The multiwire drift chambers at the target area of the External Target Facility of Cooler Storage Ring were constructed to track radioactive ion beams that enter and exit the target. Two drift chambers with sensitive areas of 80 mm × 80 mm were positioned upstream of the target, whereas two additional drift chambers with sensitive areas of 160 mm × 160 mm were placed downstream of the target. The drift chambers were tested using 350 MeV/u ^78Kr beams and cocktail secondary beams. To improve drift-time precision, the time-walk effect was corrected using the measured energy. The impact of δ -rays on the multiplicity and spatial resolution was assessed using beams with various atomic numbers and applied voltages. The optimal voltage to minimize the impact of δ -rays was obtained. An optimal spatial resolution of 35 µm for the drift chambers was achieved for heavy nuclei.
The internal surface quality of superconducting radio frequency niobium (Nb) cavities directly affects their performance. Plasma technologies, such as plasma processing (PP) and plasma electrolytic polishing (PeP), are safe and environmentally friendly surface treatment methods for obtaining clean and smooth surfaces. To study the effect of these two techniques on the surface roughness of Nb, the Monte Carlo simulation program Stopping and Range of Ions in Matter 2013 was used to assess how argon ions ( Ar^+ ) interact with Nb and niobium oxides ( Nb_xO_y ). We present the sputtering yields for Nb and O and simulate the penetration depth. Second, Ar and Ar/O _2 PP experiments were performed on the Nb samples. The mean values of R_a (average roughness), R_q (root-mean-square roughness), and S_z (maximum profile depth) were reduced by approximately 10 R_a≈0.1 m , R_q≈0.123 m , and S_z≈1 m at an etch rate of 3.21 m min^-1 .
In classical physics, observation provides state information without influencing its evolution. However, quantum theory predicts that the act of observation itself can fundamentally alter the system’s dynamics. This work investigates the quantum Zeno effect (QZE) and anti-Zeno effect (AZE) in a three-level system by using the Lindblad master equation to model measurement-induced decoherence. Three distinct cases are examined, namely discrete measurements that induce the QZE, discrete measurements that induce the AZE, and continuous measurements leading to the QZE. The applicability of the instantaneous-pulse approximation (IPA) is assessed against the exact piecewise integration method (PIM) for solving the master equation. For the parameter sets considered, both methods yield closely matching results. The coherence terms play a critical role in governing the system evolution. Moreover, both QZE and AZE can be observed in the same physical system depending on the measurement cadence and detuning. These findings provide a theoretical foundation for investigating QZE and AZE in laser-induced nuclear excitation and related phenomena in nuclear physics.
A new Monte Carlo optimization (MCO) method called the hybrid adaptive response surface methodology–genetic algorithm (RSM-GA) Monte Carlo optimization (HRG-MCO) is proposed to address the strong empirical dependence and low efficiency of global multiparameter optimization in traditional neutronics design. HRG-MCO integrates the advantages of the response surface methodology (RSM) and genetic algorithm (GA). Specifically, the neutron Monte Carlo simulation results were iteratively utilized to adaptively construct an RSM model to ensure the required accuracy. Subsequently, a GA was employed to perform multiparameter optimization based on the constructed RSM model, which makes it possible to rapidly determine the optimal design parameters. These optimized parameters were then fed back into the Monte Carlo simulation model to derive the final optimized values. The superior optimization efficiency of the HRG-MCO method was demonstrated through a comparative analysis of the exhaustive enumeration method and the standalone GA. To further validate its effectiveness, the method was applied to the optimization design of a moderator–collimator for accelerator-based thermal neutron radiography. Two optimization tasks were performed in this study: (1) determining the optimal moderation efficiencies at different source-neutron energies and (2) optimizing the thermal neutron-induced photon yield ratio. The results underscore the effectiveness and practical applicability of the HRG-MCO method in neutronics optimization design.
Separation of uranium isotopes is both a demanding scientific challenge and a complex engineering task. A temperature-assisted dynamic liquid chromatography system was developed for uranium isotope separation on the basis of dynamic liquid chromatography and the liquid membrane tidal diffusion model. This work constructed “organic” and “inorganic” chromatographic columns packed with ABS pellets and SiO_2 pellets, respectively. In order to improve the efficiency of separation, the self-controlled injection/outflow system and temperature-assisted cells were integrated with the chromatographic columns. The organic column optimal working conditions obtained by experiments were pH = 2, a heating temperature of 70 ^∘C , and an injection flow rate of 15 mL min−1. Meanwhile, multistage separation experiments verified the feasibility of uranium isotope separation with the organic column; the average separation factor reached 1.0184, and more than 79 stages were required to enrich the ^235 U abundance to 3 50 ^∘C , and an injection flow rate of 15 mL min−1. Multistage separation experiments with the inorganic column yielded a separation factor of 1.0103, requiring more than 112 stages to enrich the ^235 U abundance to 3 ^235 U from ^238 U under the present experimental conditions, thereby providing a new perspective for chromatography-based isotope separation.
