分类： 物理学 >> 核物理学 提交时间： 2023-09-15
摘要：The Trojan horse method was employed to indirectly measure the bare-nucleus reaction cross-section and astrophysical S-factor of the 9Be(p,α) 6Li reaction in the low-energy region , utilizing the three-body reaction 2H(9Be,α 6Li)n. Comparing the two-body reaction data extracted from the Trojan horse method with that obtained through direct measurements, compatibility is observed in the energy region above approximately 100 keV. Additionally, the THM data successfully reproduces the expected low-energy resonance peak around 270 keV. The THM extraction of the astrophysical factor yields S(0) = 21.0 ± 0.8 MeV b, which surpasses the extrapolation obtained from direct measurements. The 9Be(p,α) 6Li reaction channel exhibits a subthreshold resonance with a width of 25 keV, positioned approximately -23 keV below the threshold. However, the strong electron shielding effect near the zero energy position in direct measurements often masks the influence of the subthreshold resonance on the low-energy region. In contrast, the THM method allows us to neglect the electron shielding effect. The THM experimental data were subjected to fitting using the Breit-Wigner function and subsequently compared with directly measured data. Following a comprehensive comparative analysis, it was discerned that the S(0) value obtained through THM exceeded the extrapolated value derived from direct measurements. This disparity was primarily attributed to the influence of the subthreshold resonance.
分类： 物理学 >> 核物理学 提交时间： 2023-09-13
Ma, Pufang
Wang, Jiarong
Zhang, Zixiao
Meng, Tianming
Xia, Zihan
Ren, Baihui
Wei,Long
Yao, Ke
Xiao, Jun
Zou, Yaming
Tu, Bingsheng
Wei, baoren
摘要：The total absolute cross sections of single- and double-electron capture (SEC and DEC) in the collisions of He2+ with He and Ne8+ with O2, N2, and CH4 were studied in the energy ranges 3.5 to 50 keV/u and 2.8 to 40 keV/u, respectively. Through a deep analysis of the experimental systematic uncertainties in the measurement procedure and data evaluation, the error in the experimental results of the SEC cross sections is less than 9%. Within the uncertainties, the present results of the He2+ -He collision show good consistency with previous measurements, validating the experimental system and paving the way for precise measurements of EC cross sections for a variety of ions and neutral gases. The present measurements allow for a test of EC theory and provide crucial EC cross section data for the establishment of plasma models in fusion research and astrophysical X-ray studies.
分类： 物理学 >> 核物理学 提交时间： 2023-09-13
摘要：Abstract: In this experimental study, involving deuterium–deuterium 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-γ 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–γ 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-γ 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-γ 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-γ discrimination algorithms, and record entire pulse waveforms without any data loss.
分类： 物理学 >> 核物理学 分类： 物理学 >> 地球物理学、天文学和天体物理学 提交时间： 2023-09-12
Yang, Gaole
An, Zhendong
Jiang, Wei
Li,Xiankai
Qiu, Weiwei
Liao, Zhengfa
Zhuang, Ziyue
Zhang, Xiaoping
Chen,Shengli
Xiao, Erxi
Fang,Xiao
Li,XinXiang
Hu, Xinrong
Jiang, Bing
Wang, Jincheng
Ren, Jie
Luo, Wen
Zhu, ZhiChao
Lan, Haoyang
Cao, Zongwei
摘要：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.
分类： 物理学 >> 核物理学 提交时间： 2023-09-11
摘要：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.
分类： 物理学 >> 核物理学 提交时间： 2023-09-11
摘要：本工作制作了一套由快发光塑料闪烁体耦合快光电倍增管组成的塑料闪烁体飞行时间探测器的样机，通过皮秒脉冲激光测试了探测器的时间性能，旨在为将来的 HIAF-HFRS 飞行时间探测器作预研。对于两种不同尺寸的塑闪探测器，通过改变激光的光斑大小、频率、光强和位置等各项参数来模拟真实束流的情况，并使用 CAEN-DT5742 数字化仪以及 Mesytec-MCFD16+MTDC32 电子学系统进行了系统的测试。使用聚焦激光照射在塑闪中心位置时，小尺寸 (7 cm×7 cm) 塑闪探测器的 ToF 分辨最好可达 8 ps；小-大 (26 cm×10 cm) 塑闪探测器的 TOF 分辨最好可达到 12 ps。在改变激光各项参数后，得到的响应时间分辨为 10–16 ps 和 19–46 ps。测试结果表明，所得到的 ToF 分辨满足 HFRS 束线的时间分辨性能要求，为飞行时间探测器的优化奠定了基础。
分类： 物理学 >> 核物理学 提交时间： 2023-09-11
Liu, Xiangman
Tang, Shuwen
Wang, Wei
Yu, Yuhong
Sun, Zhiyu
Zhang, Yongjie
Fang, Fang
Yan, Duo
Wang, ShiTao
Zhang, Xueheng
Jin, Shuya
Hu, Bitao
摘要：Gamma-ray polarimetry is a new and prospective tool for studying various extreme high-energy celestial objects and is of great significance for the development of astrophysics. With the rapid development of microsatellite technology, the advantages in space exploration are becoming increasingly apparent. Therefore, in this paper, we conducted a simulation study on a soft gamma-ray polarimeter for a microsatellite in space. Here, we proposed a unique design structure for the polarimeter based on the microsatellite design concept and the Compton scattering principle. And then, the detailed Monte Carlo simulations using mono-energetic gamma-ray linear polarization sources and the Crab-like sources in the energy range of 0.1-10 MeV with full consideration of the orbital background were performed. The simulation results show that the polarimeter can exhibit excellent polarization detection performance. The modulation factor is 0.80±0.01, and the polarization angles are accurate within an error of 0.2° at 200 keV for on-axis incidence. For the Crab-like sources for on-axis incidence, the polarization degrees are consistent with the set values within the error tolerance, the modulation factor is 0.76±0.01, and the minimum detectable polarization reaches 2.4% at 3σ for an observation time of 106 seconds. In addition, the polarimeter has recoil electron tracking, imaging, and powerful background suppression at a large field of view (∼2π sr). The polarimeter designed can meet the requirements of a space-soft gamma-ray polarization detector very well and has a bright research prospect.
分类： 物理学 >> 核物理学 提交时间： 2023-09-11
Guo, Dong
Haoqian Xyu
DongDong Qi
HeXiang Wang
Lei Zhang
Zhengyang Sun
Zhi Qin
Botan Wang
Yingjie Zhou
Zekun Wang
Yuansheng Yang
Yuhao Qin
Xianglun Wei
Herun Yang
Yuhong Yu
Lei Zhao
Zhigang Xiao
摘要：A trigger system has been designed and implemented for the HIRFL-CSR external target experiment (CEE), the spectrometer for studying nuclear matter properties with heavy ion collisions in the GeV energy region. The system adopts master-slave structure and serial data transmission mode using optical fiber to deal with different types of detectors and long-distance signal transmission. The trigger logic can be accessed based on command register and controlled by a remote computer. The overall field programmable gate array (FPGA) logic can be flexibly reconfigured online to match the physical requirements of the experiment. The trigger system has been tested in beam experiment. It is demonstrated that the trigger system functions correctly and meets the physical requirements of CEE.
分类： 物理学 >> 核物理学 提交时间： 2023-09-07
摘要：In this study, we developed a neural network that incorporates a fully connected layer with a convolutional layer to predict the nuclear charge radii based on the relationships between four local nuclear charge radii.
The convolutional neural network (CNN) combines the isospin and pairing effects to describe the charge radii of nuclei with $A geq $ 39 and $Z geq $ 20. The developed neural network achieved a root--mean--square (RMS) deviation of 0.0195 fm for a dataset with 928 nuclei. Specifically, the CNN reproduced the trend of the inverted parabolic behavior and odd--even staggering observed in the calcium isotopic chain, demonstrating reliable predictive capability.
分类： 物理学 >> 核物理学 提交时间： 2023-09-07
摘要：Helium–xenon cooled microreactors are a vital technological solution for portable nuclear reactor power sources. To examine the convective heat transfer behavior of helium–xenon gas mixtures in a core environment, numerical simulations are conducted on a cylindrical coolant channel and its surrounding solid regions. Validated numerical methods are used to determine the effect and mechanisms of power and its distribution, inlet temperature and velocity, and outlet pressure on the distribution and change trend of the axial Nusselt number. Furthermore, a theoretical framework that can describe the effect of power variation on the evolution of the thermal boundary layer is employed to formulate an axial distribution correlation for the Nusselt number of the coolant channel, under the assumption of a cosine distribution for the axial power. Based on the simulation results, the correlation coefficients are determined, and a semi-empirical relationship is identified under the corresponding operating conditions. The correlation derived in this study is consistent with the simulations, with an average relative error of 5.3% under the operating conditions. Finally, to improve the accuracy of the predictions near the entrance, a segmented correlation is developed by combining the Kays correlation with the aforementioned correlation. The new correlation reduces the average relative error to 2.9% and maintains satisfactory accuracy throughout the entire axial range of the channel, thereby demonstrating its applicability to turbulent heat transfer calculations for helium–xenon gas mixtures within the core environment. These findings provide valuable insights into the convective heat transfer behavior of a helium–xenon gas mixture in a core environment.
分类： 物理学 >> 核物理学 提交时间： 2023-09-07
摘要：The thermodynamic properties of charged particles, such as the energy density, pressure, entropy density, particle density, and squared speed of sound at the kinetic freeze-out in the $ mathrm{Au+Au}$ collisions from the relativistic heavy ion collider (RHIC) beam energy scan program ($ sqrt{s_ text{NN}}$=7.7--200 GeV) and in the $ mathrm{Cu+Cu}$ collisions at $ sqrt{s_ text{NN}}$=62.4, 200 GeV are studied using the thermodynamically consistent Tsallis distribution. The energy density, pressure, and particle density decrease monotonically with the collision energy for the same collision centrality; These properties also decrease monotonically from the central to peripheral collisions at the same collision energy. While the scaled energy density $ varepsilon/T^4$ and scaled entropy density $s/T^3$ demonstrate the opposite trend with the collision energy for the same collision centrality. There is a correlation between $ varepsilon/T^4$ and $s/T^3$ at the same centrality. In addition, the squared speed of sound was calculated to determine that all the collision energies share nearly the same value at different collision centralities.
分类： 物理学 >> 核物理学 提交时间： 2023-09-07
Zehua Yang
Jingtao Zhu
Zhongliang Li
Hongxin Luo
Shangyu Si
Yunping Zhu
Li Zhao
Kuan Ren
Feng Wang
Rongqing Yi
摘要：Multilayer interference mirrors play a pivotal role in spectroscopic diagnostic systems, which probe electron temperature and density during inertial confinement fusion processes. In this study, aperiodic Mo/B4C multilayer mirrors of varied thicknesses were investigated for X-ray plasma diagnostics at the 9.67-keV W-Lbeta line. The thickness distribution of the aperiodic multilayers was designed using the 1st Bragg diffraction condition and then optimized through a simplex algorithm to realize a narrow bandwidth and consistent spectral response. To enhance spectral accuracy, further refinements were undertaken by matching the grazing incidence X-ray reflectivity data with actual structural parameters. X-ray reflectivity measurements from the SSRF synchrotron radiation facility on the optimized sample showed a reflectivity of 29.7% ±2.6%, flat-band range of 1.3 keV, and bandwidth of 1.7 keV, making it suitable for high-temperature plasma diagnostics. The study explored the potential of predicting the 9.67 keV reflectivity spectrum using the fitting data from the Grazing incidence X-ray reflectivity (GIXRR) curves at 8.05 keV. Additionally, the short-term thermal stability of an aperiodic multilayer was assessed using temperature-dependent in situ X-ray measurements. Shifts in the reflectivity spectrum during annealing were attributed to interdiffusion and interfacial relaxation. The research team recommends the aperiodic Mo/B4C multilayer mirror for operations below 300 ℃.
分类： 物理学 >> 核物理学 提交时间： 2023-09-04
Li, Yunxiang
Meng, Lu
Huang, Zinan
Li, Song
Wang, Disi
Liu, Bo
Zhang, Youpeng
Peng, Tianji
Zhang, Lu
Su, Xingkang
Jiang, Wei
摘要：Steam generator tube rupture (SGTR) accident is an important scenario needed to be considered in the safety analysis of lead-based fast reactors. When the steam generator tube breaks close to the main pump, water vapor will enter the reactor core, resulting in a two-phase flow of heavy liquid metal and water vapor in fuel assemblies. The thermal-hydraulic problems caused by the SGTR accident may seriously threaten reactor core’s safety performance. In this paper, the open source CFD calculation software OpenFOAM was used to encapsulate the improved Euler method into the self-developed solver LBEsteamEulerFoam. By changing different heating boundary conditions and inlet coolant types, the two-phase flow in the fuel assembly with different inlet gas content was simulated under various accident conditions. The calculation results show that the water vapor may accumulate in edge and corner channels. With the increase of inlet water vapor content, outlet coolant velocity increases gradually. When the inlet water vapor content is more than 15%, the outlet coolant temperature rises sharply with strong temperature fluctuation. When the inlet water vapor content is in the range of 5% to 20%, the upper part of the fuel assembly will gradually accumulate to form large bubbles. Compared with the VOF method, Euler method has higher computational efficiency. However, Euler method may cause an underestimation of the void fraction, so it still needs to be calibrated with future experimental data of the two-phase flow in fuel assembly.
分类： 物理学 >> 核物理学 提交时间： 2023-09-04 合作期刊: 《核技术》
摘要： 中国原子能科学研究院核天体物理研究组在HI-13串列加速器核物理国家实验室建成了我国首条低能放射性次级束流线，产生了从6He到22Na等11种放射性核束，利用这些放射性束流通过测量逆运动学转移反应开展了一系列核天体物理重要反应的研究，另外还通过厚靶实验方法和电荷交换反应开展了天体物理相关重要核结构信息的研究。在串列加速器Q3D磁谱仪上，利用稳定束测量了许多单核子转移和α基团转移的角分布，基于渐进归一化系数（Asymptotic Normalization Coefficient，ANC）或谱因子方法得到了一系列天体物理关键反应的天体物理S因子和反应率，为元素丰度、天体模型等相关研究提供了重要实验依据。
分类： 物理学 >> 核物理学 提交时间： 2023-09-04 合作期刊: 《核技术》
摘要： 北京串列加速器核物理国家实验室HI-13串列加速器（以下简称串列加速器）投入运行已有35周年的时间了。为了保持这台加速器的性能，运维团队以保障加速器的运行能力为中心，分别从攻克加速器关键部件研制、培养好运维人员队伍以及提高机时利用效率等几个方面开展了工作。其中，重点阐述了关键部件研制及子系统的升级改造。通过这些工作的开展，保持并提升了这台加速器的性能，加速器也处于良好的安全稳定运行状态。最后，指出了串列加速器所面临的问题及未来的发展规划。
分类： 物理学 >> 核物理学 提交时间： 2023-09-04 合作期刊: 《核技术》
摘要：空间环境中存在大量的高能粒子，单个高能粒子穿过航天器壳体轰击到电子器件，引发器件逻辑状态翻转、功能异常等单粒子效应，进而影响航天器的可靠运行和任务达成。基于地面加速器辐照试验模拟空间单粒子效应是评估电子器件在空间应用时发生单粒子错误风险的重要手段，只有其抗单粒子效应的指标符合宇航应用要求的器件才能在航天器中使用。航天器面临的空间辐射粒子主要是重离子和质子，它们诱发的单粒子效应也最为显著。开展宇航器件单粒子效应地面模拟试验主要依托重离子加速器和质子加速器，为满足单粒子试验需求，需要研发大面积束流扩束及均匀化、高精度束流快速诊断等技术，以及满足大批量试验任务需求的高效试验终端，重点介绍中国原子能科学研究院的基于加速器的重离子单粒子效应模拟试验技术、质子单粒子效应模拟试验技术和用于器件辐射损伤敏感区识别的重离子微束技术，以及上述技术在宇航器件单粒子效应风险评估中的应用。
分类： 物理学 >> 核物理学 提交时间： 2023-09-04 合作期刊: 《核技术》
摘要： 原子核是主要由短程相互作用制约的量子复杂多体系统，储存着宇宙间绝大部分可见的质量和能量。对原子核的研究，近百年来对人类的生存发展和国家的地位与安全产生了重大影响。过去几十年，短寿命放射性原子核的奇特结构现象不断被揭示，打破了人们对原子核结构的经典认知，开启了不稳定核（放射性核）结构研究的新领域。北京串列加速器核物理国家实验室在过去30多年为我国低能核物理实验提供了基础平台。北京大学实验核物理团队长期以来发展特色实验设备，在北京HI-13串列加速器上完成了系列核物理实验，在原子核奇特结构研究中取得了一批重要成果。本文将介绍团队基于北京HI-13串列加速器开展的几项代表性工作，如基于在束γ谱学的A = 70质量区Ge同位素形状演化研究，基于直接核反应实验的轻丰中子核集团结构研究，以及基于北京放射性束装置发展的共线激光谱设备和首次在线激光核谱实验等。
分类： 物理学 >> 核物理学 提交时间： 2023-09-04 合作期刊: 《核技术》
摘要：中国原子能科学研究院核反应团队依托国内外的大科学装置，在重离子熔合-裂变机制、垒下熔合增强机制、奇特核反应机制、奇异结构和奇异衰变方面取得了多项原创性成果。本文对其中的代表性成果进行了简要回顾。主要包括：（1）系统调查了正Q值中子转移的耦合道效应，并提出了自洽的方法评估转移耦合的贡献，发现了异常的同位素效应；（2）提出了用高精度背角准弹散射方法抽取原子核的形变参数，确证了原子核存在十六极形变；（3）提出了用轻带电粒子的替代俘获反应方法，基于此方法给出了关键的239Pu（n，2n）反应截面；（4）系统考察了sd壳丰质子核奇异衰变谱学，发现了22Si的β缓发双质子衰变模式，并发现镜像核22Si/22O的β衰变中存在极大的同位旋不对称性，同时在26Si中发现了迄今为止最强的同位旋混合态；（5）系统研究了奇特核体系在近垒能区的反应机制，首次给出了实验证据表明经典色散关系不适用于中子晕核6He+209Bi体系，并对质子滴线核8B和17F的反应机制进行了细致考察。本文也对将来基于重离子飞行时间谱仪和北京放射性束流线可能开展的工作进行了展望。
分类： 物理学 >> 核物理学 提交时间： 2023-09-04 合作期刊: 《核技术》
摘要： 核数据，尤其是中子核数据，是国防建设、核能发展及核技术应用的基础，同时在核物理基础研究中也发挥重要作用。核数据的质量直接影响相关装置及产品的有效性、安全性、可靠性和经济性。实验数据是相关理论模型发展及核数据库研制的基础，因此，核数据实验研究在核数据研究中占有极其重要的地位。我国的核数据实验研究始于20世纪中期，经过数十年的发展，取得了丰硕的成果。本文将简要介绍我国核数据实验研究取得的进展，并尝试展望未来的发展。
分类： 物理学 >> 核物理学 提交时间： 2023-09-04 合作期刊: 《核技术》
摘要： 航天集成电路是空间电子系统的核心部件，抗辐射加固技术是保障航天集成电路在空间环境可靠工作的核心技术。随着电路特征尺寸缩小至纳米尺度，单粒子效应逐渐成为制约航天集成电路抗辐射能力的最主要因素。北京微电子技术研究所团队以设计加固方式作为航天集成电路抗辐射研制技术路线，基于在重离子加速器上获取的大量单粒子试验数据，提出新工艺新器件的单粒子效应试验评估新方法，开展测试分析技术和辐射效应规律研究，为加固技术研究提供准确基础信息，检验设计加固技术有效性，揭示单粒子辐射损伤机制，为优化加固提供指导，最终形成高可靠、长寿命航天集成电路产品提供了关键支撑。
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