原子能科学技术2025，Vol.59Issue(3)：524-531,8.DOI:10.7538/yzk.2024.youxian.0572
高功率飞秒激光脉冲诱导181Ta核激发
Nuclear Excitation of 181Ta Induced by High Power Femtosecond Laser Pulses
摘要
Abstract
The study focuses on investigating the nuclear excitation of 181Ta induced by femtosecond laser pulses.The objective is to explore the excitation mechanisms and yield of nuclear states under high-intensity laser conditions.Utilizing a commercial Ti:Sapphire laser system,femtosecond laser pulses with power densities exceeding 1016 W/cm2 were directed at solid 181Ta targets.The laser pulses,characterized by a wavelength of 800 nm and pulse width of 33 fs,interact with the target to create dense plasma,inducing nuclear excitation.The experimental setup included precise control of laser parameters and the detection of de-excitation γ-rays using NaI scintillation detectors.These detectors were calibrated with a 55Fe standard source,ensuring high detection efficiency and accuracy.The experimental conditions were optimized by adjusting the lens-to-target distance,monitored via a CCD camera,to maintain stable power density on the target surface.Results show that upon reaching the threshold laser intensity of 1016 W/cm2,characteristic γ-ray signals with an energy of(6.40±2.37)keV are observed.Each laser pulse induces(7.51±1.07)×104 nuclear excitations,resulting in(1.05±0.15)×103 γ-ray signals.Comparative experiments with 184W targets,which have similar plasma characteristics but different nuclear energy levels,confirm that the observed γ-ray signals are specific to 181Ta.The study also includes theoretical calculations to estimate the number of excited nuclei and the expected γ-ray yield.These calculations consider the plasma conditions and the interaction dynamics between superheated electrons,ions,and 181Ta nuclei.The theoretical estimates of the γ-ray yield,ranging from 0.4×103 to 1.2×103 γ-rays per pulse,are in good agreement with the experimental data.The investigation highlights the significance of direct photoexcitation as primary mechanism for nuclear excitation in high-temperature laser plasmas.The results emphasize the role of laser intensity and plasma conditions in achieving efficient nuclear excitation.Additionally,the study notes the challenges in attributing specific excitation pathways due to the complex interplay of various mechanisms in the plasma environment.In conclusion,this research provides new experimental data supporting the feasibility of femtosecond laser pulses in inducing nuclear excitation in 181Ta.The findings contribute to a better understanding of the underlying physical mechanisms and highlight the potential for further optimization of experimental methods and theoretical models.Future studies are recommended to refine detection techniques and explore the influence of different plasma parameters on nuclear excitation yields.This comprehensive analysis provides a better understanding of the relationship between theoretical predictions and experimental observations in nuclear excitation studies using high-intensity laser systems.The insights gained from this work may have broader implications for applications in nuclear spectroscopy,isotope separation,and the development of γ-ray lasers and nuclear batteries,although further research is necessary to explore these possibilitities.关键词
飞秒激光/181Ta/同核异能态/核激发/γ射线Key words
femtosecond laser/181Ta/isomer/nuclear excitation/γ-ray分类
核科学引用本文复制引用
徐永生,贺创业,兰小飞,赵保真..高功率飞秒激光脉冲诱导181Ta核激发[J].原子能科学技术,2025,59(3):524-531,8.基金项目
国家重点研发计划(2022YFA1602403) （2022YFA1602403）
国家自然科学基金(12205378) （12205378）
