短基线近探测器（SBND）：设计与初始性能
Short-Baseline Near Detector (SBND): Design and Initial Performance
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中文总结 AI 辅助
本文介绍了费米实验室 SBN 计划中 112 吨的 SBND 探测器，给出其第一年束流运行的性能结果，所有系统均达标，液氩纯度、TPC、光子探测等性能优异，数据效率高，代表多吨级 LArTPC 性能的最新水平。
中文摘要 AI 辅助
短基线近探测器（SBND）是一台位于费米实验室 Booster 中微子束中的 112 吨活性质量液氩时间投影室（LArTPC），是短基线中微子（SBN）计划的组成部分。SBND 于 2024 年开始运行，此后积累了全球最大的中微子-氩相互作用样本。本文描述了已建成的探测器，并给出了第一年束流运行的性能结果。所有探测器系统的性能均达到或超过设计要求：液氩纯度在 Run 1 的 95%以上时间内实现了超过 30ms 的电子寿命，是设计要求的十倍；TPC 丝平面读出系统达到了给定丝几何的理论最低噪声水平（4 米长收集平面丝的平均噪声为 388 个电子），99.3%的读出通道正常工作。液氩纯度和 TPC 性能共同使 SBND TPC 能够实现极其干净的事例重建。光子探测系统由被动反射器和多个有源组件（光电倍增管（PMT）和 X-ARAPUCAs）组成，在整个探测器体积内实现了超过 10 个光电子每 MeV 的光产额，以及几纳秒的时间分辨率，足以分辨 Booster 中微子束的 19ns 束团结构。近 4π 的宇宙射线标记系统环绕 TPC，以减少中微子和超出标准模型（BSM）物理分析中的宇宙本底。数据获取系统在高达 8Hz 的事例率下表现出稳定性能，在 SBND 2025 年首次中微子运行期间实现了 98.6%的数据采集效率。这些结果表明，SBND 代表了多吨级 LArTPC 探测器性能的最新水平。
英文摘要
The Short-Baseline Near Detector (SBND) is a 112 tonne active mass liquid argon time projection chamber (LArTPC) situated in the Booster Neutrino Beam at Fermilab, forming part of the Short-Baseline Neutrino (SBN) Program. SBND began operation in 2024 and has since accumulated the world's largest sample of neutrino-argon interactions. This paper describes the as-built detector and presents performance results from the first year of beam operation. All detector systems performed at or above design requirements. The liquid argon purity achieved an electron lifetime exceeding 30ms, ten times the design requirement, for more than 95% of Run 1. The TPC wire plane readout achieved noise levels at the theoretical minimum for the given wire geometry (an average of 388e$^-$ for the 4m long collection plane wires) with 99.3% of readout channels live. Together, the liquid argon purity and TPC performance are enabling extremely clean event reconstruction in the SBND TPC. The photon detection system, consisting of passive reflectors and multiple active components (PMTs and X-ARAPUCAs), has achieved a light yield exceeding 10 photoelectrons per MeV throughout the detector volume and a timing resolution of a few nanoseconds, sufficient to resolve the 19ns bunch structure of the Booster Neutrino Beam. A nearly 4$π$ cosmic ray tagger system surrounds the TPC to mitigate cosmic backgrounds in neutrino and BSM physics analyses. The data acquisition system has demonstrated stable performance up to an event rate of 8Hz, and a data collection efficiency of 98.6% was achieved throughout SBND's first neutrino run in 2025. These results demonstrate that SBND represents the state of the art in multi-tonne-scale LArTPC detector performance.
