TIME: A Millimeter-Wavelength Grating Spectrometer Array for [CII] / CO Intensity Mapping

• Main Author: Hunacek, Jonathon Robert
• Format: Others
• Published: 2020
• Online Access: https://thesis.library.caltech.edu/13683/1/thesis-jhunacek-20200427b.pdf; Hunacek, Jonathon Robert (2020) TIME: A Millimeter-Wavelength Grating Spectrometer Array for [CII] / CO Intensity Mapping. Dissertation (Ph.D.), California Institute of Technology. doi:10.7907/hp2n-8495. https://resolver.caltech.edu/CaltechTHESIS:04272020-121646677 <https://resolver.caltech.edu/CaltechTHESIS:04272020-121646677>

<p>In this thesis I review the design, fabrication, and initial engineering deployment of the TIME (Tomographic Ionized-carbon Mapping Experiment) instrument. TIME seeks to make a first detection of the clustering amplitude of the power spectrum of redshifted [CII] emission from the Epoch of Reionization (z = 5-9). [CII], the 157.7 µm fine-structure line of singly ionized carbon, traces star formation on large scales, providing a new method for constraining the contribution of star formation to the Reionization process. [CII] intensity mapping complements traditional galaxy surveys by using spatially-broad beams to integrate signal from the many faint sources thought to be responsible for the bulk of the integrated emission from galaxies. TIME covers the 200-300 GHz atmospheric window, which also enables the study of lower-redshift CO emission (z = 0.5-2), a tracer of molecular gas in the period following the peak of cosmic star formation. The full TIME instrument consists of 32 single-polarization grating spectrometers with a resolution R ~ 100. Each spectrometer consists of an input feedhorn coupled to parallel plate waveguide with a curved diffraction grating, which focuses the diffracted light onto an output arc populated by 60 transition-edge sensor (TES) bolometers at 250 mK. The 1920 total detectors couple to the output of the parallel plate waveguide with a direct-absorbing micro-mesh and are organized into buttable arrays covering 4 spatial by either 12 (HF) or 8 (LF) spectral pixels. A partial TIME instrument was field tested in early 2019 on the ARO APA 12m dish at Kitt Peak. We intend to return to Kitt Peak in late 2020 to begin initial science observations.</p>