LQMD.RMF are able to describe the experimental data of STAR Collaboration. The directed flow difference between free neutrons and protons was associated with the stiffness of the symmetry energy, that is, a softer symmetry energy led to a larger flow difference. For various collision energies, the ratio between the π^- and π⁺ yields increased with a decrease in the slope parameter of the symmetry energy. When the collision energy was 270 MeV/nucleon, the single ratio of the pion transverse momentum spectra also increased with decreasing slope parameter of the symmetry energy in both nearly symmetric and neutron-rich systems. However, it is difficult to constrain the stiffness of the symmetry energy with the double ratio because of the lack of threshold energy correction on the pion production.

Nondestructive and noninvasive neutron assays are essential applications of neutron techniques. Neutron resonance transmission analysis (NRTA) is a powerful nondestructive method for investigating the elemental composition of an object. The back-streaming neutron line (Back-n) is a newly built time-of-flight facility at the China Spallation Neutron Source (CSNS) that provides neutrons in the eV to 300 MeV range. A feasibility study of the NRTA method for nuclide identification was conducted at the CSNS Back-n via two test experiments. The results demonstrate that it is feasible to identify different elements and isotopes in samples using the NRTA method at Back-n. This study reveals its potential future applications.

The China Spallation Neutron Source (CSNS) upgrade project (CSNS-II) aims to enhance the beam power from 100 to 500 kW. A dual-harmonic accelerating method has been adopted to alleviate the stronger space-charge effect in rapid-cycling synchrotrons owing to the increased beam intensity. To satisfy the requirements of dual-harmonic acceleration, a new radiofrequency (RF) system based on a magnetic alloy-loaded cavity is proposed. This paper presents design considerations and experimental results regarding the performance evaluation of the proposed RF system through high-power tests and beam commissioning. The test results demonstrate that the RF system satisfies the desired specifications and affords significant benefits for CSNS-II.

Radio frequency quadrupoles (RFQs), which are crucial components of proton injectors, significantly affect the performance of proton accelerator facilities. An RFQ with a high frequency of 714 MHz dedicated to compact proton injectors for medical applications is designed in this study. The RFQ is designed to accelerate proton beams from 50 keV to 4 MeV within a short length of 2 m and can be matched closely with the downstream drift tube linac to capture more particles through a preliminary optimization. To develop an advanced RFQ, challenging techniques, including fabrication and tuning method, must be evaluated and verified using a prototype. An aluminium prototype is derived from the conceptual design of the RFQ and then redesigned to confirm the radio frequency performance, fabrication procedure, and feasibility of the tuning algorithm. Eventually, a new tuning algorithm based on the response matrix and least-squares method is developed, which yields favorable results based on the prototype, i.e., the errors of the dipole and quadrupole components reduced to a low level after several tuning iterations. Benefiting from the conceptual design and techniques obtained from the prototype, the formal mechanical design of the 2-m RFQ is ready for the next manufacturing step.

To explore the kinetic adsorption under continuous and nonequilibrium states, an integration of continuous measurement and adsorption platform kinetics method was proposed, which was initially called the ICM-AP kinetics method, and a corresponding kinetic adsorption experimental method was developed. Adsorption experiments of europium (Eu) on Ca-bentonite, Na-bentonite, and the D231 cation exchange resin were performed using the ICM-AP kinetics method and continuous measurements. Because the kinetic experimental results observed in this study were different from those of traditional batch adsorption data, pseudo-first-order or pseudo-second-order kinetic models were unsuitable for fitting the experimental data. Hence, a liquid membrane diffusion (LMD) model was developed based on the assumption of simultaneous adsorption/desorption to discuss the mechanism of kinetic adsorption. The kinetic adsorption mechanism was also studied by using XPS. The results indicated that the proposed adsorption model can fit the experimental data more suitably, and the adsorption/desorption behaviors of Eu on bentonite and the D231 resin were simultaneously observed, suggesting that the adsorption kinetics of Eu(Ⅲ) was mainly dominated by hydrated Eu(III) ions on the liquid membrane.

Accurate measurements of the radon exhalation rate helps identify and evaluate radon risk regions in the environment. Among these measurement methods, the closed-loop method is frequently used. However, traditional experiments are insufficient or cannot analyze the radon migration and exhalation patterns at the gas–solid interface in the accumulation chamber. The CFD-based technique was applied to predict the radon concentration distribution in a limited space, allowing radon accumulation and exhalation inside the chamber intuitively and visually. In this study, three radon exhalation rates were defined and two structural ventilation tubes were designed for the chamber. The consistency of the simulated results with the variation in the radon exhalation rate in a previous experiment or analytical solution was verified. The effects of the vent tube structure and flow rate on the radon uniformity in the chamber; permeability, insertion depth, and flow rate on the radon exhalation rate; and the effective diffusion coefficient on back diffusion were investigated. Based on the results, increasing the insertion depth from 1 to 5 cm decreased the effective decay constant by 19.55%, whereas the curve-fitted radon exhalation rate decreased (lower than the initial value) as the deviation from the initial value increased by approximately 7%. Increasing the effective diffusion coefficient from 2.77×10^-7 to 7.77×10^-6 m² s^-1 made the deviation expand from 2.14% to 15.96%. The conclusion is that an increased insertion depth helps reduce leakage in the chamber, subject to notable back-diffusion, and that the closed-loop method is reasonably used for porous media with a low effective diffusion coefficient in view of the back-diffusion effect. The CFD-based simulation is expected to provide guidance for the optimization of the radon exhalation rate measurement method and, thus, the accurate measurement of the radon exhalation rate.

The phenomenology involved in severe accidents (SA) in nuclear reactors is highly complex. Currently, integrated analysis programs used for severe accident analysis heavily rely on custom empirical parameters, which introduce considerable uncertainty. Therefore, in recent years, the field of severe accidents has shifted its focus toward applying uncertainty analysis methods to quantify uncertainty in safety assessment programs, known as "best estimate plus uncertainty (BEPU)." This approach aids in enhancing our comprehension of these programs and their further development and improvement. This study concentrates on a third-generation pressurized water reactor (Gen-III PWR) equipped with advanced active and passive mitigation strategies. Through an Integrated Severe Accident Analysis Program (ISAA), numerical modeling and uncertainty analysis were conducted on severe accidents resulting from large break loss of coolant accidents (LBLOCA). Seventeen uncertainty parameters of the ISAA program were meticulously screened. Using Wilks' formula, the developed uncertainty program code, SAUP, was employed to carry out Latin hypercube sampling (LHS), while ISAA was employed to execute batch calculations. Statistical analysis was then conducted on two figures of merit (FOMs), namely, hydrogen generation and the release of fission products (FP) within the pressure vessel. Uncertainty calculations revealed that hydrogen production and the fraction of fission product released exhibited a normal distribution, ranging from 182.784 kg to 330.664 kg and from 15.6% to 84.3%, respectively. The ratio of hydrogen production to reactor thermal power fell within the range of 0.0578 to 0.105. A sensitivity analysis was performed for uncertain input parameters, revealing significant correlations between the failure temperature of the cladding oxide layer, maximum melt flow rate, size of the particulate debris, and porosity of the debris with both hydrogen generation and the release of fission products.

Nuclear power plants exhibit non-linear and time-variable dynamics. Therefore, designing a control system that sets the reactor power and forces it to follow the desired load is complicated. A supercritical water reactor (SCWR) is a fourth-generation conceptual reactor. In an SCWR, the non-linear dynamics of the reactor require a controller capable of controlling the nonlinearities. In this study, a pressure-tube-type SCWR was controlled during reactor power maneuvering with a higher order sliding mode, and the reactor outgoing steam temperature and pressure were controlled simultaneously. In an SCWR, the temperature, pressure, and power must be maintained at a setpoint (desired value) during power maneuvering. Reactor point kinetics equations with three groups of delayed neutrons were used in the simulation. Higher-order and classic sliding mode controllers were separately manufactured to control the plant and were compared with the PI controllers specified in previous studies. The controlled parameters were reactor power, steam temperature, and pressure. Notably, for these parameters, the PI controller had certain instabilities in the presence of disturbances. The classic sliding mode controller had a higher accuracy and stability; however its main drawback was the chattering phenomenon. HOSMC was highly accurate and stable and had a small computational cost. In reality, it followed the desired values without oscillations and chattering.