CCAT-prime: Designs and Status of the First Light 280 GHz MKID Array and Mod-Cam Receiver

A summary of C. J. Duell, E. M. Vavagiakis et al., “CCAT-prime: Designs and Status of the First Light 280 GHz MKID Array and Mod-Cam Receiver,” Proc. SPIE 2020 (in submission),

The CCAT-prime project’s first light array will be deployed in Mod-Cam, a single-module testbed and first light cryostat I designed, on the Fred Young Submillimeter Telescope (FYST) in Chile’s high Atacama desert in late 2022.

The CCAT-prime project will target a diverse set of science goals, which include:

• Investigating the formation, growth, and large-scale structure of the first star-forming galaxies;
• Improving constraints on primordial gravitational waves and new particle species obtainable from observations of the cosmic microwave background (CMB);
• Probing fundamental physics such as dark energy and the sum of the neutrino masses through the Sunyaev Zel’dovich (SZ) effects;
• Probing the effects of active galactic nuclei-star formation feedback in clusters;
• Tracing the history of dusty star formation by combining measurements with optical and near-infrared surveys.

Many of the first-generation science goals will be pursued by Prime-Cam, which is capable of holding up to seven independent instrument modules for simultaneous observations (see E. M. Vavagiakis et al., “Prime-Cam: A first-light instrument for the CCAT-prime telescope,” Proc. SPIE 2018, arXiv:1807.0005).

I designed and am currently testing Mod-Cam, a 89-cm diameter, single instrument module cryostat. Mod-Cam will pave the way for Prime-Cam by serving as an instrument module testbed and first light instrument before Prime-Cam is deployed. A Bluefors LD-400 dilution refrigerator will cool the 40 and 4 K stages of Mod-Cam, and the lenses, filters, and detector arrays of the instrument module inside. At least one feedhorn-coupled array of microwave kinetic inductance detectors (MKIDs) centered on 280 GHz will be included in Mod-Cam at first light. Additional detector arrays and instrument modules are under development for deployment alongside the 280 GHz array or shortly following in Prime-Cam, including an additional broadband module centered on 850 GHz and the spectrometer module EoR-Spec (see N. Cothard et al., “The Design of The CCAT-prime Epoch of Reionization Spectrometer Instrument,” Journal of Low Temperature Physics 2020, arXiv:1911.11687). The first light array will capitalize on advances in the fabrication of large format arrays of background-limited polarimeters to deliver nearly 3,500 feedhorn-coupled, polarization-sensitive detectors on a single 15 cm wafer and will lay the foundation for the eventual 100,000+ detectors that will be deployed on Prime-Cam.

The first 280 GHz detector array was fabricated by the Quantum Sensors Group at NIST in Boulder, CO and includes 3,456 polarization-sensitive MKIDs coupled to aluminum-machined feedhorns. Current mechanical designs allow for up to three of these hexagonal arrays to be placed in each single instrument module. To learn more about the details of this first light detector array, including the mechanical designs of the focal plane assembly and the cold readout plans using a reconfigurable FPGA-based design, read the full paper here.