Subjects: Physics >> Nuclear Physics submitted time 2024-06-20
Abstract：
Synchrotron microscopic data commonly suffer from poor image quality with degraded resolution incurred by instrumentation defects or experimental conditions. Image restoration methods are often applied to recover the reduced resolution, providing improved image details that can greatly facilitate scientific discovery. Among these methods, deconvolution techniques are straightforward, yet either require known prior information or struggle to tackle large experimental data. Deep learning (DL)-based super-resolution (SR) methods handle large data well, however data scarcity and model generalizability are problematic. In addition, current image restoration methods are mostly offline and inefficient for many beamlines where high data volumes and data complexity issues are encountered. To overcome these limitations, an online image-restoration pipeline that adaptably selects suitable algorithms and models from a method repertoire is promising. In this study, using both deconvolution and pretrained DL-based SR models, we show that different restoration efficacies can be achieved on different types of synchrotron experimental data. We describe the necessity, feasibility, and significance of constructing such an image-restoration pipeline for future synchrotron experiments.
Subjects: Nuclear Science and Technology >> Nuclear Science and Technology submitted time 2024-03-12
Abstract： This paper presents a new technique for measuring the bunch length of a high-energy electron beam at a bunch-by-bunch rate in storage rings. This technique uses the time–frequency-domain joint analysis of the bunch signal to obtain bunch-by-bunch and turn-by-turn longitudinal parameters, such as bunch length and synchronous phase. The bunch signal is obtained using a button electrode with a bandwidth of several gigahertz. The data acquisition device was a high-speed digital oscilloscope with a sampling rate of more than 10 GS/s, and the single-shot sampling data buffer covered thousands of turns. The bunch length and synchronous phase information were extracted via offline calculations using Python scripts. The calibration coefficient of the system was determined using a commercial streak camera. Moreover, this technique was tested on two different storage rings and successfully captured various longitudinal transient processes during the harmonic cavity debugging process at the Shanghai Synchrotron Radiation Facility (SSRF), and longitudinal instabilities were observed during the single bunch accumulation process at Hefei Light Source (HLS). For Gaussian-distribution bunches, the uncertainty of the bunch phase obtained using this technique was better than 0.2 ps, and the bunch length uncertainty was better than 1 ps. The dynamic range exceeded 10 ms. This technology is a powerful and versatile beam diagnostic tool that can be conveniently deployed in high-energy electron storage rings.
Subjects: Physics >> Nuclear Physics submitted time 2023-08-09
Abstract： Radio frequency (RF) windows are developed and evaluated for a 650 MHz continuous-wave (CW) multibeam klystron. Thin-pillbox windows with alumina and beryllia disks are designed with an average RF power of CW 400 kW. Results of a cold test and tuning procedures are described. The final measured S11 curves under the required bandwidth are less than -32.0 and -26.9 dB for alumina and beryllia windows, respectively. The windows are tested up to CW 143 kW for traveling waves and CW 110 kW for standing waves using a solid-state amplifier as an RF power source. Multipactor simulations for windows and benchmark studies for the thermal analysis of ceramic disks are introduced.
Subjects: Chemistry >> Inorganic Chemistry submitted time 2018-10-04
Chao, Zhao
Can, Xiong
Man, Qiao
Tongwei, Yuan
Jing, Wang
Yunteng, Qu
XiaoQian, Wang
Fangyao, Zhou
Zhijun, Li
Qian, Xu
Shiqi, Wang
Min, Chen
Wenyu, Wang
Yafei, Li
Yuen, Wu
Yadong, Li
Abstract： Herein, we report a high-temperature gas-migration strategy to fabricate a heterogeneous single iron atom catalyst and demonstrate its excellent natural enzymes-like activity (defined as single atom enzymes, SAEs). The results reveal that the localized well-defined FeN4 sites of Fe SAEs is highly similar to the active metal centers of the natural heme-containing enzymes. The Fe SAEs exhibits superduper peroxidase, oxidase and catalase enzyme-like activities, exceeding that Fe3O4 nanozymes by a factor of 40. More importantly, Fe SAEs could effectively activates hydrogen peroxide (H2O2) in a hydroxyl free radicals (•OH) pathway, which makes it useful as a heterogeneous Fenton-like system to deal with the increasing environmental pollution. Our findings open up a new family of artificial material that mimics the natural enzymes.
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