The Simons Observatory Large Aperture Telescope Receiver

TL;DR

The paper describes the design, construction, and performance of the Simons Observatory Large Aperture Telescope Receiver, a large cryogenic millimeter-wave camera for high-precision sky mapping.

Contribution

It presents the first detailed account of a large, cryogenic millimeter-wave receiver with innovative design solutions for optical alignment and thermal management.

Findings

Successfully cooled 1200 kg to 4 K and 200 kg to 100 mK

Accommodates 62,000 detectors across multiple frequency bands

Achieved system performance with optimized thermal and optical design

Abstract

The Simons Observatory (SO) Large Aperture Telescope Receiver (LATR) will be coupled to the Large Aperture Telescope located at an elevation of 5,200 m on Cerro Toco in Chile. The resulting instrument will produce arcminute-resolution millimeter-wave maps of half the sky with unprecedented precision. The LATR is the largest cryogenic millimeter-wave camera built to date with a diameter of 2.4 m and a length of 2.6 m. It cools 1200 kg of material to 4 K and 200 kg to 100 mk, the operating temperature of the bolometric detectors with bands centered around 27, 39, 93, 145, 225, and 280 GHz. Ultimately, the LATR will accommodate 13 40 cm diameter optics tubes, each with three detector wafers and a total of 62,000 detectors. The LATR design must simultaneously maintain the optical alignment of the system, control stray light, provide cryogenic isolation, limit thermal gradients, and minimize the time to cool the system from room temperature to 100 mK. The interplay between these competing factors poses unique challenges. We discuss the trade studies involved with the design, the final optimization, the construction, and ultimate performance of the system.