CCAT: The 410 GHz camera module for FYST - design and testing of the MKID focal plane
Prime-Cam, the primary first-light instrument for the Fred Young Submillimeter Telescope (FYST) developed by the Cerro Chajnantor Atacama Telescope (CCAT) Collaboration, will accommodate seven modules. Here we describe the off-central 410 GHz imager/polarimeter. The 410 GHz instrument is a camera module for CCAT funded by the Canadian Foundation for Innovation, being developed as a collaboration between Dalhousie University, University of British Columbia (UBC), National Research Council (NRC) - Herzberg, and Duke University. With atmospheric loading in the 410 GHz window being significantly higher than at 350 GHz (but substantially lower than 850 GHz), we assess four MKID test devices with varying inductor volume for performance at 410 GHz. We propose a design for an array of ~6,700 horn-coupled TiN MKIDs optimized for use at 410 GHz, with a planned ~20,000 MKIDs over three arrays, exploring mapping speed versus detector number. We test the four MKID devices optically and assess optimal Qi/Qc and responsivity for the 410 GHz atmospheric window atop Cerro Chajnantor. The detectors will be designed in frequency to be efficiently readout with a second generation, two octave readout (based on the Xilinx RFSoC board), with over 4000 detectors per board.