分类: 核科学技术 >> 核探测技术与核电子学 提交时间: 2023-06-18 合作期刊: 《Nuclear Science and Techniques》
摘要: The Dragon-I linear induction accelerator (LIA) at China Academy of Engineering Physics generates 20 MeV flash X-rays mainly for radiography applications in fluid dynamics. Its spectral information is quite important for diagnostic X-ray imaging applications, but because of its short pulse and great radiation intensity, direct measurement is impossible. In this work, we propose a new method based on transmission measurements to obtain the flash X-ray spectrum. Pure iron cylinders were used as attenuation material, and alanine dosimeters were attached on their rear bottom to record the dose after different degrees of attenuation. Iterative least square method was used to unfold the spectrum, while Geant4 Monte Carlo code was used to simulate the X-ray spectrum. The unfolded spectrum and the simulated spectrum have a high degree of consistency, with the reduced chi-square value of 0.044. This shows that the method is reliable in estimating megavoltage high-intensity X-ray spectrum.
分类: 核科学技术 >> 核探测技术与核电子学 提交时间: 2023-06-18 合作期刊: 《Nuclear Science and Techniques》
摘要: In order to realize on-line real-time measurement of dynamic and time-sharing neutron spectrum of HL-2A, a tokamak fusion neutron spectrometer based on PXI bus was developed. It consists of electronics system and eight thermal neutron detectors, namely SP9 3He proportional counter, embedded in eight polyethylene spheres in different diameters. Response function of the eight polyethylene spheres was the key to calculate the neutron spectrum accurately. In this paper, response function of the eight polyethylene spheres is simulated by adopting Geant4 code, and neutron counts from an 241Am-Be neutron source are measured by the eight detectors. The calculated spectrum of the Am-Be neutron is accurate in 02 MeV region, and is similar to the theoretical spectrum. The tokamak fusion neutron spectrometer was used in HL-2A device to monitor the dynamic neutron spectrum of HL-2A on-line and real-time.
分类: 物理学 >> 核物理学 提交时间: 2023-09-13
摘要: Abstract: In this experimental study, involving deuteriumdeuterium fusion neutron emission spectroscopy (NES) measurement on the experimental advanced superconducting tokamak (EAST), a liquid scintillator detector (BC501A) was employed. This decision was based on the detector's superior sensitivity, optimal time-response, and its exceptional n- discrimination capability. This detector emits fast pulse signals that are as narrow as 100 ns, with high count rates that can peak at several Mcps. However, conventional nuclear circuits faced challenges in performing pulse height analysis, n pulse shape discrimination (PSD), and in recording the entire pulse waveform under such high-count-rate conditions. To address these challenges, a high-speed digital pulse signal acquisition and processing system was designed. The system was developed around a micro-telecommunications computing architecture (MTCA). Within this structure, a signal acquisition and processing (SAQP) module communicated through PCI Express (PCIe) links, achieving a bandwidth of up to 1.6 GB/s. To accurately capture the detailed shape of the pulses, four channels of analog-to-digital converters (ADCs) were used, each with a 500-MSPS sampling rate and a 14-bit resolution, ensuring an accuracy that surpassed 11 bits. An n- discrimination algorithm, based on the two-gate integral method, was also developed. Implemented within field programmable gate arrays (FPGA), this algorithm provided a real-time n- discrimination spectrum for pulse height analysis. The system underwent rigorous testing in a laboratory setting and during an EAST experiment. The results confirmed that the innovative SAQP system can satisfy the demanding requirements of high-parameter experiments, manage count rates of up to 2 Mcps, execute real-time n- discrimination algorithms, and record entire pulse waveforms without any data loss.
分类: 核科学技术 >> 核仪器、仪表 提交时间: 2023-06-01
摘要: 核安全防护通常需要同时探测中子和伽马射线,探测器的实时中子/伽马脉冲分辨是其关键性能参数。近年来,采用Cs2LiLaBr6 (CLLB)晶体的双读出探测器引起了广泛关注,论文研究电荷比较法、幅度比较法、时间比较法和脉冲梯度法的甄别性能,以及Sallen-Key滤波器的甄别效果。实验结果表明,通过合适的滤波,四种方法的品质因数(FOM)都有所提高。其中,电荷比较法抗噪声性能最佳,最适合CLLB探测器实时甄别中子/伽马脉冲。其甄别性能取决于参数、和。在对应脉冲峰值10%的时刻,,仅需延迟640-740 ns,此刻对应3.1-3.3 MeV的电荷比较方法最优FOM大于1.46。所提出的最大分辨差模型( MDDM)计算值与最优FOM的差异小于3.9%,表明该模型可以很好地指导电荷比较法的参数选择。