n/γ射线双粒子反应深度（Depth of Interaction，DOI）探测器可以实现中子与γ射线甄别并记录粒子在探测器中的反应位置，在对特殊核材料等危险放射性物质的定位成像研究中发挥着重要作用。传统的放射性定位成像装置都依赖具有n/γ射线甄别能力的探测器阵列，从而导致成像测量装置结构复杂、成本高。针对此问题，设计了一种基于EJ276塑料闪烁体（Φ3 cm×15 cm）的双粒子反应深度探测器，采用硅光电倍增管在闪烁体两端进行信号读出，并综合利用两端信号幅度与飞行时间对比进行粒子反应位置确定。利用Am-Be中子源和¹³⁷Cs γ源对探测器进行参数优化和分辨率刻度，结果显示：该探测器在灵敏区内探测效率均匀性较好，反应位置分辨率约4.4 cm。

Laser-accelerated electrons are promising in producing gamma-photon beams of high peak flux for the study of nuclear photonics, obtaining copious positrons and exploring photon–photon interaction in vacuum. We report on the experimental generation of brilliant gamma-ray beams with not only high photon yield but also low divergence, based on picosecond laser-accelerated electrons. The 120 J 1 ps laser pulse drives self-modulated wakefield acceleration in a high-density gas jet and generates tens-of-MeV electrons with 26 nC and divergence as small as $1.51{}^{\circ}$ . These collimated electrons produce gamma-ray photons through bremsstrahlung radiation when transversing a high-Z solid target. We design a high-energy-resolution Compton-scattering spectrometer and find that a total photon number of $2.2\times {10}^9$ is captured within an acceptance angle of $1.1{}^{\circ}$ for photon energies up to $16\;\mathrm{MeV}$ . Comparison between the experimental results and Monte Carlo simulations illustrates that the photon beam inherits the small divergence from electrons, corresponding to a total photon number of $2.2\times {10}^{11}$ and a divergence of $7.73{}^{\circ}$ .

采用溶胶-凝胶法在复合基底Pt/Ti/SiO₂/Si上制备系列Bi_3.25Ce_0.75Ti₃O₁₂（BCTO）铁电薄膜，并对薄膜进行了不同剂量的γ射线辐照。通过热重-示差扫描量热分析仪（TG-DSC）、X射线衍射仪（XRD）、扫描电子显微镜-能谱仪（SEM-EDS）和铁电测试仪等对辐照前后的薄膜的结构、微观形貌、铁电性、漏电性以及抗疲劳性等进行了对比研究。结果表明：随着对γ射线吸收剂量的增加，薄膜的晶体结构没有改变；薄膜的铁电性能显著减弱，剩余极化2Pr从辐照前的51.5 μC/cm²下降到23.7 μC/cm²；薄膜的漏电流密度增大，从辐照前的0.9×10^-7 A/cm²增大到7.2×10^-7 A/cm²；在经历10¹²次开关极化循环后，部分薄膜出现疲劳现象。

基于高亮度电子束与超短强激光相互作用的逆康普顿散射X/γ射线源具有单色性好、能量可调、偏振可控等特点，在核安全及核安保领域具有广泛的应用前景。清华大学将研制国际上首套能量达MeV的紧凑准单能伽马源装置并开展包括先进辐射成像、基于核共振荧光的物质分析检测等应用工作。给出该光源设计方案，以及针对其关键性能指标进行的优化及光源最终性能指标。目前已完成光源的设计，正在进行部件的加工采购，预计将于2023年启动装置的安装调试工作，于2025年完成项目的调试和验收。

利用BaF₂晶体对γ射线探测效率高、时间分辨率好的特点，研制了国内首套由40个BaF₂探测器单元组成的γ全吸收型探测装置，用于在线测量中子俘获反应截面。在HI-13串列加速器上建立250～850 keV的中子源，其0°角的源强约为5.09×10⁶ n/（Sr·s），使用γ全吸收型探测装置，通过瞬发γ射线法测量了⁹³Nb、¹⁹⁷Au、^natC和空样品的实验数据。根据BaF₂探测器信号的特征，采用了基线补偿、软件阈值设置、时间窗限定、脉冲幅度积分增长率设置和快慢成分比设置等多种数字化波形分析方法，剔除噪声信号以提高效应本底比。以¹⁹⁷Au样品数据为标准，^natC样品数据为样品相关性本底，空样品数据为样品无关性本底，采用相对测量法得到了⁹³Nb的中子俘获反应截面实验数据。通过与ENDF评价库数据的比较，验证了测量装置和技术方法的可行性。

In the laser plasma interaction of quantum electrodynamics (QED)-dominated regime, γ-rays are generated due to synchrotron radiation from high-energy electrons traveling in a strong background electromagnetic field. With the aid of 2D particle-in-cell code including QED physics, we investigate the preplasma effect on the γ-ray generation during the interaction between an ultraintense laser pulse and solid targets. We found that with the increasing preplasma scale length, the γ-ray emission is enhanced significantly and finally reaches a steady state. Meanwhile, the γ-ray beam becomes collimated. This shows that, in some cases, the preplasmas will be piled up acting as a plasma mirror in the underdense preplasma region, where the γ-rays are produced by the collision between the forward electrons and the reflected laser fields from the piled plasma. The piled plasma plays the same role as the usual reflection mirror made from a solid target. Thus, a single solid target with proper scale length preplasma can serve as a manufactural and robust γ-ray source.