Subjects: Physics >> Nuclear Physics submitted time 2024-05-20
Abstract: 氚是核电站排放的一种放射性核素,对去除氚提出了挑战。水中氚的连续在线监测对于实时辐射数据至关重要,因为它主要存在于环境中,就像水一样。本文介绍了利用塑料闪烁光纤 (PSF) 阵列的氚监测设备的设计、仿真和开发。实验验证证实了该器件的检测效率和最小可检测活性。该器件记录的检测效率为1.6×10−3,比理论模拟值4×10−4高出4倍。在没有屏蔽的情况下,该器件可以在 1600 秒的测量持续时间内实现 3165 Bq L−1 的最小可检测活性。根据仿真和实验结果,通过增加PSF的数量和长度以及实施严格的屏蔽措施,可以提高检测效率。此外,减小PSF的直径也可以提高检测效率。使用上述方法可以进一步降低设备的最小可检测活性。
Subjects: Nuclear Science and Technology >> Radiation Physics and Technology submitted time 2024-05-11
Abstract: Carbon-based nanomaterials have important research significance in various disciplines, such as composite materials, nanoelectronic devices, biosensors, biological imaging, and drug delivery. Recently, the human and ecological risks associated with carbon-based nanomaterials have received increasing attention. However, the biosafety of carbon-based nanomaterials has not been investigated extensively. In this study, we used different types of carbon materials, namely, graphene oxide (GO), single-walled carbon nanotubes (SWCNTs), and multiwalled carbon nanotubes (MWCNTs), as models to observe their distribution and oxidative damage in vivo.
The results of Histopathological and ultrastructural examinations indicated that the liver and lungs were the main accumulation targets of these nanomaterials. SR-μ-XRF analysis revealed that SWCNTs and MWCNTs might be present in the brain. This shows that the three types of carbon-based nanomaterials could cross the gas–blood barrier and eventually reach the liver tissue. In addition, SWCNTs and MWCNTs could cross the blood–brain barrier and accumulate in the cerebral cortex. The increase in ROS and MDA levels and the decrease in GSH, SOD, and CAT levels indicated that the three types of nanomaterials might cause oxidative stress in the liver. This suggests that direct instillation of these carbon-based nanomaterials into rats could induce ROS generation. In addition, iron (Fe) contaminants in these nanomaterials were a definite source of free radicals. However, these nanomaterials did not cause obvious damage to the rat brain tissue. The deposition of selenoprotein in the rat brain was found to be related to oxidative stress and Fe deficiency. This information may support the development of secure and reasonable applications of the studied carbon-based nanomaterials.
Subjects: Nuclear Science and Technology >> Nuclear Science and Technology submitted time 2024-03-08
Abstract: Various electromagnetic signals are excited by the beam in the acceleration and beam-diagnostic elements of a particle accelerator. It is important to obtain time-domain waveforms of these signals with high temporal resolution for research, such as the study of beam-cavity interactions and bunch-by-bunch parameter measure#2;ments. Therefore, a signal reconstruction algorithm with ultrahigh spatiotemporal resolution and bunch phase compensation based on equivalent sampling is proposed in this paper. Compared with traditional equivalent sampling, the use of phase compensation and setting the bunch signal zero-crossing point as the time reference can construct a more accurate reconstructed signal. The basic principles of the method, simulation, and experi#2;mental comparison are also introduced. Based on the beam test platform of the Shanghai Synchrotron Radiation Facility (SSRF) and the method of experimental verification, the factors that affect the reconstructed signal qual#2;ity are analyzed and discussed, including the depth of the sampled data, quantization noise of analog-to-digital converter (ADC), beam transverse oscillation, and longitudinal oscillation. The results of the beam experiments show that under the user operation conditions of the Shanghai Synchrotron Radiation Facility (SSRF), a beam excitation signal with an amplitude uncertainty of 2% can be reconstructed.
Subjects: Physics >> Nuclear Physics submitted time 2024-02-28
Abstract: Shanghai Laser Electron Gamma Source (SLEGS) is a quasi-monoenergetic, and energy-tunable MeV gamma-rays source generated by the inverse Laser Compton Scattering (LCS) of lasers and electrons. SLEGS is the only LCS gamma source in the world with a continuously variable collision angular range. The gamma activation analysis is one of the effective methods to study the properties of materials. This paper introduces the gamma activation platform of SLEGS, including the online activation experiment, the low background offline measurement, and the energy and efficiency calibration for the high purity germanium (HPGe) detector. The counting rate of the shielded HPGe has been controlled down to 5.2 cps/s within 60 keV-3 MeV region under the current low background environment. The activation platform of the SLEGS has provided favorable conditions for gamma activation measurements, which will play an important role in future research in the fields of nuclear physics, nuclear astrophysics, medical applications, materials science, and environmental science.
Subjects: Physics >> Nuclear Physics submitted time 2024-02-16
Abstract: The Shanghai Laser Electron Gamma Source(SLEGS) has delivered a quasi-monochromatic, continuously energy-tunable gamma-ray beam. Based on the photon activation analysis(PAA) method, SLEGS has built and developed a photon activation analysis platform, including online activation and offline low-background HPGe detector measurement systems, as an alternative to direct measurement methods and a cross-tests at low throughput. Due to the short half-lives spanning from minutes to days and characteristics such as ease of fabrication, cost-effectiveness, and stability, gold (197Au) and zinc (64Zn) emerge as favorable activation targets in the gamma-ray beam flux monitor. Notably, their utility shows a multitude of advantages in monitoring the gamma-ray beam flux typically 105 photons/s with the energy of 13.16 to 19.08 MeV under the condition of the 3 mm coarse collimator. Especially in high-flux $\gamma$-ray beam experiments can be well applied.
Peer Review Status:Awaiting Review
Subjects: Physics >> Nuclear Physics Subjects: Physics >> Interdisciplinary Physics and Related Areas of Science and Technology submitted time 2024-01-10
Abstract: Traditional particle identification methods are time consuming, experience-dependent, and poor repeatability challenges in heavy-ion collisions at low and intermediate energies. Researchers urgently need solutions to the dilemma of traditional particle identification methods. This study explores the possibility of applying intelligent learning algorithms to the particle identification of heavy-ion collisions at low and intermediate energies. Multiple intelligence algorithms, including XgBoost and TabNet, were selected to test datasets from the neutron ion multi-detector for reaction-oriented dynamics (NIMROD–ISiS) and Geant4 simulation. Machine learning algorithms based on tree structures and deep learning algorithms e.g. TabNet show excellent performance and generalization ability. Adding additional data features besides energy deposition can improve the algorithm's identification ability when the data distribution is nonuniform. Intelligent learning algorithms can be applied to solve the particle identification problem in heavy-ion collisions at low and intermediate energies.
Subjects: Physics >> Nuclear Physics submitted time 2023-11-16
Abstract: The corrosion behavior of 316H stainless steel (SS) in the impure and purified NaCl-KCl-MgCl2 salt was investigated at 700 °C . Results indicate that the main deleterious impurity induced corrosion in the impure salt was the absorbed moisture, present in the form of MgCl2·6H2O. 316H SS occurred severe intergranular corrosion with a corrosion depth of 130 μm for 1000 h in the impure NaCl-KCl-MgCl2 salt. In contrast, the purification treatment of molten chloride salt by the dissolved Mg metal can remove the absorbed moisture, and the corresponding reactions were also discussed. As a result, the corrosiveness of NaCl-KCl-MgCl2 salt is reduced significantly. 316H SS occurred slight uniform corrosion with a depth of less than 5 μm for 3000 h in the purified NaCl-KCl-MgCl2 salt.
Subjects: Physics >> Nuclear Physics Subjects: Physics >> Geophysics, Astronomy, and Astrophysics submitted time 2023-09-12
Abstract: The neutron capture cross sections (${n, upgamma}$) of Bromine was performed with the time-of-flight (TOF) technique at the Back-n facility of the China Spallation Neutron Source (CSNS). Prompt $ upgamma$-rays originating from neutron-induced capture events were detected by four C${}_6$D${}_6$ detectors. The pulse height weighting technique (PHWT) and the double-bunch unfolding method based on the Bayesian theory were used in the data analysis. To obtain reliable measurement results, background deductions, normalization, and corrections were carefully considered. The multilevel R-matrix Bayesian code SAMMY was used to extract the resonance parameters in the resolved resonance region (RRR). The average cross sections in unresolved resonance region the was obtained from 10 to 400 keV. The experimental results were compared with the data of several evaluated libraries and previous experiments in the resolved and unresolved resonance region. The TALYS code was used to describe the average cross sections in the unresolved resonance region. Astrophysical Maxwell average cross sections (MACSs) of ${}^{79,81}$Br from $ kT $ = 5 to 100 keV was calculated over a sufficiently wide range of neutron energies. At a thermal energy of $kT=30$ keV, the MACS value for ${}^{79}$Br 638$ pm$64 mb is in good agreement with the KADoNiS recommended value. By contrast, the value of 293$ pm$29 mb for ${}^{81}$Br is substantially higher than those of the evaluated database and the KADoNiS recommended value.
Peer Review Status:Awaiting Review
Subjects: Physics >> Nuclear Physics submitted time 2023-09-11
Abstract: The NaI:Tl scintillator is an innovative material for dual-gamma-ray and neutron detection with a low 6Li concentration. To achieve real-time n/γ discrimination, a zero-crossing time comparison algorithm based on trapezoidal pulse shaping was developed. The algorithm can operate efficiently at low sampling rates and was implemented on a single-probe portable digital n/γ discriminator based on a feld-programmable gate array (FPGA). The discriminator and NaI:Tl,6Li detector were tested in a neutron-gamma mixed field produced by an 241Am-Be neutron source to evaluate the performance of the algorithm. The Figure of Merits (FoM) was measured as 2.88 at a sampling rate of 50 MHz, indicating that the discriminator with its embedded algorithm has a promising n/γ discrimination capability. Efficient discrimination at sampling rates of 40 and 25 MHz demonstrates that the capability of this method is not limited by low sampling rates.
Subjects: Physics >> Nuclear Physics submitted time 2023-06-09
Abstract: A diffraction-limited storage ring with a multi-bend achromat lattice suffers from a small dynamic aperture for conventional off-axis injection. Thus, a longitudinal on-axis injection scheme based on a new type of crab cavity is proposed in this paper. Particle tracking simulations were performed to study the disturbance of the stored beam and the motion of the injected beam during the injection process. The possibility of multi-bunch injections was discussed. In addition, the effect of the long-range wake field induced by the stored beam was analyzed. A C-band standing-wave crab cavity was designed and produced as requested, and its field distribution was measured. The corresponding results are consistent with the simulation results.