CONUS+ run 1数据的本底分解
Background decomposition of the CONUS+ run 1 data
AI总结：
CONUS+实验run 1阶段以反应堆反中微子为源实现了核反应堆处相干中微子散射的首次测量，本研究基于Geant4模拟开发本底模型，明确了各能区主导本底源，且模型预测与实验测量高度吻合。
AI中文摘要：
CONUS+实验以反应堆反中微子为源，采用四个低能阈值点接触型高纯度锗谱仪进行探测，旨在测量相干弹性中微子-原子核散射（CEνNS）过程。该实验在run 1阶段实现了对核反应堆处相干中微子散射的首次测量，探测能量阈值为160 eVₑₑ。本研究对run 1分析所用三台探测器的本底能谱进行了分解，并基于Geant4蒙特卡罗模拟开发了对应的本底模型，该模型作为分析似然拟合的基础输入。结果表明，在所有能区中，与反应堆相关的本底均属于次主导成分，尤其在CEνNS搜寻的感兴趣能区（低于350 eVₑₑ），其贡献比预期的CEνNS信号低一个数量级；此外，宇宙射线μ子和中子是低于1 keVₑₑ能区的主导本底源，约占记录本底率的75%-90%。最终的本底模型预测，反应堆开启测量时，在[0.4,1.0] keVₑₑ能区的平均本底率为(47.5±3.2) d⁻¹ kg⁻¹，与测得的平均值(48.0±0.6) d⁻¹ kg⁻¹吻合度极高；在反应堆开启与关闭测量的所有能区均观察到类似的吻合结果。
英文摘要：
The CONUS+ experiment is measuring the coherent elastic neutrino nucleus scattering (CE$ν$NS) process using reactor anti-neutrinos as a source and four low energy threshold point-contact high-purity germanium spectrometers for their detection. It achieved the first measurement of coherent neutrino scattering at a nuclear reactor in run 1 of the experiment with a detection energy threshold of 160 eV$_{ee}$. This work presents the decomposition of the background spectra of the three detectors used in the run 1 analysis and the development of the corresponding background model with Geant4-based Monte Carlo simulations. The background model is used as the underlying input for the likelihood fit of the analysis. It is shown that reactor-correlated backgrounds are subdominant in all energy regions, specifically in the region of interest for CE$ν$NS searches below 350 eV$_{ee}$ where their contribution is one order of magnitude below the expected CE$ν$NS signal. Furthermore, cosmic ray muons and neutrons are identified as the dominant background source below 1 keV$_{ee}$ contributing approximately 75 - 90 \% of the recorded background rate. The final background model predicts an average rate of (47.5 $\pm$ 3.2) d$^{-1}$ kg$^{-1}$ in reactor on measurement in the energy region between [0.4, 1.0] keV$_{ee}$, which is in excellent agreement with the average measured value of (48.0 $\pm$ 0.6) d$^{-1}$ kg$^{-1}$. Similar agreement is found in all energy regions of both reactor on and off measurements.
