Design of SPT-SLIM focal plane; a spectroscopic imaging array for the South Pole Telescope

TL;DR

The paper presents the design and initial testing of a multi-pixel superconducting spectrometer array for the South Pole Telescope, aiming to demonstrate technology for future mm-wave line intensity mapping experiments.

Contribution

It introduces the preliminary design and architecture of the SPT-SLIM focal plane array with 18 dual-polarization pixels and microstrip filterbank spectrometers, advancing detector technology for mm-LIM.

Findings

Initial test results inform final design choices.

Predicted performance meets design specifications.

The array demonstrates feasibility for future mm-LIM applications.

Abstract

The Summertime Line Intensity Mapper (SLIM) is a mm-wave line-intensity mapping (mm-LIM) experiment for the South Pole Telescope (SPT). The goal of SPT-SLIM is to serve as a technical and scientific pathfinder for the demonstration of the suitability and in-field performance of multi-pixel superconducting filterbank spectrometers for future mm-LIM experiments. Scheduled to deploy in the 2023-24 austral summer, the SPT-SLIM focal plane will include 18 dual-polarization pixels, each coupled to an $R = \lambda/\Delta\lambda$ = 300 thin- film microstrip filterbank spectrometer that spans the 2 mm atmospheric window (120-180 GHz). Each individual spectral channel feeds a microstrip-coupled lumped-element kinetic inductance detector, which provides the highly multiplexed readout for the 10k detectors needed for SPT-SLIM. Here we present an overview of the preliminary design of key aspects of the SPT-SLIM the focal plane array, a description of the detector architecture and predicted performance, and initial test results that will be used to inform the final design of the SPT- SLIM spectrometer array.