湘江长潭株段河床沉积物重金属污染Pb同位素地球化学分析

湘江长沙-湘潭-株洲(简称"长潭株")段是湘江流域重金属污染最严重的河段。以往研究得到沉积物严重受Cd、Cu、Pb、Zn、Mn等多种重金属的污染。但河流沉积物是一个复杂的环境单元,其物质组成既是流域岩石风化的产物,又是人为作用的反映。且湘江流域基岩(如花岗岩等)、土壤等环境介质本身就存在Cd、Cu、Pb、Zn、As等重金属元素高背景值。加上城市工业活动等人为排放,使得沉积物重金属的来源复杂化。因此,认识沉积物重金属

Prediction of Energy Resolution in the JUNO Experiment

International audienceThis paper presents the energy resolution study in the JUNO experiment, incorporating the latest knowledge acquired during the detector construction phase. The determination of neutrino mass ordering in JUNO requires an exceptional energy resolution better than 3% at 1 MeV. To achieve this ambitious goal, significant efforts have been undertaken in the design and production of the key components of the JUNO detector. Various factors affecting the detection of inverse beta decay signals have an impact on the energy resolution, extending beyond the statistical fluctuations of the detected number of photons, such as the properties of liquid scintillator, performance of photomultiplier tubes, and the energy reconstruction algorithm. To account for these effects, a full JUNO simulation and reconstruction approach is employed. This enables the modeling of all relevant effects and the evaluation of associated inputs to accurately estimate the energy resolution. The study reveals an energy resolution of 2.95% at 1 MeV. Furthermore, the study assesses the contribution of major effects to the overall energy resolution budget. This analysis serves as a reference for interpreting future measurements of energy resolution during JUNO data taking. Moreover, it provides a guideline in comprehending the energy resolution characteristics of liquid scintillator-based detectors