SPT-3G+接收机设计
The SPT-3G+ receiver design
AI总结：
本文介绍为南极望远镜研发的SPT-3G+接收机的低温恒温器及光学系统热机械设计，明确其探测器配置、制冷方案、结构参数及制造安装计划，以支撑后续观测。
AI中文摘要：
我们介绍为南极望远镜（South Pole Telescope, SPT）研发的新型接收机SPT-3G+的低温恒温器（cryostat）及相机光学系统的热机械设计。该接收机包含14个探测器阵列，每个阵列搭载90/150 GHz双色偏振敏感像素，总计24080个过渡边缘传感器（transition-edge sensor）探测器。每个探测器阵列位于一根光学管末端，光学管直径约240 mm、长度约772 mm，按六角密排构型排列，以实现4度直径的视场。每根光学管包含4片由不同材料（氧化铝、硅、尼龙）制成的增透涂层透镜，这些透镜同时用于红外滤波，以降低低温级的辐射负载。光学系统与探测器通过组合制冷机制冷却：40 K和4 K级采用脉冲管制冷机，1 K和100 mK级采用稀释制冷机。热建模预测显示，40 K级的热负载小于26 W，4 K级的热负载小于1 W。该低温恒温器重1550 kg，真空窗处直径1.1米（位于望远镜格里高利焦点附近），高和长均为1.75米。低温恒温器的制造将于2026年启动，计划于2028-29南极夏季安装到SPT上，以赶上2029年冬季观测季。
英文摘要：
We present the thermo-mechanical design of the cryostat and camera optics for SPT-3G+, a new receiver being developed for the South Pole Telescope (SPT). The receiver consists of 14 detector arrays of 90/150 GHz dichroic polarization-sensitive pixels, totaling 24,080 transition-edge sensor detectors. Each detector array lies at the end of an optics tube, each approximately 240 mm in diameter and 772 mm in length, which are arranged in a hexagonal close-packed configuration to achieve a 4 degree diameter field of view. Each optics tube contains four anti-reflection coated lenses fabricated from different materials (alumina, silicon, and nylon) that are designed to also provide infrared filtering that reduces the radiative loading on the cryogenic stages. The optics and detectors are cooled by a combination of a pulse tube cooler for the 40 K and 4 K stages, and a dilution refrigerator for the 1 K and 100 mK stages. Thermal modeling predicts the heat load to be less than 26 W and 1 W for the 40 K and 4 K stages, respectively. The 1,550 kg cryostat has a 1.1 meter diameter at the vacuum window, which is located near the telescope Gregorian focus, and 1.75 meters in height and length. Fabrication of the cryostat will begin in 2026, with installation on the SPT scheduled for the 2028-29 austral summer, ahead of the 2029 winter observing season.
