排序方式: 共有7条查询结果,搜索用时 8 毫秒
1
1.
The influences of UV light irradiation (313 nm) and diffused daylight on the polymerization of methyl acrylate initiated by the ceric ammonium nitrate without any reducing agent have been studied both in aqueous nitric acid and in pure water. The rate of polymerization was found to be accelerated and the overall activation energy and the induction time were found to be decreased sharply by the UV light irradiation. Under UV light, the rate of polymerization is 8 times as high as the rate in dark. The rate of polymerization was found to attain a maximum with the increase of nitric acid concentration and the rate of polymerization became less sensitive to UV light in the presence of nitric acid whereas the induction period reduced outstandingly. Based on the experimental results, the mechanism is proposed. 相似文献
2.
3.
A stopping layer concept to improve the spatial resolution of gas-electron-multiplier neutron detector
下载免费PDF全文
![点击此处可从《中国物理 B》网站下载免费的PDF全文](/ch/ext_images/free.gif)
Jianjin Zhou 《中国物理 B》2022,31(5):50702-050702
In recent years, gas electron multiplier (GEM) neutron detectors have been developing towards high spatial resolution and high dynamic counting range. We propose a novel concept of an Al stopping layer to enable the detector to achieve sub-millimeter (sub-mm) spatial resolution. The neutron conversion layer is coated with the Al stopping layer to limit the emission angle of ions into the drift region. The short track projection of ions is obtained on the signal readout board, and the detector would get good spatial resolution. The spatial resolutions of the GEM neutron detector with the Al stopping layer are simulated and optimized based on Geant4GarfieldInterface. The spatial resolution of the detector is 0.76 mm and the thermal neutron detection efficiency is about 0.01% when the Al stopping layer is 3.0 μ m thick, the drift region is 2 mm thick, the strip pitch is 600 μ m, and the digital readout is employed. Thus, the GEM neutron detector with a simple detector structure and a fast readout mode is developed to obtain a high spatial resolution and high dynamic counting range. It could be used for the direct measurement of a high-flux neutron beam, such as Bragg transmission imaging, very small-angle scattering neutron detection and neutron beam diagnostic. 相似文献
4.
5.
Development of Time-of-Flight Polarized Neutron Imaging at the China Spallation Neutron Source
下载免费PDF全文
![点击此处可从《中国物理快报》网站下载免费的PDF全文](/ch/ext_images/free.gif)
Ahmed Salman 周健荣 杨建清 张俊佩 黄楚怡 叶凡 秦泽聪 蒋兴奋 Syed Mohd Amir Wolfgang Kreuzpaintner 孙志嘉 王天昊 童欣 《中国物理快报》2022,(6):53-57
A time-of-flight polarized neutron imaging setup was realized by integrating an in situ pumped polarized 3He spin filter and energy dispersive neutron camera on the neutron technique development beamline(BL-20) of the China Spallation Neutron Source(CSNS). Test experiments were performed with a solenoid with aluminum wire as a sample. These demonstrated that polarized radiography with a field of view in diameter 2.0 cm at different wavelengths can be obtained. The wavelength-dependent... 相似文献
6.
7.
1