Fast neutron absorption spectroscopy is widely used in the study of nuclear structure and element analysis. However, due to the traditional neutron source pulse duration being of the order of nanoseconds, it is difficult to obtain a high-resolution absorption spectrum. Thus, we present a method of ultrahigh energy-resolution absorption spectroscopy via a high repetition rate, picosecond duration pulsed neutron source driven by a terawatt laser. The technology of single neutron count is used, which results in easily distinguishing the width of approximately 20 keV at 2 MeV and an asymmetric shape of the neutron absorption peak. The absorption spectroscopy based on a laser neutron source has one order of magnitude higher energy-resolution power than the state-of-the-art traditional neutron sources, which could be of benefit for precisely measuring nuclear structure data.

We present detailed characterization of laser-driven fusion and neutron production ( $\sim {10}^5$ /second) using 8 mJ, 40 fs laser pulses on a thin (<1 μm) D ${}_2$ O liquid sheet employing a measurement suite. At relativistic intensity ( $\sim 5\times {10}^{18}$ W/cm ${}^2$ ) and high repetition rate (1 kHz), the system produces deuterium–deuterium (D-D) fusion, allowing for consistent neutron generation. Evidence of D-D fusion neutron production is verified by a measurement suite with three independent detection systems: an EJ-309 organic scintillator with pulse-shape discrimination, a ${}^3\mathrm{He}$ proportional counter and a set of 36 bubble detectors. Time-of-flight analysis of the scintillator data shows the energy of the produced neutrons to be consistent with 2.45 MeV. Particle-in-cell simulations using the WarpX code support significant neutron production from D-D fusion events in the laser–target interaction region. This high-repetition-rate laser-driven neutron source could provide a low-cost, on-demand test bed for radiation hardening and imaging applications.

镍、铁和钨基合金常被用来作为反应堆的候选结构材料，在反应堆中面临中子辐照的严苛服役环境。本文采用分子动力学方法研究了金属镍、铁、钨三种金属材料的辐照级联过程，获得材料在不同温度（300?500 K）下、不同初级碰撞原子（Primary Knock-on Atom，PKA）能量（<20 keV）沿不同晶格方向（<135>、<122>和<100>）入射的辐照级联损伤过程。结果表明：金属镍和铁的稳态辐照缺陷数相当，当PKA能量较低（<5 keV）时，金属镍的稳态缺陷数比金属铁略少；而当PKA能量较高（>5 keV）时，金属镍的稳态缺陷数逐渐超过铁；在相同辐照条件下，金属钨的稳态辐照缺陷数最少，表现出更为良好的抗辐照性能。通过分析三种金属辐照级联过程中不同阶段的缺陷复合率及缺陷存活率，进一步理解其耐辐照损伤能力的差异。相关计算结果为理解不同金属的辐照性能提供数据支撑，作为金属初级辐照损伤数据集，为更大尺度的速率理论和团簇动力学等模拟材料辐照效应提供微观缺陷结构和参数。

中子照相系统因其特定的成像结构，使得成像后的中子照相图像不可避免地存在几何不锐度。为提升中子照相图像的质量，本文提出一种基于改进Richardson–Lucy算法的中子照相图像几何不锐度修正方法，该方法首先根据几何不锐度的形成原理构建点扩散函数，然后通过拉普拉斯算子和中值滤波方法去除图像中的γ白斑噪声，最后采用Richardson–Lucy算法对图像进行复原。采用线对模板样品进行测试，并与4种现有的中子照相图像几何不锐度修正算法进行对比，验证了本文算法可将衡量中子照相图像几何不锐度修正效果的平均梯度、空间频率指标分别提升60.23%和29.90%，能够实现几何不锐度的修正，同时解决图像复原过程中γ白斑噪声的放大问题，为实现高分辨率的中子照相提供重要技术支撑。