湖南大围山杜鹃灌丛木本植物种群空间格局

以大围山山顶杜鹃灌丛为研究对象,设置了6个15 m×15 m的样地。采用方差/均值比率法的t检验对杜鹃灌丛的空间格局进行了分析,同时采用负二项式参数、丛生指数、平均拥挤度指数、聚块性指数、扩散指数、格林指数和Cassic指数分析了群落内木本植物的聚集强度。结果表明:14种常见木本植物(如杜鹃Rhododendron simsii、湖南白檀Symplocos hunanensis、四川冬青Ilex szechwanensis)中,有85.7%的物种表现为聚集分布格局;聚集强度随种群密度的增大而减小;非优势种群直角荚蒾(Viburnum foetidum var.rectangulatum)、水马桑(Weigela japonica var.sinica)、鹿角杜鹃(Rhododendron latoucheae)的聚集强度大于优势种群杜鹃、湖南白檀等;植物对山顶温凉湿润气候条件的适应能力,种子扩散方式、萌生能力和耐荫特性等生物学特性,以及干扰是决定杜鹃灌丛木本植物空间格局的主要驱动因子

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

Determination of the number of ψ(3686) events taken at BESIII

The number of ψ(3686) events collected by the BESIII detector during the 2021 run period is determined to be (2259.3±11.1)×106 by counting inclusive ψ(3686) hadronic events. The uncertainty is systematic and the statistical uncertainty is negligible. Meanwhile, the numbers of ψ(3686) events collected during the 2009 and 2012 run periods are updated to be (107.7±0.6)×106 and (345.4±2.6)×106, respectively. Both numbers are consistent with the previous measurements within one standard deviation. The total number of ψ(3686) events in the three data samples is (2712.4±14.3)×10^