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The Fred Young Submillimeter Telescope (FYST), which is the telescope of the CCAT-prime project, will be located at 5600 m near the summit of Cerro Chajnantor in northern Chile, and will host the modular instrument called Prime-Cam. Two of the instrument modules in Prime-Cam will be a spectrometer with a resolving power of R ∼ 100 and populated with a detector array of several thousand KIDs (Kinetic Inductance Detectors). The main science goal of this spectrometer module, called EoR-Spec, is to probe the Epoch of Reionization (EoR) in the early universe using the Line Intensity Mapping (LIM) technique with the redshifted [CII] fine-structure line. This presentation provides an overview of the optical, mechanical, and spectral design of EoR-Spec, as well as of the detector array that will be used. The optical design consists of four silicon lenses that have anti-reflection metamaterial layers. A scanning Fabry-Perot Interferometer (FPI) will be located at the pupil and provides the spectral resolution over the full spectral coverage of 210 GHz to 420 GHz in two orders, resulting in a redshift coverage of the [CII] line from z = 3.5 to z = 8. The detector array consists of three subarrays of KIDs, two of which are tuned for the frequency range between 210 GHz and 315 GHz, and one that is tuned for the 315 GHz to 420 GHz range. The angular resolution will be between about 30'' to 50''. This presentation also addresses the spectral and spatial scanning strategy of EoR-Spec on FYST. EoR-Spec is expected to be installed into Prime-Cam about 1 year after first light of FYST. 

Abstract We present power spectra of the cosmic microwave background (CMB) anisotropy in temperature and polarization, measured from the Data Release 6 maps made from Atacama Cosmology Telescope (ACT) data. These cover 19,000 deg²of sky in bands centered at 98, 150 and 220 GHz, with white noise levels three times lower thanPlanckin polarization. We find that the ACT angular power spectra estimated over 10,000 deg², and measured to arcminute scales in TT, TE and EE, are well fit by the sum of CMB and foregrounds, where the CMB spectra are described by the ΛCDM model. Combining ACT with larger-scalePlanckdata, the joint P-ACT dataset provides tight limits on the ingredients, expansion rate, and initial conditions of the universe. We find similar constraining power, and consistent results, from either thePlanckpower spectra or from ACT combined withWMAPdata, as well as from either temperature or polarization in the joint P-ACT dataset. When combined with CMB lensing from ACT andPlanck, and baryon acoustic oscillation data from the Dark Energy Spectroscopic Instrument (DESI DR1), we measure a baryon density of Ω_bh²= 0.0226 ± 0.0001, a cold dark matter density of Ω_ch²= 0.118 ± 0.001, a Hubble constant ofH₀= 68.22 ± 0.36 km/s/Mpc, a spectral index ofn_s= 0.974 ± 0.003, and an amplitude of density fluctuations ofσ₈= 0.813 ± 0.005. Including the DESI DR2 data tightens the Hubble constant toH₀= 68.43 ± 0.27 km/s/Mpc; ΛCDM parameters agree between the P-ACT and DESI DR2 data at the 1.6σlevel. We find no evidence for excess lensing in the power spectrum, and no departure from spatial flatness. The contribution from Sunyaev-Zel'dovich (SZ) anisotropy is detected at high significance; we find evidence for a tilt with suppressed small-scale power compared to our baseline SZ template spectrum, consistent with hydrodynamical simulations with feedback.