Michael Niemack, Cornell University for the CCAT-prime Collaboration CCAT-Prime 6 meter aperture extreme field-of-view  sub-millimeter telescope on Cerro Chajnantor at 5600m, Chile Michael Niemack, Cornell University for the CCAT-prime Collaboration CCAT-prime Director: Martha Haynes, Project Scientist: Gordon Stacey 28 February 2017 CMB-S4 Meeting, SLAC

CCAT-Prime Telescope & Site 6m aperture crossed-Dragone design delivers large, flat 8 degree focal plane Can illuminate ~10 times more detectors than Stage III telescopes Surface accuracy ~10 um at an outstanding sub-mm site with access to 350um – 3mm Plan to start building this year (Niemack, Applied Optics 2016) CCAT site has better optical depth majority of time Median simultaneous PWV: ALMA = 1.0 mm Chajnantor = 0.6 mm (Consistent with Grace et al. 2014) Cumulative fraction (Radford & Peterson, arXiv:1602.08795) 28 February 2017 CMB-S4 Meeting, SLAC

CCAT-Prime Science Potential CMB-S4 platform Multiple mm/sub-mm science goals Galactic Ecology: tracing gas flows into cores and young stars in Milky Way and Nearby Galaxies Galaxy Cluster Machine: high S/N measurements of individual cluster kSZ, rSZ, dust, and foregrounds Polarized dust foregrounds [CII] Intensity Mapping: Measure star forming galaxies at reionization z=5-9, complement 21cm obs. Potential CMB-S4 platform submm galaxies radio sources rSZ kSZ (Stacey et al. 2015) Simultaneous bands 350 m – 3 mm (Figure from Mike Zemcov) 28 February 2017 CMB-S4 Meeting, SLAC

CCAT-prime: CMB-S4 Considerations Large ~8 degree diameter FOV Can host up to ~ 3m diameter CMB-S4 receiver with ~105 CMB detectors Natural baffle around telescope to help control far sidelobes Partial boresight rotation => separate ground pickup from sky Studying monolithic mirror options with telescope vendors 2.5m diameter receiver design (by Shawn Henderson) CCAT-prime Engineering Design (by Steve Parshley) 28 February 2017 CMB-S4 Meeting, SLAC

CCAT-prime Status CCAT-prime Collaboration: 6m aperture with excellent potential for CMB-S4 Completed telescope design studies with two vendors, and internal reviews are underway Aim to sign contract in March and start telescope build in 2017 Exploring partnerships with additional collaborators CCAT-prime Collaboration: Cornell, U. Cologne, U. Bonn, AUI, 10 Canadian University consortium, and other institutions in Chile, Germany, and elsewhere TBD 28 February 2017 CMB-S4 Meeting, SLAC