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Direct measurement of the resonance strengths and branching ratios of low-energy(p, γ) reactions on Mg isotopes 下载免费PDF全文
Hao Zhang Zhi-Hong Li Jun Su Yun-Ju Li Chen Chen Long Zhang Fu-Qiang Cao Yang-Ping Shen Wei Nan Wei-Ke Nan Xin-Yue Li Li-Hua Chen Gang Lian Bao-Qun Cui Bing Guo Wei-Ping Liu 《中国物理C(英文版)》2021,45(8):084108-084108-7
Proton capture reactions on Mg isotopes are significant in the Mg-Al cycle in stellar H-burning.In particular,the resonance strengths and branching ratios of low-energy resonances in Mg(p,y)26 A1 reactions determine the production of ~(26)Al,which is one of the most important long-lived radioactive nuclei in nuclear astrophysics.In this article,we report our first experiment using the intense proton beam of approximately 2 mA provided by the JUNA accelerator ground laboratory and a new technique that can minimize the composition change of targets under intense beam irradiation.The resonance strengths and branching ratios of E=214,304,and 326 keV resonances in the reactions of ~(24)Mg(p,γ)~(26)Al,~(25)Mg(p,γ)~(26)Al,and ~(26)Mg(p,γ)~(27)Al,respectively,were measured with high accuracy.The success of this experiment provides a good calibration for the nuclear astrophysical experiment at the Jinping underground laboratory. 相似文献
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在材料的电磁冶金过程及磁约束核聚变装置中, 金属液滴在磁场和壁面温度影响下的撞击过程表现出复杂的动力学特性. 本文对水平磁场作用下液态镓(Ga)液滴撞击等温和过冷壁面的铺展和回弹特性进行了实验研究. 采用高速相机拍摄液滴撞击过程中轮廓的变化, 通过图像处理获得不同磁场强度、不同撞击速度和不同底板温度下的最大铺展因子、回弹过程中的最大高度以及产生的二次液滴的半径和速度. 碰撞速度由0.45 ~ 1.8 m/s, 磁场强度从0 ~ 1.6 T, 底板温度为30 °C, ?20 °C和?10 °C. 基于实验结果分析了磁场和壁面温度对液滴铺展和回弹的影响规律. 实验结果表明, 液滴撞击等温壁面和过冷壁面的最大铺展因子随We的变化均与理论预测关系式一致. 液滴撞击等温壁面的情况下, 不同的We下, 出现不同的回弹现象. 磁场抑制了平行于磁场方向的液滴铺展和回弹过程中二次液滴的产生, 而对回弹过程中的液滴在平行磁场方向上有拉伸作用. 液滴撞击过冷壁面时, 在一定的We值范围内, 同样会出现二次液滴分离现象, 此时产生的二次液滴的速度较小. 磁场的增强和We的增大都会导致液滴在高度方向的振荡减弱, 加速凝固过程. 相似文献
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A study of intersubband transitions in quantum well infrared detectors working at high temperatures has been reported. This study allows a greater tunability in the device designs, with the ability to control the peak wavelength, the absorption coefficient, the dark current, the quantum efficiency and the detectivity of the modeled structure operating around 3.3 μm wavelength. The detection energy and absorption coefficient dependences with an applied electric field are given. Then, the electro-optic performances of the modeled mid-infrared detector are estimated, the dark current dependence with the applied voltage and temperature as well as the quantum efficiency and the detectivity are investigated and discussed. High detectivities were found at high temperatures revealing the good performances of the designed photodetector, especially at 3.3 μm wavelength. 相似文献
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在研究生基础理论课程学习中,存在所学知识僵化,不能运用于科研实践中;与科研活动脱节,对科学研究的支持作用不明显等情况。因此,我们以胶体与界面化学课程为例,通过课堂讲授与启发式讨论的精确配合、理论知识的学与用并重、基础理论与前沿研究的良好衔接以及挖掘经典理论发展中的科研历程等措施,使学生有能力灵活运用所学理论知识解决实际科研中的问题,避免理论课程与实验室科研活动脱节,培养从实验结果中抽象模型、演绎理论、批判性解读现有结果等科研能力,启蒙其科学思维,为研究工作打下基础。 相似文献