Purpose Background removal is an important issue in data reduction for the follow-up X-ray telescope(FXT)onboard the Einstein Probe(EP),particularly for the particle-induced background.They appear in various charge pa...Purpose Background removal is an important issue in data reduction for the follow-up X-ray telescope(FXT)onboard the Einstein Probe(EP),particularly for the particle-induced background.They appear in various charge patterns in the focal plane PN-CCD,such as straight tracks,isolated showers and broad rectangular swathes.Methods We use the data obtained with the FXT mirror assembly covered,which are due to particle-induced background,to study the methods for rejecting such background.Results The particle-induced background in the FXT comprises background directly caused by particles,as well as instrument events that are also due to particles.A new rejection method,which involves cluster identification,and threshold veto for number of hits in rows and columns,is applied to remove the particle-induced background.The remaining background can be eliminated by the event reconstruction algorithm and event veto in subsequent FXT data reduction.Conclusion It is shown that their methods can achieve a background rejection efficiency of>99.8%.Additionally,there has been a notable decrease in the number of spikes in the light curves of the FXT.Furthermore,we found the instrument background is attributed to a combination of particles and CAMEX electronics.展开更多
The presence of solid particles or water droplets in continuous fluid flow can either induce turbulence attenuation or amplification. The modification of the state of the turbulence depends on the characteristics of t...The presence of solid particles or water droplets in continuous fluid flow can either induce turbulence attenuation or amplification. The modification of the state of the turbulence depends on the characteristics of the particles, such as volume fraction, mean diameter, mass density, or carrier phase flow properties. In this brief review, the main physical concepts related to the most important physical aspects of turbulence modulation are summarized. Different criteria used to distinguish the enhancement or the attenuation effects of the particles on the carrier phase flows are recalled. For the interest of large-scale industrial applications, several theoretical,experimental and empirical approaches are discussed, which provides an interesting framework for the study of the effect of particles on turbulence behavior modification.展开更多
基金supported by the Einstein-Probe(EP)Program which is funded by the Strategic Priority Research Program of the Chinese Academy of Sciences Grant No.XDA15310000the National Natural Science Foundation of China under grant No.U1938102.
文摘Purpose Background removal is an important issue in data reduction for the follow-up X-ray telescope(FXT)onboard the Einstein Probe(EP),particularly for the particle-induced background.They appear in various charge patterns in the focal plane PN-CCD,such as straight tracks,isolated showers and broad rectangular swathes.Methods We use the data obtained with the FXT mirror assembly covered,which are due to particle-induced background,to study the methods for rejecting such background.Results The particle-induced background in the FXT comprises background directly caused by particles,as well as instrument events that are also due to particles.A new rejection method,which involves cluster identification,and threshold veto for number of hits in rows and columns,is applied to remove the particle-induced background.The remaining background can be eliminated by the event reconstruction algorithm and event veto in subsequent FXT data reduction.Conclusion It is shown that their methods can achieve a background rejection efficiency of>99.8%.Additionally,there has been a notable decrease in the number of spikes in the light curves of the FXT.Furthermore,we found the instrument background is attributed to a combination of particles and CAMEX electronics.
基金the financial support from Electricitéde France(EDF)within the framework of the Generation II&III nuclear reactor research program。
文摘The presence of solid particles or water droplets in continuous fluid flow can either induce turbulence attenuation or amplification. The modification of the state of the turbulence depends on the characteristics of the particles, such as volume fraction, mean diameter, mass density, or carrier phase flow properties. In this brief review, the main physical concepts related to the most important physical aspects of turbulence modulation are summarized. Different criteria used to distinguish the enhancement or the attenuation effects of the particles on the carrier phase flows are recalled. For the interest of large-scale industrial applications, several theoretical,experimental and empirical approaches are discussed, which provides an interesting framework for the study of the effect of particles on turbulence behavior modification.
