分类: 物理学 >> 核物理学 提交时间: 2024-03-18
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
分类: 物理学 >> 核物理学 提交时间: 2024-03-18
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.
分类: 数字出版 >> 数字技术 提交时间: 2024-03-18
摘要: 摘要: 目的/意义 剖析数字人文项目扶助边缘群体的实践案例,旨在为我国开展以数字人文项目扶助边缘群体探索提供经验与启示。 方法/过程 采用案例分析法,于国内外78个边缘群体扶助类数字人文项目中提取实践要素,从扶助主体多元参与,聚力共创;扶助对象兼顾显隐,与时偕行;扶助举措立破并举,多管齐下;扶助成果形式纷呈,稳中求进四个维度追踪扶助效用,解析扶助经验。 结果/结论 得出我国边缘群体扶助类数字人文项目建设启示:着眼社会制度优势,释放政府主体动能;面向扶助对象需要,开展精准靶向扶助;统一务实举措进向,助力数字红利落地;构筑轻量化成果集群,推动集体智慧可持续复利。
分类: 物理学 >> 核物理学 提交时间: 2024-03-18
摘要: 通过在 Nilsson 势中引入八极关联相互作用,基于推转壳模型(CSM)下的粒子数守恒方法(PNC)处
理包含单极和四极对力的哈密顿量,研究了反射不对称(RA)原子核的基态转动带。基于此, PNC-CSM 的计
算结果重现了轻锕系区偶偶核 236,238U 和 238,240Pu 的交替宇称带,以及奇-𝐴 核 237U 和 239Pu 的宇称带双重带
的转动惯量实验值。与相邻偶偶核 236,238U 和 238,240Pu 相比,奇-𝐴 核 237U 和 239Pu 的 𝑠 = −𝑖 内禀转动带的转
动惯量增加了 50% ∼ 60%。这些增加的转动惯量主要是由费米面附近中子轨道的泡利堵塞效应减弱了中子体
系的对关联导致。 U 和 Pu 同位素中,转动惯量随着转动频率缓慢增加则可以解释为转动使得体系的对关联减
弱。在低频率区,反射不对称原子核的转动惯量明显高于相对应的反射对称(RS)原子核的转动惯量。并且,
与反射对称原子核相比,较大的八极形变将导致反射不对称原子核体系的对关联减弱更加明显。