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Nuclear Science and Techniques [Nuclear Science and Techniques]

基本信息

  • ISSN:1001-8042
  • 语种: Chinese;
  • 出版格式:
  • 期刊网址: 点此访问

出版信息

  • 出版时间:1990-
  • 出版者:中国科学院上海应用物理研究所联合编辑部
  • 出版格式:
  • 总访问量:206362次
  • Chord length sampling correction analysis for dispersion fuel in Monte Carlo simulation

    关键词: Stochastic media; Monte Carlo; Chord Length Sampling; Excluded-volume effect; Chord Length Correction;

    DOI:10.12074/202403.00394V1

    提交时间: 2024-03-28

    摘要:Due to their excellent safety performance, dispersion fuels are widely used in advanced reactors, such as high-temperature gas-cooled reactors (HTGRs). Compared with deterministic methods, the Monte Carlo method has more advantages in the geometric modeling of stochastic media. The explicit modeling method has high computational accuracy and high computational cost. The chord length sampling (CLS) method can improve computational efficiency by sampling the chord length during neutron transport using the matrix chord length’s probability density function (PDF). This study shows that the excluded-volume effect in realistic stochastic media can introduce significant deviations into the CLS. A chord length correction approach is proposed to obtain the chord length correction factor by developing the Particle code based on equivalent transmission probability. Through numerical analysis against reference solutions from explicit modeling in the RMC code, it was demonstrated that CLS with the proposed correction method provides good accuracy for addressing the excluded-volume effect in realistic infinite stochastic media.
     

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  • Design and Construction of Charged Particle Telescope Array for Study of Exotic Nuclear Clustering Structure

    关键词: luster decay; toroidal structure; telescope array; SiPM; energy resolution;

    DOI:10.12074/202403.00255V1

    提交时间: 2024-03-19

    摘要:The exploration of exotic shapes and properties of atomic nuclei, e.g., α cluster and toroidal shape, is a
    fascinating field in nuclear physics. To study the decay of these nuclei, a novel detector aimed at detecting
    multiple alpha-particle events was designed and constructed. The detector comprises two layers of double-sided
    silicon strip detectors (DSSD) and a cesium iodide scintillator array coupled with silicon photomultipliers array
    as light sensors, which has the advantages of their small size, fast response, and large dynamic range. DSSDs
    couple with cesium iodide crystal arrays are used to distinguish multiple alpha hits. The detector array has a
    compact and integrated design that can be adapted to different experimental conditions. The detector array was
    simulated using Geant4, and the excitation energy spectra of some alpha-clustering nuclei were reconstructed
    to demonstrate the performance. The simulation results show that the detector array has excellent angular
    and energy resolutions, enabling effective reconstruction of the nuclear excited state by multiple alpha particle
    events. This detector offers a new and powerful tool for nuclear physics experiments and has the potential to
    discover interesting physical phenomena related to exotic nuclear structures and their decay mechanisms

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  • Feasibility study of the photonuclear reaction cross section of medical radioisotopes using a laser Compton scattering gamma source

    关键词: Medical radioisotope; Photonuclear reaction; GEANT4; Shanghai Laser Electron Gamma Source (SLEGS); lowbackground gamma-ray spectrometer;

    DOI:10.12074/202403.00254V1

    提交时间: 2024-03-19

    摘要:In recent years, the gap between the supply and demand of medical radioisotopes has increased, necessitating new methods for producing medical radioisotopes. Photonuclear reactions based on gamma sources have unique advantages in terms of producing high specific activity and innovative medical radioisotopes. However, the lack of experimental data on reaction cross sections for photonuclear reactions of medical radioisotopes of interest has severely limited the development and production of photonuclear transmutation medical radioisotopes. In this study, the entire process of the generation, decay, and measurement of medical radioisotopes was simulated using online gamma activation and offline gamma measurements combined with a shielding gammaray spectrometer. Based on a quasi-monochromatic gamma beam from the Shanghai Laser Electron Gamma Source (SLEGS), the feasibility of the measurement of production cross section for surveyed medical isotopes was simulated, and specific solutions for measuring medical radioisotopes with low production cross sections were provided. The feasibility of this method for high precision measurements of the reaction cross section of medical radioisotopes was demonstrated.

    点击量 28 下载量 14 评论 0
  • FPGA implementation of 500-MHz high-count-rate high-time-resolution real-time digital neutron-gamma discrimination for fast liquid detectors

    关键词: Neutron–gamma discrimination; Liquid scintillation detector; Real-time spectrum analyzer;

    DOI:10.12074/202403.00210V1

    提交时间: 2024-03-11

    摘要:Fast neutron flux measurements with high count rates and high time resolution have important applications in equipment such as tokamaks. In this study, real-time neutron and gamma discrimination was implemented on a self-developed 500-Msps, 12-bit digitizer, and the neutron and gamma spectra were calculated directly on an FPGA . A fast neutron flux measurement system with BC-501A and EJ-309 liquid scintillator detectors was developed and a fast neutron measurement experiment was successfully performed on the HL-2M tokamak at the Southwestern Institute of Physics, China. The experimental results demonstrated that the system obtained the neutron and gamma spectra with a time accuracy of 1ms. At count rates of up to 1 Mcps, the figure of merit was greater than 1.05 for energies between 50 keV and 2.8 MeV.



     

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  • Feasibility of medical radioisotope production based on the proton beams at China Spallation Neutron Source

    关键词: CSNS proton beam; medical isotope production; α-emitting radionuclides; nuclidic purity analysis ;

    DOI:10.12074/202403.00185V1

    提交时间: 2024-03-10

    摘要:The utilization of a proton beam from the China Spallation Neutron Source (CSNS) for producing medical radioisotopes is appealing owing to its high current intensity and high energy. The medical isotope production based on the proton beam at the CSNS is significant for the development of future radiopharmaceuticals, particularly for the α-emitting radiopharmaceuticals. The production yield and activity of typical medical isotopes were estimated using the FLUKA simulation. The results indicate that the 300-MeV proton beam with a power of 100 kW at CSNS-II is highly suitable for proof-of-principle studies of most medical radioisotopes. In particular, this proton beam offers tremendous advantages for the large-scale production of alpha radioisotopes, such as 225Ac, whose theoretical production yield can reach approximately 57 Ci/week. Based on these results, we provide perspectives on the use of CSNS proton beams to produce radioisotopes for medical applications.

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  • Application of Deep Learning Methods Combined with Physical Background in Wide Field of View Imaging Atmospheric Cherenkov Telescopes

    关键词: VHE Gamma-Ray Astronomy; HADAR; Deep Learning; Convolutional Neural Networks.;

    DOI:10.12074/202403.00300V1

    提交时间: 2024-03-10

    摘要:The HADAR experiment, which will be constructed in Tibet, China, combines the wide-angle advantages of traditional EAS array detectors with the high sensitivity advantages of focused Cherenkov detectors. Its physics objective is to observe transient sources such as gamma-ray bursts and counterparts of gravitational waves. The aim of this study is to utilize the latest AI technology to enhance the sensitivity of the HADAR experiment. We have built training datasets and models with distinctive creativity by incorporating relevant physical theories for various applications. They are able to determine the kind, energy, and direction of incident particles after careful design. We have obtained a background identification accuracy of 98.6 %, a relative energy reconstruction error of 10.0 %, and an angular resolution of 0.22-degrees in a test dataset at 10 TeV. These findings demonstrate the enormous potential for enhancing the precision and dependability of detector data analysis in astrophysical research. Thanks to deep learning techniques, the HADAR experiment’s observational sensitivity to the Crab Nebula has surpassed that of MAGIC and H.E.S.S. at energies below 0.5 TeV and remains competitive with conventional narrow-field Cherenkov telescopes at higher energies. Additionally, our experiment offers a fresh approach to dealing with strongly connected scattered data.

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  • Opportunities for production and property research of neutron-rich nuclei around N=126 at HIAF

    关键词: HFRS; fragmentation; ; neutron-rich nuclei around N=126; mass measurement; lifetime;

    DOI:10.12074/202403.00188V1

    提交时间: 2024-03-09

    摘要:The study of nuclide production and its properties in the N=126 neutron-rich region is the frontier and hot topic in nuclear physics and astrophysics research. The upcoming High energy FRagment Separator (HFRS) at the High Intensity heavy-ion Accelerator Facility (HIAF), an in-flight separator at relativistic energies, is characterized by high beam intensity, large ion-optical acceptance, high magnetic rigidity, and high momentum resolution power. It provides an opportunity for the study of the production and properties of neutron-rich nuclei around N=126. In this paper, an experimental scheme is proposed to produce the neutron-rich nuclei around N=126 and simultaneously measure their mass and lifetime based on the HFRS separator, and the feasibility of this scheme is evaluated by the simulations. The results show that under the high resolution optical mode many new neutron-rich nuclei approaching the r-process abundance peak around A=195 can be produced for the first time, and many nuclei with unknown mass and lifetime can be produced with high statistics. Using the time-of-flight corrected by the measured dispersive position and the energy loss information, the cocktails produced from the 208Pb fragmentation can be unambiguously identified. Moreover, the masses of some neutron-rich nuclei in the vicinity of N=126 can be measured with high precision using the time-of-flight magnetic rigidity technique. This indicates that the HIAF-HFRS facility has potential for the production and property research of neutron-rich nuclei around N=126, which is of great significance for expanding chart of nuclides, developing nuclear theories, and understanding the origin of heavy elements in the universe.

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  • Multi-distortion suppression for neutron radiographic images based on generative adversarial network

    关键词: Neutron radiography; Multi-distortion suppression; Generative adversarial network; Coordinate attention mechanism;

    DOI:10.12074/202403.00190V1

    提交时间: 2024-03-08

    摘要:Neutron radiography is a crucial nondestructive testing technology widely used in the aerospace, military, and
    nuclear industries. However, because of the physical limitations of neutron sources and collimators, the resulting
    neutron radiographic images inevitably exhibit multiple distortions, including noise, geometric unsharpness,
    and white spots. Furthermore, these distortions are particularly significant in compact neutron radiography systems
    with low neutron fluxes. Therefore, in this study, we devised a multi-distortion suppression network that
    employs a modified generative adversarial network to improve the quality of degraded neutron radiographic images.
    Real neutron radiographic image datasets with various types and levels of distortion were built for the first
    time as multi-distortion suppression datasets. Thereafter, the coordinate attention mechanism was incorporated
    into the backbone network to augment the capability of the proposed network to learn the abstract relationship
    between ideally clear and degraded images. Extensive experiments were performed; the results show that the
    proposed method can effectively suppress multiple distortions in real neutron radiographic images and achieve
    state-of-the-art perceptual visual quality, thus demonstrating its application potential in neutron radiography.

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  • Ultrahigh spatiotemporal Resolution Beam Signal Reconstruction with bunch phase compensation

    关键词: turn-by-turn bunch phase compensation technique; equivalent sampling; signal reconstruction algorithm; ultrahigh spatio-temporal resolution; SSRF.;

    DOI:10.12074/202403.00191V1

    提交时间: 2024-03-08

    摘要: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.

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  • Effect of Multiple Coulomb Scattering on the Beam Tests of Silicon Pixel Detectors

    关键词: 硅像素探测器; 束流望远镜; 多次库伦散射; 空间分辨率;

    DOI:10.12074/202403.00395V1

    提交时间: 2024-03-07

    摘要:在硅像素探测器的研究和开发中,配备高分辨率的像素束望远镜的准直单能带电粒子测试束流对探测器原型验证和性能评估是至关重要的。当束流能量较低时,必须考虑多次库仑散射对被测设备(DUT)测量分辨率的影响,以准确评估像素芯片和探测器的性能。本研究旨在调查多次库仑散射对DUT测量分辨率的影响,特别是在低束流能量下。使用Allpix2软件进行模拟,研究了不同束流能量、物质量和望远镜布局下多次库仑散射的影响。模拟还提供了多次库仑散射影响可忽略的最低能量。与在DESY用电子束测试的的结果相比,模拟结果与束流测试结果一致,验证了模拟的可靠性。

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