Enhancing the direct search for dark matter in the XENON nT experiment with a water Cerenkov neutron detector

使用水切伦科夫中子探测器增强 XENON nT 实验中对暗物质的直接搜索

• 批准号: 19H00675
• 负责人: MARTENS Kai
• 金额: $ 26.04万
• 依托单位: The University of Tokyo
• 依托单位国家: 日本
• 项目类别: Grant-in-Aid for Scientific Research (A)
• 财政年份: 2019
• 资助国家: 日本
• 起止时间: 2019-04-01 至 2023-03-31
• 项目状态: 已结题
• 来源: https://kaken.nii.ac.jp/en/grant/KAKENHI-PROJECT-19H00675/
• 关键词: neutron veto; dark matter; direct detection; gadolinium; water Cherenkov; neutron tagging; gadolinium sulfate; WIMP; solar axion; 暗黒物質; 水チェレンコフ型検出器; 中性子検出器

Three major neutron veto milestones were reached in FY2022:1.) The gadolinium water purification system (GdWPS) was first commissioned with pure water in closed loop circulation (CLC), separate from the 700 tonne water shield that contains also the neutron veto. We thus verified the basic functions of all its components.2.) Maintaining water quality in the full 700 tonne XENONnT water shield - which comprises the detector's muon and neutron veto - our GdWPS proved that it improved the quality of the shields pure water.3.) After returning to CLC operation we finally added gadolinium sulfate (GdS) to the ~3 tons of water in the closed loop, bringing it up to the ultimate target concentration of 0.5 % of gadolinium sulfate in January. We optimize operating parameters for coming neutron veto operation with GdS dissolved in the whole water shield.Together these three milestones mean that now the neutron veto systems are all ready to be loaded with GdS and thus reach our design neutron tagging efficiency. Unfortunately the rest of the experiment is not yet in a state that we can proceed at this point in time, but we are ready and all our systems have been shown to work as expected. We can dissolve GdS at any time and reach full efficiency as soon as the GdS is evenly distributed in the 700 tonne water shield.

2022 财年实现了三个主要的中子否决里程碑：1。）钆水净化系统 (GdWPS) 首次使用闭环循环 (CLC) 纯水进行调试，与也包含中子否决的 700 吨水盾分开。因此，我们验证了其所有组件的基本功能。2.) 在整个 700 吨 XENONnT 水屏蔽（包括探测器的 μ 子和中子否决）中保持水质 - 我们的 GdWPS 证明它提高了屏蔽纯水的质量。3 .) 返回 CLC 操作后，我们最终将硫酸钆 (GdS) 添加到闭环中的约 3 吨水中，使其达到最终目标浓度 0.5一月份硫酸钆的百分比。我们优化了未来中子否决操作的操作参数，将 GdS 溶解在整个水盾中。这三个里程碑意味着现在中子否决系统已准备好装载 GdS，从而达到我们设计的中子标记效率。不幸的是，实验的其余部分尚未处于我们可以立即进行的状态，但我们已经准备好了，并且我们的所有系统都已证明可以按预期工作。我们可以随时溶解 GdS，只要 GdS 均匀分布在 700 吨水盾中即可达到最高效率。

项目成果

Weizmann Institute of Science(イスラエル)

魏茨曼科学研究所（以色列）

INFN - LNGS/University of Bologna/University of Napoli(イタリア)

INFN - LNGS/博洛尼亚大学/那不勒斯大学（意大利）

MPIK Heidelberg/Muenster University/Mainz University(ドイツ)

MPIK 海德堡/明斯特大学/美因茨大学（德国）

Material radiopurity control in the XENONnT experiment

XENONnT 实验中的材料放射性纯度控制

• DOI: 10.1140/epjc/s10052-022-10345-6
• 发表时间: 2022
• 作者: E. Aprile et al. XENON collaboration

First Results from XENONnT

XENONnT 的初步结果

• 发表时间: 2022
• 作者: Khai Bui