反应堆几何效应对超短基线反应堆中微子实验中微子流强的影响

Geometry Effects of the Reactor on Neutrino Flux in Neutrino Experiments of Ultra-short Baseline Reactors

在超短基线反应堆中微子实验中,探测器与反应堆的距离较短,反应堆的几何效应对中微子能谱和中微子流强的影响可能无法忽略,需要对其影响进行评估。本文根据EPR(European Pressurized Reactor)堆芯的结构建立反应堆中微子源模型和点中微子源模型,研究了超短基线反应堆中微子实验中反应堆尺寸对中微子能谱和流强的影响,讨论了堆芯内功率误差分布对点源模型下预期中微子流强的影响。研究结果表明,由于反应堆的几何效应,使用点源模型会使预期中微子事例率低约0.08%~0.40%,堆芯的几何效应对中微子能谱的形状影响则在10-6量级。在超短基线反应堆中微子实验中,计算中微子流强时可以采用基于堆芯几何中心的点中微子源模型,在这种模型下,由统计误差和系统误差引入的误差可以忽略不计。

In short baseline reactor antineutrino experiment,the distance between the detector and the reactor is relatively short,the impact of reactor geometry effects on the neutrino spectrum and flux may not be neglected.In this paper,a volume neutrino source model and a point neutrino source model is established based on the structure of the EPR reactor core.The impact of the geometric effect to the antineutrino spectrum and flux in short baseline neutrino experiments is studied,the impact of the uncertainty of the power distribution in the core to the expected neutrino flux in the point model is also discussed.Because of the geometry effect of the core,the point source model can lead to a reduction in the expected neutrino event rate by approximately 0.08%to 0.40%,and the impact of the geometry effects on the shape of neutrino spectrum is on the order of 10−6.In a short baseline reactor antineutrino experiment,a point neutrino source model based on the geometric center of the reactor core can be used to calculate the neutrino flux,the uncertainty introduced by statistical and systematic uncertainties can be neglected in this model.