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Topic

Optical, Mechanical, and Detector Developments for the Prime-Cam 850 GHz Module

Department of Physics and Astronomy

Date & location

• Tuesday, December 17, 2024
• 9:00 A.M.
• Clearihue Building, Room B017

Examining Committee

Supervisory Committee

• Dr. Justin Albert, Department of Physics and Astronomy, University of Victoria (Co-Supervisor)
• Dr. Scott Chapman, Department of Physics and Astronomy, UVic (Co-Supervisor)
• Dr. Michael McGuire, Department of Electrical and Computer Engineering, UVic (Outside Member)

External Examiner

• Dr. Keith Vanderlinde, Dunlap Institute for Astronomy and Astrophysics, University of Toronto

Chair of Oral Examination

• Dr. Matt Moffitt, Department of Chemistry, UVic

Abstract

Prime-Cam is a first-generation instrument designed for the Fred Young Submillimeter Telescope (FYST) in the Cerro Chajnantor Atacama Telescope (CCAT) Facility, which will be sited on Cerro Chajnantor in the Chilean Atacama Desert at an elevation of 5600 m. Among the instrument modules being developed for the Prime-Cam receiver, the 850 GHz module will probe the highest frequency and presents unique challenges in optical design, coupling, detection, and readout. The 850 GHz module is of particular importance to the astronomical community due to the absence of near-future proposals for instruments at similar wavelengths and at equivalent sites. This work describes the parameter space of the 850 GHz optical system between the Fλ spacing, beam size, pixel sensitivity, and detector count. The optimization of an optical design for the 850 GHz instrument module for CCAT-prime is also presented.

Success of the 850 GHz module hinges on the development of state-of-the-art, photon-noise-limited kinetic inductance detector (KID) arrays which will facilitate quality single-frequency, dual-polarization measurements in the given atmospheric windows. The 850 GHz module will consist of approximately 45,000 titanium-nitride, polarization-sensitive, lumped-element kinetic inductance detectors, meaning the module will field more microwave kinetic inductance detectors than any other millimeter-wave receiver to date. We present the critical aspects of the detector design and discuss solutions to the challenges of efficient optical coupling and a multi-octave readout band. The detectors are being designed to be read out using a multi-octave readout architecture, allowing for approximately double the multiplexing of other Prime-Cam modules. The parameter space in the development of these detectors is explored, including testing a means of shorting inductors to modify the resonance with minimal changes to the absorber architecture and testing different volumes of the inductor. Results and optical characterization of the prototype pixels for the 850 GHz instrument module are presented. The results of this work will directly inform the design of microwave KIDs for the multi-octave readout architecture as part of the development of densely packed arrays for the Prime-Cam instrument. The 850 GHz module is expected to be observing in 2026.

Also included is a report on a blind, millimeter-wave redshift survey of the brightest, unlensed submillimetre galaxies from the SCUBA-2 Cosmology Legacy Survey. The 14 brightest submillimetre galaxies (S850 >11 mJy) identified as single sources by the SMA were selected from the Lockman Hole, AEGIS, and CDF-N fields. 12 of these 14 sources were observed using the IRAM NOEMA interferometer, where at least one strong emission line was detected in each galaxy. Redshifts are assigned to each of the observed galaxies, unambiguously in five cases with two or more detected lines, and guided by photometric redshifts for the seven single line cases. The luminosities and widths of the CO lines, as well as the flux density, are used to probe the properties of these hyper-luminous infrared galaxies. The extreme nature of these galaxies is then contrasted with the results of previous surveys.