We present a first on-chip positron accelerator based on dielectric laser acceleration.This innovative approach significantly reduces the physical dimensions of the positron acceleration apparatus,enhancing its feasib...We present a first on-chip positron accelerator based on dielectric laser acceleration.This innovative approach significantly reduces the physical dimensions of the positron acceleration apparatus,enhancing its feasibility for diverse applications.By utilizing a stacked acceleration structure and far-infrared laser technology,we are able to achieve a seven-stage acceleration structure that surpasses the distance and energy gain of using the previous dielectric laser acceleration methods.Additionally,we are able to compress the positron beam to an ultrafast sub-femtosecond scale during the acceleration process,compared with the traditional methods,the positron beam is compressed to a greater extent.We also demonstrate the robustness of the stacked acceleration structure through the successful acceleration of the positron beam.展开更多
Optical vortices generated by the conventional vortex lens are usually disturbed by the undesired higher-order foci,which may lead to additional artifacts and thus degrade the contrast sensitivity. In this work, we pr...Optical vortices generated by the conventional vortex lens are usually disturbed by the undesired higher-order foci,which may lead to additional artifacts and thus degrade the contrast sensitivity. In this work, we propose an efficient methodology to combine the merit of elliptical reflective zone plates(ERZPs) and the advantage of spiral zone plates(SZPs) in establishing a specific single optical element, termed elliptical reflective annulus quadrangle-element coded spiral zone plates(ERAQSZPs) to generate single-focus phase singularity. Differing from the abrupt reflectance of the ERZPs, a series of randomly distributed nanometer apertures are adopted to realize the sinusoidal reflectance. Typically, according to our physical design, the ERAQSZPs are fabricated on a bulk substrate;therefore, the new idea can significantly reduce the difficulty in the fabrication process. Based on the Kirchhoff diffraction theory and convolution theorem, the focusing performance of ERAQSZPs is calculated. The results reveal that apart from the capability of generating optical vortices,ERAQSZPs can also integrate the function of focusing, energy selection, higher-order foci elimination, as well as high spectral resolution together. In addition, the focusing properties can be further improved by appropriately adjusting the parameters, such as zone number and the size of the consisted primitives. These findings are expected to direct a new direction toward improving the performance of optical capture, x-ray fluorescence spectra, and forbidden transition.展开更多
康普顿照相是用于压缩靶丸成像、诊断内爆压缩对称性的一种有效技术手段。如何屏蔽成像过程中的背景噪声是康普顿照相技术的重点问题,同时也是一个难点问题。分析了靶环境以及各种背景信号的来源,并提出了相应的屏蔽建议。通过分析可以...康普顿照相是用于压缩靶丸成像、诊断内爆压缩对称性的一种有效技术手段。如何屏蔽成像过程中的背景噪声是康普顿照相技术的重点问题,同时也是一个难点问题。分析了靶环境以及各种背景信号的来源,并提出了相应的屏蔽建议。通过分析可以看到,在中子产额小于1013sr-1、压缩靶丸中心温度小于5 ke V时,通过使用相应的屏蔽措施并采用合适的诊断措施和记录设备,可以把背景噪声降至109sr-1以下,使康普顿照相中的面密度测量精度达到5%左右。展开更多
基金supported by the National Natural Science Foundation of China(Grant No.11975214).
文摘We present a first on-chip positron accelerator based on dielectric laser acceleration.This innovative approach significantly reduces the physical dimensions of the positron acceleration apparatus,enhancing its feasibility for diverse applications.By utilizing a stacked acceleration structure and far-infrared laser technology,we are able to achieve a seven-stage acceleration structure that surpasses the distance and energy gain of using the previous dielectric laser acceleration methods.Additionally,we are able to compress the positron beam to an ultrafast sub-femtosecond scale during the acceleration process,compared with the traditional methods,the positron beam is compressed to a greater extent.We also demonstrate the robustness of the stacked acceleration structure through the successful acceleration of the positron beam.
基金Project supported by the National Natural Science Foundation of China (Grant Nos.12174350,12275253,and 12275250)the Program of Science and Technology on Plasma Physics Laboratory,China Academy of Engineering Physics (Grant No.6142A04200107)the National Natural Science Foundation,Youth Fund (Grant No.12105268)。
文摘Optical vortices generated by the conventional vortex lens are usually disturbed by the undesired higher-order foci,which may lead to additional artifacts and thus degrade the contrast sensitivity. In this work, we propose an efficient methodology to combine the merit of elliptical reflective zone plates(ERZPs) and the advantage of spiral zone plates(SZPs) in establishing a specific single optical element, termed elliptical reflective annulus quadrangle-element coded spiral zone plates(ERAQSZPs) to generate single-focus phase singularity. Differing from the abrupt reflectance of the ERZPs, a series of randomly distributed nanometer apertures are adopted to realize the sinusoidal reflectance. Typically, according to our physical design, the ERAQSZPs are fabricated on a bulk substrate;therefore, the new idea can significantly reduce the difficulty in the fabrication process. Based on the Kirchhoff diffraction theory and convolution theorem, the focusing performance of ERAQSZPs is calculated. The results reveal that apart from the capability of generating optical vortices,ERAQSZPs can also integrate the function of focusing, energy selection, higher-order foci elimination, as well as high spectral resolution together. In addition, the focusing properties can be further improved by appropriately adjusting the parameters, such as zone number and the size of the consisted primitives. These findings are expected to direct a new direction toward improving the performance of optical capture, x-ray fluorescence spectra, and forbidden transition.
文摘康普顿照相是用于压缩靶丸成像、诊断内爆压缩对称性的一种有效技术手段。如何屏蔽成像过程中的背景噪声是康普顿照相技术的重点问题,同时也是一个难点问题。分析了靶环境以及各种背景信号的来源,并提出了相应的屏蔽建议。通过分析可以看到,在中子产额小于1013sr-1、压缩靶丸中心温度小于5 ke V时,通过使用相应的屏蔽措施并采用合适的诊断措施和记录设备,可以把背景噪声降至109sr-1以下,使康普顿照相中的面密度测量精度达到5%左右。
