[论文解读] VUV Reflectance Measurements for Materials Relevant to Argon and Xenon Experiments

J. Soto-Oton, H. Amar+2 more|arXiv (Cornell University)|Jan 22, 2026

Atmospheric Ozone and Climate被引用 0

一句话总结

本文在气态氩中开发了一个角分辨反射测量系统，用于测量探测材料的VUV反射率，发现铝和不锈钢在45°时的VUV反射率约为10–15%，UV-VIS 值分别约为 ~60% 和 ~40%。

ABSTRACT

Accurate knowledge of material reflectance in the vacuum ultraviolet (VUV) range is crucial for optimizing photon detection in noble gas detectors such as DUNE. Despite its importance, reflectance values for detector materials in the VUV region remain poorly characterized, with literature values showing significant variation depending on surface termination and finish. We present an angular-resolved reflectance measurement system developed at IFIC that operates in a gaseous argon atmosphere, enabling realistic measurements of detector materials under controlled conditions. The setup couples a deuterium lamp to a monochromator and employs a motorized PMT rotating around the sample to measure reflected light distributions across a wide angular range. We have characterized two key DUNE materials -- aluminum field cage profiles and stainless steel cryostat membranes -- in both the UV-VIS (300-500 nm) and VUV (128-200 nm) ranges. In the UV-VIS region, we confirm literature values of approximately 60% reflectance for aluminum and 40% for stainless steel. Preliminary VUV measurements at 45° angle of incidence yield reflectance values of 10-15% for both materials, significantly lower than their UV-VIS counterparts. The reflected light distributions exhibit a mixed character between specular and diffuse reflection. These results have direct implications for detector simulations and light yield predictions in next-generation experiments.

研究动机与目标

• 通过表征VUV范围内材料反射率来推动贵金属气体探测器的准确光输出模拟。
• 开发在气态 argon 中工作的角分辨反射测量系统以模拟探测器条件。
• 在UV-VIS 和 VUV 范围内测量两种与 DUNE 相关材料（铝和不锈钢）的反射率。
• 提供数据以改进光子传输模型和未来代实验的探测器仿真。

提出的方法

• 使用与单色仪耦合的氘灯和钨灯以从115–550 nm选择波长。
• 在暗室中维持纯气态氩环境以进行VUV测量。
• 使用电动 PMT 在固定入射角下对反射光在广泛角度范围内进行扫描。
• 用两项阴影函数模型来表征反射强度：I(theta)=sum_i A_i cos^n_i(theta-x0)。
• 对金属样品应用环形模型修正以估计超出PMT 接受角的总半球反射率。

Figure 1 : A picture of the measurement setup inside the black box is shown on the left, while a diagram of the setup on the right.

实验结果

研究问题

• RQ1 在气态氩环境中，以代表性入射角（如45°）时铝和不锈钢的VUV反射率值是多少？
• RQ2 VUV反射光的角分布与UV-VIS相比在探测器相关材料中有何不同？
• RQ3 角分辨VUV反射测量是否能提升贵金属气体探测器的光子传输仿真？
• RQ4 测得的VUV反射率是否与DUNE 仿真中常用的数值不同，差异有多大？
• RQ5 在VUV波长下，这些材料的镜面反射与漫反射的程度如何？

主要发现

• 铝的UV-VIS反射率约为60%，不锈钢约为40%，与用于实际探测器样品的文献一致。
• 在VUV范围（128–200 nm）以45°入射时，初步反射率为铝和不锈钢均为10–15%。
• VUV的角分布显示出混合的镜面-漫反射特征，既非纯镜面也非朗伯分布。
• 测量系统在气态氩中工作，提供了相较于真空基设置在角分辨VUV测量中的灵活性。
• 45° AOI 的VUV综合反射率显著低于UV-VIS数值，也低于常用于DUNE仿真的假设（10–15% vs 60%/40%）。
• 结果提示需重新评估表面对光输出的贡献，以及在仿真中引入真实的角分布。

Figure 2 : Left: Angular-resolved reflectance intensity for the stainless-steel sample at an angle of incidence of 45º and a wavelength of 300 nm. Right: Reflectance of the SS and Al samples.